A native plant species cover crop positively impacted vineyard water dynamics, soil health, and vine vigor

Authors: FERNANDO, MARGARET - Former ARS Employee; Scott, Natalie; SHRESTHA, ANIL - Fresno State University; Gao, Suduan; Hale, Lauren

Submitted to: Agriculture Ecosystems and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2024
Publication Date: 3/11/2024
Citation: Fernando, M., Scott, N.M., Shrestha, A., Gao, S., Hale, L.E. 2024. A native plant species cover crop positively impacted vineyard water dynamics, soil health, and vine vigor. Agriculture Ecosystems and the Environment. 367. Article e108972. https://doi.org//10.1016/j.agee.2024.108972.
DOI: https://doi.org/10.1016/j.agee.2024.108972

Interpretive Summary: To assess the utility of cover crops in table grape production in Mediterranean climates, we compared two cool season cover crop treatments, Phacelia and Merced Rye, to a control, wherein vineyard alleys were maintained as bare ground. Phacelia, a forb with low carbon to nitrogen ratio in plant tissues, had a quicker return on investment with respect to improvements in soil microbial biomass, soil aggregate stability and water savings. Overall, cool season cover crops increased soil health properties as well as vineyard water dynamics, but these impacts diverged based on cover crop plant traits.

Technical Abstract: Cover cropping is associated with multiple ecosystem and agronomic benefits. However, in irrigated orchards and vineyards of the dry Western United States cover crop adoption rates are low, often owing to concerns over their uptake of critical soil water. Regional concerns, such as this, must be addressed to identify sustainable agricultural practices that meet unique needs of diverse growing regions. A two-year study was conducted to determine the impacts of cover crops on soil water dynamics, soil health, and crop growth during the establishment of an Autumn King table grape vineyard in a semi-arid, Mediterranean climate, specifically the Southeastern San Joaquin Valley of California. Phacelia (Phacelia tanacetifolia), a plant species native to the region, and an introduced species, rye (Secale cereale L. ‘Merced’), were planted as cool season cover crops in the interrow spaces of the grapevines and compared to a standard management practice of no cover crop interrow spaces. The cover crop treatments differentially impacted soil microbial biomass and soil aggregate stability, with the phacelia treatment enhancing both metrics from the first season. The phacelia treatment plots resulted in higher soil moisture beneath the vines in both years, while the rye treatment showed similar benefits only after two consecutive years of cover cropping. Vine vigor was also higher in the phacelia treatment, which was likely because of enhanced soil moisture in the rows. Compared to the rye, the phacelia had lower plant tissue carbon to nitrogen ratio and higher above ground plant biomass, which likely underpin the soil health benefits associated with the phacelia, although variances in soil total carbon and nitrogen and ammonium and nitrate were not determined for any treatment. Altogether, we present information on cover crop plant traits that show quicker return on investment with regards to soil health improvements and water savings. Further, we demonstrate that cool season cover crops offered benefits for vineyard water productivity. In summary, for Mediterranean vineyards cover crops can promote vineyard soil quality and be a component of sustainable water management.