Effect of nitrogen stabilizers and cropping sequence on soil carbon and nitrogen pools, biochemical attributes, active microbial populations in podzolic soil in boreal climate

Abstract

Nitrogen (N) is a fundamental macronutrient required for the growth and yield of crops. N stabilizers mitigate ammonia volatilization, N leaching, and gaseous losses, while enhancing soil organic matter and nutrient cycling. Different crops, with their own unique root systems, have an influence on levels of soil organic carbon (SOC) and microbial activity. A field trial was carried out to examine the impact of N stabilizers and cropping sequence on microbial biomass nitrogen (MBN), SOC, particulate organic matter N (POM-N), microbial biomass carbon (MBC), total N (TN), particulate organic matter C (POM-C), pH, enzyme activities (urease and β glucosidase), and microbial community in podzolic soils in boreal climate. Experimental treatments were five N treatments [control, Urea, urea split, and three N stabilizers (Agrotain, Super-U, and eNtrench)] and three cropping sequences (corn- corn-corn, corn-wheat-corn, and corn-faba bean-corn). Soil samples were collected after harvesting the crop in 2020 and 2021. Results showed N sources significantly impacted active microbial population, SOC, POM-N, TN, pH, and enzyme activities in 2021. In 2020, N sources had significantly influenced TN and β glucosidase enzyme activity only. Cropping sequence significantly affected MBN, MBC, and POM-C in 2021, however, in 2020, MBN, gram positive bacteria (G⁺), total bacterial phospholipid fatty acids (Σ B-PLFAs) and total phospholipid fatty acids (Σ PLFAs) were significantly affected. In 2021, cropping sequence and N stabilizers interaction significantly influenced G⁺, gram negative bacteria, Σ B-PLFAs and Σ PLFAs. Our results conclude that N stabilizers and cropping sequence improved soil biochemical attributes, microbial activities, and improved soil C pools in podzol soil. However, N stabilizers with different application rates and long-term crop rotation are required to fully understand the effect of these management practices on soil biochemical and microbial processes in podzolic soils under boreal climate.