Effect of iron modified biochar on enzyme activity in rhizosphere soil of lettuce

Abstract

Cadmium (Cd) pollution of soil mainly comes from industrial exhaust and wastewater, mainly manifested in soil dysfunction, soil quality decline, endangering plant physiology and human health, with long-term, hidden and irreversible characteristics. Soil enzymes are biological catalysts in soil, and their main functions include promoting organic matter decomposition, nutrient conversion and energy metabolism. Cd has a certain influence on soil enzyme activity, which affects soil biochemical processes and fertility. Biochar is characterized by rich surface functional groups as well as high carbon content and pore structure, which plays an important role in improving and maintaining the soil organic carbon pool. In recent years, some metals such as iron oxides have been widely used in the modification of biochar adsorbent materials, which have all achieved better results. In this study, we investigated the effect of Fe-modified biochar on the inter-root soil of lettuce through potting experiments. The iron-modified biochar had a significant amelioration effect on lettuce inter-root soil with or without Cd. The application of 1% and 3% Fe-modified biochar increased the soil pH by 11% and 13.3% compared with that of the original soil, and by 1.9% and 0.8% compared with that of the soil with 1% and 3% added original biochar. Relative to the original soil, the organic matter content of the soil with 1% and 3% Fe-modified biochar was increased by 26.6% and 60.9%, and the urease activity was elevated by 38.7%, respectively, 46.4%, and sucrase activity increased by 34.1% and 38.8%, respectively. In 2 mg/Kg Cd-contaminated soil, 1% and 3% Fe-modified biochar enhanced urease activity by 17% and 1.3%, sucrase activity by 11.9% and 2%, respectively, compared with 1% and 3% virgin biochar. It provides theoretical support for the study of Fe-modified biochar in modifying the growth and development of lettuce.