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REGIONAL MANAGEMENT AND SUSTAINABLE LIVELIHOOD OF THE POOR

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VOLUME 1 - 2011

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Agrobiodiversity of cactus pear (Opuntia, Cactaceae) in the Meridional Highlands Plateau of Mexico 1

Authors: Juan Antonio Reyes-Agüero, Juan Rogelio Aguirre Rivera DOI: 10.5027/jnrd.v1i0.01

Climate responsive and safe earthquake construction: a community building a school 10

Authors: Hari Darshan Shrestha, Jishnu Subedi, Ryuichi Yatabe, Netra Prakash BhandaryDOI: 10.5027/jnrd.v1i0.02

Analysis of water footprints of rainfed and irrigated crops in Sudan 20

Authors: Shamseddin Musa Ahmed, Lars RibbeDOI: 10.5027/jnrd.v1i0.03

Journal of Natural Resources and Development 2011; 01: 1 - 28Volume I

Contents




JOURNAL OF NATURAL RESOURCES AND DEVELOPMENT

Agrobiodiversity of cactus pear (Opuntia, Cactaceae) in the Meridional Highlands Plateau of MexicoJuan Antonio Reyes-Aguero ab*, Juan Rogelio Aguirre Rivera a

a Instituto de Investigación de Zonas Desérticas, Universidad Autónoma de San Luis Potosí. Mexico.

b Center of Natural Resources and Development, Cologne University of Applied Sciences. Betzdorfer Straße 2. 50679 Cologne, Germany.

*Corresponding author: [email protected]

Article history Abstract

Received 13.04.2011Accepted 09.07.2011Published 22.08.2011

Mexico is characterized by a remarkable richness of Opuntia, mostly at the Meridional Highlands Plateau; it is also here where the greatest richness of Opuntia variants occurs. Most of these variants have been maintained in homegardens; however, the gathering process which originated these homegardens has been disrupted over the past decades, as a result of social change and the destruction of large wild nopaleras. If the variants still surviving in homegardens are lost, these will be hard to recover, that is, the millenary cultural heritage from the human groups that populated the Mexican Meridional Highland Plateau will be lost forever. This situation motivated the preparation of a catalogue that records the diversity of wild and cultivated Opuntia variants living in the meridional Highlands Plateau. To this end, 379 samples were obtained in 29 localities, between 1998 and 2003. The information was processed through Twinspan. All specimens were identified and preserved in herbaria. Botanical keys and descriptions were elaborated. The catalogue includes information on 126 variants comprising 18 species. There were species with only one variant (Opuntia atropes, O. cochinera, O. jaliscana, O. leucotricha, O. rzedowskii and O. velutina), two (O. durangensis, O. lindheimeri, O. phaeacantha and O. robusta), five (O. joconostle and O. lasiacantha), seven (O. chavena), 12 (O. hyptiacantha and O. streptacantha), 15 (O. ficus-indica), 22 (O. albicarpa), and up to 34 (O. megacantha). Additionally, 267 common cactus pear names were related to those variants.

Keywords

AgrobiodiversityEx situIn situOpuntia streptacanthaOpuntia ficus-indica

Introduction

In Mexico there are 78 wild species of the genus Opuntia (sensu stricto) (Guzmán et al., 2003), several of them prosper in Meridional Highland Plateau of Mexico (Reyes-Agüero and Aguirre, 2006) (Figure 1); relicts of the cactus shrubland, also known as nopaleras for the prevalence of Opuntia populations, still exist in this region (Rzedowski, 1978); furthermore, it is here where the greatest richness of Opuntia variants is found (Barbera, 1995). Many of these variants have become cultivars and have been preserved in homegardens (Figueroa et al., 1980), and in Mexico only less than ten of them have been grown in over 51,112 ha for the production of cactus pear, and in over 10,200 ha to produce nopalito (Gallegos et al., 2009).Cactus pear cultivars have evolved from a long relationship between

Homo sapiens and Opuntia, and most of them are concentrated in homegarden nopaleras (Reyes-Agüero et al., 2005a); however, the process that gave rise to peasant homegardens over the centuries is being lost steadily over the past decades as a result of either the destruction of the large nopaleras and abandonment after emigration of homegardens owners. Therefore, if the Opuntia cultivar richness of the homegardens is lost, it will be hard to recover, that is, this millenary cultural heritage of the human groups that inhabited Meridional Highland of Mexico will be lost forever. The above motivated the preparation of a catalogue to record the richness of wild and cultivated Opuntia variants.

Journal of Natural Resources and Development 2011; 01: 01-09 01DOI number: 10.5027/jnrd.v1i0.01

Field collections were carried out in 29 localities (Table 1) across the Meridional Highland (Figure 1). Opuntia specimens were collected: (1) if variant was valued and grown for the cladode, nopalito or fruit; (2) if the variant was given a clear and unmistakable common name; and (3) if the variant grew preferentially in a homegarden or commercial plantation, although specimens were also collected from wild populations and experimental plantations. A total of 379 variants were sampled, obtaining six replicates from each. Morphological features were recorded using a descriptor (Reyes-Agüero and Aguirre, 2000). One two-year cladode, one nopalito and one fruit were assessed from each replica, and information on 118 traits was recorded. Specimens were processed for preservation (Reyes-Agüero et al., 2007) and deposited in the SLPM, MEXU and CHAP herbaria.For the statistical analyses, a basic matrix was elaborated followed

by a multivariable analysis of classification, using Twinspan program (McCune & Mefford, 1999). All the specimens collected were previously identified based mostly on the keys by Britton & Rose (1919) and Bravo (1978). Afterwards, these identifications were matched to the Twinspan output. Both dichotomous keys and poly-keys were elaborated, based primarily on indicator traits revealed by the Twinspan In most cases, the botanical descriptions comprised the 118 morphological traits. Each description was elaborated according to a standard sequence: starting with the life form and ending with seed characteristics; was described based on mean and modal values from the six replicates; in turn, the description of each species was prepared based on their variants, and the description of the genus was prepared based on its species.

Material and Methods

Figure 1. Orogenic units and geomorphic regions of Mexico. Highlighting the Meridional Highland Plateau (Tamayo 1988).

Results and Discussion

The information derived from the 379 samples was used to prepare a catalogue in a book format (Reyes-Agüero et al. 2009); into the catalog the arrangement of species and its cultivars (Table 2) reflect the Twinspan analysis; a complementary multivariate ordination analysis was made in order to review the relationship of morphological variation and process of domestication (Reyes-Agüero et al., 2005a); the core of catalog consists of identification keys and botanical descriptions, including photographs for 126 resulted variants, most of them as cultivars. Almost fifty percent, 197 samples, were carried out from in situ and 182 from ex situ localities (Table 3). About in situ, is important to note that there are cultivars in wild environments and other few are in cropland as fences and/or on agricultural terraces,

to give them firmness. The most high percent of samples were from home gardens; this environment is a crucial space for the in situ conservation in order to protect and use the genetic diversity, but also for to develop new variants (Engels 2002; Galluzi et al. 2010), and in this process is important to maintain the link between home gardens and wild environment, from one side and the same time home gardens with commercial croplands, from the other side (Engels 2002).There are 18 Opuntia species with 126 cultivars appreciated for their cladodes, nopalitos or fruits. There were species with only one cultivar (Opuntia atropes, O. cochinera, O. jaliscana, O. leucotricha, O. rzedowskii and O. velutina), two (O. durangensis, O. lindheimeri, O. phaeacantha and O. robusta), five (O. joconostle and O. lasiacantha),

02Journal of Natural Resources and Development 2011; 01: 01-09DOI number: 10.5027/jnrd.v1i0.01

seven (O. chavena), 12 (O. hyptiacantha and O. streptacantha), 15 (O. ficus-indica), 22 (O. albicarpa), and up to 34 (O. megacantha) (Table 2). This richness of cultivars is high if is comparable with Zea mays, with 59 landraces in Mexico (Bellón et al. 2008) and 52 in Peru (Tapia

2000) or Persea americana and its three landraces in Mexico (Bellón et al. 2008); but in comparation with Solanum tuberosum with its 1000 landraces also in Peru (Tapia 2000), the richness of Opuntia is very low.

Locality, county, state LAT /LON ALT(m) Samples

Chapingo, Texcoco, Méx.* 19º30’/98º50’ 2275 37

San Martín de Las Pirámides, Méx. 19º42’/98º50’ 2280 9

San Bartolo, Axapusco, Méx. 19º42’/98 45’ 2350 1

Camino a Sahagún, Axapusco, Méx. 19º43’/98 48’ 2350 2

Milpa Alta, D. F. 19º60’/99º00’ 2600 2

Real del Monte, Real del Monte, Hgo. 20 09’/98 40’ 2853 2

Chicavasco, Actopan, Hgo. 20º12’/98º57’ 2020 6

El Rincón, Actopan, Hgo. 20º16’/98º57’ 2000 1

González, Santiago de Anaya, Hgo. 20º23’/98º58’ 2040 8

El Nith, Ixmiquilpan, Hgo. 20º29’/99º11’ 2060 1

San Andrés Daboxtha, Cardonal, Hgo. 20º31’/99º03’ 2000 22

San Luis de la Paz, Gto.* 21º18’/100º31’ 2020 90

Las Papas de Arriba, Ojuelos, Jal. 21º43’/101º39’ 2280 18

Rancho El Palmar, Villa de Arriaga, SLP 21º54’/102º22’ 2160 11

La Trinidad, Pinos, Zac. 22º02’/101º24’ 2120 6

La Pila, San Luis Potosí, SLP 22º02’/100º52’ 1870 18

La Monteza, Villa García, Zac. 22º03’/101º49’ 2180 13

Villa de Pozos, San Luis Potosí, SLP 22º06’/100º46’ 1900 13

San Luis Potosí, S.L.P. 22º09’/100º58’ 1860 3

Palma de la Cruz, Soledad de Graciano, SLP* 22º11’/100º56’ 1850 52

La Victoria, Pinos, Zac. 22º15’/101º40’ 2310 1

Los Retes, Mexquitic, SLP 22º15’ /101º04’ 1950 20

San Elías, Armadillo de los Infante, SLP 22º18’/100º41’ 1950 8

Loma Larga, Ahualulco, SLP 22º23’ /101º09’ 1850 8

La Mantequilla, San Luis Potosí, SLP 22º25’/100º52’ 1850 11

Trancoso, Guadalupe, Zac. 22º44’/101º21’ 2190 1

Charco del Lobo, Moctezuma, SLP 22º45’/101º05’ 1720 8

Albercones, Dr. Arroyo, NL 23º24’/100º11’ 1720 3

Potrero, Real de Catorce, SLP 23º42’/100º54’ 1700 4

Total: 379

Table 1. Locations where samples Opuntia variants were collected

* Experimental plantation in scientific research institutions or ex situ localities


The automated classification enabled to confirm the great Opuntia variant richness previously documented by Figueroa et al. (1980) and Rodríguez and Nava (1998) for Meridional Highlands Plateau of Mexico, but at the same time confirmed the need to use multivariate methods to demonstrate this agrobiorichness in a formal way. This variant richness of wild and cultivated Opuntia valued by the Meridional Highlands inhabitants reveals that the cactus pear has been an important plant for both ancient and current populations. The continued and systematic gather of cactus pear favored that some plants with outstanding traits (fruit shape and size; flavor and texture of pulp or peel; seed hardness and amount; peel thickness and glochid density; and nopalitos shape, color, abundance, precocity, flavor, tenderness and fiber content) were subjected to different degrees of tolerance, favored or planting, and they began to be taken to the homegardens (Colunga et al. 1986, Figueroa et al. 1980). In homegardens, the cactus pear selected found the conditions needed to prosper. In this way, homegarden cactus pear plantations summarize the efforts by generations of collectors to gather the most useful traits out of the genetic diversity of Opuntia in their respective gathering territories, coupled with hundredths of years of care to preserve these cultivars (Reyes-Agüero et al., 2005a).

