The effects of three nitrogen fertilization rates on the fruit composition of Vitis vinifera cv. Cabernet Sauvignon

The nitrogen in grape juice has important implications in winemaking. Juices deficient in nitrogen may result in stuck or sluggish fermentations. Yeast assimilable nitrogen (YAN) in the juice of Cabernet Sauvignon, clone 8, berries was evaluated as a function of nitrogen (N) application in the vineyard. Berries were collected from vines receiving applications of 7, 21, or 42 kg N/ha. No significant differences as a result of N application were seen in yields, Brix, titratable acidity or pH at harvest in 2001 and 2002. When YAN was measured, there were treatment differences at harvest in 2001 but not 2002 as a result of nitrogen applications of 7, 21, or 42 kg N/ha to vines. When nitrogen sources were broken down into "order of preferred N compounds," treatment differences at harvest were seen in juice from vines receiving applications of 7, 21, and 42 kg N/ha in 2001 but not 2002.