Effects on major edaphic properties across various contexts: light drought vs. extreme drought

Abstract

Abstract Under climate change, there is a drastic increase in the frequency of drought events, which significantly impacts the biogeochemical processes in regional soil. However, the specific patterns of how different drought intensities affect the physicochemical and biological properties of soil remain unclear. Therefore, this study is based on the utilization of meta-analysis to investigate the impact patterns of drought, light drought, and extreme drought on crucial physicochemical and biological properties of soil under different conditions (soil depth, rhizosphere, experimental conditions, and land use types). The results indicate that: (1) During extreme drought, the variation in soil water content follows the pattern: surface (0-15cm) soil > shallow (15-45cm) soil, rhizosphere > non-rhizosphere, potted soil > field soil, cropland > grassland > forest. On the other hand, during light drought, the pattern is: surface (0-15cm) soil < shallow (15-45cm) soil, rhizosphere < non-rhizosphere, potted soil < field soil, cropland < forest < grassland. (2) Soil C:N ratio decreases during light drought, while soil AP (available phosphorus) and BG (β-1,4 glucosidase activity) activities decrease or are reduced during extreme drought. In terms of soil chemical properties under different conditions, extreme drought increases pH and MBC:MBN in shallow soil, non-rhizosphere, field soil, grassland, and forestland. Light drought decreases C:N ratio and BG activity in shallow soil, non-rhizosphere, field soil, and forest. (3) Extreme drought and light drought significantly decrease F:B (Fungal:Bacteria) ratio in shallow soil (15-45cm) by 119.6% and 217.4% respectively. They also increase F:B ratio in forestland and non-rhizosphere soil by 161.5% and 91.5% in the case of forestland, and 161.4% and 86.5% in the case of non-rhizosphere soil. Light drought significantly increases soil microbial diversity (Shannon index increase by 2.7%), while extreme drought significantly decreases soil microbial diversity (Shannon index decrease by 7.6%). This study contributes to the understanding of the impact of extreme drought and other drought events on regional soil ecosystems and provides scientific support for identifying the mechanisms through which extreme hydrological events affect soil biogeochemical processes. These findings are important for soil management and ecological conservation.