Ammonia volatilization from nitrogen fertilizers with and without gypsum

Ammonia volatilization with and without gypsum incorporation was measured i n Gujranwala soil (Udic Haplustalf) in an incubation study using different nitrogen fertilizers e.g. urea, ammonium sulphate GAS), calcium ammonium ni trate (CAN), and urea nitrophos (UNP). Nitrogen from different fertilizers was applied at the rate of 200 mg N kg(-1) to two sets of soils in plastic bags (1.0 kg soil) and plastic jars (0.5 kg soil). Soil moisture was mainta ined at field capacity. Application of urea increased soil pH to 9, three h ours after its addition. Ammonium sulphate and calcium ammonium nitrate had little effect on soil pH. Ammonium volatilization losses from fertilizers were related to the increase in soil pH caused by the fertilizers. Conseque ntly maximum losses were recorded due to application of urea. Losses throug h ammonia volatilization were significantly lower with AS, CAN and UNP in d escending order. Gypsum incorporation significantly; reduced the losses. Th erefore, application of gypsum to soil before urea may substantially improv e N use efficiency for crop production by reducing N losses.