Abstract

The impacts of post-plantation management practices (urea, farm yard manure, and combinations of urea and farmyard manure) on the growth and survival rates of selected indigenous and exotic tree species Cordia africana, Olea europaea, Grevillea robusta, and Cupressus lusitanica at Sutte micro-watershed, Morode kebele in Mirab Abaya district, South Ethiopia were investigated. Soil samples were collected from the experimental site by the zigzag method at 10 m intervals from a 40 m by 80 m plot of land and analysed in Arba Minch University for their physical and chemical properties. Results showed that the mean soil texture was 94.12% sand, 4.66% silt and 1.19% clay, pH (6.95), and total nitrogen and available phosphorous were low, with corresponding results of 0.04% and 2.1 mg/L, respectively. Similarly, soil organic matter, available potassium and cation exchange capacity (CEC) were 2.8%, 1.33 mg/L and 13.2 mg/L, respectively. On the other hand, micronutrients like copper and zinc were 1.18 and 3.2 mg/L, respectively. The concentration of iron was 1.95 mg/L which no longer hampered the growth of planted tree seedlings. The growth of height and root collar diameter (RCD) of planted tree seedlings was measured, and the survival rate was calculated for each tree species for twelve months. Tree seedlings that received the combination of urea and farmyard manure (FYM) showed the longest height, RCD and the highest survival rate in C. lusitanica compared to other three planted seedlings species. The lowest growth in height and survival rate was recorded in O. europaea. The major limiting factors of the study included experimental site due to the presence of sandy soil and the toxicity of copper and zinc. However, these limitations were avoided by testing the soil before planting tree seedlings on selected sites and preparing plantation pits during dry seasons 2 to 3 months before the plantation period.

Key words: Farmyard manure, growth, Mirab Abaya, post plantation management, survival rate, tree species, urea.