Responses of Eucalyptus species to fertilizer applications made at planting on granitic parent materials in the Mpumalanga and Northern Provinces of South Africa

Abstract

Early research trials in South Africa have shown that Eucalyptus species generally respond positively to the addition of nutrients at planting. However, as most of these research trials were located in KwaZulu-Natal, it was important to investigate the nature of the response in other afforested regions of the country where this genus is planted. Consequently, a number of fertilizer trials were established in the late 1980's and early 90's in Mpumalanga and the Northern Province to investigate the nature of fertilizer responses in Eucalyptus species. Three of these trials form a series and were established to investigate the impact of nitrogen (N), phosphorus (P) and potassium (K) additions made both individually and in combination. In addition, two trials in Mpumalanga were initiated to investigate genotype by fertilizer interactions. Viewed as a whole, the results indicate that growth improvements in response to the nutrient additions are readily obtainable. Highly significant positive responses to N and P, each applied individually, occurred immediately after planting. The response to N appeared more sustained than the response to P. The best growth was observed when N and P were applied together. The ratio of N to P that gave the best response ranged from 3:1 to 3:2. No genotype by fertilizer interactions were observed in the trials investigating this aspect.


Southern African Forestry Journal No.191 2001: 29-38