Field Evaluation of Yield Response of Winter Wheat to Uniformity of Sprinkler Applied Fertilizer

The influence of uniformity of sprinkler water and fertigation on crop yield is fundamentally important for determining the target uniformity. Field experiments were therefore conducted to evaluate the influence on winter wheat yield of the uniformity of sprinkler applied water and fertilizer. Christiansen uniformity coefficient (CU) was used in this article. Three experimental plots, designed as low uniformity, medium uniformity and high uniformity, were used in the field experiments. Catch cans were placed above and below canopy in a 3 m×3 m grid for each plot. The amounts of water and the concentrations of fertilizer solution caught in the cans were measured after fertilizer was applied. Total nitrogen of plant stem for each grid was also tested when winter wheat was harvested. The experimental results showed that the uniformity of fertigation increased with sprinkler water uniformity. Christiansen uniformity coefficients for fertilizer concentration caught in the cans is usually higher than CUs of water application. The distributions of both fertilizer and water applied through sprinkler system can be represented by an approximate similar normal distribution function. Field experiments also demonstrated that the uniformity of sprinkler-applied water and fertilizer has insignificant effect on the yield of winter wheat grown in north China plains for the studied CU range of 62%～82%.