Climate change variables modify microbial community structure and soil enzymes involved in nitrogen and phosphorus metabolism

Abstract

Anthropogenic activities have threatened soil biodiversity which has a direct link with agricultural sustainability and ecosystem functionality. This study is aimed at investigating the changes in soil microbial biomass and enzyme activity in response to variations of primary climatic variables such as temperature and water regimes. Rhizosphere and non-rhizosphere soil samples were collected from an agricultural field of a rainfed area and transported to the laboratory for physicochemical analysis. These soil samples were preserved at 4 °C to be used for studying microbial biomass and enzymatic activities at varying soil temperatures (22, 33, and 44 °C) and water levels (30, 45, and 60% water holding capacity (WHC)). Urease and phosphatase activity showed a significant increase with increasing temperature. The urease and phosphatase values at a temperature of 44 °C after six weeks showed an increase of 19% and 67%, respectively, compared to the values before incubation. The microbial biomass carbon and the microbial biomass nitrogen decreased with increasing temperature and increasing time intervals. Under different temperatures, the diversity analyses of field samples showed maximum dominance of phylum proteobacteria with 70% relative abundance. With increasing water content, a relative decrease in the abundance of proteobacteria was observed. Water variability had non-significant effects on enzyme activity except at 30% WHC where a significant decrease (up to 14%) in urease activity was observed. The results showed a positive correlation between urease (r = 0.81) and phosphatase activity (r = 0.84) vs. an increase in temperature from 22 to 44 °C in soil. Based on these findings, it is concluded that changes in temperature and water levels modify microbial biomass, microbial community structure, and soil enzymatic activities involved in nitrogen and phosphorus metabolism.