Explained: How SRI method of sowing paddy saves 15-20% water, gives better yield

What is this water and environment saving technique?

System of Rice Intensification (SRI) was first developed in Madagascar in the 1980s and since then several countries in the world have been practising it, including India. It promises to save 15 to 20% ground water, improves rice productivity, which is almost at a stagnant point now. Experts said that it gives equal or more produce than the conventional rice cultivation, with less water, less seed and less chemicals. The net effect is a substantial reduction in the investments on external inputs.

How does it take place in the field and in which soil?

First, the field is prepared by ploughing. It should be laser levelled before transplanting for proper water management and efficiency for a good crop stand. Then irrigation is applied in the field which is not a flooding of field like traditional methods but less than that of a well irrigated field. Then 10-12 days old nursery (young paddy plants) along with soil particles around the root with minimum disturbance to the roots are transplanted in lines, which are marked at a distance of 10 inches from each other with the help of a rope meter. The purpose of making lines is to provide a favourable environment for growth and development of rice plants through such spacing. Seedlings or nurseries should be located adjacent to the main field to avoid a time lag between uprooting and planting, which should not be more than 30-40 minutes so that the roots do not dry out.

Experts said that unlike DSR, which is suitable only for mid to heavy textured soils, SRI is suitable in all types of soil including less fertile soil as in such soil the number of seedlings can be increased to double.

Under SRI 2kg seed is required to grow a nursery for one acre against 5kg seed required in the traditional method.

Does the SRI method require continuous flooding after transplantation of nursery?

In traditional sowing from the day of transplanting till the crop turns 35-40 days fields are kept under flood-like conditions. And then fields are filled every week till a few weeks before harvesting. “But SRI doesn’t require continuous flooding, it needs intermittent irrigation. Indeed the plants’ roots should not be starved for oxygen through flooding. Irrigation is given to maintain soil moisture near saturation initially, and water is added to the field when the surface soil develops hairline cracks. Irrigation intervals will vary according to field conditions. During our experiments in the fields of Gurdaspur district wherein Pusa 1121 was planted, we measured through water meters that 50 lakh litres ground water was used against the 62 lakh litres groundwater used for the same variety in puddled method field,” said Dr Amrik Singh, Agriculture Development Officer, Pathankot, who is an expert on SRI method and under whose supervision several demonstration plots were sown with this method in the villages of Gurdaspur over a decade back.

Why does SRI matter in the state?

Any rice sowing method which saves ground water is important for Punjab where 116 of 138 agricultural blocks of the state are under dark zone or semi-dark zone because of overexploitation of groundwater. “Besides, this system increases productivity because of its sowing method more tillers shoots up from a single seedling as 30 to 50 tillers could be seen against 15 to 20 tillers in traditional method,” said Dr Amrik, adding that it also maintains soil health, lowers input costs by 10-20% as it requires 25% less urea and it’s root system is quite strong due to young plants’ transplantation which prevents lodging from rain or wind. Also small and marginal farmers can increase their income by spending less and getting more yield. This matures in 5-15 days less time. In Punjab, huge amounts of chemicals are used and this prevents the usage of weedicides which keeps the soil in good health.

How are weeds controlled in SRI?

Unlike DSR when weeds are major problem and weedicides are sprayed simultaneously at the time of sowing, in SRI, which permits greater weed growth because of alternate wetting and drying of fields, the weeds are incorporated into the soil by operating a cono-weeder between rows, which are made at the time of sowing, which adds nutrients to the crop like green manures. First weeding is to be done 10-12 days after planting. Further weedings may be undertaken, depending on the necessity, at 10-15 days intervals, until the crop reaches panicle stage. Each weeding enhances yield through a process of soil aeration. For smoother and easier operation of cono-weeder, it is advisable to coincide the weeding with irrigation.

What are the comparative results of traditional and SRI methods?

Experts said that because of planting in rows and keeping proper spacing, it gives more yield. Dr Amrik Singh said that a large number of demonstrations on SRI have been organised by the Gurdaspur Agriculture department over a decade ago and the results reported clearly indicated the superiority of SRI practices over the traditional method. “SRI plots witnessed around 22.34% more rice yield of Basmati PUSA 1121 as compared to other methods of rice cultivation. There is a great potential of increasing yield under SRI,” said he, adding that even net total return is higher per acre with SRI as trials conducted in the field of farmers at Kothe and Khokhar villages said that Rs 21,000 to Rs 40,000 more net return was received against the conventional DSR and mechanical methods.

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What are the limitations of SRI?

If unchecked, greater weed growth will cause substantial loss of yield. In Punjab, it is not promoted by the government except demonstration plots sown over a decade ago. Experts said that it can be sustainable if organic inputs in the soil structure are maintained. Also more research is required by the scientists at Punjab Agriculture University (PAU), Ludhiana, along with farmers by conducting trials on small lands in the beginning and proper study records need to be maintained. “In Telangana, a sizeable area was brought under SRI to conduct a study and the results are quite encouraging in terms of water saving, less input cost and improved plant growth, said Devinder Sharma, agriculture and food expert, adding that to save water, Punjab’s farmers must have options available with them after proper studies.