The effect of biochar on the migration theory of nutrient ions

Abstract

As the acidification of arable soils increases, the utilization of nutrient ions such as N, P, and K decreases substantially. It causes environmental pollution and reduces crop yields. Through previous studies, acidified soil amendments have problems such as easy-retrograde and unclear mechanism. Therefore, in this study, biochar prepared by pyrolysis using peanut shells was used as a green amendment for acidified soil. Biochar with 0, 5 and 10 % biochar ratios were applied to the acidified soil, and the improvement and mechanism were investigated via experiments and software simulations. Analysis of the software simulation results revealed that biochar had the highest unit adsorption of K+ through physical adsorption at 820.38 mg/g. This was followed by PO43−, NO3−, and NH4+ as 270.51, 235.65 and 130.93 mg/g, respectively. These ions were controlled by both electrostatic and ion-exchange adsorption processes. During the improvement, the 10 % biochar ratio group performed the best with a 65.32 % reduction in the outlet volume, and the accumulated levels of nutrient ions in the leachate dropped by 48.40–68.28 % and increased by 437.80–913.87 % in the surface soil. Nutrient ion levels decreased gradually with the increase of soil depth, which agreed with the software simulation results. This study found that applying biochar to acidified soils can provide a solution to low nutrient utilization efficiency and unclear improvement mechanism of acidified soils, and provide a partial theoretical basis for the large-scale application of biochar. Future research on biochar for soil carbon sink and microbial expansion can be strengthened to contribute to environmental protection and multi-level utilization of energy.