WOODY SPECIES DIVERSITY AND EFFECT OF SELECTED TREE SPECIES ON SORGHUM YIELD IN PARKLAND AGROFORESTRY PRACTICE IN KERSA DISTRICT, EAST HARARGHE ZONE, ETHIOPIA

Abstract

Parkland agroforestry woody species are prominent features in many landscapes worldwide, and their ecological, social and economic importance is widely acknowledged. Farmers have different objectives for retaining trees on their farm. This study was conducted to assess woody species diversity and evaluate the effect of selected tree species on sorghum yield components. For woody species inventory in the farmland with diameter at breast height (DBH) ≥5 cm were identified and measured in each 50 m*50 m plot size. Saplings below 5 cm were counted within the major plots, five subplots of 10 m*10 m, at four corners and one in the center. A total of 29 woody species, belonging to 19 families were recorded in the PAF of the study area. Among the families, Fabaceae and Euphorbiaceae were the first and second more diverse species represented by 7 and 3 respectively. The sorghum yield experiment had three factors which were distances from tree trunk with three levels; at radius of 2.5m, edge crown radius and at five times total crown radius away from tree trunk (open field) which was used as control, and two locations. Collected data were analyzed by two-way ANOVA and mean separation was done with LSD at 5%. The highest value of sorghum grain yield were under F. albida (2052.05), followed by C. africana (1738.10), C. machrostachyus (1857. 00) and A. tortilis (1835.78) kg/ha, at the distance of 2.5 m away from the trunk in Yabeta lencha and Bereka kebeles at Kersa district. The grain yield of sorghum (sorghum bicolor) were significantly higher (P<0.05) under canopy of four trees species as compared to the open field. 31.76% increment were detected for Sorghum grain yield under the canopy of four tree species. It can be concluded that these tree species have the potential to increase grain yield beneath its canopy. So retaining these tree species in the agricultural setting of the study areasto maintaining soil fertility and provide services to the farmers.