Seventy six percent of cultivars most of them are related to eight species of the series or section Streptacanthae, with rise to 88% if the O. ficus-indica cultivars are added. This richness of the section Streptacanthae makes of it the likely source of numerous “…horticultural varieties and forms” (Bravo 1978). O. megacantha stands out as the species with the largest amount of variants. There are only 15 O. ficus-indica cultivars which, along with another 22 for O. albicarpa, are the most extensively cultivated in commercial plantations and home gardens; from this two species only O. ficus-indica is absent in wild populations (Bravo 1978; Reyes-Agüero et al. 2004, 2005a, b)

and only one sample of O. albicarpa was located in wild environment.

From the cultivars, 31 were obtained only in one in situ locality, without representatives samples in ex situ localities; on the contrary, 32 were only in ex situ localities without representatives samples in in situ localities and 63 were in both kinds of spaces. About this 63, 71.4 % are in one or two in situ localities, 25.4 % are from three to five localities and only 3.17 % are in six or seven localities. During the development of this work, live samples of several cultivars were sent to the three ex situ localities and also to one fourth scientific collection in the Centro Regional Universitario Centro Norte, from the Universidad Autónoma Chapingo in El Orito, Zacatecas, where is the national official depository of the Opuntia cultivars.

As regards the cladode, the Twinspan revealed indicator traits included: shape, length, width, thickness and texture; for areoles: width and length, amount in each cladode side, and the number of areoles with spines, distance between areoles, distribution of spiny areoles in the cladode, and amount of areole rows in each cladode side; for spines: color, texture and form, length of the largest and smallest spine in each areole, average number of erect, radial or diffuse spines per areole, mean number of spines < 1.0 cm, between 1.0 and 3.0 cm and > 3.0 cm per areole. For the fruit, the indicator traits were weight, shape, width and length, depth and diameter of the floral scar; as regards peel: color, weight, diameter and amount of areoles; for the pulp: dimensions (length and diameter), weight, color and sweetness in Brix degrees; for the seed: number of normal and sterile seeds, weight of sterile seeds, width, thickness and hardness of normal seeds. The supplementary indicator traits were tepal apex shape, perianth color at flowering and pericarpel length; and, last nopalito leaf length and its number of spines per areole.

Scientific name

CultivarsCommon names

O. albicarpa Scheinvar

O. albicarpa cv. Mango B7 INIFAP & Mango

O. albicarpa cv. Burro Copena 18K & Burro

O. albicarpa cv. Cristalino Cristalino, Cascarón, Blanca papa, San migueleño & Nopal calabaza

O. albicarpa cv. Reina Chapeada, Reina & Cristalina

O. albicarpa cv. Blanca Blanco manso, Cristalino, Cañatierra & Blanca.

O. albicarpa cv. Reinita Reinita

O. albicarpa cv. Fafayuco Fafayuco, Blanco & Reina

O. albicarpa cv. Blanca chapeada B6 INIFAP, Blanca chapeada & Clavijudo

O. albicarpa cv. Amarillo pera Chapeada, Amarilla, Plátano, Amarillo tardío & Amarillo pera

O. albicarpa cv. Anaranjado Anaranjado & Fafayuco

O. albicarpa cv. Amarilla olorosa Sandía, 153 INIFAP & Amarilla olorosa

O. albicarpa cv. Copa de oro Copa de oro, Fafayuco & Blanco

O. albicarpa cv. Gavia Mango, Esmeralda, Burrona & Gavia

O. albicarpa cv. Bola de masa Bola de masa & Chapeada

Table 2. Check-list of the agrobiodiversity of Opuntia in Meridional High Land Plateu of Mexico


Scientific name


O. albicarpa cv. Octubreña Octubreña, Virginia & Fafayuco

O. albicarpa cv. Pepino Pepino & Chapeada SJZ

O. albicarpa cv. Esmeralda Esmeralda, Forrajera, Tuna blanca, Blanca tipo & Alfajayucan

O. albicarpa cv. Copena T12 Copena T12 & Tuna blanca

O. albicarpa cv. Burrona Alfajayucan, Amarillo aguado, Blanco de Castilla, Burrona & Copena T15

O. albicarpa cv. Papantón Papantón, Reina, Copena 12, Copena 1-A, Calabazona tardía, Copena G14, Co-pena 2-B, Pepino, Burrona & Fafayuco

O. albicarpa cv. Cristalina Burrona, Cristalina, Blanca suave & Promotora 3

O. albicarpa cv. Dadokäjä Blanca E Z, Dadokäjä & Promotora 8

O. atropes Rose

O. atropes cv. Blanco espinoso Blanco espinoso

O. chavena Griffiths

O. chavena cv. Cascarón Cascarón & Rebusco

O. chavena cv. Cimarrón Cimarrón, Güeras & Mión

O. chavena cv. Forrajera Forrajera S

O. chavena cv. Pachona Pachona

O. chavena cv. Hartón Hartón & Cascarón

O. chavena cv. Chiquihuitillo Cochinillo, Chiquihuitillo, Tempranillo, Pachoncilla, Pachón, Negrito, Camueso con espinas & Galarzo

O. chavena cv. Negrito Negrito

O. cochinera Griffiths

O. cochinera cv. Cacalote Cacalote

O. durangensis Britton & Rose

O. durangensis cv. Xoconostle moro Xoconostle, Xoconostle chivo & Xoconostle moro

O. durangensis cv. Iskäjä Iskäjä & Coconoixtle

O. ficus-indica (L.) Mill.

O. ficus-indica cv. Copena V1 Copena V1 & Telokäjä

O. ficus-indica cv. Copena F1 Copena F1, Milpa Alta & ACNF-INIFAP

O. ficus-indica cv. Amarillo huevo Amarillo huevo & 33 INIFAP

O. ficus-indica cv. Liso blanco Liso blanco

O. ficus-indica cv. Atlixco Amarillo (Tipo Atlixco)

O. ficus-indica cv. Tlaxcalancingo Tlaxcalancingo & A3 INIFAP

O. ficus-indica cv. Camuesa Lisa-34 & Camuesa 58

O. ficus-indica cv. Amarilla Milpa Alta Amarilla Milpa Alta, Atlixco, Plátano & Verdulero de Don Erasmo

O. ficus-indica cv. Doctor Mora Doctor Mora, Amarillo grande, RDR-INIFAP & Cristalino

O. ficus-indica cv. Liso Rojo vigor, Copena V1, Liso & Liso de Milpa Alta

O. ficus-indica cv. Telokäjä Telokäjä, Verdulero de María Durán, B10 INIFAP, Copena F1, Amarilla UACH, At-lixco, Celaya, Forrajero & Copo de nieve

O. ficus-indica cv. Solferino Amarilla, Solferino, RSB-INIFAP, Roja, Pelón & Rojo 8

Most of the indicator traits are related to the Opuntia general domestication process (Colunga et al. 1986; Reyes et al. 2005a); these include fruit color and length, and pulp weight, followed by areole and spine traits (Reyes et al. 2005a). However, in cultivars characterized by large fruits, spine abundance displays three modalities: total absence, reduced or minimal presence, and persistence of the normal

number per areole, that is, the amount of spines normally present in wild species, in dependence of domestication environment.The variants described in the catalog (Reyes-Agüero et al. 2009) represent only a fraction of the Opuntia richness in Mexico. This effort is only a first approximation. Further in depth botanical exploration is required, both in the Meridional Plateau Highland and in the rest of the country.

Table 2 continuation. Check-list of the agrobiodiversity of Opuntia in Meridional High Land Plateu of Mexico


Scientific name


O. ficus-indica cv. Promotora Promotora & Promotora 6

O. ficus-indica cv. Telokäjä rojo Amarilla Milpa Alta, Copena CE, Tuna roja lisa & Telokäjä rojo

O. ficus-indica cv. Liso forrajero Liso forrajero, Promotora 7, RSA-INIFAP, Rojo liso, Rojo 72, Telokäjä, Rojo pelón, Guanajuato, Rojo pelón de Zacatecas, Rojo 3509 & Liso-V, Tlaconopal

O. hyptiacantha A. Web.

O. hyptiacantha cv. Ladrillo Ladrillo

O. hyptiacantha cv. Jaqueña Granada roja, RCH-INIFAP, Nopal blanco, Jaqueña-29 & Morado

O. hyptiacantha cv. Camueso Cardón & Camueso

O. hyptiacantha cv. Amarilla 24 Amarilla 24

O. hyptiacantha cv. Pachón Tempranillo, Charol, Pachón, Camueso & Cardón

O. hyptiacantha cv. Cardón de Las Papas Cardón de Las Papas

O. hyptiacantha cv. Roja rubí Roja rubí

O. hyptiacantha cv. Jokjä Jokjä

O. hyptiacantha cv. Cardón blanco Rojo 9, 79 INIFAP & Cardón blanco

O. hyptiacantha cv. Blanca Victoria Blanca Victoria

O. hyptiacantha cv. Nistokäjä Nistokäjä & RSD-INIFAP

O. jaliscana Bravo

O. jaliscana cv. Chamacuero Chamacuero

O. joconostle A. Web.

O. joconostle cv. Xoconostle colorado Xoconostle colorado

O. joconostle cv. Xoconostle de Las Pirámides Xoconostle de San Martín de Las Pirámides & Iskäjä de burro.

O. joconostle cv. Xoconostle blanco Xoconostle blanco

O. joconostle cv. Xoconostle agrio Xoconostle agrio

O. joconostle cv. Huevo de gato Huevo de gato rojo, Huevo de gato rojo blanco, Duraznillo & Xoconostle

O. joconostle cv. Xoconostle blanco Xoconostle blanco, Coyonostle & Xoconostle

O. lasiacantha Pfeiff

O. lasiacantha cv. Sanjuanero Sanjuanero

O. lasiacantha cv. Blanca cristalina Blanca cristalina or Cuero de rata

O. lasiacantha cv. Nopal del Real Nopal del Real

O. lasiacantha cv. Madokäjä Madokäjä

O. lasiacantha cv. Tuna Iris Tuna Iris

O. leucotricha DC.

O. leucotricha cv. Duraznillo Duraznillo & Duraznillo-xoconostle

O. lindheimeri Engelm.

O. lindheimeri cv. Oreja de elefante Oreja de elefante

O. lindheimeri cv. Guilanchi Guilanchi or Arrastrerilla

O. megacantha Salm-Dyck

O. megacantha cv. Cuervo tuna Cuervo tuna & Hartón

O. megacantha cv. Jarrilla Piniche & Tuna jarrilla

O. megacantha cv. Sgt-INIFAP Sgt-INIFAP

O. megacantha cv. Juanita käjä Juanita käjä

O. megacantha cv. Chirriona Chirriona, Revilla & Pastosa

O. megacantha cv. Chamacuero Monteza Chamacuero Monteza

O. megacantha cv. Naranjona Mango, Naranjona & Promotora 2

O. megacantha cv. Sangre de toro Sangre de toro



Scientific name


O. megacantha cv. Manso apastillada Anaranjada, Amarilla, Manso apastillada & Anaranjada 33

O. megacantha cv. Mieluda Mieluda & Tuna perra

O. megacantha cv. Ushikäjä Ushikäjä

O. megacantha cv. Reventón Morado, Sangre de toro, Apastillada, Nopal chiva, Reventón, Morada, Trompa de cochino, Tazaja, Nopal duro & Jarrillo.

