Effects of Biochar Combined with Lime on the Acidity Characteristics of Red Soil and Nitrogen Absorption by Maize

Purpose To study the effect of biochar combined with lime on the acidity characteristics of subtropical red soil in Yingtan, Jiangxi and the nitrogen absorption of maize, providing theoretical basis for slowing down the rate of red soil acidification and promoting maize nitrogen absorption.

Methods A pot experiment was conducted on the maize variety Zhengdan 958, with two factors: different amounts of biochar (0%, 2%, 4%, and 6%) and different amounts of lime (0 and 2 g/kg). The effects of different treatments on soil exchangeable acid content, soil nutrient content, soil enzyme activity, maize growth, and nitrogen absorption were analyzed and compared.

Results Different amounts of biochar combined with lime could significantly increase the pH of maize rhizosphere soil, significantly reduce the content of exchangeable aluminum and its proportion in exchangeable acids, thereby reducing soil acidity and slowing down the process of red soil acidification. Compared with the control group (0% biochar+0 g/kg lime), treatment with 4% biochar+2 g/kg lime significantly increased the activities of urease, sucrase, and acid phosphatase in maize rhizosphere soil, as well as significantly increased soil organic matter content and nitrate nitrogen content. The application of biochar combined with lime had a significant impact on soil exchangeable acid content and maize rhizosphere soil enzyme activity, and there was an extremely significant interaction effect. The exchangeable aluminum in soil was significantly negatively correlated with the enzyme activity and nutrient content of maize rhizosphere soil, and the soil pH was significantly negatively correlated with soil exchangeable aluminum and soil exchangeable acid.

Conclusion Biochar combined with lime treatment can increase the pH of maize rhizosphere soil, reduce the harm of aluminum toxicity to maize roots, and promote maize root growth and nitrogen absorption. The treatment of 4% biochar+2 g/kg lime can significantly reduce the acidity of red soil and improve soil fertility, and its corn nitrogen absorption is the highest, making it a suitable biochar lime application scheme for subtropical red soil in Yingtan, Jiangxi.