Regulating pathway for bacterial diversities toward improved ecological benefits of thiencarbazone-methylisoxaflutole application: A field experiment

Herbicide abuse has a significantly negative impact on soil microflora and further influences the ecological benefit. The regulating measures and corresponding mechanisms mitigating the decreased bacterial diversity due to herbicide use have rarely been studied. A field experiment containing the application gradient of an efficient maize herbicide thiencarbazone-methylisoxaflutole was performed. The relationship between soil bacterial community and thiencarbazone-methylisoxaflutole use was revealed. Modified attapulgite was added to explore its impacts on soil microflora under the thiencarbazone-methylisoxaflutole application. Based on the analytic network process-entropy weighting method-TOPSIS method model, the ecological benefit focusing on microbial responses was quantitatively estimated along with technical effectiveness and economic benefit. The results showed that the diversity indices of soil microflora, especially the Inv_Simpson index, were reduced at the recommended, 5 and 10 times the recommended dosages of thiencarbazone-methylisoxaflutole use. The Flavisolibacter bacteria was negatively correlated with the residues in soils based on the random forest model and correlation analysis, indicating a potential degrader of thiencarbazone-methylisoxaflutole residues. The structural equation model further confirmed that the high soil water content and soil pH promoted the function of Flavisolibacter bacteria, facilitated the dissipation of thiencarbazone-methylisoxaflutole residues and further improved the diversity of soil microflora. In addition, the presence of modified attapulgite was found to increase the soil pH, which may improve bacterial diversity through the regulating pathway. This explained the high ecological benefits of the treatment where the thiencarbazone-methylisoxaflutole was applied at the recommended dosage rates in conjunction with modified attapulgite addition. Therefore, the comprehensive benefits of thiencarbazone-methylisoxaflutole application with a focus on ecological benefits can be improved by regulating the soil pH with modified attapulgite.