O. megacantha cv. Jagüeño Amarillo de tuna chica, Jagüeño, Camueso & Mieludo

O. megacantha cv. Bola de masa Bola de masa, Redonda, Chapeada, Nopal ligero, Morado & Nopal loco

O. megacantha cv. Amarilla raleña Camuesa Matancillas, Amarilla raleña

O. megacantha cv. Apastillada anaranjada Apastillada anaranjada

O. megacantha cv. Tzebekäjä Tzebekäjä & Jarrillo

O. megacantha cv. Roja saeta Roja saeta

O. megacantha cv. Pico chulo Tuna sabina, Amarilla, Morada, Morado, Pico chulo & Naranja

O. megacantha cv. Torreoja Torreoja

O. megacantha cv. Naranjona dulce Naranjona dulce

O. megacantha cv. Amarilla Monteza Amarillo Monteza o Huesos, Amarillo de Tuna grande & Amarilla Monteza

O. megacantha cv. Sangrita Sangrita

O. megacantha cv. Amarilla naranjona Amarilla naranjona & Amarilla redonda

O. megacantha cv. Rojo 10 Naranjona, 25 INIFAP & Rojo 10.

O. megacantha cv. Naranjona Helia Naranjona Helia, 26 INIFAP & 25 INIFAP

O. megacantha cv. Astikäjä Astikäjä

O. megacantha cv. Rubí reina Amarillo con espinas, Colorada, Monteza & Rubí reina

O. megacantha cv. Amarilla mansa Amarilla mansa

O. megacantha cv. Amarilla china Amarilla china

O. megacantha cv. Jarrilla grande Juanita käjä, Pico chulo, Amarilla, Jarrilla grande & Jokjä

O. megacantha cv. Sangre Sangre

O. megacantha cv. Tenikäjä Tenikäjä, Apastillada & Amarilla

O. megacantha cv. Morada de San Martín Solferino, Morada de San Martín & Tuna roja

O. phaeacantha Engelm.

O. phaeacantha cv. Pintadera Pintadera

O. phaeacantha cv. Pintadera de Daboxtha Pintadera de Daboxtha

O. robusta Wendl.

O. robusta cv. Tapón Bonda, Tapona de mayo, Tapón macho, Tapón (macho), Tapón hembra & Tapona

O. robusta cv. Tapón pelón Tapón pelón

O. rzedowskii Scheinvar

O. rzedowskii cv. Cenizo Cenizo & Cuatroalbo

O. streptacantha Lem.

O. streptacantha cv. Cardoncillo Cardoncillo & 66 INIFAP

O. streptacantha cv. Burra Burra & Masona

O. streptacantha cv. Sandía Sandía & Pachón rojo.

O. streptacantha cv. Amarilla Cardona Amarilla cardona

O. streptacantha cv. Isbini Isbini, Madokäjä & Cardón

O. streptacantha cv. Dojä Dojä, Tomatillo & Redondilla

O. streptacantha cv. Santo Tomás Jarrillo, Cardón & Santo Tomás

O. streptacantha cv. Cardón potosino Cardón potosino



Scientific name

Cultivars

Common names

O. streptacantha cv. Jocoquillo Cardón, Cardona, Color de rosa, Chino & Jocoquillo

O. streptacantha cv. Cardón Cardón

O. streptacantha cv. Trompa de cochino Trompa de cochino

O. streptacantha cv. Demshikäjä Cayahual, Isbini, Tomatillo o Demshikäjä, Cardón, Colorada & Cardón blanco

O. streptacantha ssp. aguirrana Scheinvar & Rodr. Apalillo, Chiquihuitillo, Nopal del monte, Zarco & Charola

O. velutina Scheinvar

O. velutina cv. Ukäjä Ukäjä


Conclusion

A total of 126 variants were identified in association with 18 species of cactus pear; most of them preserved in homegardens, but several are also present in wild populations and commercial plantations. Seventy six percent of variants are associated with eight species of the series Streptacanthae, rising to 88% if the O. ficus-indica cultivars are also considered. O. megacantha stands out as the species with

the largest number of cultivars and for being the most broadly distributed species in the study area (wild populations, homegardens and plantations). Most of the morphological characteristics that turn out to be indicator traits are related to the Opuntia domestication process.


Scientific name In situ Ex situ Total %

WildFences and/or terraces

Home garden CP* Sub

Total % EP** %

O. albicarpa 1 2 22 9 34 9.0 54 14.2 88 23.2

O. atropes 1 0.2 1 0.2

O. cochinera 1 1 0.2 1 0.2

O. chavena 5 9 14 4.0 5 1.3 19 5.3

O. durangensis 2 3 5 1.3 5 1.3

O. ficus-indica 12 6 18 4.7 41 10.8 59 15.1

O. hyptiacantha 3 3 8 14 3.7 11 2.9 25 6.6

O. jaliscana 1 1 0.2 1 0.2

O. joconostle 3 1 6 3 13 3.4 13 3.4

O. lasiacantha 4 1 5 1.3 3 0.8 8 2.1

O. leucotricha 1 2 3 1.2 3 1.2

O. lindheimeri 1 1 0.2 2 0.5 3 0.7

O. megacantha 5 2 34 5 46 12.1 58 15.3 104 27.4

O. phaeacantha 1 1 2 0.5 2 0.5

O. robusta 4 5 9 2.3 1 0.2 10 2.5

O. rzedowskii 2 2 0.5 2 0.5

O. streptacantha 8 3 17 28 7.4 6 1.6 34 9.0

O. velutina 1 1 0.2 1 0.3

Total 33 12 128 24 197 182 379

% 8.71 3.17 33.77 6.33 52.0 48.0 100.0

Table 3. Number of in situ and ex situ localities of the samples of Opuntia cultivars in Meridional High Land Plateau of Mexico

*CP = Commercial plantations** EP = Experimental plantation in Scientific Research Institutions

09

The authors wish to thank SAGARPA, CONACYT and INIFAP for financing most of the field work. SNICS and SINAREFI funded the final stages of field work. The universities UNAM and UASLP also provided resources. Thanks also to all informers, technicians, people in charge and owners of nopaleras, homegardens and plantations, who uninterestedly shared their knowledge, time, stories and cactus pear variants.

Barbera G, Inglese P, PimientaE. 1995. Agroecology, cultivation and uses of cactus pear.

Food and Agriculture Organization of the United Nations. Rome. Italy. 1-11.

Bellón MR, Barrientos-Priego AF, Colunga-GarcíaMarín P, Perales H, Reyes-Agüero JA,

Rosales SR, Zizumbo-Villarreal D. 2009. Diversidad y conservación de recursos

genéticos en plantas cultivadas. In Sarukhán J, Dirzo R, González R, March I. Capital

natural de México. Vol II. Comisión Nacional para el Conocimiento y Uso de la

Biodiversidad. México DF. 355-382.

Bravo HH. 1978. Las cactáceas de México. Universidad Nacional Autónoma de México.

Britton NL, Rose JN. 1919. The Cactaceae. Vol I. Carnegie Institution of Washington.

Washington DC.

Colunga-GarcíaMarín P, Hernández XE, Castillo MA. 1986. Variación morfológica,

manejo agrícola tradicional y grado de domesticación de Opuntia spp en el Bajío

guanajuatense. Agrociencia. 65: 7-49.

Esparza SS. 2010. Distribución geográfica del género Opuntia en México. Tesis de maestría.

Programa Multidisciplinario de Posgrado en Ciencias Ambientales. Universidad

Autónoma de San Luis Potosí. 85 p.

Engels J. 2002. Home gardens, a genetic resources perspective. In Watson JW, Eyzaguirre

PB. Home gardens and in situ conservation of plant genetic resources in farming

systems: Proceedings of the second international home gardens workshop.

Witzenhausen, Germany. 3–10.

Figueroa HF, Aguirre RJR, García ME. 1980. Estudio de las nopaleras cultivadas y silvestres

sujetas a recolección para el mercado en el altiplano potosino-zacatecano. Avances

en la Enseñanza e Investigación. Chapingo México. 31-32.

Galluzzi G, Eyzaguirre P, Negri V. 2010. Home gardens: neglected hotspots of agro-

biodiversity and cultural diversity. Biodiversity and Conservation. 19: 3635–3654.

Gallegos-Vázquez C, Mondragón JC, Reyes-Agüero JA. 2009. An update on the evolution

of the cactus pear industry in Mexico. Acta Hort. 811: 69-76.

Guzmán U, Arias S, Dávila P. 2003. Catálogo de cactáceas mexicanas. Universidad

Nacional Autónoma de México y Comisión Nacional para el Conocimiento y Uso de

la Biodiversidad. México.

McCune B, Mefford MJ. 1999. PC-ORD. Multivariate analysis of ecological data, version 4.

MjM Software Design. Gleneden Beach, Oregon.

Reyes-Agüero JA, Aguirre JR. 2000. Formato para la descripción morfológica de variantes

silvestres y cultivadas de Opuntia. Proc. Congreso Nacional de Fitogenética. Irapuato,

Gto. 15-20.

Reyes-Agüero JA, Aguirre JR, Carlín CF. 2004. In Esparza FG, Valdez ZRD, Méndez GSJ.

El nopal, tópicos de actualidad. Universidad Autónoma Chapingo y Colegio de

Postgraduados. Chapingo, México. 21-47.

Reyes-Agüero JA, Aguirre JR, Carlín CF, González DA. 2009. Catálogo de las principales

variantes silvestres y cultivadas de Opuntia en la Altiplanicie Meridional de México.

UASLP, SAGARPA y CONACYT. San Luis Potosí, México.

Reyes-Agüero JA, Aguirre JR, Flores JL. 2005a. Variación morfológica de Opuntia

(Cactaceae) en relación con su domesticación en la Altiplanicie Meridional de

México. Interciencia. 30: 476-484.

Reyes-Agüero JA, Aguirre JR, Hernández H. 2005b. Systematic notes and detailed

description of Opuntia ficus-indica (L.) Mill. (Cactaceae). Agrociencia 39: 395-408.

Reyes-Agüero JA, Carlín CF, Aguirre JR, Hernández H. 2007. Preparation of Opuntia

herbarium specimens. Haseltonia. 13: 76-82.

Rodríguez E, Nava CA. 1998. Nopal, riqueza agroecológica de México. Secretaría de

Educación Pública. México.

Rzedowski J. 1978. La vegetación de México. Limusa. México.

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20: 220-225.

Journal of Natural Resources and Development 2011; 01: 01-09DOI number: 10.5027/jnrd.v1i0.01

Acknowledgements

References


Climate responsive and safe earthquake construction: a community building a schoolHari Darshan Shrestha a, , Jishnu Subedi a , Ryuichi Yatabe b, Netra Prakash Bhandaryb

a Department of Civil Engineering, Pulchok Campus, Institute of Engineering, Tribhuvan University, Pulchowk Nepal.

b Graduate School of Science and Engineering, 3 Bunkyo, Matsuyama 790 - 8577, Ehime University Japan.

*Correponding author: [email protected]

Article history Abstract


This article outlines environment friendly features, climate responsive features and construction features of a prototype school building constructed using green building technology. The school building has other additional features such as earthquake resistant construction, use of local materials and local technology. The construction process not only establishes community ownership, but also facilitates dissemination of the technology to the communities. Schools are effective media for raising awareness, disseminating technology and up-scaling the innovative approach. The approach is cost effective and sustainable for long-term application of green building technology. Furthermore, this paper emphasizes that such construction technology will be instrumental to build culture of safety in communities and reduce disaster risk.

