Effects of organic–inorganic compound fertilizer with reduced chemical fertilizer application on crop yields, soil biological activity and bacterial community structure in a rice–wheat cropping system

Abstract

The development of more stable and sustainable agroecosystems for improving food production has caused wide public concern in recent years. In the present study, we conducted a field experiment to investigate the effect of pig manure organic–inorganic compound fertilizer with reduced chemical fertilizer on the crop yields, soil physicochemical properties, biological activities and bacterial community structure in a rice–wheat cropping system over two crop seasons (rice and wheat). The results showed that at all sampling times, this fertilizer regime enhanced the soil nutrient availability, microbial biomass, enzymatic activities, and soil nitrogen processes and, to some extent, promoted crop yields. Across all soil samples, bacterial communities were dominated by Proteobacteria, Acidobacteria, and Chloroflexi at the phylum level. Hierarchical cluster analysis based on the weighted UniFrac distance revealed that the bacterial community structures were strongly separated by the sampling time, and the treatments in the wheat harvest soils. A Venn diagram of shared OTUs showed a core microbiome across different treatments and sampling times, in which the relative abundance of each abundant phylum (class) was stable in the different treatments and at different sampling times. Specifically, the relative abundance of Alphaproteobacteria, Gammaproteobacteria, Nitrospirae, Bacteroidetes, and Actinobacteria was largely and particularly enriched under the organic–inorganic compound fertilizer regime, indicating that soil functions, such as nitrification and the turnover of organic matter, might be strengthened under this treatment. Collectively, these results indicate that the application of organic–inorganic compound fertilizer may reduce chemical fertilizer use and improve the long-term productivity and sustainability of agroecosystems.