小麦地土壤水溶性有机物动态及对土壤铜镉活性的影响:田间微区试验

Dynamics of Dissolved Organic Matter and Its Effect on Copper and Cadmium Activity in the Contaminated Wheat Soil:Field Micro-Plot Trials

采用田间微区试验研究秸秆与化肥配施（SM），猪粪与化肥配施（PM）以及纯化肥（F）3种不同施肥处理下土壤水溶性有机物（DOM）在小麦不同生长阶段的动态变化情况及对土壤中重金属Cu、Cd活性的影响，也研究了上述处理麦田土壤DOM在不同土层中的分布．结果表明，随着小麦的生长各处理土壤DOM均呈不断下降的趋势，特别是在小麦拔节期以前下降趋势更为明显．与施化肥相比，施用有机肥后土壤中DOM含量有明显增加．施用有机肥后土壤DOM以0—20cm层最高，越向下含量越低．在供试的旱地土壤中DOM主要迁移深度为40cm，少量DOM可迁移到60cm．在小麦拔节期之前，各处理根际DOM含量的动态变化趋势和与之对应的非根际DOM变化趋势基本一致，没有显著差异．但之后随着小麦越冬结束，新陈代谢强度迅速增大，其根际DOM含量也迅速增加，并在抽穗期达到最大，随后逐渐下降．试验还发现，在小麦生长过程中根际及非根际土体中土壤交换性cu的变化与相应的DOM变化趋势极其相似，对3个处理根际和土体共60个土壤样本的DOM与交换性Cu的相关分析表明，二者呈极显著直线相关，说明DOM对土壤Cu的活化有明显促进作用．土壤中Cd的活化虽也受DOM的促进，但其影响不如对Cu那样显著．显然，在重金属污染的旱地土壤中，在当季大量施用新鲜的有机肥可能有增加重金属污染的风险．

Studies were carried out to investigate effect of application of straw manure, pig manure, and pure fertilizer on dynamics of dissolved organic matter （DOM） as well as copper and cadmium activity in the soil cultivating wheat by field micro-plot trials. Also the distribution of DOM in the different depth of soil was studied. The results showed that the concentration of DOM in three treated soils decreased with wheat growth, especially before the wheat joiuting stage. Compared with the control treatment without the addition of organic manures, the concentration of DOM in the orangic manure-treated soils increased drastically. The concentration of DOM was highest in the depth of 0 to 20 cm and decreased with depth. Meanwhile the mainly transference depth of DOM was 40 cm and a little of DOM can transfer to the depth of 60 cm. Before the wheat joiuting stage, the concentration of DOM in rhizosphere soil was consistent with that in the bulk soil, and increased drastically after that period. It reached the maximum in heading stage then decreased gradually. The study also observed that the dynamic trend of exchangeable copper in rhizosphere and bulk soil was highly similar to the corresponding DOM. Also there was a significant correlation （ r = 0.672, n = 60） between the concentration of DOM and exchangeable copper in three treatments of total 60 samples. The result showed that the activity of soil copper could be accelerated by DOM while cadmium not obviously.