Aboveground Litter Input is Not Important for Soil Microbes During the Non-Growing Season

Purpose Plant inputs provide the main food and energy for soil organisms. Considering substantial aboveground litter on the soil surface but few belowground input in the non-growing season, we hypothesize that aboveground input would have an important role in sustaining microbial abundance and community at this period. Methods We initiated a manipulative temperate grass experiment with four types of plant inputs, i.e., no input (NI), only belowground input (+B), only aboveground input (+A), and both aboveground and belowground inputs (+A +B) in 2018. We tested whether plant aboveground input plays an important role in maintaining soil microorganisms in the non-growing season, i.e., before and after the growing season of 2019. Results Microbial activities, abundance, composition, and diversity were all similar among the four plant treatments before the growing season. However, after the growing season, microbial activity and diversity were higher at the plots with belowground input (+B and +A +B) than at those without belowground input (+A and NI). Similarly, the abundance of saprophytic fungi, AM fungi, and gram-positive bacteria were larger in the plots with belowground input than NI plot. Microbial community composition was similar between +B and +A +B plots (with belowground input), but they were different with those at +A and NI plots (without belowground input). These results indicated that belowground plant input plays a determining role in maintaining soil microorganisms after the growing season. This may link with the legacy of the rhizodeposition carbon in the growing season. Conclusion We demonstrate that aboveground input does not play a substantial role in maintaining soil microbial community in the non-growing season, although aboveground input amount dominates relative to belowground input.