Understanding the role of soil microbes and enzymes in regulating nitrogen dynamics: Promoting sustainable crop rotation systems

Abstract

Abstract Aims Soil nitrogen is recognized as a vital nutrient influencing soybean growth and yield. Hence, a comprehensive understanding of the intricate connections between shifts in nitrogen patterns and the behaviors of soil microbial communities and crucial enzymes in the nitrogen cycle is highly desirable. Methods This study involved a rotation positioning experiment spanning 9 to 11 years. Measurement of soil microenvironment changes during the mature period for three consecutive years, focusing on the corn-soybean rotation with varying fertilizer application rates. Six distinct treatment groups were established for investigation. Based on these groups, the study delved into the alterations in nitrogen patterns within the soybean rotation, examining both soil enzyme activity and microbial community dynamics. Results Long-term crop rotation and nitrogen application led to an increase ranging from 2.16% to 108.34% in the nine components of soil nitrogen. The variations in total nitrogen, heavy fraction organic nitrogen, and light fraction organic nitrogen were primarily influenced by the enrichment of the Actinobacteriota phylum. The environmental factors affecting the changes in inorganic nitrogen, alkaline hydrolyzable nitrogen, exchangeable ammonium and acid hydrolyzable nitrogen were linked to the Ascomycota phylum. The Proteobacteria phylum and urease were key factors in the variations of organic nitrogen and nitrate-nitrogencomponents, respectively. Conclusions Changes in inorganic nitrogen and total organic nitrogen resulting from crop rotation enhanced the richness of soil microbial communities, reducing their diversity. This alteration influenced the bacterial and fungal communities composition, ultimately augmenting their functional capacities.