Effect of Indigenous Tree Species Component in Homegarden Agroforestry System on Selected Soil Physicochemical Properties in Habro District, Oromia Regional State, Ethiopia

Abstract

Homegardens are one of the most important niche in which farmers feel confident to plant and maintain tree and shrub species. Indigenous tree species that are used for soil fertility improvement in Homegardens in western Harerghe in general and Habro district have not been given much research attention. The study assessed the effect of indigenous tree species components of homegarden agroforestry system on selected soil physicochemical properties. The study was carried out in Habro district at three sites (Melka Belo, Haro Chercher and Lega Bera). Soil samples were collected from under Cordia africana and Faidherbia albida canopy and outside canopy at three distances (at half of the canopy radius under the tree, at canopy edge and at three times canopy radius away from the tree trunk outside the canopy) within the 0-20cm and 20 to 40cm soil depths. Mean total nitrogen, available phosphorus, available potassium and organic carbon were significantly higher under the tree canopy than outside the canopy area (P<0.05). Bulk density was significantly higher at subsurface than surface soil while organic carbon was significantly higher at surface soil than subsurface soil. The analysis of variance revealed that moisture content, soil texture and soil pH were not significantly affected by tree species, distance from the tree trunk and by soil depth. The present study demonstrates that Cordia africana and Faidherbia albida tree that were planted or maintained in homegarden agroforestry system of Habro district improved soil properties and they can be used as an economically feasible, environmentally friendly and sustainable alternative to maintain soil fertility of the resource poor farmers in similar agro-ecological conditions. Hence, the research encourages indigenous tree species that are found to have positive effects on soil physical and chemical properties.