The relationships between microbial communities and environmental factors in agricultural soils in Saraburi

Abstract

The diversity of soil microbial communities are the main factors in the biogeochemical cycles due to their ability to control underground activities, meanwhile the disturbed soils from agricultural practices often perturb microbial communities. This study aims to 1) investigate the microbial diversity in agricultural soils. 2) determine the relationships between the relative abundance of microbes and soil environmental factors such as pH, organic matter (OM) , electrical conductivity (EC), nitrogen (N) and available phosphorus (P) in the agricultural soil of Saraburi. Thirty soil samples at 15 cm depth were collected from agricultural soil in thirty sub-districts of Saraburi Province in August 2020. Three diversity indices indicated microbial diversity as follows: 1.77 for Shannon diversity index (H’), 0.74 for Simpson's diversity index, and 0.19 for Evenness index. Principal component analysis (PCA) was conducted to observed the relationship between Shannon's diversity index of microbial communities and soil properties. Shannon's diversity index correlated with available P in a positive direction and negative correlation with pH, EC and OM. Canonical correspondence analysis (CCA) determined the relationship between soil microbial communities and soil properties. The phyla Firmicutes (26.9%), Proteobacteria (16.9%), Bacteroidetes (16.8%), Acidobacteria (11.5%), and Actinobacteria (8.3%) were abundant in all soil samples. Firmicutes was a positive correlation with soil pH, OM, and EC, this phylum also shows the negative correlation between N and available P. Proteobacteria were positive correlation with both nutrients. Bacteroidetes was positive significant correlation with EC and OM. Acidobacteria indicating that a strong positive correlation with available P and negative correlation with OM. Actinobacteria was negatively correlated with soil pH. The findings indicated that soil properties influence on the microbial community. The distribution of microbial communities and relationships with environmental factors could help farmers for balancing fertilizer application of soil improvement.