How much determinant could be the nitrogen fertilization around harvest for the vine

Abstract

This work starts from the idea that the nitrogen application in pre-harvest would have positive effects on biomass accumulation of the vine plant before its winter rest, and that would enable a better and faster sprouting in the following season, without sacrificing the oenological quality of the grapes. In a malbec vineyard located in El Peral, Tupungato (Mendoza-Argentina), and trough 3 crop cycles (2014/2015-2016/2017), 5 modes of nitrogen fertilization around harvest were proven: 1) 30-days-before, 2) 15-days-before, 3) same day, 4) 15-days-after, and 5) without fertilization. The experimental design was a randomized complete block with 4 replicates, considering six consecutive plants in a trellis as a plot. The nitrogen dose was adjusted for each block according to soil analysis, with 60% applied in spring, in all treatments, and 40% around harvest according to each treatment. Also in autumn, 100% of the required phosphorus was incorporated. Every cycle, pruning weight and cuttings length, sprouting percentage, sprout length variation, cluster weight, number of berries per bunch, and weight and volume of berries were measured. Maturity analysis of the grapes harvested was performed by treatment. Results indicate that nitrogen fertilization around harvest did not have any significant effect on crop productivity, although some trends in favor of fertilizing 15 days before harvest began to mark in the third year. Nor did the oenological quality of grapes varied substantially. Under the conditions tested, the crop was indifferent to the application of 40% of the dose of nitrogen around harvest.