Introduction to major field crops (1+1)

Water Management

Although it is generally assumed that rice requires an abundant supply of water, it can be cultivated with the same supply of water as other cereals and the distinguishing feature lies in the fact that unlike other cereals it can tolerate standing water or swampy condition for its growth. Rice in not an aquatic plant and does not necessarily need to be grown under inundated conditions. S.R.I. advocates growing rice plants with sufficient but never excess water so that the roots do not suffocate and degenerate and the agronomic management aims at alternate wetting and drying management. Intermittent irrigation helps to increase the root activity which is closely related to carbon assimilation. This also prevents various diseases and root rot induced by the excessive reductive conditions of the soil.

Maintain water at just soil saturation level by intermittent light irrigation (1-2 cm) coinciding with appearance of fine hair cracks (alternate wetting and drying). However, maintain thin film of water while operating the weeder and same water is retained for weed incorporation. Provide sufficient drainage channels to drain the excess water and also to avoid submergence. Maintain shallow submergence (2-3 cm) from panicle initiation to maturity. Dry the field completely about 10-15 days before harvest.

Weed Management
Weed growth is generally more in S.R.I. due to wider spacing and alternate wetting and drying. Effective and timely weed management is crucial for the success of S.R.I. Adopt invariably mechanical weeding so as to incorporate the weeds and to provide aeration to soil. Weeding should be done from 10 days after transplanting using suitable mechanical weeder and perform at least four weedings at an interval of 10 days. Manual weeding may be taken to remove weeds which are not incorporated by the weeder.

Use of mechanical weeder in S.R.I. not only remove the weeds but also incorporate them into the soil thereby adding organic matter to the soil. In addition, it does intercultural operation which results in aeration to roots and some earthing up action also. This earthing up results in formation of new roots above the original soil level and also reduces lodging problems.

Fig: Rotary weeder. Fig: Motorised weeder.

Fig: Weeding.