Alternate wetting and drying, a sustainable irrigation technique, is helping paddy farmers in Assam reduce the cost of irrigation, enhance crop production and decrease methane emissions from their fields.
Tankeshwar Patowary, a rice farmer from Garibhitha village in Assam’s Barpeta district, cultivates boro paddy in his 4-bigha land. But he no longer floods his paddy field with water like he used to. He left the practice after learning about alternate wetting and drying – a cost-effective sustainable irrigation method.
In Assam – the land of the red river and blue hills – farming is the main livelihood for over 70 percent of the population in rural areas. Rice is the main crop and it is grown using traditional irrigation practices.
Research shows that the traditional irrigation method requires flooding of the field. This leads to generation of methane (CH4), a greenhouse gas, and change in climatic parameters like rainfall pattern, temperature shift and relative humidity.
To promote sustainable farming practices, mitigate methane emission from rice fields, reduce irrigation cost and increase productivity, Sanjog, a grassroots organisation working on rural livelihood, disaster management and promotion of micro-enterprises in Assam, has introduced an alternate wetting and drying method of irrigation.
This sustainable irrigation method is being implemented by farmers of Barpeta and Nalbari districts with the support of Sanjog and Kosher Climate, a consultancy in the sustainability domain.
Initially hesitant, Patowary decided to test the new method. He grew rice in a part of his land using the AWD irrigation technique while he used the traditional method in the other part. Not only did he see a drop in costs but he also saw an increase in yield and apparent robustness in the crop.
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Alternate wetting and drying (AWD) is an irrigation method that was developed by the International Rice Research Institute (IRRI) in 2002. It reduces methane emission from the field while also cutting the cost of irrigation. It also minimises the incidence of diseases and pests in the nursery and in the field.
To monitor the water level in the field, a 30cm-long field water pipe with perforations in about 15-16 cm of its length is used. The part with perforations is inserted into the ground and remains under the surface, while the remaining half remains above the soil surface.
The root system of rice usually goes 15-17 cm deep into the soil. When the pipe is inserted below the soil surface up to 16 cm, the water level below the soil surface can be easily monitored. This generally does not affect the land adversely. It is advisable to irrigate the field when the water level comes to the last one or two perforations of the pipe.
It is generally understood that AWD helps in saving 30 percent irrigation water, reduces methane emission by up to 50 percent and reduces the incidence of diseases and pests. The traditional rice farming methods degenerate the micro environment of the paddy seedlings.
On the other hand, AWD is a labour-intensive technique, fraught with weed problems if the flooding and drying period is not maintained properly. If drying is done during flowering and panicle initiation stage, the yield may get reduced.
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As AWD is a new technique to the farmers, its implementation has not been easy in the field, especially with the farmers of Nalbari and Barpeta, where the system was introduced.
However, awareness creation among the communities, stakeholder meets, baseline surveys, training of community cadres, field water pipe installation and monitoring of water level has led to an increasing adoption. The desirable results witnessed by farmers like Patowary have worked to convince others too.
A baseline survey with 50 farmers about the conventional irrigation practices and use of agrochemicals, fertilisers and manure helped the Sanjog team in planning the implementation.
Prior to field implementation of AWD, community members like jeevika sakhis (friends of livelihood), pashu sakhis (friends of animals) and self-help group members were trained properly in the overall process of AWD and the benefits that farmers would earn by adopting this technique.
Cluster-level federation presidents, krishi sakhis (friends of agriculture) of Assam State Rural Livelihood Mission and village heads led the awareness creation. The farmers of the locality joined agriculture scientists and the block project manager for an interactive consultation.
Field water pipes were installed in the fields, after geo mapping each individual plot. After fixing the pipes, it was noticed that the fields dried within 3-5 days, depending on the soil’s physical properties.
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As part of the monitoring process, details like time of irrigation; interval between two irrigations; time and dose of fertiliser, pesticide and fungicide application; types of variety; and nursery preparation date are recorded properly.
Initially for the first season, the Sanjog team mobilised around 1,800 farmers in Nalbari and Barpeta districts. Of them, 966 farmers adopted the AWD technique covering around 627 hectares, and 800 farmers continue to practise it.
The farmers said that the average cost of irrigation per bigha (one bigha equals 0.3 acre) reduced to Rs 200-300 and the yield increased by 40-60 kg per bigha or remained the same. But it should be emphasised that none of the farmers recorded any reduction in yield.
The farmers have demonstrated that the alternate wetting and drying irrigation technique can reduce the cost of irrigation and save them money, increase the yield and help them earn more while also reducing methane emissions.
It is a viable and sustainable irrigation technique which will be cost effective for the farmers. However, because of its novelty, it requires proper technical support and infrastructure for more farmers to successfully adopt it.
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The lead image at the top shows an AWD-irrigated paddy field of a farmer. (Photo by Sanidul Islam, Sanjog)
Abinash Mazumder, who has done his post graduation in agriculture, is passionate about sustainable agriculture and rural development. He is presently working as Programme Coordinator at Sanjog.
