Soil Chemical Attributes and Grape Yield as Affected by Gypsum Application in Southern Brazil

Yields of many crops are limited to subsoil acidity. Crop positive responses to gypsum have been shown, however, information regarding the use of gypsum in vine is scarce. A field trial was performed in Parana State, Brazil, on a clayey Rhodic Hapludox to evaluate the effects of gypsum application (0, 3, 6, 9, and 12 Mg ha(-1)) on soil chemical attributes and grape (cv. 'Niagara Rosada') yield. Gypsum was surface applied in July 2005 and the soil and plant evaluations were realized during the years of 2006 and 2007. Gypsum decreased the subsoil exchangeable aluminum (Al) level, increased the calcium (Ca) and sulfate (SO4) contents in the soil profile, and caused leaching of magnesium (Mg) from the topsoil. The leached Mg resulted in decreases of leaf Mg concentrations and fruit production. The researchers estimated a critical level of Ca/Mg ratio in soil as well as in leaves of 1.9 for vine.