长期施磷对旱地冬小麦产量及土壤无机磷形态的影响

目的]旱地石灰性土壤上磷肥利用率普遍较低,研究长期施用磷肥对旱地冬小麦产量及土壤无机磷形态及有效性的影响,为合理施磷提供理论依据.方法]基于2004年在陕西杨凌开始的长期定位试验,设置施P2O50、50、100、150?kg/hm2共4个施磷水平.于2009、2013、2017年小麦收获期采样、测产,并分析植株和籽...

Effects of long-term phosphorus application on winter wheat yield and soil inorganic phosphorus forms in dryland

  【Objectives】  Due to the low efficiency of phosphorus (P) fertilizer in calcareous soil, we studied the variation of soil P forms and their availability to crop under long-term application of P fertilizer, to provide a theoretical basis for optimal P application.  【Methods】  The long-term experiment, established in 2004, was located in Yangling, Shaanxi Province. The tested P₂O₅ application rates were 0, 50, 100, and 150 kg/hm2. The wheat plant samples were collected during 2009, 2013, and 2017 harvesting periods for the investigation of yield and P uptake, as well as the inorganic P forms and available P in the soil at 0–20 cm depth.  【Results】  Regression analysis revealed that the P₂O₅ application rate was 118 kg/hm2 for the highest wheat yield (5174 kg/hm2) and the highest grain P uptake (14.5 kg/hm2). When the P₂O₅ rate reached 100 kg/hm2, the Olsen-P in 0–20 cm soil layer was increased significantly by 28.9%–35.4% from 2009 to 2017, with the annual increase of 0.73 mg/kg in Olsen-P content by every 100 kg/hm2 of P₂O₅ input per year. When the P₂O₅ rate exceeded 100 kg/hm2, the Ca₂-P, Al-P, Fe-P and O-P contents in soil were increased significantly, and the Ca₂-P and Al-P kept increasing as experimental years progressed, while Ca₈-P was decreased. At more than 150 kg/hm2 P₂O₅ rate, the Ca₁₀-P were decreased significantly compared with other treatments. The decrease in Ca₁₀-P was accompanied with increases in Ca₂-P and Olsen-P. The availability of inorganic P forms descended in order: Ca₂-P>Al-P>Ca₈-P>Fe-P>O-P> Ca₁₀-P.   【Conclusions】  Without P application, there is deficit of P in calcareous soils. The Ca₂-P is mainly supplemented by Ca₈-P and Al-P. When surplus, soil P is mainly accumulated in the forms of Ca₂-P, Al-P and Ca₈-P. Based on the regression of wheat yield, P uptake and P application rate, the optimal annual P₂O₅ application rate is 118 kg/hm2.