Surinder Sud: A breakthrough in rice yields

FARM VIEW

A new technique helps cut down production costs and ensures significantly higher yields

Rice cultivation will not be the same again if a new system of growing this main staple cereal, which is being tested throughout the country, gets peer approval. Called system of rice intensification (SRI), the new method not only requires less water, but also helps save significantly on cash costs, while ensuring substantially higher grain yields.

This is because it requires far less seeds, chemical fertilisers and pesticides compared to conventional practices followed by farmers. Of course, environmentally safe organic manure is applied to boost crop productivity and maintain soil health.

Higher yields result from relatively larger root volume, profuse and strong tillers (number of plant shoots arising from one seed), bigger panicles (to accommodate more grains), and well-filled spikes (for higher grain weight per tiller).

Although, the SRI method is said to have been developed in Madagascar in the 1980s, it has caught the attention of Indian agricultural scientists only recently.

Under the All-India Coordinated Rice Improvement Project of the Indian Council of Agricultural Research (ICAR), experiments are now being conducted at various locations. The results of these experiments will lead to the validation of this technology by the Indian national research system.

However, an evaluation of the SRI technology by the Hyderabad-based Acharya N G Ranga Agricultural University has given a green signal to this system.

Its results show a remarkable increase of 25 quintals a hectare in crop yield compared to yields using conventional paddy cultivation methods. It also shows a significant drop in the cost of cultivation.

The SRI paddy-growing technique rests on six basic principles. These are: use of relatively younger seedlings for transplanting in main fields; careful transplanting to ensure proper crop stand; sowing at wider spacing to permit enough room to plants with profuse tillers; weed control to prevent misappropriation of plant nutrients by unwanted competitors; water management to save this fast-depleting natural resource; and use of organic manures to take care of the physical and nutritional health of the soil.

What is notable is that only 5 kg of seed is required for planting a hectare of land with the SRI method, against as much as 45 to 50 kg under traditional methods. Considering the high cost and scarce availability of good quality of seeds, this is viewed as a significant advantage offered by the new method.

At the time of transplanting, only eight to 12 days old seedlings, having only two leaves, are recommended for use under this method. Normally, seedlings of even twice this age are used by rice farmers for transplanting. In some cases, farmers transplant even a month-old seedling.

As far as spacing of plants is concerned, the SRI technique suggests planting of only 16 seedlings per sq metre, against between 30 and 35 planted normally by the paddy growers.

Also, the new method does not favour planting of three or more seedlings at the same place in a bunch as is the common practice. It substantially reduces the requirement of seedlings and, hence, seeds, for planting the same area.

Younger seedlings with fewer leaves and proper spacing are believed to trigger more root growth and higher number of tillers per seedling. Around 30 tillers per plant are said to be fairly common under this method. With greater precision and better management, the number of tillers can be stepped up to even 50 per plant.

The most surprising part of this technology "" which many rice farmers may tend to disbelieve "" is the water management. Contrary to the common practice of keeping the paddy field flooded with water all the time, the SRI method strictly prohibits water stagnation in paddy fields.

Instead, it recommends regular irrigation at suitable intervals just to keep the soil moist. Alternative wetting and drying, recommended under SRI, provides aerobic and anaerobic conditions to the soil to facilitate better nutrient mobilisation by microbes living in the soil.

Besides, this averts root degeneration that often happens when rice fields are kept submerged under water all the time. This apart, the lack of stagnant water allows mechanical weeding to remove unwanted plant growth in the fields and, thus, allows better aeration of the soil and more vigorous growth of roots to tap soil nutrition.

As far as the use of fertilisers in concerned, the SRI method relies essentially on the use of organic manures, although chemical fertilisers are not totally barred.

It suggests chemical fertilisers (containing nitrogen, phosphorous and potash) to be applied only once at the time of planting. It does not recommend supplementary doses of fertilisers that are normally applied by rice growers at different intervals and at different stages of plant growth.

sud@business-standard.com