Skip to main content
SLU publication database (SLUpub)

Research article2015Peer reviewed

Effects of Soil Substrate and Nitrogen Fertilizer on Growth Rate of Acacia senegal and Acacia sieberiana in North Eastern Uganda

Otuba, Moses; Weih, Martin

Abstract

Low tree production as a result of soil nutrient depletion is a major challenge in Uganda. Trees are often planted in marginalized land characterized with very low soil nutrients or absolutely no soil nutrients. The farmers practice poor farming methods such as continuous cultivation and monoculture. The farmers especially smallholders rarely use inorganic fertilizers due to their associated high cost involved. An experiment was set up in North Eastern Uganda to investigate the effects of soil substrate and nitrogen fertilizer on the growth rate of Acacia senegal and A. sieberiana. It aimed at determining the effects of soil substrate and nitrogen fertilizers on the growth rate of A. senegal and A. sieberiana seedlings. A multi-factorial experiment design was used for collecting the data to address the objective of this study. Soil N was determined by Kjeldahl method, P by spectrophotometric method and K by Flame photometry method. The seedlings were subjected to four rates of N treatments (0, 50, 100, 150 mg per plant) as a single dose of ammonium nitrate at the start of experiment and using a randomized complete block design. Two-way analysis of variance (ANOVA) was used to test if the magnitude of effect of soil substrates on growth rate and leaf nitrogen concentration varies between the two acacia species. Pearson correlation analysis was used to test if the leaf N concentration functionally relates to the growth. There was a significant effect (P ≤0.05) of the soil substrate and the species- soil interaction on the growth rate between two acacia species. The mean relative leaf length of A. sieberiana (0.013 mm mm-1 d-1 ) in unfertilized (N0) soil A was higher compared to those in the soils treated with N fertilizer. While there also was no significant effect (P ≤0. 05) of species, soil substrate and speciessoil interaction on the relative stem, leaf biomass growth and the relative root biomass growth at final harvest, there was a significant species effect (P≤0. 05) on the leaf N concentration. There was no statistically significant effect (P≤0. 05) of the leaf N concentration on the growth traits of the two acacia species in all treatments. It can be concluded that unfertilized soil substrates increased the growth rate of A. senegal and A. sieberiana seedlings more than N fertilizer treatments.

Keywords

Trees; Production; Ammonium nitrate; Nutrients; Seedlings; Semi-arid areas

Published in

International Journal of Agriculture and Forestry
2015, Volume: 5, number: 1, pages: 10-16