So shall you reap: new tech sows a seed for larger rice harvest

Farmers in India will be able to meet the target of paddy harvest by 2025 with the widespread implementation of the System of Paddy Intensification (SRI) technique that promises more harvest with lesser inputs. Implementating the SRI method in at least 25% of irrigated area in India will increase paddy harvest by 20 mt while cutting down on water consumption by 25%, Tamil Nadu Agricultural University (TNAU) vice-chancellor C Ramasamy said in a paper presented at a recent conference on SRI at the university.

System of Paddy Intensification (SRI), a methodology doubling the paddy yield, was first developed in Madagaskar, Africa, by a Jesuit priest in the 1980s.

SRI uses less external inputs, 2 kg seed for an acre, instead of 20 kg an acre, fewer plants per unit (25×25 cm), 40% to 50% less water and less fertilisers and plant protection chemicals. The yield increase is 2-3 times more than the normal.

The production using SRI leads to a dramatic increase in paddy harvest, of seven to eight tonne per hectare, nearly double the present world average of 3.8 tonne.

According to Ramasamy, ?India?s target to produce 140 million tonne paddy by 2025 can be achieved by increasing its production by over two million tonne a year through the implementation of SRI??.

The technology has being tried out in more than 10 states, including Andhra Pradesh, Haryana, Madhya Pradesh, Orissa, Punjab and Tripura.

In India, the method was first evaluated in TNAU during 2002 and with the financial aid of the government, it was introduced in the Cauvery delta and Thamirabarani tracts of the state. A yield increment of minimum 1.5 tonne to 2.5 tonne per hectare and maximum yields of 13 tonne to 14 tonne was witnessed in some holdings, the vice-chancellor said. In Tamil Nadu, paddy was widely cultivated in 20 lakh hectares in 28 districts with an annual harvest of 80 lakh tonne to 86 lakh tonne and an average yield of four tonnes per hectare. The method emphasising `plant less to harvest more? has lured paddy farmers across the globe.

Since 1990s its potential has been under test in countries like China, Indonesia, Cambodia, Thailand and other paddy growing Asian countries. SRI method was refined by thousands of researchers and farmers all over the world.

However, for the widespread adoption of SRI, certain policy interventions were needed to overcome the constraints, especially in areas of uncontrolled water supply and places where field-to-field irrigation is practiced. In order to drain the excess water, necessary structures must be created, the farm scientists said.

Currently, SRI technology is being introduced in over 2,500 hectare, with a World Bank-funded project. Efforts were under way to bring 7.5 lakh hectare of paddy growing area of the state under SRI cultivation. However, for the widespread adoption of SRI, certain policy interventions were needed to overcome the constraints, especially in areas of uncontrolled water supply and places where field-to-field irrigation is practiced. In order to drain the excess water, necessary structures must be created, the farm scientists said.

Special care for nursery preparation, perfect land leveling and skilled labour for transplanting, non-suitability of SRI marker for all types of soil, drudgery in operation of manually operated cono weeder were some of the intricacies of SRI cultivation, said the scientists. S Natarajan, director, Centre for Soil and Crop Management, TNAU, told FE ?SRI involved a few simple but major changes in farming methods. Not expensive, but challenging because it involves a major change in mindset??.

Farmers have been used to transplant three-week-old or older paddy seedlings. Under SRI, 14-day old seedlings are transplanted. Earlier farmers used to flood their fields but under SRI anything longer than a three-day flooding is avoided. Wetting the soil, or intermittent flooding and drying is instead encouraged. Farmers planted seedlings at a distance of 15 cm or closer. Under SRI, planting distances start at 25 cm and can be even greater. Farmers used to plant a bunch of seedlings per hill but under SRI, one seedling per hill is encouraged. Farmers in the past used chemical fertilisers but in SRI they are encouraged to use organic manure. Instead of herbicides, a mechanical weeder is being used not only to control weeds but also to aerate the soil.

He said these simple changes in practices could bring about a desirable yield. The plants produce much more tillers?30 upwards, instead of the usual 5-10 tillers per plant.

With proper use of SRI, individual plants can have even more than 100 fertile tillers. The tillers produce the grain, and the more tillers, the more grain, the greater the harvest. The loss of yield from wider spacing is more than offset by the bigger gain in yield from the greater number of tillers and the greater number of grains per tiller.