The activity of ammonia-oxidizing bacteria on the residual effect of biochar-compost amended soils in two cropping seasons

Ammonia-oxidizing bacteria (AOB) are vital in regulating nitrification in agricultural soils. Nevertheless, the knowledge of the AOB community's response to fortified and composted biochar application in the maize/ soybean agroecosystem is scarce. This study examined the residual effects of a control soil (CNZ), biochar (BIZ), compost (CPZ), composted biochar (CBZ), and fortified biochar (FBZ) on the AOB community composition, soil chemical properties, and enzyme activities in 2018 and 2019 of a maize/soybean agroecosystem. The AOB community was unravelled using Illumina Miseq sequencing, and multivariate approaches were used to explain the data collected. In 2018, FBZ increased the content of NO3--N, while CPZ, CBZ, and FBZ improved total nitrogen (TN) in the soil. In 2019, CBZ and FBZ increased NO3--N content, while CPZ improved TN and NO2--N in the soil. Likewise, CPZ significantly differed from FBZ, CBZ, and BIZ in AOB richness, while CBZ significantly differed from BIZ in AOB diversity in 2019. Furthermore, distance-based redundancy analysis (db-RDA) and Spearman correlation showed a significant correlation with NH4+-N and NO2--N in 2018 and TN and NO3--N in 2019, while Nitrosomonas eutropha and Nitrosomonas nitrosa had the highest weighted degree in the co occurrence network in both years. This research demonstrates that co-application of biochar with compost in the maize/soybean agroecosystem could result in changes in the AOB community structure.

Automated summary

The study investigated the residual effects of different soil amendments on the ammonia-oxidizing bacteria (AOB) community in a maize/soybean agroecosystem. Results showed that the co-application of biochar with compost could lead to changes in the AOB community structure.