Jedediah Fitzgerald, Zhi Wang, David Garcia, Robert Guzman, and Qun Sun*
*California State University, Fresno, 2360 E. Barstow Avenue, MS VR89, Fresno, CA, 93740 (qsun@mail.fresnostate.edu)

The San Joaquin Valley is facing drought and saline conditions, both of which have adverse effects on grapevine growth. Approximately 3000 to 5000 L wastewater are generated per metric tonne of crushed grapes annually, posing risks to vineyard soil physical and chemical properties, and ultimately affecting grape and wine quality. This study aims to examine the effects of cover crops on soil properties, determine the effect of cover crops on grape and wine quality, and promote effective water and soil management within the framework of sustainable viticulture.

Eight-year-old Ruby Cabernet vines from a commercial vineyard in Fresno, California were used for this study. The experimental design was a randomized complete block design with eight treatments replicated four times. The treatments were: a control (no-till with residential vegetation), tilled, UC 937 barley, WB patron wheat, Pacheco triticale, Sierra oats, rye grass, and Dairyland magnum salt alfalfa. Each experimental unit consisted of one vine row, a quarter-mile in length. The vineyard was furrow-irrigated with wastewater before planting the cover crop.

Results from the two years of the study revealed significant effects of cover crops on soil chemical compositions. Barley, oat, rye grass, triticale, and wheat sequestered carbon at higher levels (200 to 400 kg/acre) than the control. Oat, rye grass, triticale, and wheat absorbed nitrogen at higher levels (6 to 10 kg/acre) than the control. Barley and rye grass absorbed higher sodium content than the control. Triticale and wheat reduced soil electrical conductivity. Rye grass, triticale, and wheat resulted in lower soil sodium. Yield components exhibited no difference among treatments. However, preliminary wine sensory analysis has shown that the treatments may influence both aromatic properties and color. The project is ongoing and additional data will be provided after completion of the third-season trial.

Funding Support: Agricultural Research Institute (ARI)