The influence of site factors on nitrogen mineralization in forest soils of the Mpumalanga escarpment area: South africa

Abstract

The complex biophysical environmental conditions that occur in South Mrican forestry plantations prompt appropriate guidelines for nutrient management applications. Nutrient budget studies in plantation ecosystems indicated a negative nitrogen (N) balance on many sites. Empirical fertilizer trails have shown that, although responses are highly variable, the application of inorganic fertilizers remain an efficient means of improving tree growth. This study was carried out to investigate the influence of variable site conditions on N mineralization, as well as the effect of N mineralization on forest productivity. Data were collected from 31 sample plots, covering a wide range of site conditions in the study area. N mineralization was monitored using multi-week in situ incubations, and compared to a wide spectrum of site factors recorded at each sample plot. The phase of plantation canopy closure (age 6-10 years) was used as the reference age.