Chemical composition of the green biomass of indigenous trees and shrubs in the highlands of Central Ethiopia: implications for soil fertility management.

Received August 2007KINDU, M., GLATZEL, G., SIEGHARDT, M., BIRHANE, K. & TAYE, B. 2008. Chemical composition of the green biomass of indigenous trees and shrubs in the highlands of Central Ethiopia: implications for soil fertility management. The use of green biomass of indigenous trees and shrubs to supply nutrients to agricultural crops is a traditional practice in the highlands of Central Ethiopia. A study was carried out from 2004 till 2006 to characterize the quality of the green biomass of indigenous trees and shrubs based on the content of water, macronutrients, lignin and soluble phenolics. The tree and shrub species studied were Senecio gigas, Hagenia abyssinica, Dombeya torrida, Buddleja polystachya and Chamaecytisus palmensis. The first four are indigenous species, while the last is an exotic species. The water content of the foliage in S. gigas was the highest. The N content of the foliage of the indigenous species was comparable with C. palmensis. The highest K content was found in the foliage, flower bud and stem of S. gigas. The lignin content in the foliage and flower bud of H. abyssinica was the lowest. Based on the N content, lignin and soluble phenolics, indigenous species had intermediate to high quality, whereas exotic species had high quality green biomass for managing soil fertility.Keywords: Foliage, flower bud, macronutrient, lignin, soluble phenolicsKINDU, M., GLATZEL, G., SIEGHARDT, M., BIRHANE, K. & TAYE, B. 2008. Komposisi kimia biojisim hijau pokok asli dan pokok renek di tanah tinggi Ethiopia Tengah: implikasi terhadap pengurusan kesuburan tanah. Penggunaan biojisim hijau pokok asli dan pokok renek sebagai nutrien kepada tanaman pertanian merupakan amalan tradisi di tanah tinggi Ethiopia Tengah. Kajian dijalankan dari tahun 2004 hingga tahun 2006 untuk menilai kualiti biojisim hijau pokok asli dan pokok renek berdasarkan kandungan air, makro nutrien, lignin dan fenol larut. Spesies pokok dan pokok renek yang dikaji ialah Senecio gigas, Hagenia abyssinica, Dombeya torrida, Buddleja polystachya dan Chamaecytisus palmensis. Empat spesies yang pertama merupakan spesies asli manakala spesies yang akhir ialah spesies eksotik. Kandungan air dedaun S. gigas paling tinggi. Kandungan N dalam dedaun spesies asli agak serupa dengan nilai C. palmensis. Kandungan K adalah tertinggi dalam dedaun, kudup bunga dan batang S. gigas. Kandungan lignin dalam dedaun dan kudup bunga H. abyssinica adalah terendah. Berdasarkan kandungan N, lignin dan fenol larut, kualiti biojisim hijau spesies asli adalah antara pertengahan dengan tinggi manakala spesies eksotik adalah berkualiti tinggi dari segi pengurusan kesuburan tanah.