FAU conference, CBS, 14-15 May 2008

Crop water use under urban conditionsChistian R. JensenDepartment of Agricultural Sciences,

Faculty of Life Sciences,

University of Copenhagen

Smedema and Rycroft 1983. Land Drainage: planning and design of agricultural drainage systems. Batsford Acad.

ET from soil water balance method

ET=I + P- RO- DP+ CR± ∆SF ± ∆SWI=irrigation

P=precipitation

RO= Surface runoff (often large under urban conditions, could be used for water harvesting)

DP=deep percolation

CR=capillary rise

∆SF=surface flow

∆SW=change in soil water content over time

After: Oliver Bühler 2008

Efficiency of Water Use (EWU) is affected

by genotype, environment & managementLitres of water per kg of fresh tomatoes in…

Israel (field) 60

Spain (unheated plastic house) 40

Israel (unheated glasshouse) 30

Holland (climate- controlled glasshouse) 22

with re-use of drain water 15

Increasing management save up to 50% fertilizers

(Dr Stangellini; Inter-drought II satellite meeting; Sept 2005)

Water savings using different irrigation method

After: EU water saving potential (2007)

Sprinkler irrigation

Micro irrigation in an orchard (Naan).

Drip irrigation system

Container yards in nurseries

High tide/low tide irrigation system

KVL; NOVO-House

Drip irrigation Sprinkler irrigation

Advantages Disadvantages Advantages Disadvantages

Smal pumping costsLow water amountEven distributionEasy to add fertilizerLow fungicide needCan be automised

High initial costsHigh water quality No frost protectionMany tubesFixed pot position

Frost protection+Cools, reduce dryingLow maintenanceRobust and flexibleEasy to controlLess clogging riskCheap

Low WUESpill on paths etc.Greater need for

fungicides.Difficult to work

during watering.Irrigation frame with

sprinklers reduce difficulties

(After: Nielsen 2002)

Container yards: Assessment of irrigation methods ++ very good; +good; -bad; --very bad (After: Nielsen 2002)

Method Price Work Water

use

Distri-

bution

Wind

Sensit.

Frost

Protec.

Fertili-

zation

Sprinkler ++ ++ -- -- - ++ (-)

Sprinkler

bar- - + + +/- -- (+/-)

Drip irrigation

- -- ++ ++ ++ -- ++

Mat irrigation

- + + + ++ -- +

Sand bed -- + + ++ ++ -- +

Low tide/

high tide-- + + ++ ++ -- +

Potential water saving in agriculture:

• Conveyance (22%);

• Irrigation Scheduling (10%),

• Deficit irr. (10%),

• Waste water (10%)

(After EU Water saving potential, 2007)

Fordampning(Latent varme)

Vind

Opvarmning(Sensibel varme)

Blad

Absorberetenergi (Rn)

Biokemiske processer (CO2 -indlejring)Opvarmning

Latent heat of evaporation (λET )

Absorped

Energy (Rn)

WindLeaf : Heating

Biochemical processes

(CO2-uptake)

Heating (H)

Sensible heat

Evaporation on a typical Nordic summer day

Energy in radiation 20000 kJ m-2

For evaporation, 40 % 8000 kJ m-2

Heat of evaporation of water 2450 kJ kg-1

Evaporated water 8000/2450 = 3.3 kg m-2

or 33 tons ha-2

Corresponding to 0.0033 m3 / m-2 = 3.3 mm

Potentiel evaporation, max 6-7 mm day-1

Common evaporation 3- 5 mm dag-1

APPROXIMATE VALUES OF SEASONAL CROP WATER NEEDSCrop Crop water need

(mm/total growing period)

Alfalfa 800-1600

Banana 1200-2200

Barley/Oats/Wheat 450-650

Bean 300-500

Cabbage 350-500

Citrus 900-1200

Cotton 700-1300

Maize 500-800

Melon 400-600

Onion 350-550

Peanut 500-700

Pea 350-500

Pepper 600-900

Potato 500-700

Rice (paddy) 450-700

Sorghum/Millet 450-650

Soybean 450-700

Sugarbeet 550-750

Sugarcane 1500-2500

Sunflower 600-1000

Tomato 400-800

After:Brouwer C & Hwibloem M. 1986

Measurement of ET from pan evaporation Measurement of precipitation by rain gauge

TrådnetVandstands-mærke

NN

E

Precipitation

Waterlevel

ET

Mesh

(FAO: Class A Pan)

