WATER USE EFFICIENCY OF IRRIGATION SYSTEM

OPPORTUNITIES OF WATER SAVING AND COST REDUCTION IN IRRIGATED BORO

RICE AT FARMERS’ LEVEL IN BANGLADESH

Md. Rezaul Hasan

Abul Fazal M. Saleh Md. Afzal Hussain

Issues Related to Boro Rice

• Rice sector ~ half of the agricultural GDP.

• Boro rice ~ About 60% of the total rice production.

• Boro rice ~ About 88% of the total irrigated area of 5.1 million ha (mha).

• Boro rice ~ Maximum irrigated area of about 1.3 mha in Northwest region followed by about 1 mha in North-central.

• Growing period ~ dry period (Mid January – Mid May).

• Boro cultivation ~ dependent on irrigation.

• Major mode of irrigation ~ Shallow tubewell (STW) irrigating about 3.24 mha (about 63% of the total).

Alternate Wetting and Drying (AWD) Technique

• Out of several water saving techniques, the alternate wetting and drying (AWD) technology is being researched extensively in many countries including Bangladesh.

• In AWD, irrigation water is applied to flood the field a certain number of days after the disappearance of ponded water. Hence, the field is alternately flooded (wet) and non-flooded (dry).

• The number of days of non-flooded soil in AWD between irrigations can vary from 1 day to more than 10 days.

Justification/Objective

• Measurement of field water status in farmers’ fields.

• A questionnaire survey of the farmers on irrigation cost, input use, yield and possible adoption of AWD technology.

• Analyses on the water savings potentiality in irrigation using AWD by superposition.~ re-irrigation when water level falls to 10 cm below ground~ re-irrigation 5 days after disappearance of standing water

Methodology

Most research works on AWD ~ individual field experiments and/or simulated models. Farmers, ultimate users of the technology, have remained as bystanders. The objective is to evaluate the potentials of the water saving techniques in irrigated Boro rice production at farmers’ level.

Study Sites • The study area covers 18

upazilas under four districts ~ Panchagarh, Thakurgaon, Dinajpur and Joypurhat.

• Eight sites were finally used in the analyses.

• The soil texture ~ varies from silty loam to silt.

• The seasonal rainfall ~ 85 mm to 150 mm (Jan-Apr, 2008).

• Average seasonal rainfall is 112 mm and the 80% dependable rainfall is only about 13 mm.

AWD Treatments

The treatments considered in this study are:

• T1 = Traditional practice by farmers; no AWD (control)• T2 = AWD with irrigation when water level falls to 10 cm

from field surface • T3 = AWD (same as T2) from 30 days after transplantation• T4 = AWD (same as T2) but not in critical stages (crop

establishment and flowering)• T5 = AWD with irrigation 5 days after disappearance of

standing water• T6 = AWD (same as T5) from 30 days of transplantation• T7 = AWD (same as T5) but not in critical stages (crop

establishment and flowering)

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Wat

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Circle indicating application of irrigationTriangulation indicating rainfall occurrances

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Days

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Circle indicating application of irrigationTriangulation indicating rainfall occurrances

(c)

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Circle indicating application of irrigationTriangulation indicating rainfall occurrances

Arrow indicating end of each stage

No AWD

T3 Treatment

T6 Treatment

Comparison of Field Water Status

Impacts of AWD and Irrigation Costs at Study Sites

Total water requirement (mm)

AWD and Rice Yield

• There was no scope to find out the effect of AWD on yield in this study.

• Although some researchers have reported a yield increase using AWD, according to Bouman et. al., (2007), these are exceptions rather than the rule.

• A number of studies conducted locally (BRRI and BADC) have all reported either an increase or similar yields between AWD and continuous flooding.

• AWD method may not increase the yield but there would not be a significant difference in yield between AWD technique and the farmers’ practice of continuous flooding.

Questionnaire Survey of the Farmers • 50 sample farmers • Irrigation timings, input use and cost of irrigation• Cost of Boro rice production and yield• Pertinent details on adoption of AWD.

Farmers’ Perception• Boro has turned out to be the main rice crop in the study area• Water stress at the flowering stage is not acceptable• Re-irrigation when water level falls to 10 cm below the ground

level is difficult for the farmers to perceive• The 5-day re-irrigation strategy of AWD would be accepted at

farmers’ level. • AWD technology would be accepted if there is no yield loss.

Conclusions

• Irrigation water savings with AWD varied from 10% to 28% over traditional practice of continuous flooding.

• The irrigation cost saving varied from 11% and 29%.

• With the IRRI recommended practice of AWD, the water saving varied from 10-12% and the cost saving varied from 11-14%.

• Farmers are willing to accept AWD method (with cost reduction) keeping standing water during the 30 days after transplantation and at flowering.

• Farmers are willing to accept AWD method only if there is no yield reduction due to adoption of AWD technology.

Thank You