Seven-year long-term inoculation with Funneliformis mosseae increases maize yield and soil carbon storage evidenced by in situ C-labeling in a dryland.

Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with roots of most plants, contributing to plant water uptake and soil carbon (C) sequestration. However, the interactive contribution and of long-term field AMF inoculation and water conservation on maize yield and soil organic carbon (SOC) sequestration in drylands remain largely unknown. After 7-year long-term field inoculation with AMF Funneliformis mosseae, AMF suppression by fungicide benomyl, and no-AMF/no-benomyl control, and two water conservation practices of half-film and full-film mulching (∼50 % and ∼100 crop planted area covered with plastic film), this study thus applied in situ CO-C labeling and high-throughput sequencing to quantify newly photosynthetically assimilated C into different soil C pools including soil aggregates and respiration, and their effects on maize growth and productivity. Results showed that 7-year long-term AMF inoculation significantly increased the relative abundance of F. mosseae in rhizosphere soil and root AMF colonization, indicating that F. mosseae successfully dominated in AMF communities. Compared to no-AMF/no-benomyl control, AMF colonization significantly increased shoot biomass and maize yield by 17.9 % and 20.3 % while mitigated the less water conservation effects of half-film mulching on maize performance. The SOC content under field AMF inoculation SOC was increased from 7.9 to 8.4 g kg and also the mean weight diameter of aggregates (1.21 to 1.35), e.g. aggregate stability. After 1 and/or 40 days C labeling, the enhanced C translocations into macro-aggregates with decreased C emissions from microbial decomposition under field AMF inoculation had contributed to SOC conservation in bulk soil. These results suggest that AMF inoculation in dryland crops is promising to increase crop yield while promoting more atmospheric CO fixation in soil aggregates. A long-term field AMF inoculation will enhance our understanding of applying beneficial mycorrhizal fungi to enhance soil C sequestration and also crop yield via plant-fixed atmospheric CO in semi-arid and arid farmlands.