Improved soil fertility management of eucalyptus plantations in Luweero district,Uganda

Abstract

The eucalyptus cultivation is gaining momentum in Luweero district due to increasing urban development of nearby cites. This comes with increase in the demand of wood products for timber, fuel and wood, making the growing of eucalyptus trees of huge economic importance to the farmers however harvesting of eucalyptus biomass parts exports nutrients from eucalyptus plantation fields. This study was carried out to evaluate the soil fertility management practices carried out in eucalyptus plantations field and also to determine the amount of nutrient that are exported through biomass harvesting of the different eucalyptus biomass parts. A questionnaire was administered to 50 farmers to investigate how often the soil fertility management practices were carried out by farmers in the eucalyptus plantations in Luweero district. A total 10 farmers were randomly selected from the 50 farmers, where 4 trees of different sizes were cut at standard height. Thereafter each sampled tree was divided into stem, bark, branch, twigs and leaves. The fresh weight of the different eucalyptus parts was taken. The samples were collected from each eucalyptus biomass parts that were taken to the laboratory for oven drying at 60 0 C till constant weight. The dry weight was taken from the samples. The samples where composited then smashed and passed through a 2 mm sieve which, were then analyzed for the different nutrient N, P, K and Ca following standard laboratory procedures. The mean nutrient application rate was 0 Kg ha-1 for N, P, and Ca. Exceptional was k whose mean rate was significantly (P<0.001) different from 0 Kg ha-1. The nitrogen, phosphorus, potassium and calcium concentrations were high in the leaves. The stems and branches had the least mean concentrations of the nutrients. The concentration of calcium in the bark was high as that in the leave (above 4%). The uptake of nitrogen in leaves was similar to that in the stems but not exceeding 14 kgha-1 like for other nutrients (P, K and Ca) which were constantly high in the stem. Calcium was the nutrient with highest uptake in the eucalyptus biomass parts overall, but highest uptake in the stems at mean over 120 Kg ha-1.