Background

Schools provide the space to produce human resources which are required for betterment of the future of the world in all walks of life such as peace, safety, quality of living, technology, knowledge and philosophy. In addition to its central role as an education facility, schools also have a significant contribution to the community as they provide space for public purpose in a normal situation and it is also used as shelter in emergencies. Schools should be the model providing examples of quality education, better environment, safer physical facilities, and of social advancement and development. Activities in schools are the most contributing factors on children and their contributions are, in turn, reflected on the whole society. Schools facilities not only provide formal education or knowledge but also contribute to the social development, impartment of livelihood skills and nourishment of social norms. Schools should be like the field laboratory where children can see, explore, learn and implement. School is not only a provider of safer spaces for learning, but it also can act as a center to disseminate culture of safety and how

to make environment friendly physical facilities to the communities. “School facilities, whether functioning well or not, serve as powerful pedagogical instruments‘. If the power of these attributes as ―three-dimensional text books was harnessed the impact on learning for the next generation of students would be limitless (Barr, 2011).”Nepal’s current literacy rate below 65 percent and Nepal needs to build 10,000 classrooms each year in order to meet the Millennium Development Goal of education for all. Nepal has net enrollment rate at primary level at 93.7 percent, net enrollment rate at lower secondary level at 63.2 percent and net enrollment rate secondary level i.e. grade 9-10 at 40.8 percent. By the year 2013, Nepal has target to increase the net enrollment rate at primary level to 97 percent, net enrollment at lower secondary level to 72 percent and net enrollment rate at secondary level at 46 percent (GoN, 2010). One of the major challenges of imparting education in Nepal has been observed as fewer enrollments in higher grades.

Journal of Natural Resources and Development 2011; 01: 10-19 10DOI number: 10.5027/jnrd.v1i0.02

One of the main factors which force the students to be absent from school is extreme indoor climate – hot and cold. The study in school of Bardiya, a district in southern plains of Nepal, on January 2007 observed very thin attendance in almost all the primary schools. It was observed that the main reason behind absentia is mainly due to cold in the class rooms. While the teachers used layers of warm clothes to protect themselves from cold and to attend the school the students stayed in their homes as they were hardly able to afford the warm clothes (Wangchuk, 2009-(Sonam Wangchuk, Green School to Promote Education for all in Nepal, report submitted to DOE Feb 2009). The situation is equally true in the summer as well. The hot classrooms in summer are a deterrent for the children to join the school, because their own traditional dwellings with thick thatched roof often covered with the foliage of creepers plants and cool earthen floors are many times cooler than the school with Corrugate Galvanized Iron (CGI) sheet roof (Figure 1). It has to be noted that a comfortable indoor climate in school not only helps to retain students in the school but also contributes towards better performance of the students. Research has shown that the best temperature range and humidity for reading and learning is between 68 F and 74 F and 40-60%, respectively (Johnson et al, 2005). Issa et al. (2011) conducted a study aimed to compare a number of quantitative and qualitative aspects of usage across a sample of 10 conventional, 20 energy-retrofitted and three green Toronto schools. The statistical analysis to investigate satisfaction of teachers with the indoor air quality, lighting, thermal comfort and acoustics of their schools buildings showed that “teachers in green schools were in general more satisfied with their classrooms and personal workspaces’ lighting, thermal comfort, indoor air quality, heating, ventilation and air conditioning than teachers in the other schools. Nevertheless, they were less satisfied with acoustics. Student, teacher and staff absenteeism in green schools also improved by 2–7.5%, whereas student performance improved by 8–19% when compared with conventional schools. However, these improvements were not statistically significant and could not therefore be generalized to all Toronto public schools. Whether these marginal improvements justify the extra cost premium of green buildings remains an active contentious topic that will need further investigation (Issa et al. 2011).” Recent academic research in Denmark, indicates that a temperature

reduction from 25°Celsius (considered hot in Denmark) to 20° Celsius resulted in an improved academic performance of primary level students of between 10% and 20% - all being equal and with other necessary educational resources available and good air circulation in place (Figure 2).

These studies underscore the fact that without proper intervention to make schools child friendly, comfortable, functional, safe and climate responsive, the notion of quality education remains as dream.

Figure 2. Classroom temperature directly influence students academic performances. Source: HVAC bladet nummer 8, 2006 - http://www.techmedia.dk

Despite of this fact, design and construction of school buildings in the whole subcontinent of Asia - whether it is India, Pakistan, Nepal or Bangladesh - has been a highly neglected area. Nepal has an elevation difference from 70 meter to 8848 meter from Mean Sea Level (MSL) in a short stretch of 200 KM in north-south direction. At present, existing school buildings in the Hill and Himalayan areas (elevation > 2000 meter from MSL) are terribly cold and unusable during winter season (four month), schools in the terai (elevation about 70 meter from MSL) on the other hand are very hot in summer season (four month).

Figure 1. A snapshot of a classrom and teachers room in a cold winter day in Bardiya, Nepal and a house of a poor villager (All images by Sonam Wangchuk).

11Journal of Natural Resources and Development 2011; 01: 10-19Introduction

Abili

ty to

per

form

Temperature

DOI number: 10.5027/jnrd.v1i0.02

12Journal of Natural Resources and Development 2011; 01: 10-19


Compressed stabilized earth blocks and environment friendly features

Most of the materials used in the construction of prototype - CSEB,CSET, timber, bamboo, straw, cow dong etc - are locally available and reduce the vehicular transportation significantly. The CSEB blocks need only curing in water and no firing is required. Therefore, the production of CSEB emitted eight times less carbon compared to fired bricks. Very little (6%) cement is added in CSEB for stabilizing and even this can be replaced by lime which is easily available in Nepal. Lime is carbon neutral and together with earth we get a very clean building material which is healthy for the environment. The comparative advantages of use of CSEB over commonly used fired bricks are listed in Table 1 below. Furthermore, the energy consumption during operation of such buildings is far less because of the climate responsive features listed in section beside.

Production of CSEBSoil earthen block are not a new material, it has been used as construction material since 18th century and is in practice all over the world.

Table 1. CSEB has these advantages compared to fired bricks.

Note: Wire Cut bricks are also called Kiln fired bricks.(Source: Development Alternatives 1998)

The existing school buildings in terai are mainly of brick masonry having opening on most sides and a corrugated galvanized iron roof on top, which makes inside class room terribly hotter than outside during the summer. This forces the school authorities to change the normal school times and the school hours start early morning and close before mid day. The shift of school hours is not considered child friendly as children have to wake up in early morning and walk long distance to reach the school before they are even fully awake. Additionally, they have to walk back to home in the hottest hour. Climate responsive design is the one that would provide a comfortable indoor environment in response to the seasonal variations of the climate (Dili eat al). In National Environmental Guidelines for School Improvement and Facility Management in Nepal (NEGSIFM), 2004 listed indoor climate and comfort as main criteria.Therefore, there is an urgent need to create a greater awareness of safer and climate responsive schools. At the same time, the schools in Nepal must be earthquake safe as the country lies in highly earthquake risk prone zone. The new schools need to have all five components of a school: Child friendly, safe against disasters, hygienic, environment friendly, fast to construct, economical and climate responsive.

In collaboration with Department of Education (DoE), Institute of Engineering (IoE) prepared a model prototype school building suitable for warm regions of southern Nepal (Figure 3). The project was supported by MS Nepal. This paper is based on the prototype class room school buildings built in the premises of IOE, Kathmandu, Nepal as a pilot project. Prototype class room building is built with Compressed Stabilized Earth Blocks (CSEB) and green roofing with bamboo and Compressed Stabilized Earth Tile (CSET) is used to

enhance its environment friendly and climate responsive features. The building is expected to be climate responsive (cool in summer and warm in winter), environment friendly, cost effective and earthquake resistant. The labor intensive techniques and use of local materials not only make the project cost effective and generate employment in the villages but also ensures community participation and empowerment in the vicinity. The construction approach and sequence is such that it also helps to raise awareness about environment and transfer the knowledge on green building technology to the communities. Additionally, the green and earthquake safer school buildings serve as three-dimensional textbooks to the students and “the school facility, including building and grounds, plays a large role in the curriculum program and culture of a school (Barr, 2011).”

Figure 3. The completed prototype climate responsive school building at the premises of IoE.

Pollution emission(Kg of CO2/m

2)Energy consumption (MJ)

7.9 times less than country fired bricks 15.1 times less than country fired bricks

Ecological comparison of building materials

Product and thickness

No of Units

(per m2)

Energy consumption(NJ per m2)

CO2emission

(Kg per m2)

Dry compressive

strength(Kg/cm2)

CSEB-24 cm 40 110 16 40 - 60

Wire Cut Bricks-22 cm

87 539 39 75 - 100

Country Fired bricks-22cm

112 1657 126 30 - 100

Concrete blocks-20 cm

20 235 26 75 - 100


Figure 4. CSEB production: Mixing of soil, compression in the Auram3000 machine, laying for curing and laying the blocks in the wall


Since its emergence in the ‘50s, compressed earth block (CEB) production technology and its application in building has continued to progress and to prove its scientific and technical worth. CEB production meets scientific requirements for product quality control, from identification, selection and extraction of the earth used, to quality assessment of the finished block, procedures and tests on the materials which are now standardized. The setting up of compressed earth block production units, whether on a small-scale or at industrial level, in rural or urban contexts, is linked to the creation of employment generating activities at each production stage, from earth extraction in quarries to building work itself.

The production of CSEB involves selection of soil, mixing of soil with proper composition of different percentages of clay, sand and gravel, silt and cement, pressing the mix in compressor machine and curing the pressed block for at least 28 days (Figure 4).

As the soil in the vicinity of IoE premises was found not suitable for construction of blocks, soil was transported from nearby areas (it should, however, be noted that in the real construction site this should be avoided as far as practicable). The soil had following composition as obtained from soil report: gravel 1.12 percentage, sand 78.16 percentages, silt 19.72 percentages and clay 1 percentage. About 15 percent clay was added from another soil as clay percentage was very low in the soil and another 5 percent of cement was added as stabilizer.

CSEB in NepalAttempts were made to introduce it in Nepal decades ago; however it did not seem to have picked up. The reasons seem to be partly the prejudice in our minds against earth as an inferior and ‘backward’ material as compared to cement, which is considered an ‘advanced’ material. Recently, in Bardiya, for the construction of green school (Action Aid program) established the production unit and produces blocks of different forms, from plain blocks for normal walls to hollow blocks for earthquake resistant construction, U blocks for lintel and ring beams, coping blocks for the top of a wall and even tiles for the floor and roof.

Green and climate responsive buildings

The design and construction of building should be based on Bioclimatic Design or Climatic Responsiveness, use of local material and technology, and community participation as far as practicable. The main criteria that make architecture green are:

• Use of material and constructional technology that is indigenous, has less embodied energy, and environment friendly

• Architectural design that assures comfort and human health with utilization of natural forces such as use of passive solar features and less use of active energy system such as HVAC

• Incorporation of renewable Energy System in the building to get high quality energy (such as water heating and electricity)

• Conservation of water in the building system itself



• Self incorporated storm water management system so that it harms the environment less and assures ground water recharge

• Self incorporated waste management system that reduces, reuses and recycles waste to make less waste-burden to the environment

• Healthy indoor air quality through use of healthy constructional material and proper natural ventilation

There are many features in a building that contribute to the comfort. “Elements impacting thermal comfort are building envelope, outside air treatment, temperature and humidity control, and air distribution. A preferred air distribution system for a classroom is under floor supplies with high exhaust / return grilles. Unfortunately preliminary studies or the first value engineering session typically try to rule this option out due to higher construction costs. Hence, distributing from the ceiling and returning low is sometimes utilized as a compromise (Johnson et al, 2005).” The prototype construction was planned, developed and constructed in order to realize most of the above features. Special attention was given so as to ensure that the process is simple, replicable and environment friendly. The school is designed to be relatively more functional and comfortable in all seasons. This is expected to have effect not only on the comfort and health of the children but also on their attendance, academic performance and efficiency.

