Additional effects of fertilizing on several foliar nutrient concentrations and ratios inEucalyptus grandis

Abstract

The interaction responses to N, P, K fertilizing and limimg in four experiments withEucalyptus grandis are described. Inclusion of the N—P and P—K relationships gives a clearer understanding of the nutrient requirements of this species. Phosphorus and nitrogen supply is of great importance, but must be well balanced when either or both are adequately supplied in specific circumstances. Potash supply is also of importance, especially in conjunction with phosphorus, although no direct benefit has been found in these experiments. Increased soil pH reduces the uptake of these latter two nutrients. Magnesium is of greater importance and more readily taken up than calcium inE. grandis. Zinc seems to be the most important of the micro-nutrients and its interactions make it evident that Zn-enriched fertilizers should be used. Manganese levels are generally high where growing conditions are adverse. The great importance is indicated of the foliar N/P and P/K ratios as diagnostic criteria for evaluating fertilizer needs inE. grandis.