Abstract
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 (P>0.05) by tree species. Soil bulk density was significantly (p 0.05) influenced by both tree species. The grain yield of sorghum (sorghum bicolor) were significantly (P<0.05) 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.
Highlights
Growing parkland trees in farmlands characterize a large part of the Ethiopian agricultural landscape and it is the most dominant agroforestry practice in the semi-arid and sub humid zones of the country
The interaction effect of distance from tree trunk and soil depth was not significant different (P>0.05). This higher soil bulk density recorded in subsurface soil than surface soil and open field than under canopy might be due to declining of soil organic matter both with distance and depth
This decline in bulk density under tree canopy might be due to higher accumulation of organic matter than the open land. [1], reported the same result for C. macrostachyus, F. albida and C. africana trees in the Hararghe highlands of Ethiopia
Summary
Growing parkland trees in farmlands characterize a large part of the Ethiopian agricultural landscape and it is the most dominant agroforestry practice in the semi-arid and sub humid zones of the country. Agroforestry parkland systems is defined as areas where scattered multipurpose trees characterized by the diversity of woody or often indigenous species occur on farmlands as a result of farmer selection and protection, landscapes in which mature trees occur scattered in cultivated or recently fallowed areas, [3]. A preliminary survey of seven coffee producing provinces in eastern Ethiopia revealed that there is a traditional scattered tree-crop based agroforestry system being practiced by the farmers in the region, [7]. Cordia africana and Corton macrostachyus, on farmlands is very well practiced in the eastern parts of Ethiopia, including study area
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