A presentation at the WCCA 2011 event in Brisbane.

1. Economics of growing mungbean
after rice in the rainfed lowlands of
Cambodia
CARDI
Chea Sareth, Rob Cramb and Shu Fukai
School of Agricultural and Food Sciences

2. Constraints
• Rainfed lowland - 84% of rice land
• Single rice crop
• Subsistence level of rice production
• Erratic rainfall, low soil fertility, insect pests
• Large families but 0.5 ha of paddy land
• Risk of below subsistence

3. Potential for second crop
• IR66 in early wet season (EWS) is profitable
– Requires high supplementary irrigation
• EWS mungbean with no supplementary
irrigation has problem
• Non-rice crops following wet season rice
– ACIAR project identify mungbean to be most
suitable
– Different methods of irrigation – manual, gravity
and pump

4. Objectives
• Project
– To develop profitable double-cropping options
for rice/non-rice crops
– To define the water requirements for non-rice
crops and predict level of risk
• Paper
– To conduct economic analysis of mungbean
cultivation following rice
– To examine net returns with 3 irrigation
methods

5. Methodology
• Mungbean cultivation
– Paddy fields with typically sandy soils of low fertility
from January to April
– Raised bed condition – a broadbed formation
– Two levels of irrigation and three irrigation methods
• Economic measures
– Yield and gross incomes (cash)
– Outlay of cash for inputs
– Family labour input
– Net cash return per unit of family labour (NCRL)
Gross income – Cash expense
NCRL =
No. labour-days

6. Agronomic range of irrigation
Yield (kg/ha)
Water level (mm)

7. Yields response to irrigation
800
700
Yield (kg/ha)
689
600
500
477
400
0.9ML 1.3ML
Irrigation levels

8. Inputs requirement for irrigation
300
282
250
Labour-day
200 195
Manual
150
Gravity
100
50
0 5 8
0.9ML 1.3ML
Irrigation levels 75
72
70
Pumping hours
65
60
55
50 50
45
40
0.9ML 1.3ML
Irrigation levels

9. Total labour inputs
500
Irrigation
400
Other acitivities
Labour-days
300 282
195
200
5 8 0
0
100
136 149 136 149 136 149
-
0.9ML 1.3ML 0.9ML 1.3ML 0.9ML 1.3ML
Manual Gravity Pumping

10. Costs and returns
Irrigation Gross Cash costs Net cash returns
level income (USD/ha) (USD/ha)
(ML/ha) (USD/ha) M/G P M/G P
0.9 716 179 213 536 503
1.3 1,034 179 227 854 806
M: manual watering; G: gravity-fed; P: pumping

11. Net cash returns to labour
(grain price: USD 1.5/kg)
6.0 5.3
5.3
5.0
NCRL (USD/day)
4.0 3.6 3.7
Manual
3.0 Pumping
1.9
1.6 Gravity
2.0
1.0
-
0.9ML 1.3ML
Irrigation levels

12. Net cash returns to labour
(grain price: USD 2.0/kg)
8.0 7.6 7.5
7.0
6.0 5.3 5.4
NCRL (USD/day)
5.0
Manual
4.0 Pumping
2.7
3.0 2.3 Gravity
2.0
1.0
-
0.9ML 1.3ML
Irrigation levels
• Rural wage: USD 2/day
Benchmark • Minimum wage: USD 1.25/day
• Industrial wage: USD 1.7-2.8/day

13. Conclusion
• Economic potential if agronomic issues
resolved
• Access to supplementary irrigation at
between 0.9 and 1.3 ML/ha
• Manual irrigation gives low returns (NCRL)
• Pumping or gravity methods give a
reasonable return
• Improving returns
– increasing effective demand
– improved access to fertiliser and credit
– electrification
• Irrigation and labour limit production

14. Acknowledgement
• Australian Centre for International
Agricultural Research
• The University of Queensland