ETr from Penman-Monteith equation (Monteith 1971)

Rn is the net radiation, G is the soil heat flux, (es - ea) represents the vapour pressure deficit of the air, r a is the mean air density at constant pressure, cp is the specific heat of the air, D represents the slope of the saturation vapour pressure temperature relationship, g is the psychrometric constant, and rs and ra are the (bulk) surface and aerodynamic resistances. λ=heat of evaporation

(FAO: See Allen et al. 1998)

From ETo and estimates of crop evaporation rates, expressed as

crop coefficients (Kc) ETcrop = Kc × ETo    

200

150

100

50

0

1 2 3 4 5 6 7 8Jordtype, JB-numre

Vinterraps

Kartofler

Fra tabel 2.5

Max root zone capacity, mm

Potatoes

Winter rape

Soil classificication, JB No.

Irrigation scheduling

Upward lines are rainfall or irrigation.

RAW= readily available water (0-50 % of TAW)

TAW=total available water

RAW

TAW

.

Time Domain Reflectance TDR equipment for measurement of soil water content

Tidskontol-enhed

Oscilloskop

Impuls-generator

Impuls-detektor

Transformer

MåleprobeL

System water supply claim m3/ha/hr for different % of coverage and daily precipitation deficit

Irrigation

interval

(Days)

2 2 2 4-10 4-10 4-10

%coverage 90 95 100 90 95 100

Daily precipita-

tion deficit3.8 4.2 5.0 2.6 3.2 5.0

Sprinkler (12 hrs)

(4-5 bars )2.5 2.8 3.3 1.7 2.1 3.3

Drip (24 hrs)

(2 bars)1.1 1.2 1.4 0.8 0.9 1.4

Take home message

• Due to dwindling municipal water resources better water management needed by:– Utilizing water havesting of surface runoff water after

filtering– Precision irrigation and fertigation, – Measurement of soil water content to control irrigation

Ongoing projects at KU/AU

• Danish Research Counsil:Project : SJVF project 1.9 mill kr. Starting 15/9/04-2009 Physiological basis for improving water use efficiency in crop plants under ‘partial root zone drying (PRD)’ irrigation strategy.

• Strawberries – New irrigation Techniques (PRD-irrigation) for Better Tast , Quality Keeping and Reducing Pesticide and Water Use. ‘Direktoratet for FødevareErhverv, DFFE. Funding 1.977.345,- kr for 1/1 2007-31/12/2010 Coop project between Research Centre Årslev, Århus University and the Applicant.

• New Irrigation Schemes. Responsible for Partner 3 UoC Faculty of Life Sciences activities (8 mill kr.) in the SAFIR:EU-project. Safe and High Quality Food Production using Low Quality Waters and improved Irrigation System and Management (Contract No.: 023168 SAFIR) 1/10/2005-31/9/2009. 17 partners 55 mill kr.

• SWUP-MED: EU-project. Sustainable Water Use Securing Food Production in Dry Areas of the Mediterranean Region. 1/7/2008-31/6/2012. Coordinator S.-E. Jacobsen; EU project with 10 partners, DK IJV KU-Life participants Fulai Liu, C.R. Jensen. Total budget 24 mill kr.

Sources:• Brouwer C et al. 1985. Irrigation water management: Training manual No. 1-

Introduction to Irrigation. http:www.fao.org• Brouwer C & Hwibloem M. 1986. Irrigation water mangement: Irrigation water

needs. Training manual No. 3. http:www.fao.org• Allen et al. 1998. Crop evapotranspiration - Guidelines for computing crop water

requirements - FAO Irrigation and drainage paper 56• Hagin et al. 2004. Fertigation. Fertilization through Irrigation. IPI Research Topics

No. 23. International Potash Institute. CH-4001 Basel• Mogensen V.O. 1990. Markvandingssystemer. DSR-forlag• Mogensen V.O., Jensen C.R., 2002 Markafgrøder, Klima og Vandforsyning. KVL,

Samfundslitteratur KVL-Bogladen. 376 sider.• Mogensen V.O., Jensen C.R 2004 Mekaniske Vandingssystemer. Kompendie• Nielsen HK 2002. Vandingsystemer til containerpladser. Høyskoleforlaget. Norge. P.

127• Nakayama FS, Bucks DA 1986. Trickle irrigation for crop production. Design,

opration, mangemant. Development in Agricultural Engineering 9• Stewaret et al. (Co.editors) 1990. Irrigation of agricultural crops. Agronomy No. 30.

ASA