酸化猪炭对土壤中不同形态磷质量分数及相互转化的影响

通过培养试验，采用修正的Hedley磷形态分级方法，以不添加任何肥料处理为空白对照，以施加未经处理的猪炭、过磷酸钙和钙镁磷肥处理为对比，研究酸化猪炭对土壤中各形态磷质量分数及其相互转化的影响。结果表明:与对照相比，施用猪炭和酸化猪炭可使土壤电导率分别提高24%和14%，而对土壤pH值无显著影响。在施加量相同的情况下，酸化猪炭提高土壤活性磷和中稳活性磷占全磷百分比的效果优于猪炭处理；且与施磷量相同的过磷酸钙和钙镁磷肥处理无显著差异。与空白对照相比，施用酸化猪炭、猪炭和2种磷肥均可以显著（P < 0.05）提高活性磷的质量分数，且各处理之间对于活性磷质量分数的提高无显著差异；中稳活性磷占总磷的百分比提高36.2%~77.2%，其提高程度为:酸化猪炭>过磷酸钙>钙镁磷肥>猪炭；非活性磷占总磷的百分比显著（P < 0.05）下降，与活性磷和中稳活性磷所占比例均呈极显著（P < 0.01）负相关。施用酸化猪炭可以提高土壤中各形态磷的质量分数，同时把土壤中非活性磷的比例维持在较低水平。施用酸化猪炭对土壤中各形态磷质量分数及转化影响的效果与2种化学磷肥无显著差异。在农业生产中，经酸化处理的猪炭来替代过磷酸钙和钙镁磷肥具有潜在的可行性。

Concentration and fractionation of phosphorous in soils with acidulated pig biochar

To determine the effect of addition of acidulated pig biochar on phosphorus (P) availability and fractionation in soils, an incubation experiment was carried out using a randomized complete block design having five treatments:an untreated control(ck), acidulated pig biochar, raw pig biochar, single superphosphate, and calcium magnesium phosphate, with three replications. Each amendment was mixed with soil at 0.1% (w/w) and placed in a plastic pot. Soil samples were taken from each pot after a 210-day incubation period to assess P fractionation using modified Hedley's sequential extraction procedures. A correlation analysis was also included. Results showed that, compared to ck, electrical conductivity (EC) of the soil increased (P < 0.05) with raw pig biochar (24%) and acidulated pig biochar treatments (14%), but there was no significant effect on soil pH. Compared to ck, with the same application rate acidulated biochar was more effective (P < 0.05) than pig biochar for improving the proportions of soil labile and moderately labile phosphorus; whereas, no significant differences in these P proportions between the acidulated biochar and the fertilizer treatments were found. Compared to ck, the percentage of labile P pools significantly (P < 0.05) increased in all treatments, but there were no significant differences between biochar and fertilizer treatments. In comparison with ck, moderately labile P pools increased (P < 0.05) in biochar (36.2%) and fertilizer treatments (77.2%) in the following order:acidulated pig biochar > superphosphate > calcium magnesium phosphate > raw pig biochar. The percentage of stable P pools decreased (P < 0.05) with addition of the amendments, and the proportion of the stable P pools was negatively correlated to the proportion of labile (R2=0.86, P < 0.01) and moderately labile (R2=0.94, P < 0.01) P pools. The acidulated pig biochar treatment significantly (P < 0.05) increased the concentration of all P fractions and maintained a relatively low proportion of stable P in the treated soil. In conclusion, with significant differences in soil P concentrations and fractionations between acidulated pig biochar and chemical P fertilizers treatments tested, it would be potentially viable to use acidulated pig biochar as an alternative P fertilizer and substitute for superphosphate and calcium magnesium phosphate in agricultural production.