The main components of the prototype which makes the building climate responsive are: solar orientation, passive solar gain, light shelf, earth berming and evaporative cooling. The designs considering above mentioned issues are relatively more comfortable and functional in all seasons.

Solar orientationThe orientation of building is such as to maintain indoor temperature suitable both in winter and summer. The orientation of long walls is towards south, i.e. long axis stretching along east-west is favorable feature for both hot and cold seasons. In hot season (or region), short east and west walls reduces skin dominated heat load due to low-angle east and west suns that are extremely irritating. In cold season (or region), long south wall provides maximum exposure to the low angle south sun that allows solar gain through wall and fenestrations.

Passive solar gain (for cold regions)The roof has been designed and constructed in such a way that it slopes downwards in the north so that the wall area is maximum in the south. In cold regions (Figure 5), addition to normal fenestration, there are corresponding sets of fenestrations above, the whole stretch of extra fenestration and wall being covered with polycarbonate sheet for maximizing radiant heat gain. The extra fenestration allows direct gain as well as light that provide diffuse natural light inside. The natural and passive climate control system of traditional housing style provides a comfortable indoor environment irrespective of the outdoor climatic conditions (Radhakrishnan. et al, 2011).

Figure 5. Direct gain of sun light in cold regions

The covered wall increases solar gain through solar entrapment that increases radiant temperature of wall inside. Though the radiant heat from wall is not directly used for increasing Mean Radiant Temperature (MRT) for thermal comfort as the wall in doesn’t face occupants, the stored heat reduces heating requirement that would otherwise be needed to heat up cold walls by the sun, which would loss the credibility of the first hour sun. The U-value (thermal transmissivity) of CSEB is more than the normal U-value demanded for the light weighted insulative envelope. So somehow capacitive insulation is desirable than resistive insulation. This is possible as the same quality that becomes reason for the decrease of insulative resistance of CSEB is also the reason for the increase in capacitive resistance because high density compact materials are poor resistance but good thermal mass.

Light shelfThere is contradiction, especially in colder region, between the direct solar-gain that favors direct contact of human body with the solar radiation, with the glare created due to the same reason. Glare should be avoided not because it is just uncomfortable but because it is adverse to human eyes. The continuous exposure to glare can contribute in impairment of human vision. This can be solved by using curtain on the window that converts ‘hole allowing direct beam radiation’ to ‘uniformly lit light source’ analogous to ‘plane’ source of light. It is usually good to get diffused light from the left in the school as students are usually right handed. However, the students closer to the window shadow the students further. It is better if light is provided from the ceiling because there is less chance of obstructed light. Carefully designed sun shading can provide visual comfort, minimise heat gains and maximise thermal comfort whilst reducing plant requirements, energy consumption and carbon emissions (Clare et al, 2009). So the concept of light shelf is to provide diffuse light out of direct solar beam radiation by twofold reflection: one on the shelf and the other on the ceiling.

Earth berming The constant temperature of the earth few meters below the surface can be used to create thermal comfort condition on the account of the fact that human acclimatized comfort temperature is closely related



Figure 6. Combined evaporative cooling cum solar chimney

to the mean annual temperature that is retained inside the earth due to its large specific heat capacity. This fact is fully utilized only when the building is completely sheltered below the earth (called as Earth Sheltered House). However, some advantages can be taken by earth berming at least taking advantage of perimeter earthen insulation that prevents heat loss from perimeter of floor slab in case of cold regions or conductive heat transfer to the cool earth in the hot region. The earth berming also provides lateral support to the outgoing walls and acts as extra tie to the walls.

Evaporative cooling (for hot regions)The same extra fenestration on the top of the southern wall used for the radiant solar gain in the cold region can be made open (of course protecting from rain) to allow hot air accumulated due to heat of sun and internal gain to escape out to draw air from the opposite side. This is what we call as solar chimney effect (Figure 6). The opposite side, here the north, is shaded and so air is relatively cooler and so natural convection takes place. In order to ensure the air entering the building really sensitively cooled down, the concept of cooling bench is devised, which underneath cools the air drawn from outside in the north through dissipation of heat as latent heat of evaporation of water. The cooling bench consists of wetted U-blocks that hold and distribute wetness to the support of bench. However, contact with structural wall is avoided. The Dear & Brager of the Center for the Built Environment at the University of California show that natural ventilation can also improve indoor environment quality comparedto air conditioned systems as a result of higher levels of fresh air and greater occupant control (Dear et al, 1998).This combination of evaporative cooling cum solar chimney effect for convection provides comfort condition in hot regions.

Safer and earthquake resistant design

Nepal lies on earthquake prone zone and entire Himalayan belt falling in Zone IV, highest hazard, of earthquake risk. Therefore, it is essential that the design and construction of school buildings should

be earthquake resistant. The recent experience in Pakistan and China earthquakes, in 2005 and 2008, respectively, where an unusually large number of children were killed by collapse school buildings once again underscored the urgent need to build safer schools. The large number of people killed in different earthquakes around the globe is a reminder of the possible scale of disaster in Nepal. The children and people killed are not due to earthquake but due to poor design and construction practices - mostly due to construction of RCC structure without proper engineering input in design and construction.

The prototype building is designed as per earthquake resistant criteria for masonry structure. It has six horizontal tie beams starting from the foundation level ring beam (Figure 7). The others are at plinth level, window sill level, lintel level, roof level and finally at rooftop level. These are made of Reinforced Cement Concrete (RCC) cast inside U shaped CSEB blocks. It also has numerous vertical reinforcements - one at every 1.5 meters length of wall, each corner and also on each side of all openings like doors and windows. The six horizontal ring beams are tied together by the vertical ties make a structure a skeleton like mesh of reinforcement (Figure 7).

The idea is that the metal reinforcements bring ductility (flexibility) to the building and the building is able to absorb a lot of energy before a major damage. In the event of an earthquake it should get cracks but should not collapse completely. The collapse prevention feature in buildings is essential to save lives of the people inside the building. Apart from this, the CSET roof in bamboo mesh and timber rafter is lighter than a conventional concrete (RCC) slab roof which is advantaged as it decreases the amount of force coming in the structure and also will cause less fatality in case of collapse.

Fast to build

In addition to the above qualities, it is essential that the school construction is completed in short time in order to be considered as an alternative for the planned 50000 classrooms by 2015. The


Figure 7. Horizontal and vertical ties along with roofing rafters as a cage system in the building design.


construction of the prototype from foundation to final finish took 20 days. It was carried out by 17 masons roughly 30.labour/volunteers each day and 2 supervisors. This does not include time for production of CSEB, CSET , door and window frame and truss, which were made in advance or supplied by manufacturer. The making of blocks and tiles were carried out by an average of 4 masons and 20 labour/ volunteers in roughly 20 days. When the processes are mainstreamed for mass application, this can easily be reduced significantly.

Cost effective

The cost of a CSEB block with CSET roof of 100 square meter plinth area comes to roughly NRs 0.9 million on 2008, which is comparable to the Department of Education cost for a conventional brick masonry CGI roof school. In fact a significant part of the cost of this building goes towards the steel and cement used for earthquake safety features, otherwise with lower earthquake safety features it would easily be cheaper than the conventional school design. Furthermore as the construction is labour intensive is possible for the villagers to contribute voluntary labour and some wood, locally made CSEB thus the actual cash requirement might be less than in a conventional school.

According to Auroville Earth Institute CSEB blocks are most of the time cheaper than fired bricks. This varies from place to place and specially according to the cost of cement. The cost break up of a 5 % stabilised block would be roughly as follows, for manual production with an AURAM press 3000: Labour: 20 - 25 % Soil & sand: 20 - 25% Cement: 40 - 60 % Equipment: 3 - 5 % In the context of Auroville the following cost comparison was found— A finished meter cube of CSEB masonry is always cheaper than fired bricks: 19.4% less than country fired bricks and 47.2 % less than wire cut bricks (Auroville, 2004).On other hand, the green school construction will contribute significantly on economy of country. The construction material such as roofing material CGI sheets or UPVC sheets are imported either

from India or China required lot foreign currency. Apart from being an environmental challenge and a big drain on Nepal‘s economy, the life of both the UPVC sheets and GI Sheets is only 30 years. On the other hand the life of a CSET roof is many more years and also sustainable. This will help to save its precious foreign currency reserve by reducing the import of CGI sheet from India and UPVC sheet from China.

Technology transfer through proper use of local material and appropriate technique

Most of the materials of prototype class room building are available or can be produced in Southern belt and hill. Both the construction material and technique are known to people of Nepal for many years.

Participation, empowerment, employmentThe construction technique of green school is labor intensive and it offers the possibility of creating employment for thousands of masons and skilled labor provided the project is implemented at a large scale. In this regard the school buildings later could inspire the local population to switch over from polluting and costly materials and that could generate thousands of green jobs for rural youth in their own regions. Due to the known material and technology, maintenance will not be a challenge to the local communities as in other type of construction.

From the educational point of view it could be a process of engaging the community to participate in education - first in the construction and then the resulting sense of ownership is expected to encourage the community to participate in the management of the school thereby ensuring accountability in the education system itself.

Community contribution is encourage mainly to make community to fill ownership and also reduce the overall cost of construction. For this reason the process of this participatory school construction involved meetings, gatherings and orientation sessions with the community at various stages of construction.



The process of community engagementThe engagement of the community is a key to this participatory school construction movement. Engaging community from the conceptualization and planning phase of the schools is essential for their sustainability. A review report of high performance school in the US suggests that “community planning process has yielded an increased emphasis on sustainability that is evident in several new school buildings (Bernstein et al. 2003).” Although the prototype school building didn’t require community participation, school planning process in real situation requires community participation. At least four formal meetings with the village leaders and communities is essential. In the first meeting, mainly village leaders and teachers are invited to present basic features of the green building and how it can be used to improve the educational status of the village. Usually this meeting is a bit challenging with many questions, doubts and sometimes misunderstandings as people are not aware about the CSEB and green construction technique. After convincing to the village leaders and teachers, second meeting to be carried out to present the basic concept and benefit to the community and also discuss on plan, elevation, location and possible community participation.

The third and fourth meetings to be carried out closer to the time of the construction; leader level meeting followed by a general public level meeting to discuss the design and the logistical and technical issues of construction. At this time the villagers to establish the School Construction Committee (SMC) and take the responsibility of volunteer mobilization and organization as well as the arrangements for the visiting masons.

Disaster risk reduction through schoolsThe outcome of investing in green and safer schools may have broader impact in the communities. The construction of disaster resilient school will provide an opportunity to raise awareness among the communities for culture of safety. The notion attached with the school project is that the buildings must be safer, user friendly, affordable and simple to construct. In most part of the country, access to technology is very much limited and large multi story construction is beyond the reach of the people. Therefore, simple and affordable technology is recommended.

The people killed in West Sumatra earthquake and Haiti earthquake had huge difference although the magnitude and epicenter distance are more or less same. As shown in table 2, in West Sumatra earthquake about 250000 building collapsed and only 1100 people were killed where as in Haiti earthquake about 900000 building collapsed/damaged but 2400000 people were killed.

