不同降水年型下长期施肥的小麦产量效应

合理施用氮磷化肥是提高小麦产量的主要措施之一.用二元二次回归方程探讨不同降水年型下的氮磷优化用量,为黄土旱塬小麦施肥提供依据.结果表明: 不同降水年型小麦最高产量所需要的氮磷肥用量不同,平水年小麦最高产量4229 kg·hm^-2时的氮用量为172 kg·hm^-2、磷用量164 kg·hm^-2;丰水年最高产量4896 kg·hm^-2时,施氮量较平水年多2%,为175 kg·hm^-2,施磷量较平水年少约1%,为162 kg·hm^-2;干旱年施氮磷量较平水年少约16%和5%,当施氮磷量超出这个用量时,小麦产量开始呈下降趋势.不同降水年型最佳经济施肥量不同,平水年最佳经济施氮量为161 kg·hm^-2、施磷量为151 kg·hm^-2;而干旱年的最佳氮、磷量为135、143 kg·hm^-2;丰水年最佳经济氮、磷量分别较平水年多约3%和1%,为167、153 kg·hm^-2.最佳经济氮磷施用量比最高产量氮磷施用量低6%~8%.实际生产中建议氮磷减少10%的用量,提高肥料利用率,获得最大经济效益.

Effect of long-term fertilization on wheat yield under different precipitation patterns

Rational application of nitrogen and phosphorus is one of the main pathways to enhance wheat yield. The optimum dosage of nitrogen and phosphorus used in different precipitation patterns was studied using the binary quadratic regression equation, which could provide a basis for fertilization of wheat in Loess Plateau. The results showed that the amount of nitrogen and phosphorus ferti-lizer required for the maximum yield was dependent on precipitation patterns. The maximum wheat yield in normal years was 4229 kg·hm^-2, with the dosage of nitrogen and phosphorus applied being 172 and 164 kg·hm^-2, respectively. The maximum wheat yield in wet years was 4896 kg·hm^-2, with the dosage of nitrogen fertilizer being 2% more than that in normal years, 175 kg·hm^-2, and the dosage of phosphorus was about 1% less than that in normal years, 162 kg·hm^-2. The application of nitrogen and phosphorus in dry years was about 16% and 5% less than that in normal years. When the dosage was more than that, wheat yield began to decline. The economic optimum fertilization differed in different precipitation patterns. The economic optimum nitrogen and phosphorus fertilization in normal years was 161 and 151 kg·hm^-2, while in dry years it was 135, 143 kg·hm^-2, respectively. The economic optimum fertilization in wet years was about 3% and 1% more than that in normal years, 167 and 153 kg·hm^-2. The economic optimum fertilization was 6%-8% lower than optimum amount of fertilization. In actual production, it was recommended to reduce the amount of nitrogen and phosphorus by 10% in order to improve the utilization rate of fertilizer and get the maximum benefit.