Nutritional status of commercial apple orchards in the Aland Islands

Soil, leaf and fruit samples were collected from nine apple orchards in the Aland Islands during 1993-95. Early, intermediate and late apple cultivars were studied. Leaves were sampled three times during fruit development. In the experimental orchards, mean soil pH was 7.0 and the concentrations of extractable nutrients (mg l(-1) soil) were: P 30; K 216; Ca 6000; Mg 180. The mean values of nutrients in the leaves (% DM) were: N 2.2; P 0.22; K 1.7, Ca 1.7; Mg 0.22, and in the fruit (mg 100 g(-1) FW): N 47; P 10; K 125; Ca 5; Mg 5. During the sampling period (22 July-26 August), N, P and K in the leaves decreased and Ca increased. Nutrient levels in the leaves were satisfactory, but N, P and K concentrations in the fruit were low. There were significant linear correlations between the corresponding fruit and leaf nutrients, positive for N, P, K and Mg and negative for Ca. Leaf Mg and fruit K correlated significantly with the corresponding soil nutrients. P and Ca in leaves and fruits correlated with soil pH more closely than with the corresponding soil nutrients.