Paddy crop is strongly influenced by water supply. Water should be kept standing in the field throughout the growth period. In water scarcity areas, saturated soil in a chemical reduced stage is desirable. The characteristics of flooded soil which are conducive to high yields are (i) greater availability of nurtients such as phosphorus, iron and manganese, (ii) suppression of weed competition, (iii) elimination of moisture stress as a limiting factor, (iv) micro-climate favourable to crop production. In order to achieve the above mentioned objectives, the following practices should be adopted.
- Raise paddy nursery at a place where assured irrigation is available.
- Level the fields uniformly
- Where irrigation facilities are not available, store all the rain water in paddy fields by making 25 to 30 cm raised bunds.
- Maintain about 8-10 cm of water level in the fields at puddling time and subsequently depth of ponded water may be maintained throughout the growing period.
- It is desirable to control the water in the individual fields.
- Withhold water for few days till the seedlings have established.
- In areas of low temperature of irrigation water, the practices of continuous running water from field to field should be stopped and water should be kept ponded in the fields at 4-5 cm level.
- Drain-off water for about 2 days prior to the application of fertilizers.
- Drain-off water completely for 5 to 7 days following tillering and flowering stages. This helps to remove the toxic substances like sulphides and regulates oxygen supply to roots.