Exploring plant indicators for soil quality assessment in Laos: improving the roles of communities...

THINKING beyond the canopy

Exploring plant indicators for soil quality assessment in Laos:

improving the roles of communities in land management

Imam Basuki et al. – 18th ISSRM Alberta University, Edmonton, 2012

Laos

• Laos covers 236,800 km2

–68% (1986) forest reduced to 47% (2010)

–43% (2010) agricultural lands

• Of 5.23 M people in Laos 39% are poor (WB 2009)

Context

Urban area

Rural area

• Land use planning as a national policy to reduce shifting cultivation and poverty in Laos: lack of capacity and information (Saito et al. 2006)

• Would land use planning be more effective with participatory and multidisciplinary approaches?

Context

Objectives

• To examine and demonstrate the need for local land assessment for effective land use planning in Laos, and

• To clarify whether locally recognised plant indicators of soil productivity can play a useful role.

Study sites

• Community meetings – Soil types and plant

indicators

– Scoring exercise

• Participatory mapping and group discussions

Approach

• Field tests for plant indicators (14 sites)

• Soil sampling (25 sites)

Approach

1. Soil

• Local soil map

• Local soil types

• Soil fertility

• Land suitability for rice

• Local & scientific approaches

2. Plant indicators

• Identification of plant indicators

• Index of soil productivity

Results in two parts

Result 1/1 – Local soil map

The grey and reddish areas are the better soils;

Potential for land zoning in land use planning.

Result 1/2 – Local soil types

Soil type Mean

Importance (%) Mean productivity

(kg/ha) Trend in

productivity Area

(hectare)

Dark soil 32 1785 -7 7716

Sandy soil 20 1245 -2 1293

Reddish soil 16 600 -5 4279

Dark red soil 14 1465 -3 1343

Rocky soil 13 630 -1 1988

Soil with roots 5 665 -1 1984

Productive soils are more extensive than non productive, but… productivity for rice cultivation is decreasing.

Table of importance and productivity by soil types, as perceived by communities

Result 1/3 – Land evaluation: soil fertility

Village Fertility Status Limiting Factors Boummi Low Phosphorus, CEC, Base sat. Don Keo Low Phosphorus, CEC, Base sat. Houaykhon Low Phosphorus, CEC Muangmuay Low Phosphorus, CEC, Base sat. Paklao Low Phosphorus, CEC Padheng Low Phosphorus, CEC, Base sat. Vangkham Low CEC

Evaluation of five chemical indicators of soil fertility; phosphorus, potassium, cation exchange capacity (CEC), base saturation and carbon content

Table of fertility status and limiting factors of the soils in villages

Result 1/4 – Land suitability for rice

Suitability class Oryza sativa L. S1 0 S2 3 S3 6

N (Not suitable) 16

Main limiting factors are:

– water shortage, erosion and soil fertility.

Table of soil suitability class for rice

Result 1/5 – Local & scientific approaches

Local classes of soil productivity are significantly correlated with soil pH and nutrients (p-value < 0.1).

77N =productivenon-productive

Pote

ntia

l pot

assiu

m (p

pm)

120

80

40

077N =

productivenon-productive

pH (

KC

l)

5.0

4.5

4.0

3.5

3.0

5

• Current land use zoning has shortened the fallow period and eroded soils decreased productivity + land degradation

• Local land assessment can improve current land zoning

Implications 1

Result 2/1 - Identification of plant indicators

Example of identified plant indicators Plant scores in villages Local name Scientific name DK MM HK VK VM BM PL

yak kee lor Eupatorium odoratum L. 10 10 10 10 10 10 10

thong koop Macaranga denticulata (Blume) Müll. Arg. 5 - - - - 6 -

------- -------

may muem Aporosa villosa (Lindl.) Baillon 6 4 - - - 2 3

may tiou Cratoxylum formosum (Jack) Dyer subsp. 1 1 1 2 2 1 1

------- -------

•52 plant indicators were identified

•29 plants indicate productive soils

Table of plant indicators and index-score of productivity by village (example)

Result 2/2 - Index of soil productivity

Indicator plants MM VK HK VM BM DK PL

Eupatorium odoratum L. 1 0 1 0 1 1 1 0 1 1 - - 0 0

Imperata cylindrica (L.) Beauvois

0 1 1 0 1 0 1 0 0 0 0 0 0 0

---

---

Soil Productivity Index 7.0 2.0 6.6 4.6 6.4 4.4 5.3 4.0 7.4 4.1 6.7 4.3 6.6 4.1

Local index range:

Productive (>5) and Non-productive (<5) Table of Local index of soil productivity (example)

A plant-index is a quick and simple approach: • Complements the current approaches • Appropriate land allocation • Can detect change in soil productivity better land management

Implications 2

Conclusion

• Local land assessment and the local plant-index could inform a better land use planning.

• We advocate wider use of the local index

with follow up trials in other areas.

THINKING beyond the canopy

• SDC

• CIFOR/ICRAF

• NAFRI/NAFREC

• Communities in Viengkham District

• 18th ISSRM 2012 Organizers

Cifor website: http://www.cifor.org

Acknowledgement