Surging success

AN IRRIGATION system that reduces waterconsumption, increases yield and eliminates dependency on rainfall, is nothingshort of a boon for farmers. A novelmethod of crop irrigation - surge irrigation - incorporating these features,is currently under trial on the experimental farms of Tamil Nadu Universityof Agriculture in Coimbatore.

What makes this new system wortha mention is its promise to reduce agricultural water consumption by morethan 50 per cent, while boosting up thecrop yield by nearly 15 per cent. The system, reportedly, has the potential of saving 40 per cent of the present water supply during summer, and upto 60 percent during the rainy season.

Sigr@ificarttly, 70 per cent of the netsown area in India still depends on rainfall for cultivation. The problem is compounded by the fact that rains occur inheavy showers for short periods and alarge proportion of it goes waste as runoff. The method of surge irrigation,apart from saving water, also ensuresthat minimum land is wasted as irrigation channels. Under the present 'basinfarroV system of irrigation, upto 20 percent of the land houses water channelsand hence, goes waste. In surge irrigation, the fields are first levelledto avoid water stagnation indepressions. The c*op is thenplanted in single or double rowsbetween furrows that are 60 cmapart in the former case, and120 cm apart in the latter. Awater supply channel that runsat right angles to the furrowsbears a bund that is pierced atregular intervals by short inletpipes. Each pipe is capped onthe channel side to cut off thewater flow when desired.

To operate the system, water is letout of the source - a tank or a well -into the supply channel. Starting from'one end, 'a fixed number of inlet pipesare uncapped for a fixed time period.Water gurgles through the pipes andrushes down the length of the furrow.The pipes are recapped after the furrowsare adequately filled with water. Studiesindicate that this intermittent watersupply reduces water run-off and deeppercolation losses. Successfully tried outfor sunflower cultivation, the tests arecurrently being conducted on maize.

Surge irrigation is, however, ruledout for closely-planted crops like ricewhich requires standing water. It is idealfor crops like maize, cotton, tomato andbrinjal. With trials of all major crops onthe anvil, researchers are now lookinginto means of perfecting the system.