Table 2. People killed and building collapsed/damaged in different earthquake

Earthquake Magnitude and time Building/damaged collapsed

People Killed

Sumatra7.6 Richter Scale, Sept 30, 2009, at 5:16 pm

115000 houses collapsed & 135000 damaged

1100

Haiti 7 Richter Scale, January 12, 2010, at 16:53 pm

900000 – 1100000 shelter required 240000

The main reason of less number of death in West Sumatra was the typology of building as the majority of buildings collapsed were simple one storey rectangular buildings with light roof. Which shows the simple rectangular one storey building with light roof reduces significantly the death toll in the event of earthquake mainly because of light structure. The green school building with CSEB material will reduced death toll significantly in the school and the notion of one storey school building with local technology will be instrumental to increase awareness about building safer houses in the community.

Construction features The design and construction of prototype building construction is based on Bioclimatic Design or Climatic Responsiveness, safe, and cost effective. The building is single storey with consist of 2 classroom. The built school in the prototype has only one usable room and other room is partly exposed for visitors to see the built-in features (Fig 8).

The main constructional features of prototype classroom building are as follows:

FoundationInitially, four different options of foundation as in below were discussed in the Advisory Panel Meeting.

• Rammed Earth, developed by Auroville • CSEB in stabilized soil mortar 1:4:8• RCC strip • Stone work in stabilized soil mortar 1:19

The analysis on selection of foundation type carried out mainly with the consideration of influencing factors; cost, cement requirement, possibility of unequal settlement, moisture penetration control, workmanship control, sturdy formwork and construction period. On the basis of above mentioned factors and also due to special consideration of the site being in doubt of water logged, it was decided to use stone work in Stabilized Soil Mortar 1:19. The foundation sized 70 cm depth and 75 cm width.

Wall The wall was decided to construct out of CSEB blocks applying Auroville’s technology. It consists of wall built out of 24 cm X 24 cm X 9 cm Compressed Stabilized Earth Blocks made out from Auram 3000 Press. The wall system has vertical ties at every corner: L-joints and T-joints. Also these are provided on the sides of each fenestration. The continuous wall has vertical tie in every level less than 1.5 meters. This is meant for avoiding lateral buckling due to long continuous wall.

Bands – vertical and horizontalThere are ring beams in plinth level, sill level, lintel level and roof level. These are connected to the vertical ties to give rigid box effect during earthquake. The ring beams are cast in situ out of U-blocks. The lintels are precast before they are made continuous with the lintel band during actual construction.



Figure 8. Drawing showing different elements of the prototype school building

The vertical ties and the ring beams consist of reinforcement of 2-10 mm diameter bars whereas the lintel consists of reinforcement of 2-12 mm diameter bars owing to more flexure that it has to bear from the above wall. The bands, at corners and T-joints, consist of extra bars of 10 mm extending 50 cm along each adjacent wall for additional reinforcement. The details can be seen in the figure. The stirrups of 8 mm bars are arranged in all case at spacing of 25 cm.

RoofThe roof has challenge to span 5.5 meters without use of truss that would otherwise invite costly non-green steel truss or heavy timber-consuming wooden truss. The solution to this problem was solved with design trussed beam section. A Trussed Beam consists of rafter sizing 7.5 cm X 12.5 cm with 12 mm diameter rod or high tensile steel wire pulling the rafter ends to be supported in form of triangle at the middle by 60 cm long and 7.5 cm X 15 cm section timber strut. The structural concept behind this is: the timber takes only compression and the steel takes tension. So small cross-section of rafter is sufficient; otherwise flexure beam has to take both compression and tension that demands large cross section. There are several Trussed Beams spaced 120 cm center to center that would support bamboo purlins above without deflection. Architecturally this gives single pitched roof. The purlins are spaced 35 cm center to center above which layed the bamboo strips transverse direction touched to one another. On the top of bamboo strip placed layer of plastic sheet for water proofing. This is followed by bamboo mesh that supports thick layer of mixture composed out of soil, cow-dung and straw that provides insulation to the roof. Then thin slurry of stabilized mud is layed that supports Compressed Stabilized Earth Tiles (CSET) made from the same machine.

Windows and doorsWindows and doors frame are of timber of 3 inch x 5 inch section. Timber is preferable as it is in common practice and available locally.

VerandahVerandah is independent structure that stands in front of class rooms. There is no tie beam below as no severity was realized from earthquake viewpoint. The pillars of the verandah are two-third CSEB and one-third bamboo (or timber) with strut that supports the roof verandah above. Verandah can be used for outdoor classroom activities.

Rain water harvesting and low cost solar water heatingThe roof of class room faces north and the roof of verandah faces south to meet at the notch of ‘V’. This notch can be used to harvest rain water that can be supplied to the low-cost solar water heater. The solar water heater lies on the verandah roof that faces south.

As the school in this part of the world is common to all and also the centre of community activities, school may become learning center for environment friendly, disaster resilient and green house design and construction. In the same time with many environment friendly features the school building can provide a comfortable learning space in itself for the students and communities to grow up with and learn about ecological issues, climate change and sustainable development. Nepal, which is in high earthquake risk zone, needs to building additional 50,000 classrooms in order to meet the Millennium Development Goal of education for all.

Because of high earthquake risk in almost all the country, the priority should be given on proper design and construction to ensure the school buildings are safe and disaster resilient. Similarly, most of the places in Nepal have extreme climate condition both cold and hot, there is a need of design and construction technique on cost effective climate responsive structure.

Conclusion



The design and construction of Prototype classroom building is done to provide an alternative to current practices of adding school buildings which are neither comfortable nor disaster resilient. The nature of production and design technology not only address today’s global warming issues, but also is instrumental for disaster risk reduction. In particular, by providing the climate responsive and safe school building will help to increase the attendance and enrollment of children in school. Furthermore, the process helps to create awareness among the communities and spreads the message of culture of safety. The prototype classroom – building with SCEB, SCET may be the best building type for the school construction as it ensures the basic need of school buildings:

• Climate responsive• Environment friendly and sustainable• Cost effective• Fast to built• Safe and earthquake resistant

This intervention will help to make schools/houses functional and comfortable in all seasons and in same time contribute lot on green movement. Ultimately this will help to minimize the carbon emission and unhealthy exploitation on earth for getting resources.

The authors would like to extend their sincere thanks to contributions of Mr. Sonam Wangchuk, who was the technical advisor of the project, Mr. Sammer Bajracharya and Mr. Badri Rajbhandari, who were the person in-charge of the field to make the project successful. The report draws heavily from the write-up and contribution of the all the project team.

Arvind Krishan, 2001. Climate Responsive Architecture: A Design Handbook for Energy Efficient Building

Auroville Earth Institute -www.earth-auroville.com

Barr, S.K. 2011. Green Schools That Teach: Identifying Attributes of Whole-School Sustainability., Masters Thesis, Colorado State University, Fort Collins, Colorado, USA

Bernstein, T., Lamb, Z. 2003. Building Healthy, High Performance Schools: A Review of Selected State and Local Initiatives, Environmental Law Institute, Washington, DC

Clair, P and Richard Hyde, 2009. Towards A New Model for Climate Responsive Design at the University of the Sunshine Coast Chancellery, Journal of Green Building

CRA Terre, “A Mannual of CEB Production‘‘ developed by CRATerre in France, a world leading Institute on Earthen Architecture.

Dear, D. R. and Brager, G. 1998, Developing an Adaptive Model of Thermal Comfort Preference, ASHRAE Transactions

Development Alternatives 1998Dili, A. S, Naseer, M.A, and Zacharia Varghese. Climate Responsive Design

for Comfortable Living in Warm-Humid Climate: The Need for a Comprehensive Investigation of Kerala Vernacular Architecture and its Present Status, Journal of Design Principle and Practices

GoN: Government of Nepal, 2010. The Approach Paper to National Plan 2011-2013. Kathmandu, Nepal.

Heschong , Mahone, 1999. Daylighting in Schools – An Investigation into the Relationship between Day lighting and Human Performance

Issa, Mohamed, Attalla, Mohamed, Rankin, Jeff and Christian, A. John. 2011. Absenteeism, Performance and Occupant Satisfaction with the Indoor Environment of Green Toronto Schools in Indoor and Built Environment

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NEGSIF, 2004. National Environmental Guidelines for School Improvement and Facility Management in Nepal, Kathmandu, Nepal

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Acknowledgements

References



Analysis of water footprints of rainfed and irrigated crops in SudanShamseddin Musa Ahmed a*, Lars Ribbe b

a Water Management and Irrigation Institute, University of Gezira, Wadmedani, Sudan.b Center of Natural Resources and Development, Cologne University of Applied Sciences. Betzdorfer Straße 2. 50679 Cologne, Germany.

*Corresponding author: [email protected]

AbstractArticle history


Keywords

Water footprintVirtual waterRainwater harvestingSudan

Introduction

The global increase in population and changing consumption patterns undoubtedly will put more pressure on food supply and natural resources. For instance, the worldwide required increase in the cereal production is projected at 55-80% by the year 2050 (De Fraiture et al. 2010). This can be achieved either through increasing the cultivated area (horizontal increasing), increasing yield per unit of cultivated area (vertical increasing) or both. In most cases water availability is the limiting factor rather than the land (Wallace 2000). Generally, irrigated (blue water) and rainfed (green water) agricultural systems provide most of the food supply. There are discernible reasons why attention should be paid towards rainfed agriculture. It covers 80% of the worldwide agricultural land (Rockström et al. 2003); there is no much remained blue water (surface and groundwater), especially in arid, semi arid and dry sub humid areas, for food production, thus green water (infiltrated rainfall, stored as soil moisture) is the viable alternative (Hoff et al. 2010; Rockström et al. 2009). Rainfed agriculture,

especially under arid and semi arid areas, still holds considerable potentiality (De Fraiture and Wichlens 2010; Rockström et al. 2010); in spite of its tremendous brought benefits, irrigation development has high environmental and social costs (Aldaya et al. 2010; De Fraiture et al. 2010; Gleick 2003); and from a water management perspective, two thirds of global rainfalls infiltrate into soils forming the green water; thus, concentration only on blue water gives no sustainable solutions (Hoff et al. 2010); however, irrigated agriculture sustains a significant and reliable share of food production, 22% of the water consumed by crops comes from blue water (De Fraiture et al. 2010). In addition, by increasing the irrigated area by 33%, irrigation water could contribute to 55% of the global total value of food supply by the year 2050 (De Fraiture et al. 2010). Thus, a better field water management for both irrigated and rainfed agriculture is of utmost important.The quantification of the water use may be a good support for conducting in depth analysis and planning.

Journal of Natural Resources and Development 2011; 01: 20-28 20

Water rather than land is the limiting factor for crop production in Sudan. This study attempts to use the water footprint (WFP) and virtual water concepts to account for crops water consumption under the Sudanese rainfed and irrigated conditions. The general average of the green WFP of sorghum and millet were found to be about 7700 and 10700 m3 ton-1, respectively. According to experimental results at three different climates, in-situ rainwater harvesting techniques could reduce the WFP of rainfed sorghum by 56% on the average. The blue component (surface water) shows the highest contribution to the total WFP of irrigated crops: 88% for cotton, 70% for sorghum, 68% for groundnut and 100% for wheat. However, the role of the green water (rainwater) is not marginal since it largely influences the operation and maintenance (silt clearance) of the gravity-fed irrigation system. Under normal conditions, the annual total virtual water demand of sorghum (the dominant food crop in Sudan) is found to be 15 km3, of which 91% is green water. During a dry year, however, Sudan could experience a deficit of 2.3 km3 of water, necessitating the adoption of a wise food stocking-exporting policy.


