ABSTRACT

Biochar (BC) is a soil fertility enhancer, regarded as a potential carbon sequester and nutrient leaching preventer. Various studies have shown better phosphorus (P) availability with adding biochar. However, limited reporting is available on absorption–desorption behaviour of added P and dose optimisation of biochar. Rice straw biochar (RSB) and acacia biochar (ACB), prepared by slow pyrolysis at optimised temperature and pyrolysis time, were incubated at different rates (0, 5, and 10 g kg⁻¹) in loamy sand and clay loam soils to study P sorption compared to the unamended control. The data was observed to be best fitted into Langmuir adsorption isotherm for P adsorption. The effects on maximum P adsorption, bonding energy, and adsorption rate constants were lower in loamy sand compared to clay loam soil. The values of maximum P desorption (D_m) and desorption rate constant (K_d) decreased with the application of biochar. A linear regression equation optimised the amount of P addition for soil amendments. For the soil with inherent P content, rice biochar was the best option (5 g kg⁻¹), while for soils lacking in P, ACB is optimised at 5 g kg⁻¹ with external P input of 1 mg P kg⁻¹ of test soil. This data can be recommended to the farmers as a best practice for the P addition, along with managing farm wastes as biochars to enhance nutrient availability.

摘要

生物炭（BC）是一种土壤肥力增强剂，被视为潜在的碳固存剂和养分淋失防止剂。各种研究表明，添加生物炭可提高磷 (P) 的利用率。然而，关于添加磷的吸收-解吸行为和生物炭剂量优化的报告有限。在最佳温度和热解时间下缓慢热解制备稻草生物炭（RSB）和金合欢生物炭（ACB），以不同速率（0、5和10 g kg ^-1）在壤土和粘壤土中研究磷的吸附与未修正的对照相比。据观察，数据最适合 P 吸附的 Langmuir 吸附等温线。与黏壤土相比，壤质砂对最大磷吸附、键合能和吸附速率常数的影响较低。随着生物炭的应用，最大解吸磷（D _m）和解吸速率常数（K _d ）值降低。线性回归方程优化了土壤改良剂的磷添加量。对于固有磷含量的土壤，水稻生物炭是最佳选择（5 g kg ⁻¹），而对于缺乏磷的土壤，ACB 的最佳选择为 5 g kg ⁻¹ ，外部磷输入为 1 mg P kg ⁻¹的测试土壤。这些数据可以推荐给农民，作为添加磷的最佳实践，同时将农场废物作为生物炭进行管理，以提高养分的利用率。