Sorghum Yield Under the Canopies of Faidherbia Albida (Delile) A.Chev and Cordia africana Lam Parkland Trees in Fedis District, Eastern Ethiopia
Abstract
Among several agroforestry practices in the east Hararghe of Ethiopia, Parkland agroforestry practices are common. However, the effect of tree species on the grain yield and aboveground biomass of Sorghum has not scientifically quantified in the study area. Therefore, the study was conducted to investigating the effect of parkland trees on the grain yield and aboveground biomass of Sorghum at Fedis District, Oromia, Ethiopia. Six isolated and nearly similar F. albida and C. africana trees of each species growing on similar site conditions were selected and the canopy coverage of each tree was divided into four radial transects. Three plots from the tree trunk were established for assessing the sorghum yields and aboveground biomass. Sorghum yield and biomass samples from three horizontal distances: 2.5m, 5.0m and 25m were collected for analysis of Sorghum yield and biomass .The result revealed that sorghum grain yield were significantly (p<0.05) higher under the tree canopies than open field that means its higher by 2089.51 and 1789.53 kg /ha under F. albida and C. africana respectively at the distance of 2.5m and these values decreased to 1459.40 and 1266.01 kg /ha under F. albida and C. africana respectively, at the distance of 25m. The mean biomass recorded at three different distances from the two tree trunks, were not differently significant statistically (p >0.05). The research finding showed that trees have positive relation with grain yield and aboveground biomass of sorghum. Hence, the growing of Faidherbia albida and Cordia africana trees on smallholder farms improve crop productivity for improvement of this Parkland agroforestry system.
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Introduction
Climate change, soil erosion, unsustainable farming practices, excessive tillage, overgrazing and deforestation including loss of biodiversity, have led to severe land degradation and desertification Leakey et. al. [8]. Poverty levels and population growth rates of Ethiopia (more than 3% per annum) are high, the later exceeding the annual food production growth rates which stand at 2% per annum. The majority of the population (85%) practice subsistence agriculture Hiernaux and Turner, [5] and the dominant land use system and the main provider of food, nutrition, income, and environmental services is the traditional parkland system (integrated crop-tree-livestock systems). Through either farmers managed natural regeneration of trees (FMNR) or active planting, a massive-scale adoption of trees on farmlands can play an important role to enhance tree diversity and cover-at landscape level. Then potentially contribute to enhancing food security of resource poor smallholders through the provision of ecosystem goods and service.
The definition of agroforestry used by ICRAF Leakey, [7] is: “a dynamic, ecologically based, natural resources management system that, through the integration of trees on farms and in the agricultural landscape, diversifies and sustains production for increased social, economic and environmental benefits. In addition, parkland trees and shrubs provide firewood and construction materials, and a range of services such as shade for humans and animals, wind protection and aesthetic and spiritual value. Retaining of mature trees on the farmlands is a common practice inmost African countries. Thirty-nine percent of African farmland is under 10% or greater tree cover, benefitting more than 100 million people Zomeret al., [15]. Increased tree diversity at landscape level potentially contributes to enhancing food security of resource-poor smallholders through the provision of ecosystem goods and service. Therefore, the study was initiated the to investigate the effects of F.albida and C.africana trees on the grain yield and aboveground biomass of Sorghum under and outside of the canopy to evaluate the grain yield of sorghum and aboveground biomass under the canopies of trees species and compared to open field in Fedis district.
Conclusion
The study has been done on the effect of F. albida and C. africana on yield and biomass of sorghum grown under canopies of both trees in Fedis District, East Hararghe, Oromia. As a result of significant difference in nutrient available between under canopy and open plot grain yield was greater under the canopy. According to combined analysis both trees showed significant effect on grain yield and biomass of sorghum grown under canopies compared to that grown out of canopies of both trees. The higher mean of grain yield and biomass were observed under canopies than that grown on open field, which could be as result of additional nutrients, through litter fall, root turnover and exudates, and n-fixation. Parkland agroforestry system is very important in soil fertility management especially for poor farmers in order to boost their productivity. Retaining these tree species and in particularly F. albida on farms in the study area is of paramount importance for soil fertility enhancement so as to improve food security of small farming households. Based on the findings the following recommendations are forwarded. (1). Further research should be required on F. albida and C. africana trees on appropriate component management practices and the number of trees retaining per hectare associated crop productivity. (2) .In addition to their role in maintaining soil fertility, these two species provides various products and services to the farmers. Thus, the continued use of these species in the agricultural setting of Fedis district and other areas in the eastern Hararghe area to maintaining soil fertility and provide services to the farmers.(3) .The result of grain yield and biomass of sorghum reported in this study was from under farmer‟smanagement practice. So, further study is needed under controlled experiment in association with these trees.
