Response of sewage-irrigated wheat (Triticum aestivum) to level and timing of nitrogen application

A study was conducted during the winter season of 2001–02 and 2002–03 at sewage-irrigated farms in Sirsa (Haryana) for evaluating the optimal dose and time of application of nitrogenous fertilizers to wheat (Triticum aestivum L. emend. Fiori & Paol.). Seven fields, 0.4 ha each, were selected along the sewage drain during 2001–02 on the basis of variations in the build-up of organic matter (0.89–3.44%) vis-à-vis nitrogen (available N 191–413 kg/ha). Eight treatments consisting of different doses of fertilizer N (0, 60, 120 and 180 kg/ha) and times of application of 75 kg N/ha (50% of recommended N for normal soils of the area). First trial was repeated on eight other farmers’ fields during 2002–03 with 1.19–3.01 per cent organic matter. The observations on wheat yield showed improvement in basic productivity of soils with accumulation of organic matter up to 2 per cent. The latter also defined the optimal doses of nitrogen, computed to be 55–119 kg/ha. Distinct possibility of producing high yield with reduced addition of N fertilizer was found in the immediate vicinity of the sewage-disposal sites. Under reduced doses, wheat responded better to a booster basal dose, followed by at crown-root initiation. Thus the recommendations to the farmers on the use of N fertilizers should be different for waste water-irrigated soils. The reduced use of nitrogen should further help in minimizing the pollution problems by NO₃-N, especially with shallow ground waters.