Objective The aims were to study the effects of the application of tobacco and foam waste on corn growth, root secretion and soil microbial community structure, in order to reduce the amount of chemical fertilizer in agriculture.

Method Futiannuo No. 2 corn was taken as the research object, The yellow-brown soil (0-20 cm) in the topsoil layer was used as the test soil, the treatments included: CK (100% inorganic fertilizer), T1 (80% inorganic fertilizer + 20% tobacco and foam organic fertilizer), T2 (60% inorganic fertilizer + 40% tobacco and foam organic fertilizer), T3 (40% inorganic fertilizer + 60% tobacco and foam organic fertilizer), T4 (20% inorganic fertilizer + 80% tobacco and foam organic fertilizer), T5 (100% tobacco and foam organic fertilizer). Soil microorganisms, root organic acid secretion and their interaction were explored through pot experiments.

Result Compared with CK, the results showed that the above-ground and under-ground fresh weight efficiency in T1 treatment was the most obvious, and the number of nitrifying bacteria in the soil increased most significantly, with an increase of 22.84%. T2 treatment had the highest plant height and panicle height, and the number of ammonifying bacteria in soil was increased most significantly, with an increase of 72.70%. In the treatment of foam organic fertilizer with different proportions, the relative abundance of Proteobacteria and Bacteroidota increased, and the relative abundance of Chloroflexi decreased. Among them, the relative abundance of Actinobacteriota and Firmicutes increased strikingly. The total amount of organic acids secreted by roots increased to a certain extent, and the total amount of organic acids in T1 treatment significantly increased by 17.82%. High-Performance Liquid Chromatography (HPLC) analysis showed that the secretion of tartaric acid, malic acid, succinic acid, and oxalic acid increased respectively in T1 and T2 treatments compared with CK, acetic acid, and citric acid secretion was lower. The correlation analysis between the organic acid components secreted by roots and the top 10 bacterial communities at the phylum level showed that Actinobacteriota was significantly positively correlated with succinic acid. Gemmatimonadota was negatively correlated with acetic acid. Patescibacteria were significantly positively correlated with citric acid and negatively correlated with malic acid. The redundancy analysis showed that succinic acid, tartaric acid, and malic acid were significant positively correlated with Actinobacteriota, Gemmatimonadota, soil total nitrogen, ammonium nitrogen, panicle height, ammonifying bacteria, fresh weight of the above-ground part, and the dry weight of the above-ground part.

Conclusion The results showed that 20% ~ 40% organic fertilizer instead of chemical fertilizer can significantly increase the number of soil microorganisms and the content of organic acid secreted by corn roots, and promote the growth of corn.