Study on Commercial Efficiency of Nitrogen Fertilizer and Fertilizer Distribution Among Growth Stages of Winter Wheat

The dispersal field fertilizer experiments, adopted orthogonal design and simplex barycentric design,were conducted in 7 counties in sandy region of Henan Province during 1990～1995 to investigate the relationship between nitrogen fertilizer efficiency of winter wheat and precipitation,organic matter content of soil, and the rate of manure and phosphate fertilizer applied and nitrogen fertilizer distribution among growth stages of winter wheat. The results showed that marginal efficiency of nitrogen fertilizer on winter wheat decreased with the increase of N application rate. When other factors were at medium rate,the application rates of nitrogen fertilizer for the maximum yield and the maximum commercial efficiency of fertilizer were 268 kgN/hm 2 and 213 kg N/hm 2 respectively, correspondingly the yields were 4 575 kg/hm 2 and 4 556 kg/hm 2 respectively. The marginal efficiency of fertilizer decreased with the increase of soil organic matter content and precipitation and yet increased with the dose of phosphate fertilizer and manure applied, so application of nitrogen fertilizer favoured more remarkably the region with low precipitation and poor soil, meanwhile it was the key to impliment the fertilization of combining nitrogen fertilizer with phosphate fertilizer and organic fertilizer with inorganic fertilizer. The results also showed that the optimum distribution of nitrogen fertilizer, on the basis of manure and phosphate fertilizer applied as initial dressing, among different stages should be 1/2 each between overwintering and jointing or booting stage or 1/3 each among basic dressing, overwintering and jointing or booting stage,and the yield could achieve 4932 kghm -2 ～5530 kghm -2 .