WATER AND NITROGEN NEEDS OF WHEAT (TRITICUM-AESTIVUM) IN SODIC SOIL

A field experiment was conducted during the winter season of 1990-91 a nd 1991-92 to evaluate the effect of irrigation and nitrogen on wheat (Triticum aestivum L. emend. Fiori & Paol.) grown on sodic soil. Frequ ent irrigation at 1.2 irrigation water depth : cumulative pan evaporat ion (IW : CPE) ratio (IW = 50 mm) with 180 kg N/ha gave the highest gr ain yield of wheat (4 091 kg/ha). The rate of water use per day increa sed with advance in age, reaching the peak value of 3.58 mm/day during 60-90 days and was higher in irrigated crop (4.97 mm/day) under 1.2 I W : CPE ratio than in the unirrigated (1.89 mm/day). More moisture was extracted from deeper layer (60-120 cm) under unirrigated condition t han under irrigated condition. N application increased the moisture de pletion from 0-60 cm soil depth. The nitrate-nitrogen content of the s oil was more under unirrigated condition than under irrigated one. It decreased with increase in irrigation frequency, but increased with hi gher level of N. At harvest, it was higher in 15-30 cm than in 0-15 cm soil layer under 0.9 and 1.2 IW : CPE ratios.