Fertilization Significantly Changed Soil Bacterial Diversity and Dominant Microbial Community in Croplands of Northern China—Meta Analysis

This study aimed to clarify the response and driving factors of soil bacterial diversity and dominant microbial community to fertilization measures in farmland ecosystems in northern China under different natural factors, soil properties and farmland management measures, so as to provide a scientific basis for revealing the regulatory mechanism of fertilizer application on the structure of soil microbial communities, enhancing soil biological fertility, and maintaining the stability of farmland ecosystems.

In this study, 50 papers published between 2014 and 2024 were synthesized, 207 groups of relatively independent data on bacterial diversity and dominant community were obtained, and the effects of fertilizer application on soil bacterial diversity and dominant microbial community in agricultural fields in northern China from fertilizer application measures, region, climate, soil pH level, soil SOC level, crop species, and nitrogen application were quantitatively analyzed by using the meta-analysis method and the randomized forest model.

In general, fertilization significantly enhanced the number of soil bacterial OTUs (5.6%), Chao1 index (4.3%), and the relative abundance of Ascomycota (5.3%), and significantly decreased the relative abundance of Acidobacteriaceae (-5.6%) and Greenbenders (-10.4%) (P<0.05), but there was no significant effect on the bacterial Shannon's index. In those areas with mean annual temperature <10 ℃ and annual rainfall >400 mm, fertilization significantly enhanced the number of soil bacterial OTUs, Chao1 index and Ascomycota, but significantly decreased the Acidobacteria phylum and Green Benders phylum (P<0.05). In alkaline soil and soil poor in starting organic carbon (SOC) (<12 g·kg^-1), fertilization significantly increased the number of bacterial OTUs and Chao1 index; in neutral soil and different initial SOC, fertilization significantly increased the relative abundance of Aspergillus phylum, but decreased the relative abundance of Acidobacterium phylum and Greenscope phylum. Compared with wheat and other crops, fertilizer application increased the number of bacterial OTUs (9.4%), Chao1 index (6.4%), and relative abundance of Ascomycota (4.8%), and significantly decreased the relative abundance of Acidobacteria (7.4%) and Greencurvata (11.7%) in maize (P<0.05); fertilization significantly increased the number of bacterial OTUs and Chao1 index (6.4%), and relative abundance of Aspergillus species (4.8%) in Nitrogen application >200 kg·hm^-2. Nitrogen application at >200 kg·hm^-2 significantly increased the number of bacterial OTUs, Chao1 index and relative abundance of Ascomycetes, while significantly decreased the relative abundance of Acidobacteria and Green Benders. Soil organic carbon was the main controlling factor affecting the number of soil bacterial OTU and bacterial Shannon index, annual rainfall was the main controlling factor affecting bacterial Chao1 index, annual mean temperature was the main controlling factor affecting soil bacterial Aspergillus and Acidobacteria phylum, and pH was the main controlling factor affecting soil bacterial Green Benders phylum.

It was recommended that in different regions of northern China, different fertilization measures should be selected according to local conditions, taking into full consideration of local natural factors, soil properties and farmland management measures, so as to achieve the scientific fertilization to maintain soil bacterial diversity and promote soil health.