有机物料对农田土壤肥力及镉有效性的影响

Effects of Organic Material on Farmland Soil Fertility and Cd Availability

以我国南方两种不同程度Cd污染农田土壤为研究对象,通过不同有机物料(猪粪、商品有机肥、水稻秸秆及其生物质炭)施肥处理探究了土壤肥力水平及Cd有效性的变化,并对施用有机物料情况下土壤Cd有效性与土壤养分进行了关联分析。结果表明:施用有机物料显著提高了土壤氮磷钾含量及其有效性,商品有机肥提高了土壤全氮含量,施用猪粪处理土壤的全磷和有效磷含量显著升高,商品有机肥和生物质炭明显提高了土壤全钾和速效钾含量。水稻秸秆及其生物质炭处理的轻污染土壤有机质含量均达土壤肥力1级(>40 g/kg)。与不施肥相比,施加有机物料对轻污染土壤有效态Cd含量的影响不大,但中污染土壤有效态Cd含量显著下降,最高降幅达20.00%。土壤有效态Cd含量与全氮、全磷、全钾和有效磷含量均呈显著负相关关系。轻污染土壤上施加猪粪和生物质炭处理的上海青地上部Cd含量均低于0.20mg/kg。施加商品有机肥处理两种土壤肥力综合指数最高,是其他处理的1.50倍~3.18倍,但其上海青地上部Cd含量存在较高风险。因此,针对南方Cd污染农田土壤的培肥及安全利用可考虑施用猪粪有机肥。

In this study,farmland soils with two different degrees of Cd contaminated in southern China were used to study the changes of soil fertility and Cd availability during crop growth by applying different organic manures(pig manure,commercial organic manure,rice straw and biochar),and the correlations between soil Cd availability and nutrients.The results showed that the application of organic materials significantly increased the contents and availability of soil nitrogen,phosphorus and potassium,commercial organic manure increased soil total nitrogen content,pig manure significantly increased the contents of soil total and available phosphorus,and commercial organic manure and rice straw biochar significantly increased the contents of soil total and available potassium.Soil organic matter contents of the lightly-contaminated soil treated with rice straw and biochar increased to level 1(>40 g/kg).Compared with the treatment without fertilizer,the effects of organic materials on the contents of available Cd in lightly-contaminated soil were not significant,but the contents of available Cd in moderately-contaminated soil decreased significantly,with a maximum reduction of 20.00%.The content of available Cd was negatively correlated with the contents of total nitrogen,phosphorus and potassium as well as available phosphorus.Cd contents in the aboveground of Brassica chinensis L.treated with pig manure and biochar were lower than 0.20 mg/kg.Soil nutrient index treated with commercial organic manure was the highest,which was 1.50–3.18 times of other treatments,but Cd content in the aboveground of Brassica chinensis L.had a higher risk.Therefore,the application of pig manure can be considered for the cultivation and safe utilization of Cd contaminated farmlands in southern China.