钾肥对铅的植物有效性的影响

采用室外盆栽模拟试验，研究铅及铅、镉复合污染土壤中，钾肥（K2SO4）不同施用水平下小麦干重及小麦植株体内铅的积累与分布，从小麦根际、非根际土壤pH值、铅形态分布的角度阐述了钾肥对铅的影响。结果表明，施用钾肥可促进小麦干重增长，随钾肥施用水平的提高，小麦植株不同部位铅的浓度逐渐降低，吸收系数逐渐降低，表明增施钾肥可降低铅的植物有效性。钾肥的施用使根际、非根际土交换态铅先略有上升而后下降，碳酸盐态铅降低，铁锰氧化物结合态铅上升，对有机质硫化物态、残渣态铅的影响很小，由于钾肥对根际、非根际土壤pH值影响并不显著，铅形态的上述变化并非由土壤pH变化所引起，而是K^＋,SO4^2-与Pb交互作用的结果，但有些机理还尚待查明。

Effects of potash fertilizer on phytoavailability of lead

Pot experiments were conducted to study the effects of different levels of potash fertilizer(K2SO4) on the dry weight,accumulation of lead of wheat in single Pb and combined contamination of Pb and Cd soils.The influence of potash fertilizer on Pb is also expounded from the aspect of pH and distribution of Pb between rhizosphere and bulk soils.Results show that potash fertilizer can promote the dry weight of wheat.With the increasing levels of potash fertilizer,the concentrations and enrichment coefficients of lead in different parts of wheat degraded gradually,with indicates that improving the level of potash fertilizer could reduce the phytoavailability of Pb.The application of potash fertilizer led to the concentrations of exchangeable Pb rising and then descending weakly specifically adsorbed Pb descending and of Fe-Mn oxides bound Pb assending.The content of Pb in organic matter complexed and residual fractions was little influenced by potash fertilizer.Potash fertilizer had no prominence influence on pH of rhizosphere and bulk soils and the changes in the distribution of Pb in soils were induced by the interaction between K ,SO42-and Pb,while some mechanism still need to be found out.