炭化玉米秸秆对棕壤磷素组分及有效性的影响

【目的】以单施化肥和普通玉米秸秆（腐熟和未腐熟）配施化肥为对照，研究炭化玉米秸秆对棕壤磷素组分及有效性的影响，分析玉米秸秆炭化还田对改善土壤磷素肥力的效果。【方法】对未腐熟、腐熟和炭化的玉米秸秆配施化肥处理（各处理均施用等量化肥，秸秆处理均按等碳量）进行室内模拟培养试验，采用Hedley修正法顺序提取测定各处理磷素组分；采用严昶生的恒温震荡吸附法测定各处理对磷素吸附解吸特性的影响。【结果】玉米秸秆配施化肥处理比无秸秆（单施化肥）处理可以明显提高土壤中全磷的含量，其提高幅度与秸秆处理所带入的磷素数量明显相关；不同处理的玉米秸秆对土壤磷素组分的影响比较明显，虽然本身有效磷含量不高，但炭化玉米秸秆施入土壤后可以明显提高土壤中碳酸氢钠无机磷及有机磷含量；施用玉米秸秆处理可以明显降低土壤对磷酸根离子的吸附量，以炭化玉米秸秆处理最为显著，玉米秸秆腐熟与否与土壤对磷酸根离子的吸附数无明显相关。【结论】施用炭化玉米秸秆还田不但可以促进土壤中磷素的有效化，而且可以减少土壤对磷的固定，提高磷肥的利用率，但也可能增强进入土壤中磷素的活动性，增大磷素的环境风险。

Influence of Carbonized Maize Stalks on Fractions and Availability of Phosphorus in Brown Soil

【Objective】 The effects of carbonized maize stalks on the brown soil phosphorus fractions and availability were studied to ascertain whether or not the carbonized maize stalks is good for soil phosphorus fertility development.【Method】 Laboratory culture technique was used to compare the difference among the carbonized, non-carbonized and decomposed maize stalks treatments (same quantity carbon application in different maize stalks treatments), and the chemical fertilizers treatment alone with same amount application of chemical fertilizer. The fractions of soil phosphorus were determined by the modified Hedley’s sequential extraction procedure. The adsorption and desorption isotherms for soil phosphorus were determined by the method of Yan Chang-Sheng with Constant temperature shaking. 【Result】 The total phosphorus content in the soil could be significantly improved by all kinds of maize stalks treatments compared with the no maize stalks (single chemical fertilizer) treatment, and the phosphorus contents increased were significantly correlated with the quantities of maize stalks added into the soil. The soil phosphorus fractions could be affected significantly by the added different maize stalks. Although the available phosphorus content was not high in the carbonized maize stalks, but the sodium bicarbonate-extractable inorganic and organic phosphorus contents could be significantly improved by application of the carbonized maize stalks. The adsorption amount of phosphate ions could be reduced significantly by the maize stalks treatments, and the impact of carbonized maize stalks treatment was the most obvious. Whether the maize stalks was decomposed or not, the change of the phosphorus adsorption quantities was not obvious. 【Conclusion】 The application of carbonized maize stalks can promote the soil phosphorus availability, reduce soil phosphorus fixations, and improve the utilization ratio of the phosphorus fertilizer, but the increasing activity of soil phosphorus may also increase the phosphorus environmental risks.