Cover crop short-term effects on soil NO₃--N availability, nitrogen nutritional status, yield, and must quality in a calcareous vineyard of the AOC Rioja, Spain.

摘要

Cover crop use in vineyards can affect both vine vigor and must and wine quality because of the competition for soil nutrients and water. Our objective was to study the short-term effects of a cover crop on the nitrate (NO₃-)-nitrogen (N) availability throughout the grapevine vegetative cycle, the grapevine and cover crop N uptake, and the yield and must quality. By short-term effects we mean the first crop cycle after planting the cover crop. The experiment was set in 2009 on a cv. Tempranillo vineyard planted in a Oxyaquic Xerorthent soil. The soil had not been fertilized with N since 2000, and two types of soil management were studied: (1) conventional tillage (CT) and (2) barley (Hordeum vulgare L.) cover crop (B). Soil samples were taken in March (bud break), June (bloom), July (setting), and August (veraison) of 2009, and the extractable NO₃--N was determined. At bloom and veraison, N contents in both blade and petiole were determined. At bloom the grapevine N uptake was estimated using the aerial parts (leaves, shoots, and bunches), and for the cover crop N uptake was determined. Total yield, bunch, and shoot weight as well as must anthocyanin and polyphenol contents were determined. Soil NO₃--N availability decreased in the cover crop from June until August, with the reduction being similar to the cover crop N uptake. Also N contents in both petiole and blade decreased in the cover crop at veraison. Regarding must quality, the cover crop increased the anthocyanin content. The reduction of soil NO₃--N availability throughout the vegetative cycle of grapevine caused a reduction in both N nutritional status and grapevine vigor, and therefore cover crops could affect must quality in the first harvest after the cover crop was sown.