The availability of adequate, timely and assured supply of water is an important determinant of agricultural productivity. Irrigation raises cropping intensity and crop yields besides facilitating shifts in cropping patterns. The increase in food grain output during last two decades has come mainly from increase in land productivity. The gross cropped area under food grain has not changed significantly in this period. The trios of inputs, irrigation, high yielding varieties seeds and fertilizer nutrients have contributed to this increase in productivity. Irrigation alone contributed 60% to growth in agricultural productivity. However, the available water for irrigation purpose has been continuously diminishing even when India is blessed with abundant water resources. Agricultural sector is the largest consumer of water 70-80% whereas 20-30% water is consumed by Industrial and civil use.
With an estimated population of over one billion, the available and utilisable water resources per capita per year in India is 2384 m3 and 1086 m3 respectively against an estimated availability of 6008 m3 in 1947, and expected to dwindle down to 760 m3 by 2050. India houses 17% of the global population with only 2.4% of land and 4% of the water resources. Efficient utilization of available water resources may become crucial for the country. The annual food grain requirement of India, is estimated to be 450 mln tons by the year 2050. Agriculture, a main stay in the India, has 65% of its population dependent on it. To meet the food security, income and nutritional needs of the projected population in 2020, food production in India will have to be almost doubled. Adoption of water efficient irrigation technologies, may help in saving significant amounts of water and increase the quality and quantity of agriculture produce. All these emphasize the need for water conservation and improvement in water-use efficiency system in agriculture through micro irrigation. Micro irrigation is an approach to irrigation that keeps the water demand to a minimum through spray, mist, sprinkle or drip. The water discharge patterns differ, because emission devices are designed for specific applications due to agronomic or horticultural requirements.
Drip Irrigation: It is the slow and regular application of water directly to the root zone of plants through network of economically designed plastic pipes, mains, sub mains, laterals and low discharge emitters. Drip irrigation in particular offers farmers to increase their water efficiency up to 40-70% at the same time improving yields by 30% or more. LLDPE drip laterals are placed along the rows of the crop on which emitters are connected directly to provide water to the roots. The drip technology spread from Israel to Australia and the USA in the late sixties, and eventually through out the world. The US has the largest area under drip irrigation. This technology was introduced in early seventies in India but large adoption of it was in eighties particularly in fruit, vegetable and cash crops. Drip irrigation system is considered as most suitable water saving technique, eliminating water channels; bring more area under irrigation and reducing the use of purchased inputs. The crop yields by this method of irrigation are higher with reduction in cost of fertilizers, pesticides and power for irrigation.
Sprinkler Irrigation: Sprinkler irrigation system allows application of water under high pressure with the help of a pump. It releases water similar to rainfall through a small diameter nozzle placed in the pipes. Water is distributed through a system of pipes, sprayed into air and irrigates in most of the soil type due to wide range of discharge capacity. The riser and nozzles are installed on the LLDPE lateral pipes. Sprinkler Irrigation is suitable in all types of soil except heavy clay and water saving up to 30-50%.
Adoption of drip irrigation to a great extent can effectively save power due to less water use and thereby reduction in the time of operating of the pump. The power saving vary according to different micro irrigation systems and crop types and their geometry. For wide spaced orchard crop group the electricity savings with drip irrigation has been estimated to be around 278 kWhr/ha and it will be about 370 kWhr/ha for close grown crops under drip. For close grown crops under sprinkler irrigation it may be around 120 kWhr/ha only. There are some recent systems like porous pipe which works on the principle of suction irrigation requiring very low head. Hence this system will result in more electrical power saving. Based on the Savings in Electricity consumption explained above by micro irrigation system, the yearly potential savings in Electrical power that can be saved with the help of micro irrigation will be huge for entire micro irrigated area. But, farmers of many water-scarce regions are not confronted with marginal cost of using energy due to either flat rate system of pricing electricity in agriculture or free power. Hence, for them energy saving does not result in any private gain. But, from a macro economic perspective, if one wants to examine the economic viability of the system, it is important to consider the cost of supplying electricity to the farms, which would be saved due to drips/sprinkler while evaluating the economics of irrigation using the system.
Potential of Micro Irrigation in India: India is a large producer of agricultural products. Irrigation resources are limited and the water use efficiency as well as agricultural productivity is low. Micro Irrigation has become popular in India and it has been adopted on 5.57 mln hectare till March 2011. India has 172 mln hectare of cultivated land (second largest in the world). Studies of comparative crop yield and water use for flood and drip irrigation of different crops carried out at agricultural universities in India have consistently found water savings of 30-60% and yield increases of 20-40% favoring drip irrigation over conventional methods. There are some 100 private companies producing and marketing drip irrigation systems in India. According to 10th Horticultural plan, out of the total cultivated area of 172 mln ha in the country, only 65 mln (37%) is irrigated. As per the estimates, the total cropped area suitable for Drip irrigation in the country is to the tune of 27 mln ha and Sprinkler irrigation is about 42.5 mln ha.
Hence micro irrigation system has enormous advantages not only to save irrigation water but also to save electricity and the cost of cultivation besides increasing the productivity.
Author: P N Chakrawal, Asst. Manager - PADC BD-Petrochemicals, Indian Oil Corporation Ltd., firstname.lastname@example.org
Reference: www.agricoop.nic.in, www.ncpahindia.com, www.netafimindia.com, www.Jains.com, GOI 11th Five year Plan (2007-12), Book: Micro Irrigation System in India 2010)