Agricultural subsoil microbiomes and functions exhibit lower resistance to global change than topsoils in Chinese agroecosystems.

Soils play a critical role in supporting agricultural production. Subsoils, below 20 cm, underpin fundamental agroecosystem sustainability traits including soil carbon storage, climate regulation and water provision. However, little is known about the ecological stability of subsoils in response to global change. Here we conducted a microcosm experiment to determine whether subsoils were more sensitive to global changes across 40 agricultural ecosystems in China, in combination with a multiple global change factor experiment and an in situ field study. We found that subsoils exhibited greater fluctuation in species diversity, community composition, and complexity of microbial networks and ecosystem functions than topsoils, indicating lower resistance to global changes. Soil biodiversity was a major driver of ecosystem resistance, surpassing climate and soil parameters. A reciprocal microorganism transplant experiment showed that microorganisms isolated from the topsoil are more resistant to global changes than those from subsoil. Our study emphasizes that subsoil ecosystems are sensitive to global changes, underscoring the importance of including subsoils in predictions of agricultural sustainability and crop productivity under changing environmental conditions.