Effects of increasing lime application rates on microbial diversity and community structure in paddy soils

Abstract Liming is widely used to ameliorate acidic soils. However, few studies have addressed the effects of different lime application rates on soil microbial communities. Specifically, the effects of liming on fungal communities remain largely unknown. Here, we set up a gradient of increasing lime application rates, 0, 450, 900, 1350, 1800, 2250, 3000, and 3750 kg ha−1, to investigate the effects of lime inputs on soil properties and community diversity and composition of prokaryotes and fungi in paddy soils. Our results showed that the effect of liming on soil pH improvement become insignificant when the application rate exceeded 1800 kg ha−1. Prokaryotic diversity and community composition were both significantly influenced by liming, whereas fungal communities were less responsive. Nonetheless, the promotive effects of liming on soil prokaryotic diversity declined when lime application rates exceeded 900 kg ha−1 (or pH > 6.5). Soil pH was the key factor shaping the prokaryotic community, while pH and SOM were both important in explaining the observed variation in fungal communities. Distinct responses of ammonia oxidizing archaea (AOA) lineages were also observed as pH increased. Our results provide insights into the complex responses of both prokaryotic and fungal communities to lime application in paddy soils, and suggest that the amount of lime applied is also important for maintaining a healthy and sustainable soil environment.