Discussion of "Effects of Biochar and Residual Plastic Film on Soil Properties and Root of Flue-Cured Tobacco" by Chao Gao, Xiaohou Shao, Xu Yang, Xiuneng Li, and Wenbo Wu

Plastic film mulching in the field changes the soil structure and the normal distribution of soil water. Residual plastic film (RPF) in the soil causes serious environmental problems to the agricultural ecosystem. In order to determine the role of biochar in mitigating the negative effects of RPF pollution in the soil on agricultural production, in this work, we conducted a pot experiment without biochar and RPF as the control treatment. Four levels were set for biochar: no biochar (0 t/hm2), low biochar (2.5 t/hm2), medium biochar (7.5 t/hm2), and high biochar (15 t/hm2). Besides, four levels were set for the RPF: 0, 80, 320, and 720 kg/hm2. The results showed that medium biochar could improve the soil environment of the RPF, the saturation water content in the soil was increased by 4.5%-11.4%, and the root activity was increased by 6.3%-13.4%. In addition, the root density of flue-cured tobacco was also significantly increased. Medium and high biochar had a significant effect on higher residual plastic film (320 and 720 kg/hm2). It can alleviate soil tillage obstacles caused by plastic film residue, improve soil water-holding and water-releasing capacity, and optimize tobacco plant growth environment. This study provides evidence for the application of biochar as a soil ameliorant in residual film soil. This suggests that we should do more research on the environmental impact of RPF pollution on agroecosystems. © 2022 American Society of Civil Engineers.