Effect of soil hardened layers on productive potential of vineyards, Alto Valle of Rio Negro, Patagonia, Argentina

On Aridisol in the Alto Valley of Rio Negro, Argentina, the effect of hardened soil horizons on productive potential of Vitis vinifera L., cv. Merlot, Malbec and Cabernet Sauvignon was studied. The study was performed during the 2002-2003 season in 15.5 ha of vineyards. Sixty-one sampling sites were established. Yield components (weight/grape, cluster number/vine, cluster weight, vine yield and yield/ha), and quality factors (soluble solids, total titratable acidity, pH and berry skin/pulp relation and % soluble solid/berry weight) were determined on the vine. The soils were evaluated by measuring: type, thickness, and depth of the horizons, textural classes, and resistance to penetration, depths of mottles, the gravel and phreatic layers. The edaphic variables were analyzed using the principal components of soil, and 67% of the variability was explained by the three main components. This allowed the definition of five soil groups, and establishing mean soil values and vine variables for each group, via an ANOVA analysis and comparison of means. The production was significantly reduced (P< 0.05) with a tendency to have differentiated quality when soils have a depth of 35 cm or less, Btn or Ckx horizons, are extremely hard, with a thickness of 32 cm or more and resistance to penetration greater than 3MPa. These characteristics were observed in most of the Durinodic Natrargids and Aquic Durinodic Haplocalcid, with Merlot yields of 5,645 and 5,775 kg ha-1,respectively. Higher yields were obtained on Aquic Natrargids (12,524.6 kg ha-1), Durinodic and Typic Haplocambids (12,891.7 kg ha-1). Similar behavior was observed in other cultivars