施用常规磷水平的80%可实现玉米高产、磷素高效利用和土壤磷平衡

【目的】近年来，黑土有效磷含量呈逐年增加趋势。研究田间条件下，黑土的玉米产量及构成因素、磷素的吸收利用和土壤有效磷含量变化对不同施磷水平的响应，为黑土区的磷肥合理施用和地力培育提供理论依据。【方法】在土壤有效磷初始含量较高（30.15 mg/kg）的吉林公主岭黑土区，进行了3年的田间试验，以不施磷肥为对照（P0），设置当地磷肥用量的80%（P₂O₅ 60 kg/hm2，P60）和当地施肥量（P₂O₅75 kg/hm2，P75），研究不同施磷水平对玉米产量及产量性状、磷素吸收分配、磷肥利用效率的影响，并分析了土壤表观磷平衡和有效磷含量的变化。【结果】连续三年（2009~2011年）不同施磷水平下，玉米的产量随施磷水平的提高而增加，到第三年施磷处理的玉米产量显著高于不施磷处理，随施肥年限增加，P60与P75处理的增产效应差距缩小。P75处理吸收的磷素高于P60，但分配到籽粒中的磷素比例逐年下降，说明其吸收的磷素未高效转移到籽粒中，存在磷素奢侈吸收现象。两个施磷处理的磷肥利用率均为P75>P60，磷肥偏生产力均为P60>P75，说明P60处理中土壤基础养分和施入磷肥的综合效应更大。2009~2011年，土壤的表观磷平衡，P0处理一直处于亏缺状态，P60和P75处理均有盈余。P0、P60和P75处理的土壤有效磷的变化量为-15.4、-0.19和3.50 mg/kg。有效磷含量变化与表观磷盈余量呈极显著线性正相关，土壤P盈余每增加100 kg/hm2，有效磷含量增加9.6 mg/kg。【结论】在有效磷含量较高的黑土区，适当减少磷肥用量（60 kg/hm2 P₂O₅，比传统施肥减少20%）能获得与传统施磷相当的产量，维持土壤适宜的有效磷含量和供磷水平，并能保证磷肥的高效利用。可以考虑将P₂O₅ 60 kg/hm2作为黑土区的推荐施磷水平。

Application of 80% of routine phosphorus rate to keep high yield and P efficiency of maize and P balance in soil

Objectives]Soil Olsen P contents show an increasing trend in black soil in recent years. In order to provide theoretical basis for rational amount of applied phosphorus and soil fertility improvement, this study tried to investigate the response of maize yield, component factors, nutrient absorption and distribution, phosphorus use efficiency and the change of soil Olsen P to P fertilizer rates in black soil under field conditions.Methods]A 3-year field experiment was conducted in Gongzhuling City, Jilin Province, where the initial soil Olsen P content was as high as 30.15 mg/kg. The change of maize yield and component factors, P absorption and distribution, P use efficiency, the apparent P balance and change of soil Olsen P were analyzed under the P2O5 application rate of 0, 60 and 75 kg/hm2.Results]The results showed that the application of phosphorus fertilizer increased the maize yields, in 2011 the yields in P60 and P75 treatments were significantly higher than in P0, but the yield gap between the P60 and P75 treatments decreased with years. More P was absorbed in P75 than in P60, but the proportion was decreased in the P75, which indicated that the P absorption was not transported to grain effectively and there was luxury absorption of P. The P use efficiency in P75 was higher than in P60, while the partial factor productivity of P was higher in P60 than in P75 in all three years, which indicated that the combined effect of basic soil nutrient and applied P was larger in the P60. From 2009 to 2011, the apparent P balance in P0 was in deficient state, while those in P60 and P75 were surplus. The change in soil Olsen P was positively linearly correlated with the P budget (P<0.01), for every increment of 100 kg/km2 of P surplus, the corresponding increase in soil Olsen P was 9.6 mg/kg.Conclusions]In the black soil with relatively high Olsen P content, application of 20% less of the routine amount of P rate (P2O5 60 kg/hm2) will meet the demand for high yield, maintains the soil Olsen P content and effective supply ability of phosphorus, and increase the phosphorus utilization efficiency.