Additional effects of fertilizing on several foliar nutrient concentrations and ratios inEucalyptus grandis
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.
Relationship between growth rate, fertilizing and foliar nutrient concentrations forEucalyptus grandis; preliminary investigations
This is a third paper in a series on foliar nutrient concentrations for seedling crops ofEucalyptus grandis. It describes the relationship between foliar nutrient concentrations ofEucalyptus grandis and height growth rate as influenced by fertilizer application and liming in four comprehensive experiments. Tentative optimum levels for the foliar nutrient concentrations of N, P, K, Ca, Mg, S, Zn, Fe, Cu and Mn and some ratios of macro-nutrients are indicated for the growing conditions at these experimental sites as well as their practical value and limitations. In a pooled analysis, 71 per cent of the variation in height growth was explained by the levels and ratios of nutrients and the rate of N and P application. All elements determined except Cu occurred in this prediction equation. The foliar levels of N, P, K and Mn, the N/P ratio and P application appear to be the most important explaining variables.
Levels of Macro- and Micro-elements in Eucalyptus camaldulensis Dehn. (E. rostrata Schlecht)
VERY little is known about the amount and variation of major and minor elements in forest tree species1. The information on Eucalyptus species is even more limited2.