Introduction
Water is the life of plant and must be supplied in proper quantity. Too much water may suffocate the plant roots and too little may not be able to sustain the plant. Rainwater is the main source of water to soil but it also added by the way of irrigation. The application of precise quantities of water not only insures a high efficiency of water use by crops, but also reduces nutrient losses through leaching and results in better aeration of the soil. To determine the necessity of irrigation/water application to the field crop a simple and practical method of soil –cum –sand mini- plot indicate the irrigation need earlier than the raced of the field, also plants growing of a slightly higher level where soil texture is relatively light than the surrounding soil will show the symptoms of wilting earlier then growing the rest of the field. Each crop has optimum requirement of water hence water should be managed for application to the crops in a require optimum quantity.
Normally a crop has to be irrigated before soil moisture is depleted below 50% of its availability in the root-zone. The intervals are shorter during summer than in winter. Similarly the intervals are shorter in case of sandy soils than in case of heavy soils. Under the limited water availability conditions the crops are irrigated only at critical stages. The water requirement (cm) /no.of irrigation of important crops is given below: -
Rice 50/6, Maize 30/4, Jowar 20/3, Groundnut (K.40/5,S.80/10), Chillies 40/5, Cotton (Irrigated) 90/10, Wheat 40/5, Onion 40/5, Vegetables 40/5, Maize (Fodders) 60/8, Sugarcane: (Adsali 400/32, Suru 300/25), Banana 240/24.
Consideration while Applying Water
- Except for paddy fields, other fields should be kept moist close to field capacity to maintain a sufficient level of available water for crops. Crop plants should never be allowed to extract more than 60% to 70% of the available water.
- The application efficiency of irrigation should be at the maximum. Loss of topsoil and leaching or washing out of plant nutrients should be at the minimum.
- Irrigation water should soak the root-zone and water management zone and the loss of water after irrigation should be checked by adopting conservation techniques such as mulching and weed control.
- Irrigation interval and intensity should be based on soil, crop, cultivation practice and environmental conditions.
Ag.
Technologies
(Water Mgmt.)