Recently, the concept water footprint (WFP) has been introduced as a volumetric measure of water consumption and pollution, in order to obtain explicit spatiotemporal information on how water is appropriated for various human purposes (Hoekstra et al. 2009). Three kinds of WFP (volume/mass) are formulated: (1) the blue WFP: the consumption of surface and groundwater water; (2) the green WFP: the consumption of the infiltrated rainwater in the soil stored as soil moisture, and (3) the grey WFP which is related to the polluted water. These WFP can be used to assess the water use and its sustainability at different spatiotemporal levels, i.e. global, regional, national, provincial, year, and across years (Aldaya et al. 2010; Bulsink et al. 2010; Chapagain and Hoekstra 2010; Ercin et al. 2011; Hoekstra and Hung, 2005; Ma et al. 2006; Mekonnen and Hoekstra 2010).

An alternative term for the WFP of a product is its virtual water content (Hoekstra et al. 2009). While the term virtual water refers to the volume of water embodied in the product alone, the WFP refers not only to this volume but also to the sort of water used, when and where this volume is used (Hoekstra et al. 2009). Therefore, the term WFP has a broader meaning than the term virtual water. Succinctly, WFP of a product is a multi-dimensional indicator, whereas ‘virtual-water content’ or ‘embedded water’ refers to a volume alone (Hoekstra et al. 2009). Thus, WFP can be used also to assess the virtual water balance for a given area.

The arable land of Sudan is estimated at 84 million hectare, of which only 2% is under irrigation due to the limited blue water as has been stipulated in the Nile Waters Agreement in 1959. This is coupled with limited storage capacities (Table 1), which are mainly used for generating hydropower and supplying irrigation water for four main gravity-fed irrigation schemes. These are Gezira (established in 1925), New Halfa (1964), Suki (1971) and Rahad (1977). Cotton, sorghum, groundnut and wheat are the main grown crops. Sudan has almost used its share in the Nile River waters (Abdalla

2001). The Sudanese Ministry of Irrigation and Water Resources has projected that Sudan would experience a deficit of 18 km3, by the year 2030 as the total need would be 48 km3, compared to the current available of 30 km3 (Eldaw 2003). Accordingly, the current capita share (830 m3) is expected to drop down to be only 530 m3. Thus, the Sudan agricultural expansion depends entirely on the rainfed sector.

The current rainfed area is roughly estimated at 18% of the Sudan arable land, of which 60% is traditional rainfed agriculture (it depends on traditional technology and usually practices in small areas near to homesteads), which is mainly practiced in the regions of Blue Nile, Sennar, Gezira, White Nile, Kordofan and Darfur. The remaining is cultivated under the mechanized rainfed sub-sector (characterizes by its large areas and a heavy use of agricultural machineries), which is mainly practiced in Gedarif State. Sorghum, cotton, millet, sesame, and groundnuts are the main rainfed crops, where sorghum is the dominant (Food and Agriculture Organization of the United Nations, FAO 2006). The yield of rainfed crops is characterized by its high variability due to the high variability in seasonal rainfall (total annual country average ≈1000 km3). Accordingly, farmers adopt low-input rainfed agriculture as a risk management option. This reduces the yield per unit of land and water. Shamseddin (2009) found that the low yield of rainfed crops in Sudan is mainly due to rainwater mismanagement, agreeing with Rockström et al. (2010). Generally, the rainfed sector produces around 95% of the pearl millet, 78% of the sorghum, 67% of the groundnut and 100% of the sesame has grown (FAO 2010).

Studies on the quantification of the water footprint for agricultural products are rare or absent in Sudan. To the best of our knowledge, this study represents the first attempt to document the field WFP and virtual water in order to estimate crops water use (irrigated and rainfed), water saving opportunities, sustainability and food security in Sudan. Thus, this study would be a baseline for future studies.



Source: Abdalla (2006)

The green and blue WFP of crops

The calculation of the WFP has been done following the approach described in Hoekstra et al. (2009). This approach needs two main inputs, the evapotranspiration and yield. The reference evapotranspiration (ETo) is estimated on the basis of the Penman-Monteith formula using the computerized program CROPWAT 8.0, which needs minimum and maximum temperature, relative humidity, wind speed and sunshine hours that were collected from the Sudanese meteorological authority and the FAO program “CLIMWAT”.

The crop evapotranspiration (ETc) was calculated by multiplying ETo with a specific crop factor (Kc), taken from Adam (2005) and Allen et al. (1998). Mostly, the crop water requirements can be met either with green water or/and blue water. For the calculation of the green water evapotranspiration (ETgreen), the crop water requirement option (optimal conditions) in the CROPWAT 8.0 model has been used as described in (Aldaya et al. 2010; Chapagain and Hoekstra 2010; Hoekstra et al. 2010; Mekonnen and Hoekstra 2010). The ETgreen is calculated as the minimum of the total evapotranspiration and effective rainfall, Peff, (Hoekstra et al. 2009) using a time step

Dam Design capacity Actual capacity Establishment

Sennar 0.9 0.4 1925

Rosiers 3.4 1.9 1966

Khashmelgrba 1.3 0.5 1964

Geblawlia 3.0 3.0 1937

Table 1. Main storage reservoirs capacities (km3 in Sudan)


of ten days. The CROPWAT model calculates the effective rainfall on the basis of the USDA Soil Conservation Service. Sorghum and millet rainfed crop were studied as they dominate the Sudanese food supply, especially in rural communities. Sowing dates and yields data were taken from the statistical department of Sudanese Ministry of Agriculture, Mohamed (2003), Mohamed (2005), Elamin (2006) and FAO (2010). For the calculation of the blue water evapotranspiration (ETblue), the irrigation schedule option in the CROPWAT 8.0 model was used, following the local farmers’ practices, i.e. the irrigation interval and application depth are 14 days and 100 mm, respectively. ETblue is calculated as the difference between the total evapotranspiration (ETc) and the total effective rainfall. When, within the period considered, Peff is greater than ETc, the ETblue approaches zero (Hoekstra et al. 2009):

ETgreen = min(ETc , Peff ) (1)

ETblue = max(0, ETc -Peff ) (2)

ETc = Kc * ETo (3)

The green WFP (WFPgreen) and blue WFP (WFPblue) were calculated as follows:

WFPgreen = CWUgreen (4) Y

WFPblue = CWUblue (5) Y

Where CWU refers, respectively, to the green and blue components in the crop water use (m3 ha-1) and Y is the crop yield (kg ha-1). Virtual water has been defined as “the water used in the production process of agricultural or industrial product consumed in the product (Ma et al. 2006). This study concerns on assessing the virtual water of sorghum crop for selected Sudanese states by multiplying the sorghum trade amount (t year -1) with their associated volume of water content. This is done following the methodology mentioned in Ma et al. (2006), where the net import of the sorghum into a region (or net export from the region) is a function of regional production, stock changes and domestic utilization:

NI (ni , t , c) = DU (ni , t , c) - P (ni , t , c) - rS (ni , t , c) (6)

Where, NI (ni, t, c) is the net import of an importing region (ni in year t as a result of trade of product c); DU is the total domestic utilization, P is the production of a product c and ∆S is the change in stock, i.e. no change is assumed. The net virtual water import related to the trade in the product c (ni, t, c), is equal to the net import volume of the product c multiplied by its virtual water content (ne, t, c) in the exporting region ne. Sorghum crop is used because it is the dominant food

diet and the dominant cultivated crop in Sudan (FAO 2006). The per capita annual sorghum food supply has been taken from FAO (2007).

Rainwater harvesting experiments

The experiments last for two consecutive seasons, using the 1-factor completely randomize design (tillage factor). The experiment total number of runs was six; each run has a size of 13 x 70 m. Furrow and chisel tillage as in-situ rainwater harvesting techniques (IRWHT) were implemented against control plots at three different climatic zones: arid (Wadmedani station, Gezira state), semi-arid (Sennar station, Sennar state) and semi-humid (Abunaama station, Sennar state). The locations of the three sites are shown in Figure 1. For each IRWHT, three replicates were made. In order to avoid effects of water stagnation, the seeds were placed a little bit higher than the beds of the furrows by a conventional planting method (traditionally known as Saluka) with 0.2 - 0.3 m between holes (3 - 4 seeds per hole). However, for the control treatment plant distances of 0.7 – 0.8 m between holes were used (the widespread practice adopted by local farmers). Dykes at the plots ends were constructed manually in order to collect the in situ surface runoff, i.e. maximizing the infiltrated rainwater volume so as to increase the soil moisture content in the root zone. The experimental sites belong to the central clay plain, where the soil is vertisols (Elias et al., 2001; Blokhuis, 1993) with a clay percent of 52-58%. On one hand the soils are characterized by moderate to poor mineral fertility due to low content of nitrogen, available phosphorus, and sometimes potassium (FAO, 2006). In spite of these deficiencies, rainfed farmers, whether in traditional or mechanized sector, do not use fertilizers in order to reduce the cost, i.e. rainfed farmers, especially traditional farmers, receive very low percent of all formal agricultural credit, besides that they receive few support services such as research and extension (FAO, 2006). On the other hand, due to relatively higher cation exchange capacity and percentage base saturation values, these soils have greater ability to retain added nutrients and reduced tendency to lose by leaching (FAO, 2006).

Figure 1. Locations of the three selected experimental sites, central Sudan



In Wadmedani site, soil water contents were determined by the gravimetric sampling method. The gravimetric soil moisture was converted to the volumetric soil moisture (V) using the soil bulk density. Thus, the crop water use (CWU) is obtained by a water balance equation, which under heavy clay soil conditions is simplified as follows (Adam 2005):

∆S = Peff - CWU (7)Where, ∆S stands for the change in soil moisture during the period t and Peff is the effective rainfall. This simplification is adopted as the ground slope is gentle (10 cm km-1) resulting in a negligible runoff; the deep percolation is zero (heavy clay soil) and zero leaching

requirements (no salinity). Therefore, the crop water use can be easily determined from measurements of the soil moisture (Adam 2005). The CWU (mm) is converted to m3 ha-1 by multiplying it with the factor 10. Thereafter, the green water footprint of rainwater was calculated as follows:

WFP = CWU (8) Y

Where, WFp is the water footprint (m3 kg -1) and Y is the sorghum yield (kg ha-1).

Results and Discussion

Water footprints of rainfed sorghum and millet

Rainfall data of the main producing rainfed regions in Sudan are presented in Table (2). It is obvious that annual rainfalls were associated with a high variability of 25%, on average. In the total term, the green water footprint of sorghum (7700 m3 t-1) is found lower than that of the millet (10700 m3 t-1). This is mainly due to the high yield of sorghum compared to that of millet, as there is no large difference found in the ETgreen for both crops. Figure 2 shows the water footprints of sorghum and millet for each region. El Obied region shows the highest water footprints of both sorghum and millet of 21 and 33 m3 kg -1, respectively. This is caused by the low yields. Moreover, El Obied region (arid climate) is neighboring the boundaries of the semi desert climate zone and this may affect the water consumption. Moreover, there were evidences that desertification is creeping down from the northern part of the Sudan (FAO 2006). In contrast, due to the high yields, Gezira region shows the lowest WFP for both sorghum and millet of 3700 and 4200 m3 ton-1, respectively. It is probably that the Gezira irrigated scheme affects positively the micro climate of the region, i.e. a long period of cultivation (86 years) coupled with a huge gravity-fed irrigation system (0.15 million km in length). Globally, Mekonnen and Hoekstra (2010) estimated the water footprints of rainfed sorghum at 1300 m3 t-1. Accordingly, there is a large room for a water saving opportunity in the Sudanese rainfed sector. It is worth mentioning that the grey water footprint is neglected herein as the rainfed agriculture in Sudan is a free-fertilizer practice, i.e. a risk management option taken by farmers and there is no re-use of the irrigation water or waste water.The differences in climate and agricultural practices lead to a large regional variation in the green WFP for both sorghum and millet i.e. 26% and 29%, respectively, with the exclusion of El Obield region. Due to the lack of supporting services such as agricultural extension, rainfed farmers depend entirely on their own acquired knowledge, traditional technology, traditional varieties and cultural practices. For instance, farmers are used to spread seeds regardless of the rainfall onset (a dry planting) in the Kordufan region (arid climate). While farmers of Gezira (arid climate), Sennar and Gedarif (semi-arid climate) regions are permanently sowing sorghum during the period 20-30th of July so as to ensure adequate accumulation of soil

moisture (Shamseddin 2009). Figure 3 shows that proper sowing dates can help in effectively using of rainwater for crop production. For example, during the second experimental season a large amount of rainfall was misuse because the sowing date was late. In addition cultivating on a proper sowing date is one of the ARC recommended strategies for controlling the midge sorghum problems. Rainfed farmers use to cultivate traditional seeds since the improved seeds is too costly (inadequate formal credit), and these seeds are not easily available everywhere. FAO launched a program in order to provide improved seeds; however, this provision is restricted to conflict-affected and post-conflict areas (FAO 2011). In spite of its general low rate, adoption of RWHT by rainfed farmers is different from a region to another in Sudan. Shamseddin et al. (2009) reported that only 0.05% of the farmers is adopted RWHT in Sennar region. However, the adoption rate at western regions of the central Sudan (Kordufan and Darfur) is relatively high since farmers became more willing to adopt RWHT as a direct result of the witnessed historical drought events in the region. Therefore, there is a high need for conducting solid research on proper sowing dates, increasing formal credit to traditional rainfed farmers and an initiation of nation-wide RWHT capacity building programs.

