Speaker
Description
Soil biodiversity is threatened by intensive agriculture that relies on annual grain crop production, thus leading to a decline in soil functions and ecosystem services. Perennial grain crops have a positive impact on the soil microbial community, but the responsive microbial groups and the magnitude of their response remain uncertain. To better understand how soil microbial community composition is influenced by different crops and their management, we analysed soil microbial biomass and community composition, bacterial growth and soil total carbon in five cropping systems: organic perennial intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®) sole cropping, organic IWG-alfalfa intercropping, organic biennial grass-legume mixtures ley cropping, organic annual wheat or rye cropping and conventional annual wheat cropping. The analysis was carried out at three time points under two growing seasons at four different soil depths. After five years, the IWG sole crop had greater amounts of soil total fungi and bacteria, arbuscular mycorrhizal (AM) fungi, saprotrophic fungi and gram-negative (G-) and gram-positive (G+) bacteria compared to annual wheat. Crop perenniality influenced the soil microbial community structure although precipitation, soil temperature and water content were the main drivers of the patterns and temporal variations of the microbial community assembly. Perennial crops with inherent long-term land cover together with reduced tillage and low nitrogen input management increased the proportions of fungi relative to bacteria, AM fungi to saprotrophic fungi, G- bacteria to G+ bacteria, and the growth rate of total bacteria. This resulted in a more active soil microbial community with higher microbial biomass than annual wheat, which contributed to the increased soil total carbon storage in 0-30 cm soil layer in a Scandinavian climate. The findings emphasize the importance of combining a no tillage strategy with long-term vegetation cover to increase soil quality, which in turn potentially improve the delivery of final ecosystem goods.
| Keywords | perennial; intermediate wheatgrass; microbial community composition; microbial biomass; soil total carbon; soil depth |
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