Calcium-rich parent materials enhance multiple soil functions and bacterial network complexity

Parent material shapes soil properties, yet its effects on soil functions and microbial networks remain unclear. Here we investigate these relationships using a large-scale field survey comparing soils derived from calcium-rich carbonate rocks and calcium-poor clastic rocks, complemented by a microcosm experiment. Soils from calcium-rich parent materials contained 33% higher organic carbon, 58% higher total nitrogen, and 55% higher total phosphorus than calcium-poor soils, yet lower labile carbon and several hydrolytic enzyme activities, with similar water retention. Calcium-rich soils exhibited greater bacterial network complexity, which associated with enhanced soil functions. Within calcium-rich soils, rock and soil calcium were primary drivers of increased carbon, nitrogen, and phosphorus storage and bacterial network complexity. The microcosm experiment confirmed that calcium-rich rock addition stimulated soil carbon and nitrogen cycling and enhanced bacterial network complexity, even in calcium-rich soils. These findings indicate calcium-rich parent materials can play a pivotal role in improving soil ecosystem services. Soils from calcium-rich parent materials contained 33% higher organic carbon, 58% higher total nitrogen, and 55% higher total phosphorus than calcium-poor soils enhanced bacterial network complexity and soil functions, according to a large-scale field survey in Guangxi and Guizhou, China.