CONSERVATION AGRICULTURE FOR SMALL HOLDER IRRIGATED FARMING: OPPORTUNITIES AND CONSTRAINTS OF NEW MECHANIZED SEEDING SYSTEMS: A REVIEW

Small holder farmers in irrigated agriculture believe that soil tillage is needed to maximize crop yields. However, as cropping intensity, and hence tillage intensity increases, there may be a decline in particular physical, chemical and biological properties of the soil which limit crop yield. Shortage of mechanized options suitable for small holder farmers is creating an impediment to the adoption of conservation agriculture practices that would arrest the decline in soil quality in their fields.In North western India, 30-35 hp four-wheel tractors are replacing animal-drawn ploughing in small holder plots. This speeds the tillage operation and hence the turn around time between crops, which may increase opportunities for crop intensification, but the problems associated with full tillage remain. Over the previous decade planter attachments to four-wheel tractors have been developed which permit seed and fertilizer placement with minimum to zero tillage in a single-pass. Recent tests have demonstrated that use of these implements can produce crop yields equal to or better than conventional tillage involving hand broadcasting of seed and fertilizer. Further, fuel and labor costs, seed and fertilizer inputs and turnaround time between crops can be reduced.In north western India, the introduction of customer hiring tractor operated rippers and direct seeders, originally developed for small-scale farmers is considere