Hannah Krujia, SMS – Agronomy
KVK, Phek District
Water is an important component for plant growth. It constitutes three-fourth of the body weight. Water is either supplied by rain or irrigation. An efficient utilization of irrigation is essential to supply water at different critical stages during plant growth to prevent the economic loss. Though water is an economic input, it differs from other inputs in many respects. Suppose water is produced like fertilizers or chemicals, its cost would be enormous. Therefore, maximum yield per unit water applied should be more.
Climate, soil and water are the three basic resources which determine the nature of crops that can be grown successfully in a particular region. An efficient utilization of these resources is essential for optimum production of food and fibre for human life, feed for cattle and raw materials for industry.
Paddy is a semi-aquatic plant and covers about 35% of irrigated area in the country. Cultural practices like puddling and transplanting reduce percolation losses, weed growth but increase the availability of plant nutrients and regulate soil and water temperatures. It improves photosynthesis in the lower leaves due to reflected light from the water surface. These operations may require about 200 – 300 mm of water per hectare. Selective submergence during critical stages (initial tillering, panicle initiation to flowering) would be sufficient to maximize yield and to save water during the monsoon period. The critical stages for irrigation in rice crop are tillering, panicle initiation, flowering and grain filling stage.
Maize is grown both for grain and forage. It is grown primarily as a kharif crop from March to October. Crop has early vegetative, tasselling and silking stages as critical periods. After dough stage, there is no need of irrigation. Permissible depletion of soil moisture may be 25% in light soils and 50% in sandy loam to loam soils. If the draining out of water in case of heavy rains is delayed, 30 to 60 kg N/ha may be added immediately following drainage to retrieve the yield loss.
Foxtail millet is important millet grown during kharif in warm areas with a seasonal rain of about 15-20 centimeters. In most of the areas it is sown with the onset of monsoon and no post-sowing irrigation is applied. Flowering and milking stages are the critical stages of irrigation for Foxtail millet crop. Crop gives the optimum yield with irrigation based on 75% depletion of available soil moisture from the top 30 cm layer. Foxtail millet is a drought resistant crop. If there is no rain generally two irrigations are required first at flowering stage and second at the milking stage. If moisture is a limiting factor, irrigation should also be done at the time of ear head emergence because it is the most critical stage for moisture stress.
Groundnut is the most important oilseed crop of the country. Raised as kharif crop in warm areas of relatively high rainfall, it often suffers from periodic water deficits during long rainless intervals. This occasional moisture deficiency is one of the important factors contributing to low yield of kharif groundnut. If dry spell occurs, irrigation becomes necessary. First irrigation at the start of flowering and subsequent irrigations whenever required during the fruiting period to encourage peg penetration and pod development.
Mustard and Rapeseed
These crops are primarily raised as rainfed crops during the rabi season. Due to low and uncertain rainfall during their growing season, these crops generally show favourable response to irrigations. Crop requires 1- 4 irrigations, depending upon the soil moisture storage in the profile and the prevailing weather. Pre-bloom and pod filling stages are considered to be critical stages therefore irrigations at these stages are beneficial.
Potato is an important crop which has two growing seasons viz. autumn and spring. Autumn potato is the main crop and sown in September-October and harvested in December- January. A wet moisture regime is conducive not only for adequate water availability to the crop but also keeps soil strength low which permits better development of tubers. Most critical stages for irrigation in potato are germination, stolon formation followed by earthing, tuber bulking which coincide 10 – 12, 30 – 35 and 55 – 60 days after sowing. Moisture stress at these stages results in drastic reduction of tuber yields.