氮、磷、钾肥与酚对漂洗水稻土硅、铝、铁的活化效应

Activation effects of N,P,K fertilization and phenol on Si,Al,Fe in bleached paddy soil

本研究以四川盆地西缘茶区漂洗水稻土为供试土壤,采用浸提试验探讨尿素(N)、磷酸二氢钙(P)、硫酸钾(K)和邻苯二酚(Phy)对其硅、铝、铁的活化效应(以浸提液硅、铝、铁的浓度表征),结果表明,1)各种处理浸提液均以硅的浓度最大,铝次之,铁最小,即活化效应为硅>铝>铁;2)浸提液硅的浓度为NPK+Phy>NPK≈P>Phy>K≈CK≥N处理,说明磷肥通过磷酸根的配位吸附对其活化产生最重要的影响,同时酚类物质也通过弱酸作用促进其活化;3)浸提液铝的浓度为NPK+Phy>Phy>P≈NPK≈K≈N≥CK处理,说明酚类物质通过与游离铝形成可溶性络合物而对其活化起突出作用,同时磷肥中的钙离子和钾肥中的钾离子也能将强酸性供试土壤中大量交换性铝离子交换而活化;4)浸提液铁的浓度为NPK+Phy>Phy>K≈P≈NPK≈CK≈N处理,说明酚类物质通过络合溶铁、还原溶铁等作用对其活化做出重大贡献,同时钾肥中的钾离子和磷肥中的钙离子也将土壤胶体吸附的亚铁离子交换而活化;5)尿素对漂洗水稻土硅、铝、铁均无显著活化效应。综上所述,磷、钾肥和酚类物质是漂洗水稻土中硅、铝、铁活化的重要影响因素。

The activation effects of urea （N）, calcium dihydrogen phosphate （P）, potassium sulfate （K） and catechol （Phy） on Si, A1 and Fe in bleached paddy soil distributed in tea plantation region of west Sichuan Basin were studied by the soil extraction experiment. The results show that the concentration of Si in soil extracted solution is the highest, and the follows are A1 and Fe. The concentrations of Si in soil extracted solution are in the order： NPK ＋ Phy 〉 NPK ≈ P 〉 Phy 〉 K≈CK≥ N, which indicates that the phosphate has the most important impact on Si activation by ligand adsorption of PO34- , HPO4 2- , or H2PO4- , and the phenolic also promotes Si activation through its weak acid role at the same time. The order of A1 concentrations in soil extracted solution is, NPK ＋ Phy 〉 Phy 〉 P≈NPK≈ K ≈ N≥ CK, which indicates that the phenolic plays a prominent role in activation of A1 by formation of soluble complexes with free A1. In addition, K^＋ from potassium fertilizer and Ca^2＋ from phosphorus fertilizer could activate A1 by exchanging a large number of AI^3＋ in strongly acidic tested soils. The Fe concentrations in soil extracted solution are ranked as follows, NPK ＋ Play 〉 Phy 〉 K = P ≈ NPK≈ CK≈ N, indicates that the phenolic plays an important part in Fe activation by complexing and reduction of Fe. K^＋ from potassiumfertilizer and Ca^2＋ from phosphorus fertilizer could activate Fe through exchanging Fe^2＋ adsorbed by soil colloid as well. The urea application has no significant activation effect on soil Si, A1 and Fe. Above all, phosphate, potash and phenolics are important factors in activation of Si, A1 and Fe in bleached paddy soils.