钙基膨润土辅助对堆肥及土壤Cu、Zn形态转化和白菜吸收的影响

通过好氧堆肥和盆栽试验，探究不同比例（0%、2.5%、5%、7.5%和10%）钙基膨润土（CB）辅助猪粪堆肥过程及盆栽土壤中Cu、Zn形态的变化，并分析CB对白菜生物量及吸收Cu、Zn的影响.结果表明，在所有处理的堆肥过程中，可交换态Cu、Zn的分布比例逐渐下降，而可氧化态和残渣态逐渐升高，与0% CB相比，2.5%~10% CB可使堆肥结束时生物可利用态（可交换态和可还原态）Cu、Zn的分布比例分别降低19.84%~48.90%和4.94%~16.39%，并以10% CB的效果最为显著.进而开展的盆栽试验显示，施用堆肥后，土壤有机质和EC显著升高，而pH有所下降；CB辅助堆肥能够促使土壤EC的降低及pH的升高，稳定土壤有机质.与纯土处理相比，施用堆肥可显著提升白菜的生物量，且10% CB处理中的生物量最大（6.51 g·盆^-1±0.34 g·盆^-1）.施用CB辅助堆肥后，种后土壤中生物可利用态Cu含量增加；但各处理中可交换态Zn含量分别降低38.91%、43.69%、46.02%、45.12%和54.65%.白菜在施用堆肥后Cu、Zn的吸收量显著降低，并且随着CB辅助比例的增加Zn的吸收量随之减少，而Cu的吸收量呈增加趋势.本研究表明，钙基膨润土能够降低堆肥过程中Cu、Zn活性，在堆肥施入土壤后仍对Zn有持续的固定作用，同时CB辅助堆肥可以提高白菜的生物量，减少重金属Zn在白菜中的累积，并以10% CB的效果最为显著.

Effect of Ca-bentonite on Cu and Zn Forms in Compost and Soil, and Their Absorption by Chinese Cabbage

Aerobic composting was conducted to evaluate the effects of the different ratios (0%, 2.5%, 5%, 7.5%, and 10%) of Ca-bentonite (CB) on the speciation of Cu and Zn during pig manure composting, while pot experiment was performed to investigate the role of CB-added compost on the bio-availability of Cu and Zn to Chinese cabbage and its biomass. The results showed that the exchangeable fractions of Cu and Zn decreased, while their oxidized and residual fractions gradually increased during composting; CB addition reduced the distribution ratios of bio-available Cu and Zn in mature compost by approximately 19.84%-48.90% and 4.94%-16.39%, compared to those in the 0% CB-added treatment, and the best result was found in the 10% CB-added treatment.. Meanwhile, the pot experiment confirmed that the addition of compost considerably increased soil organic matter (OM) and electrical conductivity (EC) but decreased soil pH value. On the contrary, the application of CB effectively decreased EC and increased soil pH but inhibited OM mineralization in soil as compared to non-amended treatment. While addition of compost significantly increased plant dry biomass as compared to that with soil alone, maximum biomass was obtained(6.51±0.34) g·pot^-1] in 10% CB-added compost. After the application of CB-added compost, the contents of the bio-available factions of Cu in the harvested soil increased, while the contents of the exchangeable fractions of Zn decreased by 38.91%, 43.69%, 46.02%, 45.12%, and 54.65%, respectively. The absorption of Cu and Zn by Chinese cabbage was considerably reduced after the application of compost, while the uptake of Zn in the plant declined as the CB rates increased, and the absorption of Cu increased. The study indicated that 10% CB addition could significantly reduce the bioavailability of Cu and Zn in compost, and also showed a continuous effect on restricting the bioavailability of Zn after land utilization. Meanwhile CB amendment enhanced Chinese cabbage biomass and reduced the uptake of Zn.