Organic amendment mitigates the negative impacts of mineral fertilization on bacterial communities in Shajiang black soil

Abstract

Improvement of Shajiang black soil in the Huanghuai plain is crucial for sustainable agricultural production; however, the effects of intensified fertilizer input on microbial communities in this soil type remain uncertain. Here, we conducted a long-term field trial using a wheat-soybean-maize cropping system, which had five treatments: organic material (soybean cake) (OM), mineral fertilizers (NPK), standard nitrogen (N) (half from OM and half from NPK) (MNPK), high N (1.6-fold higher than other treatments, with half from OM and half from NPK) (HMNPK), and unfertilized control. The organic carbon (C) composition of the soil was analyzed by 13C nuclear magnetic resonance spectroscopy, and bacterial community structure was determined based on 16S rRNA gene sequencing analysis. Addition of NPK resulted in soil acidification, which was effectively alleviated by organic amendment. NPK significantly (P < .05) reduced the diversity and altered the composition of the bacterial community, although community structure was restored in part by combined organic fertilization. Community variation was limited by soil pH, but not by soil organic C content or chemical composition. Mineral fertilization depleted specific bacterial taxa (e.g., Chitinophagaceae and Nitrospiraceae) associated with the decomposition of polysaccharides and N transformation. Overall, our results suggest that organic amendment can mitigate the negative impacts of mineral fertilization on bacterial communities in Shajiang black soil.