NUTRITIONAL STATUS OF APPLE ORCHARDS IN SOUTHERN BRAZIL

Leaf analysis is being used as a tool to establish a fertilizer program for apple orchards in Southern Brazil. Leaf samples from apple growers of Santa Catarina, Paraná and Rio Grande do Sul, analysed 1985 through 1987 at the Research Station of Caçador, showed that the nutritional status of apple orchards is very similar in these states. High contents of nitrogen and potassium and low contents of calcium and zinc are common. Nitrogen and potassium leaf contents have been found to be "above normal" or in "excess" in about 70% and 40% of the samples respectively. This may be due to annual applications of these nutrients and to natural release by the soils, since soil organic matter and available potassium are generally high. About 75% of the orchards have been found with levels of leaf calcium within the ranges "below normal" or "insufficient". It is assumed that the current situation of unbalanced nitrogen, potassium and calcium cannot be changed in a short period of time because of the plant nutrients available in the soils, the tradition of annual fertilizers applications and the common use of dolomitic lime with a very strait Ca/Mg ratio. The percentages of samples with "below normal" or "insufficient" zinc decreased from 40% to 20% throughout the period (1985–1987) as a result of foliar spray recommendations based on leaf analysis. Leaf contents beyond the "normal" range for phosphorus, magnesium, iron, manganes, copper and boron have been found to be relatively rare.