Rangeland evaluation in the Middle Awash valley of Ethiopia: Ⅲ. Relationships among soil and vegetation variables

摘要

Two neighboring districts inhabited by pastoralists of different ethnic groups in the Middle Awash valley of Ethiopia were studied to make a preliminary investigation of the soil nutrient status and identifying the environmental factors most critical to grass production. Data were collected on soil nutrient status, grass yield (dry matter), percentage bare and covered ground, estimated soil erosion, evapotranspiration tree equivalent (ETTE), and altitude. Sites with saline soil showed high electrical conductance and high pH and low total nitrogen and organic carbon. The results of the correlation matrix and the stepwise multiple regression indicated that grass yield was affected by ETTE ha~(-1), percentage of bare and covered ground, C:N ratio, pH and available K. Future studies need to include stocking rate as one parameter to determine better relationships among the measured parameters more accurately.