长期不同施肥措施对土壤铜、锌、镉形态及生物有效性的影响

为研究长期不同施肥措施对典型土壤中铜、锌、镉形态分布特征及生物有效性的影响,采用BCR连续提取法测定了黑土、潮土和红壤在20多年不同施肥措施(不施肥、施化肥、化肥有机肥配施)下土壤中Cu、Zn、Cd形态的含量。结果表明,黑土施用磷肥提高了Cu、Zn的酸提取态和氧化物结合态比例,施用有机肥增加了土壤Cu、Zn的酸提取态和有机结合态比例,降低了Cd的有机结合态比例;潮土单施化肥或配施有机肥均能提高酸提取态、氧化物结合态和有机结合态Zn比例;红壤施磷肥提高了Zn的酸提取态和有机结合态比例,施有机肥提高了Cu、Zn氧化物结合态和有机结合态比例。对作物籽粒和秸秆Cu、Zn、Cd浓度与其在土壤中各形态含量作逐步回归分析表明,黑土中Cu、Zn、Cd的生物有效态以酸提取态为主;潮土中Zn、Cd的生物有效态以氧化物结合态和有机结合态为主;红壤中土壤酸提取态、氧化物结合态和有机物结合态Cu、Zn、Cd都具有一定的生物有效性。Cu、Zn、Cd总量和EDTA-可提取态是黑土和红壤重金属形态的主要影响因子。

Influence of Different Long-term Fertilization Practices on Fractionations and Bioavailability of Cu, Zn, and Cd in Soils

The purpose of this study was to investigate the effects of different long-term fertilization practices on fractionations and bioavailability of Cu, Zn, and Cd in different soils. BCR extraction procedure was used to determine the fractionations of Cu, Zn, and Cd in soil samples collected from black soil, fluvo-aquic soil and red soil under different fertilization practices i.e. CK, NK, NPK, and NPKM for more than 20-years. In black soil, application of P fertilizers increased the ratios of acid extractable and reducible fractions of Cu and Zn, while organic manures increased the ratios of acid extractable and organic-bonded Cu and Zn, but reduced the proportion of organic-bonded Cd. In fluvo-aquic soil, applying NPK or NPKM increased the proportions of acid extractable, reducible and organic-bonded Zn. In red soil, P fertilizer application increased portions of acid extractable and organic-bonded Zn, and manure addition increased fractions of reducible and organic-bonded Cu and Zn. Stepwise regression analysis between the content of heavy metals in crops and different fractions in soils indicated that the bioavailable fraction of Zn, Cu, and Cd was primarily acid extractable factions in black soil, and acid extractable, reducible and organic-bonded fractions in red soil. In fluvo-aquic soil, reducible and organic-bonded Zn and Cd were most bioavailable fractions. The total and EDTA extractable Zn, Cu and Cd profoundly influenced their fractionations in black and red soil.