不同水分条件下生物炭对红壤磷素形态及磷酸酶活性的影响

Effect of biochar on phosphorus forms and phosphatase activity in red soil under different water conditions

为探究土壤不同水分条件下生物炭对红壤磷素形态转化及磷酸酶活性的影响,以期为土壤磷素管理和生物炭合理利用提供参考。通过设置土壤不同含水量(33%、66%、100%)与生物炭添加量(0、0.5%、2%)进行培养试验,测定土壤的有效磷、各磷素形态(Al-P、Ca-P、Fe-P、O-P)及土壤酸性磷酸酶与碱性磷酸酶活性。结果表明:生物炭的施入显著提高了土壤有效磷含量;在培养前期,生物炭主要增加土壤中难溶态的Al-P含量,这主要是由生物炭带来的可溶性磷进入土壤中转化所导致;在培养后期,水分与生物炭都能够在一定程度上活化土壤中的Ca-P、Fe-P与O-P,释放更多磷素。生物炭本身呈碱性,添加到土壤中,有效中和了土壤酸度,使得土壤pH值上升2.82～3.13个单位,土壤酸性磷酸酶活性下降。此外,淹水条件能够降低土壤的酸性磷酸酶与碱性磷酸酶活性。研究表明,生物炭的添加能够有效提高土壤pH值、有效磷含量,同时降低土壤酸性磷酸酶的活性。

We undertook this study to explore the effects of biochar on the morphological transformation of phosphorus and phosphatase activity in red soil under different water conditions, and to provide a reference for soil phosphorus management and rational utilization of biochar. To test for effective phosphorus and phosphorus forms, soil with different water content(33%, 66%, 100%)and biochar addition(0,0.5%, 2%)were set up. Available phosphorus and various phosphorus forms(Al-P, Ca-P, Fe-P, and O-P)in soil and the activities of soil acid phosphatase and alkaline phosphatase were measured. The results showed that the application of biochar significantly increased the available phosphorus content in the soil;in the early stage of cultivation, biochar mainly increased the insoluble Al-P content in the soil,which was mainly caused by the movement of soluble phosphorus from the biochar into the soil. In the later stages of cultivation, both water and biochar can activate Ca-P, Fe-P, and O-P in the soil to release more phosphorus. Biochar itself is alkaline and when added to the soil,it effectively neutralizes the acidity of the soil, so that the pH of the soil increased,(the pH was increased by 2.82~3.13 units), and the soil acid phosphatase activity decreased. In addition, the soil under flooded conditions showed reduced acid phosphatase and alkaline phosphatase activities. Although the addition of biochar can effectively increase soil pH and the available phosphorus content, it reduces the soil acid phosphatase activity. Compared to biochar, the amount of soil moisture content has less effect on the available P in the soil.