India is infamous for its inclement climatic conditions in general and monsoon, in particular. Recent natural disasters in several parts of the country, like floods, drought, and cyclones have played havoc with the agricultural sector. The situation in Tamil Nadu is alarming. In recent times, even though some of the interior regions have been experiencing good rains, coastal areas have been bereft of the monsoons and consequently, crop planning and forecasts have become very difficult for agriculturists.
Water, which is one of nature’s most precious gifts to mankind, is turning out to be short in supply. It is also an alarming fact that world over, water resources are fast diminishing. A source from a leading establishment in India which specialises in irrigation systems informs that micro irrigation or drip irrigation is the only answer to the problem. The company had done a detailed study of inter–relationship among soil, water, crop, land terrain and related agro climatic conditions, and designed a suitable and economically viable system to deliver a measured quantity of water at the root zone of each plant at regular intervals. This is to ensure that the plants do not suffer from stress or strain of less or over watering. This system also saves labour and minimises fertilizer costs.
Micro irrigation or drip irrigation is the calculated application of water at the root zone of the plant as per the plant’s requirement. In this method, water is supplied through a pressurized loop of pipes and tubes wherein measured quantities of water is applied to each and every plant in the field, thereby ensuring uniform distribution of available water. Thus, it’s the plants that are irrigated and not the soil.
The water requirement of the plant is calculated depending upon crop age, canopy spread, relative humidity and transpirational and evaporational loss in a given area. While in the conventional method, water is flooded in the channels without measuring water requirement thereby leading to much wastage of water due to percolation loss and evaporation loss, in drip irrigation water is used in precise quantities.
It has been estimated that on an average, 1.50 to 2 times the area irrigated can be brought under drip irrigation leading to increased productivity besides ensuring additional income due to the additional area being brought under irrigation. As the soil is not irrigated and only the plants, the chances of weed growth and hence labour charges for weeding is eliminated. Given a fixed area of cultivation, water that needs to be pumped under drip irrigation is far less than the conventional method.
Benefits in Tamil Nadu
In large projects where water is released from macro and micro dams, like the Parambikulam Aliyar Project or the Lower Bhavani Project in Tamil Nadu, it is suggested that if the released water is utilised through drip irrigation, the same quantum of water can be used for additional areas. Thus, with the same quantum of water, all zones can be simultaneously irrigated, and number of irrigation days can also be increased as compared to conventional irrigation. In all these project areas, it’s also suggested that water be carried through a network of plastic pipes rather than earthen channels to reduce the water loss due to percolation.
Advantage for rice
While almost all horticultural crops can be drip irrigated, it has now been proven successfully and commercially that rice can also be drip irrigated. In the delta region of Tiruvarur district in Tamil Nadu, it was successfully proved in the field of a progressive farmer, Ravichandran, that a successful crop of rice can be raised in summer by using drip irrigation. Additional income from an additional summer crop ensures additional earnings for the farmer.
The drip system comprises of a network of PVC pipes and LLDPE tubes and filters which, under normal working conditions, have a performance guarantee of over five years. A well-maintained system can be used up to 10 years without a problem. It is a onetime investment.
Cost of a drip system is ideally determined by the crop for which it’s primarily meant for. It’s the quantum of lateral (LLDPE tubes) required for the crop that amounts to nearly 40% of the cost. The quantum depends on crop spacing. While it will be less for a coconut crop and such other perennial crops that are planted traditionally at wider spacing, the cost for a vegetable crop which is generally closely spaced will be more.
The government is trying to promote drip irrigation by subsidising it. A 75% subsidy for farmers with land ownership of above 5.01 and up to 12.50 acres and a 100% subsidy for agricultural areas of less than five acres are in the offing. The government of Tamil Nadu has successfully brought in over 1.50 lakh Ha under micro irrigation (drip + sprinkler) during the 2018-19 fiscal year.
The revolutionary drip technology of water management besides optimizing water use and increasing productivity also provides scope for hi-tech agricultural cultivation that is commercially responsive. Where water is scarce, it helps in mitigating or tiding over the difficult period by paving way for life-saving irrigation (irrigating crops with limited available water) till the monsoon sets in. Alongside quality seed/planting material, solar agri pumps and sound capacity building, the future looks secure with modern water and agro technologies.