Impact of Parkland Trees (Faidherbia albida Delile and Cordia Africana Lam) on Selected Soil Properties and Sorghum Yield in Eastern Oromia, Ethiopia

摘要

The study was conducted to investigate the impact of Parkland trees in farmland on selected soil physicochemical properties and sorghum grain yields in Fedis District, Oromia, Ethiopia. For the experiment of soil physicochemical properties, three factors: distance from tree trunk with three levels (at 2.5m of crown, edge of crown radius and open field), soil depth with two levels (0-20cm and 20-40cm depth) and tree species with two levels with factorial arrangement in RCBD replicated six times were employed. For sorghum grain yield only two factors; distance from tree trunk with three levels (at at 2.5m of crown, edge of crown radius and open field) and tree species (F. albida and C. africana) with two levels in RCBD replicated six times were used. The result revealed soil texture was not influenced significantly (P0.05) by tree species. Soil bulk density was significantly (p0.05) lower under canopy of trees than open field, and in surface than in subsurface soils. As well as soil moisture content was significantly (p0.05) higher under canopy of trees than open fields. Soil chemical properties (EC, SOC, OM, Soil Carbon Stock, total N, available P, exchangeable Na, exchangeable K, exchangeable Ca, exchangeable Mg and CEC) were significantly (p0.05) higher in canopy than open field and in surface than subsurface. Soil pH was not significantly (p0.05) influenced by both tree species. The grain yield of sorghum (sorghum bicolor) were significantly (P0.05) higher under canopy of both trees species as compared to the open field. In general, the nutrients contents increased by 84.3% and 71.5% for OC, 84.2% and 70.8% for OM, 66% and 59% for SOC Stocks, 82% and 84% for TN, 96% and 79% for AP, 15.6% and 34.2% for CEC, 30% and 10% for EC, 82% and 27.2% for Na, 41% and 30.4% for K, 33.8% and 28.2% for Ca and 58% and 87% for Mg and 13.22% and 13.15% for MC and by 43% and 41% for Sorghum yield were detected under the canopies of F. albida and C. africana tree species respectively. It can be concluded that these tree species have the potential to improve soil fertility and moisture beneath its canopy. Thus, retaining these tree species and in particular F. albida on crop field in the study area is of paramount importance for soil fertility enhancement so as to improve food security of small farming households.