Soil nitrification process played a key role in alleviating continuous cropping limitation induced by fumigation

Abstract

Continuous cropping causes enormous crop produce reduction, and soil fumigation is an effective approach to alleviate the limitation. Understanding the impacts of agriculture management on microbial community and its association with nutrient availability would provide strong supports for alleviating continuous cropping limitation. However, the mechanisms of fumigants in enhancing plant growth and alleviating continuous cropping barriers was not clear. In this study, fumigation treatments including chloropicrin (CP), dazomet (DZ), and untreated control (CK) were carried out at field scale, and rhizosphere bacterial community and plant phytochrome were analyzed. The results showed that fumigation had strong effects on rhizosphere bacterial community and soil properties. Fumigation treatment caused significantly reduction in rhizosphere bacterial diversity. The nitrifiers (Nitrospira and Nitrospirillum) and functional gene (ammonia oxidizing bacterial AOB amoA) were significantly inhibited by fumigation treatment, which caused significant reduction in nitrification potential (PNF). The inhibition of nitrifiers, AOB amoA gene and PNF led to significant reduction of soil NO3−-N, but increase of NH4+-N. Subsequently, plant photosynthesis was enhanced as a result of increasing leaf chlorophyll a content caused by fumigation treatment. Therefore, fumigation treatment would promote crop growth through increasing the photosynthetic pigment. The study indicated the key mechanisms fumigation promoting plant growth and alleviating cropping limitation were closely related to soil nitrifiers and nitrogen nutrients.