|Hanifin, Robert - US Department Of Agriculture (USDA)|
|Storm, Chris - Farmer|
|Collatz, Wesley - US Department Of Agriculture (USDA)|
Submitted to: American Journal of Enology and Viticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2013
Publication Date: 12/1/2013
Publication URL: http://ajevonline.org/content/64/4/515.abstract
Citation: Steenwerth, K.L., Mcelrone, A.J., Hanifin, R.C., Storm, C., Collatz, W. 2013. Cover crops and tillage in a mature Merlot vineyard affect yields and cluster weight but not nutrition. American Journal of Enology and Viticulture. 64:515-521.
Technical Abstract: Permanent cover crops are commonly used in vineyard floor management because of their beneficial effects to soil and vine health, but studies evaluating their competitive effects on vines have been conducted primarily in non-irrigated vineyards. Future air quality regulations could mandate the use of no till floor management practices as well in California’s Central Valley. Here, we evaluated the combined effects of cover crop type and tillage on soil nutrient availability, vine nutrition, growth, yield, and juice characteristics of Vitis vinifera cv. Merlot grapevines grown under regulated deficit irrigation in a commercial vineyard from 2008-2010. The following five treatments were used: 1) Fallow + Till; 2) Oats + Till; 3) Oats/Legumes +Till; 4) Oats + Mow; and 5) Oats/Legumes + Mow. No differences in soil nutrient availability were found among the treatments. Of the numerous nutritional constituents analyzed on leaf petioles and blades only NO3-Npetiole was affected by floor management; at nearly all growth stages among all years, NO3-Npetiole of tilled treatments was twice as great as the mown treatments. At harvest, grape yield, mean cluster weight, cluster number per vine, aboveground cover crop biomass, and the ratio of the mean cluster weight per unit of aboveground cover crop biomass differed among treatments in 2009 and/or 2010 but not in the first year; however, response trends were not consistent among treatments within each respective year. Importantly, yields were similar from all four cover crop treatments compared to the Fallow + Till treatment (i.e. business as usual for this grower), suggesting that use of cover crops and/or no-till practices may be implemented in an irrigated vineyard with little immediate effect on grape productivity in mature vineyards.