Seasonal variation in the nutrient composition of the foliage of pecan (Carya illinoensis)

Abstract

Leaves were sampled every 2 weeks throughout the 1980-81 and 1981-82 growing seasons from a commercial pecan orchard in New South Wales. Leaf concentrations of nitrogen, phosphorus and potassium were highest at leaf emergence and decreased with time. Concentrations of calcium, magnesium and boron were lowest early in the season and increased with time. There was no true seasonal pattern in leaf zinc which varied in apparent response to foliar zinc spray use. These trends were similar for the cultivars Witchita and Western Schley. Minimum seasonal variation in nitrogen, phosphorus, and potassium, the main fertiliser nutrients, occurred between 1 February and 21 March. This period is therefore the most suitable for general diagnostic purposes such as the evaluation of fertiliser programs and surveys of crop nutrient status.