Comparison of wheat yield under uniform and variable rates of fertilizer on spatially-eroded land

Field studies were made to determine the yield and quality of wheat at different landscape positions managed with uniform vs, variable rates of nitrogen (N). A moderately-eroded wheat farm near Thana (Swat) was divided into four parallel transects which were further divided into two strips each. On one strip, fertilizer was applied at a uniform rate of 120 kg N ha(-1), and along the other strip, three different rates of N (80, 1 10, and 125 kg N ha(-1)) were applied to match the crop productivity patterns. A basal dose of 90 kg P2O5 and 60 kg K2O ha(-1) was applied to the whole field. Soil profiles were described for the three different zones, i.e., low, medium, and high productivity zones. Soil in Zone I was Pirsabak, moderately deep variant, and in Zones II and III, Badwan soil series. Although uniformly fertilized strip (120 kg N ha(-1)) received 40 and 10 kg N ha(-1) more than Zone I and Zone II (variable management strategy), there were no significant differences in yield. The differences in three fertilizer management zones were due to differences inmoisture content at sowing, infiltration rate, lime content, steepness, and soil depth. Test weight of wheat grains was not significantly affected. Protein content of wheat was significantly higher in variably fertilized strips than in uniformly treated strips. Based on these results, it is suggested that farms with spatially-variable soils should be fertilized according to the crop productivity and soil fertility patterns.