Effects of rice straw biochar addition on the phosphorus bioavailability in reddish paddy soil
This study was conducted to clarify the effect of rice straw biochar addition on the bioavailability of phosphorus(P)components in reddish paddy soil.Based on a rice plant pot experiment,a simulated biologically-activated P analysis method(BBP method)was used.The study analyzed the differences in the changes of soluble P(CaCl2-P),P easily released by organic acid activation(Citrate-P),organic P easily mineralized by phosphatase(Enzyme-P),mineral-bound P(HCl-P),total P(TP),available P(Bray-P),and P activation coefficient(PAC)in paddy soils at different growth stages of rice under the following conditions:no biochar application(CK),one-year biochar application(B1),and two-year consecutive biochar application(B2).The results showed that:compared to CK,there were no significant changes in TP,Bray-P,and BBP components in the paddy soil under B1 treatment.In the B2 treatment,the content of TP,Bray-P,Citrate-P,and HCl-P in the paddy soil significantly increased,while CaCl2-P and Enzyme-P content showed no significant changes.As the rice growth stage extended,HCl-P/TP increased significantly in all treatments.Under B2 treatment,CaCl2-P/TP and Enzyme-P/TP both increased significantly.Correlation analysis showed Bray-P and TP in paddy soil were significantly positively correlated with soil pH after biochar addition.CaCl2-P was significantly positively correlated with HCl-P,TP,and negatively correlated with soil available iron.Citrate-P was highly significantly positively correlated with TP and HCl-P,positively correlated with Enzyme-P and pH,and highly significantly negatively correlated with soil available aluminum.Therefore,rice straw biochar,by influencing soil pH,available iron,and available aluminum content,indirectly and significantly increased the TP,Bray-P,PAC,and bioavailable phosphorus components in red soil paddy soil.The rational application of rice straw biochar is beneficial for the protection of the farmland ecological environment and enhancement of soil phosphorus availability.
rice straw biocharreddish paddy soilpotted experimentrice(Oryza sativa)bioavailability of phosphorus
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