Table 2. Mean annual rainfall and coefficient of variation (CV) for the studied rainfed areas

Station Mean (mm) CV

Kadugli 681 0.21

Damazine 698 0.17

Gedarif 612 0.20

Nyala 365 0.23

El Obied 329 0.30

El Renk 495 0.23

Sennar 424 0.25

Wadmedani 281 0.29

El Fasher 193 0.34


Figure 2. Water footprints (WFP m3 kg-1) of rainfed sorghum and millet crops at selected regions in Sudan.

Table 3 presents the influence of rainwater harvesting techniques (RWHT) on the rainfed sorghum WFP in the arid, semi arid and semi humid climatic zones. The average WFP of sorghum under rainwater harvesting is found to be 3000 m3 t-1. It is obvious that the implementation of RWHTs resulted in reducing the WFP of sorghum (grain) by 80, 72 and 55% compared to controls in arid, semi arid and semi humid climates. Similar influences of RWHTs were observed in the production of dry matter of sorghum, as the average WFP was found to be 800 m3 t-1 (dry matter), compared to 2100 m3 t-1 of the control plot. These are attributed to biophysical effects of RWHTs in increasing the benefits drawn from rainwater through increasing soil moisture and in turn increasing the transpired water ratio to the total evapotranspiration water. Abdelhadi et al. (2002) found that RWHTs have increased the soil moisture in the root zone by 27-46% in the Butana area (semi-arid), central Sudan. In rainfed agriculture the distribution of rainfall is more important than its total amount. For instance, a dry spell (a period of 14 days having rainfall of less than 1.0 mm) at a flowering/mid growth stage (sensitive stage) would harm the crop yield event if the crop receives enough water during the initial or harvesting stage. Therefore, Dry spell mitigation is a common water management practice for minimizing the risk of crop failure due to drought (Rockström et al., 2010). RWHTs, as water management techniques, could bridge the dry spells. For instance, in the semi-arid climatic zone, during the first experimental season a long dry spell of 42 days occurred during the sorghum mid stage i.e. after 63 days of sowing (DAS). And during the second season, a dry spell of 18 days occurred during the development stage i.e. 46 DAS. These dry spells resulted in reducing the yield of the control plots, compared to the yield of the RWHT plots. This is because RWHTs are capable to retain relative more soil moisture content. For instance, the implementation of RWHTs resulted in significant increases in the soil moisture content (P ≈ 0.01), compared to the control, especially during the period 30-September, which corresponds the mid-growth stage of rainfed sorghum (a sensitive stage for water stress) during the normal hydrological conditions of the first season in Wadmedani site (Figure 4). Accordingly, the adoption of RWHT is a very good

viable option for water saving. Noting that, the cost of the tested RWHTs is tolerable for poor farmers. FAO (2011) attributed the failure of RWHT projects during the 1980s and 1990s to the lack of technical knowledge, and to inappropriate approaches of selection with regards to the prevailing socio-economic conditions. Therefore, a technical know -how program is badly needed.

Table 3. Water footprints (m3 kg -1) of the rainfed sorghum under rainwater harvesting techniques (RWHT), compared to control plots in arid, semi-arid and semi-humid areas of Sudan


RWHT Arid conditions (Wadmedani) Average

First season Second season

Furrow 1.8 5.3 3.6

Chisel 2.6 3.8 3.2

Control 8.5 26.3 17.4

Semi-arid conditions (Sennar)

Furrow+Chisel 2.4 3.6 3.0

Control 6.5 14.6 10.6

Semi-humid conditions (Abunaama)

Furrow+Chisel 6.8 1.3 4.1

Control 13.7 4.5 9.1

Figure 3. Distribution of rainfall during the first (a) and second (b) seasons in semi-arid climate of the Sennar site. DAS is the days after sowing (positive

numbers refer to DAS).



Water footprints of irrigated crops

Figure 5 shows the WFP of the main gravity-fed grown crops (cotton, sorghum, groundnut and wheat), compared to that of the Sudanese Agricultural Research Corporation (ARC). ARC WFPs were the lowest (optimum conditions and practices), revealing that all irrigated crops in Sudan are beyond their potentiality, which gives a room for water saving opportunity. In the average term, cotton shows the highest WFP of 10400 m3 t-1 as it has the longest growing season. Spatially, the highest cotton water consumptions were found in New Halfa, Suki, Rahad and Gezira, respectively. Mekonnen and Hoekstra (2010) estimated the average WFP of cotton at 3800 m3 t-1. Gezira scheme shows the lowest WFP due to the relative long experiences of farmers, highest governmental attention (the largest and oldest scheme) and to the continuous water management building capacity program conducted by the Water Management and Irrigation Institute, University of Gezira. Generally, there are rooms found for saving about 8, 2, 4 and 4 m3 from every produced kg of cotton, sorghum, groundnut and wheat, respectively, without impairing the yield. This requires an intensive field water management capacity building program.

Figure 4. Soil moisture contents of the control, furrow and chisel plots during the first experimental season in Wadmedani site.

Globally, Mekonnen and Hoekstra (2010) estimated the irrigated agriculture WFP at 2230 km3 yr -1 (48% green, 40% blue, and 12% grey). In this study, the averages of the blue and green components for cotton, sorghum, groundnut and wheat are shown in Figure 6. It is clear that the blue water component has the largest contribution to the WFP of irrigated crops. For cotton, the blue water component contributes 88% to the total water footprint, 70% for sorghum, 68% for groundnut and 100% for wheat. This is because most of the irrigated schemes in Sudan are situated in the arid climatic zone where rainfall is not exceeding 300 mm per annum coupled with a high variability and high evapotranspiration. However, the contribution of green water is not marginal as found in groundnut and sorghum (Figure 7). In addition, the operation and maintenance of the surface irrigation systems of the four schemes are highly depended on rainfall. Because, the silt concentration in the Nile waters during July and August are high, thus, during the summer growing season (June-November) the

less the water indenting is the less the silt accumulation in the canals and fields. This only can be achieved if rainfall is good, spatially and temporally. Table (4) summarizes the silt accumulation amounts in the canals (main, major and minor) and fields of the Gezira scheme. Moreover, currently due to silt accumulation Sennar and Khasm Elgirba dams have lost more than 50% of their storage capacities, which resulted in reducing the total cultivated areas (Abdalla 2006). Thus, rainfall has indispensable role in water management in the main irrigated schemes of the Sudan.

Figure 5. Water footprints (WFP, m3 kg-1) for cotton (a), sorghum (b), groundnut (d) and wheat (d) grown in the main gravity-fed irrigation schemes, compared

with the Agricultural Research Corporation (ARC) in Sudan.



Figure 6. Averages of the green water footprint (WFPgreen, m3 kg-1), the blue water footprint (WFPblue) and the total water footprint of the main irrigated

crops, Sudan

Table 4. The annual average of silt accumulation in the Gezira irrigated scheme with a total cultivated area of 0.92 Mha

Site Main canal

Major canal

Minor canal Field

Sediment (Mm3) 0.5 2.1 3.0 3.5

Source: Elamin (2006)

Sorghum’s virtual water for selected states

Two seasons were selected. The first represents normal hydrological conditions and normal yield (season 2006/2007). The second represents below normal hydrological conditions and low yield (season 2009/2010). Table (5) shows the obtained results. It is obvious that, during the normal year there is a virtual water surplus of 5 km3, which can be either stored (strategic stock) or exported. In contrast, during the below normal year the country experiences a water deficit of 2.3 km3. During the normal hydrological year the total national water used in sorghum production is 18.9 km3, of which 91% is green water. Thus, rainwater is largely contributed in the Sudan’s food security. However, the severe droughts cycles during 1970s and 1980s in the central Sudan jeopardized the dependable rainfed sorghum supplies; it is therefore the government became more willing to tolerate grain production in the Gezira scheme, at the expensive of cotton crop (Guvele 2002).

Among the studied states, Gedarif and South Kordufan produce the highest virtual water; while the states of North Kordufan, North Darfur and South Darfur show negative virtual water. Accordingly, these states experience food supply shortages. Thus, the Sudanese food supply is fragile due to the high dependency on the green water, which in turn shows low-yield boundaries due to rainfall variability, drought and dry spells. Consequently, the Sudanese government needs to be very careful and wise in designing its exportation policy,

considering that the irrigated production alone is incapable to meet the shortage without the help of the green water.

Figure 7. Crop water requirements (CWR m3 ha-1) of groundnut (a), sorghum (b) and cotton (c) and rainwater during normal hydrological conditions of the Gezira irrigated scheme. Data of crop water requirements are obtained from Adam (2005). Rainfalls are in situ data collected during the first experimental season in Wadmedani site. The first CWR data represent pre-irrigation events (added for moistening the soil in order to make it workable), which can be

escaped in case that good showers are received


Table 5. Sorghum’s virtual water balance (km3) for selected Sudanese states during a normal year (2006) and a below normal year (2010)

The obtained results provide deeper insights into the current field water uses situation in Sudan. The water footprint concept is found easy to apply and less data – demanding while giving useful hints regarding field water uses and water saving opportunities.The Sudanese food supply is found dependent on the green water contribution. A large variation, however, in the green WFP is found, which may attribute to the variability in rainfall and agricultural practices. Using of rainwater harvesting techniques could reduce this variation as well as water consumptions without impairing yields and sustainability. The blue water has the largest contribution in the total water footprints of the irrigated schemes in Sudan. However, all irrigated crops shown high water consumption compared to that of the Agricultural Research Corporation as well as the global ones. This is suggested a large room for saving water. This study can be used as a baseline for further similar studies.

The authors would like to thank Dr. Rui Pedrosa for his valuable comments.

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Conclusion

State Normal year

Dry year

RiverNile 0.07 0.04

Gezira 0.81 0.28

W.Nile 0.63 0.05

Sennar 1.10 0.08

Gedarif 2.48 0.47

Kassala 0.44 -0.15

B.Nile 1.35 0.30

N.Kordufan -2.12 -3.23

S.Kordufan 2.30 1.80

N.Darfur -0.94 -1.00

S.Darfur -1.12 -0.93

Total 5.0 -2.29

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Volumen I - 2011