No-Till Systems and Perennial Cover Crops Show Minimal Effects on Vineyard Soil Microbiome Composition
Maria Zumkeller, Nazareth Torres, Runze Yu, and
Kaan Kurtural*
*University of California Davis, 1 Shields Avenue, Davis, CA,
95616 (skkurtural@ucdavis.edu)
Soil erosion is a major source of agricultural soil degradation and it is estimated that 1% of topsoil is lost every year. This value is predicted to increase due to climate change, as precipitation events will become more unpredictable and extreme. The increase in recognition of soils as a non-renewable resource has encouraged a major shift in attention toward conserving and improving soils to mitigate the negative effects of climate change. Practices such as cover cropping and reduced tillage have become common in vineyard systems. However, their influence on soil physical and chemical properties and belowground microbial diversity and community is not entirely understood. We conducted a study in a Fresno County Ruby Cabernet (Vitis spp.) vineyard with a perennial grass (Poa bulbosa hybrid), annual grass (Hordeum spp.), and resident vegetation winter cover crop under till and no-till systems. Neither tillage nor cover crops significantly shifted the structure of the soil microbial community (16S species richness). However, soil macro- and micronutrients responded to the different tillage systems and no-till soils exhibited a decrease in carbon fixation, an increase in aerobic respiration, and a decrease in fermentation than soils under tillage. Similarly, potassium levels were also lower in no-till systems, which was supported by decreased titratable acidity values in no-till treatment berries at harvest. Furthermore, the annual grass and perennial grass cover crops responded quite differently from each other in characterization of microbial phytohormone pathways (auxin, cytokinin, and gibberellin production) and stress adaptation pathways (exopolysaccharide production). Overall, our results provided evidence that in the initial years of adoption of a permanent cover crop and no-till system, there is minimal influence on the microbial community structure, although no-till systems may experience a reduction in carbon and nitrogen cycling despite increased phytohormone production and micronutrient content.
Funding Support: none
