Cu在黑土中形态特性分析及施用有机肥的影响

通过小麦盆栽试验研究了黑土中Cu的分布特征、动态变化及有机肥施用的影响.结果表明,无论外源Cu添加量高或低,土壤中Cu的形态均主要以可氧化态为主,所占比例为40.4%～65.0%.随着外源Cu添加量的增加,弱酸溶解态Cu所占比例稍有增加,可还原态Cu含量及其所占比例均显著增加,残渣态Cu所占比例显著降低,可见外源Cu添加量的增加能提高土壤中Cu的生物有效性.与2009年相比,黑土中弱酸溶解态Cu的分配比例在2010年迅速下降,而残渣态Cu的比例显著上升,表明随着时间的变化Cu的稳定化作用不断加强,生物有效性降低.1%有机肥施用明显降低了Cu的移动性,弱酸溶解态Cu的下降幅度和残渣态Cu的上升幅度都明显增大.低剂量Cu(<200mg·kg-1)可促进小麦的生长,使其生物量增加,但高剂量Cu(高于600mg·kg-1)对小麦有显著的毒害作用.且当Cu添加量很高时,小麦对Cu的吸收量在2010年高于2009年,表明Cu在黑土中的短期稳定作用对Cu的生物有效性和作物吸收并未产生显著影响.

Forms and stabilization of Cu in Mollisol and effect of manure applications

The form distribution and temporal dynamics of Cu in Mollisol as well as the effect of manure applications were investigated through wheat pot experiments. The results showed that the oxidable fraction accounted for the largest proportion (40.4%~65.0%) of Cu regardless of the addition amount. With increasing Cu addition, the proportion of acid-extractable fractions increased slightly and that of reducible portion increased significantly. In contrast, that the fraction of residuals decreased significantly, suggesting the increased bioavailability of Cu with increasing Cu input. Compared with 2009, the proportion of acid-extractable fraction declined while that of residual Cu increased at all levels of Cu addition, indicating that Cu tended to be stabilized in soil and thus its bioavailability declined. The application of manure at 1% rate (based on dry matter) declined the mobility of Cu significantly compared to that at 3% rate. The proportion of reducible fraction declined to higher degree while that of residual fraction increased more significantly. The low concentration of Cu (<200 mg·kg^-1)can promote the growth of wheat to increase the biomass, but the high concentration of Cu (>600 mg·kg^-1) was evidently toxic. Compared with 2009, the uptake of Cu in wheat increased in 2010, thus the short-term stabilization (for one growing season) of Cu in soil did not exhibit significant influence on the Cu bioavailability in soil as well as the uptake by wheat.