Rice does not need water
Rice consumes about 4,000 - 5,000 litres of water per kg of grain produced. But it is no aquatic crop: it has great ability to tolerate submergence. Water creates unfavourable conditions for weeds, by cutting off sunlight and aeration to the ground. So, rice farmers adopted the practice of submerging rice in water to check weeds. Over the years, it has almost become a prerequisite for rice cultivation.
But today rice productivity has stagnated. The crop does not adequately respond to higher doses of inputs. Growing water scarcity and marginal increases in yield potential makes one believe there is little hope to meet growing demand. Here, an innovative method developed in the African country Madagascar offers a way out.
Called the System of Rice Intensification (sri), the method was developed by a Jesuit priest Henri de Laulani, about 20 years back. Norman Uphoff bought the method into limelight. This scientist from the Cornell Institute for Food, Agriculture and Development, usa, stumbled upon sri while doing research in Madagascar.
Today sri is practised in 20 countries, including India. It has four components: soil fertility management, planting method, weed control, and water (irrigation) management. Several field practices have been developed around these components. The key ones are: soil nutrient management through adequate farmyard manure application, transplanting young seedlings (8 to 12 days old), transplanting with soil clump (along with seed) and regular weeding and protective irrigation to keep soil wet without flooding. Rice grown this way has larger root system and yields are almost double that of the conventional crops. The secret is that rice plants do best when a young plant is transplanted carefully in an area 25 cm long and 25 cm wide. This area is larger than that conventionally allocated to rice plants, but it ensures rice roots grow larger on soil kept well aerated with abundant and diverse soil micro-organisms.
But what about standing water requirements? Standing water only arrests weed growth; it has no other beneficial impact on rice plants. But sri encourages weeds to grow in the spaces between plants. Meticulous weeding ensures pests do not intrude in to the plant area. In fact the rice plant sucks away nutrients from the weeds.
Water conservation Studies have shown sri requires 30 to 60 per cent less water when compared to conventional cultivation methods. Biksham Gujja, policy advisor, Worldwide fund for Nature International, Switzerland remarks, "For a state like Andhra Pradesh this means a lot. The state cultivates rice in around 3.8 million ha consuming about 30 cubic km of water, annually. Adopting sri will save 10 cubic km of water, even by conservative estimates. That means Andhra Pradesh can redefine its priorities on using water."
Polarised views Scientists from organisations such as the International Rice Research Institute, Manila, Philippines admonish it as "technologically flawed". But around 250 farmers in 11 districts of Andhra Pradesh have taken to sri with great success: in many cases higher annual yields of 8 tonnes per hectare (ha) have been reported as against the average yield of 3.5 tonnes/ha in conventional method. The cost of cultivation has also reduced. Seed requirement is only 2 kg per 0.5 ha -- much less than 20 kg per ha in conventional method.
sri is an unusual case of extension taking lead over research. Further studies in areas sri impinges upon, such as soil biology or chemistry, or rice physiology may throw more understanding on the success of the method. If adopted well, it can be a solution for all the water scarcity maladies of rice cultivation.
V Vinod Goud is a Coordinator of a Worldwide Wide Fund for Nature-International Crop Research Institute for Semi-Arid Areas project based in Patancheru, Andhra Pradesh