黄土高原旱地磷肥残效及利用率研究

连续4年的冬小麦定位试验证明，旱地施磷（P₂O₅）量在75～300kg/hm²时，小麦的增产率基本随磷肥用量的增加而提高，但P₂O₅的增产作用和磷肥利用率却随磷肥用量的增加而降低；磷肥不仅当季增产显着，而且后效明显，第1季施磷后在第4季P₂O₅施用量75kg/hm²的增产率为53.9%，施用量150kg/hm²的增产率为64.3%，施用量300kg/hm²的增产率为109.6%，1kgP₂O₅累计增产小麦依次为38.7，25.5，15.1kg，分别为第1次效果的2.26倍、2.38倍和2.85倍。磷肥的利用率随用量增加而降低，当季利用率低，累计利用率高，施P₂O₅75～300kg/hm²时，当季利用率为12.0%～4.3%，累计利用率达25.0%～12.4%。

Study on Residual Effect of Phosphorus Fertilizer and Use Efficiency in Dryland of Loess Plateau

Long term oriented experiment shows that if applying P (P₂O₅) is 75~300 kg/hm² in dryland through planting winter wheat for 4 years, increasing ration is enhanced with use dose, but increase function of P₂O₅ and use ratio of P fertilizer fall with add of application.Not only increases Phosphorus fertilizer the yield of temporal season but also later efficiency is evident.Increase production ration of applying P 75 kg/hm², 150 kg/hm², and 300 kg/hm² in fourth season is respectively 53.9%, 64.3%, and 109.6% after applying P in the first season, so increase yield of 1 kg P₂O₅ is respectively 38.7 kg, 25.5 kg, and 15.1 kg, which are 2.26, 2.38 and 2.85 times of first applying P.Use ration of P fertilizer is low in that season, but accumulation use ration is high, such as use ration is 12.0% ～4.3% in that season and accumulation use ration 25.0%～12.4% with P 75～300 kg/hm².