Indigenous tree and shrub species for soil fertility improvement in Galessa and Jeldu areas, Western Shewa,

A study was conducted from 2004 to 2006 to identify and prioritise indigenous species for soil fertility improvement, and to assess soil properties, nutrient concentration and other quality characteristics of green biomass of indigenous tree and shrub species. The most preferred species for soil fertility improvement in Galessa-Jeldu areas were Senecio gigas, Hagenia abyssinica, Dombeya torrida and Buddleja polystachya. The foliage and flower bud of S. gigas contained a higher P and K content. H. abyssinica had less lignin content in its foliage and flower bud. The variation among species for soluble phenolics in the foliage was from 10 to 169 mg g-1 and in the flower bud from 9 to 234 mg g-1. The soil pH values under H. abyssinica and S. gigas were>6.34. The soil organic C content at 0-15cm depth was higher under H. abyssinica than under B. polystachya. Similarly, the soil under H. abyssinica and S. gigas had a high content of K at the 0-15cm depth. The contents of organic C, N, P, K, Ca and Mg showed a decreasing pattern from the top to the lower soil depths and from the closest to the distant horizontal positions. The soil under the vicinity of H. abysinica, S. gigas and Chamaecytisus palmensis contained a substantial amount of soil nutrients. Hence, the three species should be tested in farmlands and other land-use types of the high altitude areas, where soil erosion and soil depletion are critical problems. 1