氨基酸对三种石灰性土壤磷素有效性的影响及其作用差异机制

磷是农作物生长发育的必需元素，为了保证我国粮食安全，提高农作物的产量，提高磷肥有效性十分重要。本试验选取三种石灰性土壤（郑州潮土、周口褐土和昌图风沙土）为研究对象，通过90天的室内埋土试验，在三种土壤中研究氨基酸与磷酸一铵配施对提高土壤中磷肥有效性的影响。研究结果表明:（1）氨基酸在三种石灰性土壤中均能够提高磷酸一铵的有效性，郑州潮土、周口褐土和昌图风沙土的磷肥有效性与单施磷酸一铵相比分别提高了21.16%、10.87%和4.06%；（2）氨基酸的加入降低了土壤中Ca₂-P向Ca₈-P或其他难溶形态磷的转化，通过对三种土壤进行相关性和通径分析的得出在郑州潮土、周口褐土和昌图风沙土中主要决策因子是Ca₂-P，决策系数分别到达了0.836、0.946和0.712（P < 0.05），郑州潮土、周口褐土主要限制因子是Ca₈-P，决策系数分别为?0.066、?0.401（P < 0.05），昌图风沙土主要限制因子是Ca₈-P和Fe-P，决策系数分别为?0.080和?0.105（P < 0.05）；（3）氨基酸的加入能够降低三种石灰性土壤的pH和CaCO₃含量，有利于提高磷肥有效性；（4）通过对三种土壤的有效磷含量与土壤理化性质进行冗余分析，得出有机质（SOM）和碳酸钙 （CaCO₃）是影响磷肥在三种土壤中固定速率差异的主要原因，SOM和CaCO₃分别解释了有效磷含量全部变异的36.5%和25.6% （P < 0.05）。氨基酸在三种石灰性土壤中均能够提高磷肥有效性，主要途径是降低土壤的pH和CaCO₃含量，抑制Ca₂-P的快速转化。在三种石灰性土壤中，氨基酸作用有差异的主要原因是三种土壤中SOM和CaCO₃含量的差异，提高SOM，降低土壤中CaCO₃能够降低土壤对磷的固定，提高磷肥有效性。

Effects of Amino Acids on the Availability of Phosphorus and Different Mechanisms in Three Calcareous Soils

Phosphorus (P) is an essential element for the growth and development of crops. In order to ensure China’s food security and crop yields’ increase, it is very important to increase the utilization of P. In this study, three calcareous soils (such as fluvo-aquic soil in Zhengzhou, cinnamon soil in Zhoukou and aeolian sand soil in Changtu) were selected as the research objects. A 90-day indoor test of soil buried was conduct to investigate the effects of combined application of amino acids and monoammonium phosphate (NH₄H₂PO₄) on the improvement of phosphorus fertilizer utilization in the three soils. The results showed that: (1) Amino acids could increase the utilization rate of NH₄H₂PO₄ in all three soils. Compared with the single application of NH₄H₂PO₄, the utilization rate of NH₄H₂PO₄ from fluvo-aquic soil in Zhengzhou, cinnamon soil in Zhoukou and aeolian sandy soil in Changtu increased by 21.16%, 10.87% and 4.06%, respectively; (2) The addition of amino acids reduced the conversion of Ca₂-P to Ca₈-P or to other insoluble forms of phosphorus in soils. Through correlation and path analysis of the three soils, it was found that the dominated factor in soils was Ca₂-P, with a decision coefficient (P < 0.05) of 0.836 (fluvo-aquic soil in Zhengzhou), 0.946 (cinnamon soil in Zhoukou), and 0.712 (aeolian sandy soil in Changtu), respectively. Moreover, the main limiting factor of fluvo-aquic soil in Zhengzhou and cinnamon soil in Zhoukou was Ca₈-P, with a decision coefficient (P < 0.05) of ?0.066 and ?0.401, respectively. While the main limiting factors of aeolian sandy soil in Changtu were Ca₈-P and Fe-P, with a decision coefficient (P < 0.05) of ?0.080 and ?0.105; (3) The addition of amino acids could lower the pH of the three soils, which was beneficial to increase the utilization rate of phosphate fertilizer; (4) According to the redundancy analysis of available P and soil physical and chemical properties of the three soils treated by amino acids after 90 days, organic matter (SOM) and calcium carbonate (CaCO₃) were the main reasons, which were explained 36.5% and 25.6% of the total variation of available P (P < 0.05), respectively. In short, the amino acids could increase the utilization of phosphate fertilizer in the three calcareous soils. The main way was to inhibit the rapid conversion of Ca₂-P by reducing soil pH and CaCO₃. In the three calcareous soils, the differences in the role of amino acids were mainly by the differences in the contents of SOM and CaCO₃, showing increasing SOM and reducing CaCO₃ in the soils could decrease the fixation of P in soil thereby increase the utilization of P fertilizer.