Identifying biotic and abiotic processes of reversing biochar-induced soil phosphorus leaching through biochar modification with MgAl layered (hydr)oxides

• Published in: The Science of the total environment Vol. 843; p. 157037
• Main Authors: Peng, Yutao, Zhang, Baige, Guan, Chung-Yu, Jiang, Xiaoqian, Tan, Jinfang, Li, Xiaoyun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2022
• Subjects: Adsorption; Biochar; Dissolved organic matter; Layered double hydroxides; Phosphorus leaching; Phosphorus leaching; Dissolved organic matter; Adsorption; Biochar; Layered double hydroxides
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.157037

Biochar (BC) as a increasing widely adopted soil amendments showed potential threat to soil P leaching, but the relevant mechanisms were not clear enough and relevant strategy should be proposed to address the P leaching induced by BC application. In this study, effects of ordinary corn straw BC, and a fabricated Mg/Al-LDHs modified biochar (LBC) on soil P availability, adsorption, fraction and mobility were compared and investigated by conducting the column and incubation experiments at biochar to soil rate of 1 %, 2 % and 4 % (w/w). Chemical sequential extraction methods and various solid-state method (i.e., three-dimensional excitation emission matrix (EEM), x-ray diffraction (XRD), scanning electron micrograph (SEM) and P K-edge X-ray absorption near edge structure (XANES)) were utilized to give deep insights into the P mobilization and immobilization mechanisms by respectively applying the BC and LBC. Results of incubation experiments showed that applying the LBC reduced the labile P with significant CaP transformation to Al-retained P, while ordinary BC promoted the Fe/Al-P transformation to labile dibasic calcium phosphate and monobasic calcium phosphate evidenced by the EEM analysis, in-situ XANES investigation and chemical sequential extraction methods. Results of phosphatase and microbial analyses indicated that the decreased labile P after 30 days' incubation and the mitigated P leaching in LBC treatment were dominantly ascribed to abiotic processes of inorganic P transformation and (de)sorption. This research gave deep insights into abiotic and biotic processes of ordinary biochar promoting soil P leaching, and important implications for applying engineered biochar in reducing P leaching and improving soil productivity. [Display omitted] •1 %–4 % (w/w) conventional biochar addition increase the soil P leaching by 47.1 %–181.7 %.•1 %–4 % (w/w) MgAl-LDHs modified biochar can mitigate soil P leaching by 23.5 %–36.0 %.•MgAl-LDHs modified biochar dominantly mitigated soil labile P and P mobility by abiotic process.•The soil adsorption capacity towards P was improved after MgAl-LDHs modified biochar application.•The transformation of soil labile P into AlP and FeP was facilitated by MgAl-LDHs modified biochar.