Effect of three nitrogen fertilizer sources on wheat biomass and grain yield in irrigated soils

A field experiment conducted for two cropping seasons (1984-85) and (1985-86) on calcareous soils. Labelled 15N ammonium nitrate, ammonium sulphate and urea, were compared as sources of nitrogen (N), for wheat in southern west of Syria using broadcasting application. The results showed that urea nitrogen increased the wheat yields (grain, dry matter and straw). Wheat yields were significantly affected by the forms of nitrogen during the two seasons except at tillering stage in the first season. Fertilizer N utilization and nitrogen uptake were studied. The utilization of three forms of nitrogen suggests that urea and ammonium nitrate have a better utilization than ammonium sulphate, and higher nitrogen efficiency which reflects higher yields, and the addition of phosphorus fertilizer exceeds the nitrogen efficiency. The percentages of utilization of N fertilizer forms were: 14.77 - 44.69, 15.28 - 44.14 and 18.88 - 38.77 for ammonium nitrate, ammonium sulphate and urea respectively at different growth stages, and N-uptake varied from 10.11 - 44-69, 12.02 - 44.14 and 15.31 - 38.77 KgN/ha in the same order, as in the first year, while in the second year the utilization (the efficiency) percentages and N fertilizer uptake (kgN/ha) were 48.93 - 90.93, 33.54 - 70.30 and 30.47 - 44.7 for ammonium nitrate, ammonium sulphate and urea respectively. (author). 9 refs., 1 fig., 22 tabs