Short-term effects of sheep grazing on C and N cycling in a cover cropped vineyard

Abstract:

The use of cover crops is becoming increasingly common in wine grape production, to reduce soil erosion and improve soil health. Cover crops improve several soil physical, chemical and biological properties, but need to be terminated during the growing season to avoid competition with vines for water and nutrients. The benefits of cover crops for soil health depend largely on the termination strategy chosen. Sheep grazing could represent an environmentally friendly that would further add to the benefits of cover crops as compared to mowing or tilling. Nevertheless, N and C inputs from feces could result in increased emissions of greenhouse gases from soil. In this field study we assessed the effects of tillage and grazing on soil health and greenhouse gas emissions by using a full factorial experimental design. Soil samples were collected (0-15 cm and 15-30 cm depth intervals) for quantification of soil health (total C and N, microbial biomass C, active C and available N). Gas samples were also collected right after management events for quantification of greenhouse gas emissions (CO₂, N₂O and CH₄). The results from this project will help us improve soil management practices to help wine grape producers build healthier soils. Building healthy soils in California, which is one the top global wine grape producers, is essential for sustaining agricultural, environmental and health quality for the present and future generations.