Irrigation is difficult in Bangladesh due to scarcity of necessary and sufficient surface water required for the purpose. As a result, farmers across the country have to depend increasingly on underground water irrigation method. But excessive use of underground water for irrigation purposes has proved devastating for ecological balance of the country. Under the circumstances, a new technology called Alternate Wetting Drying (AWD) has been invented. Through this new irrigation technology, around 30 per cent irrigation water during Boro rice farming can be saved, substantially reducing pressure on underground water for irrigation purposes. To cope with the scarcity of irrigation water, experts have recommended large-scale adoption of this simple and effective technology.
Farmers generally use 3,000 to 4,000 litres of irrigated underground water to produce one kilogramme of Boro rice. Comparatively, between 1,500 and 2,000 litres are required when AWD irrigation technology is used. The AWD irrigation method determines the right times for irrigation to grow Boro rice in the fields. It requires only a PVC pipe, of seven to 10 centimetres diameter and 25 centimetres length, or hollow bamboo pieces or waste bottles of cold drinks for the purpose. Fifteen centimetres on one side of the pipe is perforated for horizontal movement of water. This is to be installed vertically with its perforated portion under the ground level. The soil within it is scooped out to make the soil at the pipe's lower end visible.
The farmers need to irrigate Boro fields in such a way that water does not overtop the imperforated portion, watch water leach down the pipe and irrigate when soil at bottom of the pipe is visible with no water on soil hat.
The horticulture specialists have stated that in recent years the AWD irrigation method has been becoming popular among farmers in all five districts under Rangpur agriculture region. In 2018, some 46,216 farmers of the region used the AWD irrigation technology for cultivating Boro rice on their 3,297 hectares of land to increase rice output at lower costs. Experts are of the opinion that farmers can be largely benefitted if they use AWD technology through reduced irrigation frequencies, improved water use efficiency, less use of diesel, electricity and increased rice yield, thus reducing cost of production and saving underground water.
The farmers have already started reaping benefits from the AWD technology following its dissemination to them by different agro organisations. Lifting of underground water must be reduced to a minimum as future of agriculture depends on availability of water besides a formidable threat of climate change with rate of demand for food on the rise.
If the AWD method is adopted for farming Boro rice on 4.8 million hectares of land in the country, 2.4 million tonnes additional paddy worth Taka 64.0 billion will be produced annually. Also, Taka 8.0 billion can be saved by less consumption of diesel and electricity.
Additionally, the adoption of the AWD technology by farmers can save 30 litres of diesel and significant cost in the form of electricity consumption during irrigation. The country's agriculture sector is facing a severe threat due to changing climate. As a result, the experts also recommended crop zoning to cultivate more crops, which require irrigation, in the southern zones and less water consuming crops in the drought-prone northern zones of the country.
Prof Sarwar Md. Saifullah Khaled is a retired Professor of Economics, BCS General Education Cadre.