WATER MANAGEMENT IN CROP PRODUCTION

Water is one of the most important inputs essential crops. It profoundly influences photosynthesis, respiration, absorption, translocation and utilization of universal nutrients and cell division besides some other processes. Both it’s shortage and excess affects the growth and development of the plants, yields and quality of produce. Rainfall is the cheapest of source of natural water supply. Its distribution is very uneven and uncertain. Artificial water supply through irrigation on one occasion and removal of excess water through drainage on the other becomes imperative. Water management in India thus comprises of irrigation and drainage or both. With proper combination of water and soil nutrients the crop yields can be boosted manifold under irrigated agriculture. Water is a costly input when canals supply it misuse of water leads to water logging, salt imbalance etc. rendering agricultural lands unproductive. Proper appreciation of the relationships among soils, crops, climate and water is essential for an efficient and economic use of water resources for maximum crop production.

Sources of water:
There are two sources of water
A. Canal or surface water including liftsb.
B. Ground water-dug wells and bore wells

Canal water:
This water becomes available from rivers after construction of dams on them and storing it in those dams. In India, rains are received during specific season from June to September called rainy season and in rest of the period there are no rains. This causes the problem of shortage or non-availability of water not only for irrigation but also for drinking. Therefore, artificial storaes are created by constructing dams across rivers. The rivers are small to big and accordingly dams of various sizes and capacity are built. They are mainly classified in three categories viz.1) minor 2) medium and 3) major or large
1. Minor-command less than 5000 ha
2. Medium-Command 5000 to 10,000ha
3. Major-Command more than 10,000 ha

Although the command of minor dams is small, their benefits are accrued in short period. The designing, planning and construction of large dams takes long time and hence there benefit is available after a very long period. There are controversies over small Vs large dams. Water from these dams is made available for drinking and other human purposes, for industries and for irrigation. Huge capital operating and administrative costs are involved in making dam water available for above-mentioned purposes. Therefore, canal water is a costly input. Few dams were constructed during British Period before Independence. But looking to the pressing needs for water large scale programmers of development of river dams were undertaken on priority basis. By now thousands of dams have been constructed, thousands of Crores of rupees have been spent and several lakhs of hectares of land has been brought under irrigation, besides providing water for drinking in cities and towns and for industrial other uses. Actual are irrigated is 12 lakh ha. In Maharashtra alone and 640 lakh ha. In India.

Well Water:-
Well is traditional source of water. Wells are mostly constructed by individual farmers from their own funds or bank loans as it does not require much technical know-how. Wells can be completed in a short period and their benefits are available immediately. The farmers have full control on the use of waste for crops. They decide what crops to grow, when to irrigate and how much water to apply. There is generally no misuse or excess use of well water and hence no spoilage of lands. The command of each well is very small (5 to 10 ha) but the number of wells is very large. Therefore total area irrigated by wells is substantial. In Maharashtra nearly 65% of irrigated is under well irrigation. Due to uncertainty of rainfall, ground water recharging and its availability in wells is uncertain. But since farmers have control on use of water, delicate crops or crops requiring frequent watering but less water at a time, are grown on well water. Fruit, vegatables and differences in cropping patterns under canal and flower crops are commonly grown on well water. There are differences in cropping patterns under canal and well irrigations.

Water requirements of crops:-
Although water is essential for crop growth, it’s requirement for each crop is definite. It may change according to the season (Kharif, Rabi or Summer) or according to soil type (light, medium and heavy) but net requirement may not change. The total water requirements, critical stages of water application and number of irrigation turns through which this water is to be given have been decided by experimentation. This information is given below:- Season & Crop Water requirement (cm) No. of turns I Kharif I Rice 50 6 ii Jowar 20 3 iii Bajri 20 3 iv Maize 30 4 v Pulses (Tur) 20 3 vi Groundnut 40 5 vii Sunflower/Soybean 25/25 3/3 viii Chilli 40 5 ix Cotton (Irri) 90 10 x Onion 40 5 xi Vegetables 40 5 II Rabi I Wheat 40 5 ii Gram 30 4 iii Groundnut 60 8 iv Sunflower 40 5 v Safflower 40 5 vi Maize (Fodders) 60 8 vii Vegetables 60 10 viii Onion 60 10 III Summer I Groundnut 80 10 ii Sunflower 60 6 iii Maize (Fodder) 80 10 iv Vegetables 80 10 v Onion 70 9 IV Perennial I Sugarcane a. Adsale 400 32 b. Suru 300 25 ii Fodder crops 200 25 (Berseme/lucern,etc) iii Banana 240 24 iv Other fruits 200 25

Irrigation Layouts:
The water requirements of different crops are different, their root systems and feeding zones are different and the soils are also of different types. Therefore, following types of layouts are used for irrigating these crops. 1. Ridges & furrows - e.g. Sugarcane and different types of vegetables, chillies. 2. Long beds (Saras) - e.g. Wheat, Jowar, Bajra, Groundnut, Maize, etc. 3. Small beds - e.g. Onion, Potato. 4. Rings - e.g. Gourds (Vine crops) 5. Raised beds - e.g. Raising seedlings of various crops. 6. Trenches - e.g. grapes, banana

Preventing Water Losses:-
Water losses from the fields can be prevented by various techniques such as -
1. Cultural methods.
2. Minimum weeds or no weeds.
3. Mulching - Straw mulch, black plastic film mulch, pebel mulch, etc.