Nutrient status of apple trees in two productive orchards in Tasmania

Abstract

The nutrient status of apple trees was assessed in two productive orchards on different soils in southern Tasmania. The concentration of nitrogen, phosphorus, potassium, calcium, and magnesium in leaf samples was determined over three growing seasons, once in the first year and at three-weekly intervals in the second and third years. Comparisons were made with overseas standards of sufficiency in the elements, and relations were sought with apple yields and tree growths. For most of the elements there was a period of relative stability in concentration towards the latter half of the growing season (late January-early February). The representative concentration of all elements, estimated during this period, declined only slightly in the successive years but remained at sufficient levels, even though growth of the trees and apple yields increased greatly. A moderately high concentration of potassium in the leaves of a number of trees appeared to be associated with a depressed yield of the apples, apparently because it lowered the concentration of magnesium in the leaves.