Growth and yield of maize in Eucalyptus tree alley cropping agroforestry practice in Kafa Zone, Ethiopia

The use of Eucalyptus species has long been debated due to both their positive and negative environmental impacts. Findings from previous studies and scientific literature indicate that the effects of Eucalyptus on the environment are complex, inconsistent, and highly site-specific. The objective of this study was to evaluate the growth and yield performance of maize ( Zea mays L.) under Eucalyptus hedgerow agroforestry practices in Decha Woreda, southwest Ethiopia. The experiment was conducted using a Randomized Complete Block Design with three replications. The study site was selected due to the widespread practice of eucalyptus maize alley cropping, the importance of maize production in the area, suitable agro-ecological conditions, and the need to evaluate the impact of expanding eucalyptus plantations on crop productivity under smallholder agroforestry systems. Maize growth and yield parameters, including plant height, number of cobs, cob weight, 100-seed weight, biomass, and grain yield, were measured. In addition, tree growth parameters such as diameter at breast height and tree height were recorded to assess the effects of different Eucalyptus species on intercropped maize. Data were analyzed using analysis of variance, and treatment means were separated using the Least Significant Difference test at the 95% probability level. In the first cropping season, maize grain yield did not differ significantly among treatments; however, a yield advantage was observed under river red gums ( Eucalyptus camaldulensis Dehn) hedgerows. In the second and third cropping seasons, grain yield differences were significant (P ≤ 0.05) and consistently declined under Eucalyptus hedgerows compared with sole maize cropping. Among the four Eucalyptus species evaluated, flooded gum ( Eucalyptus grandis W.Hill ex Maiden) and Sydney blue gum ( Eucalyptus saligna Sm.) significantly (P ≤ 0.05) reduced maize grain yield during the second and third cropping seasons. Regarding tree growth performance, Eucalyptus saligna and Eucalyptus grandis exhibited greater height and diameter at breast height, while comparatively reduced growth in height and diameter at breast height was recorded for Eucalyptus camaldulensis and lemon-scented gum ( Eucalyptus citriodora Hook.). However, their annual growth rates were not markedly different. The study also revealed no significant effect of Eucalyptus species on soil moisture content near the hedgerows, although relatively higher soil moisture was consistently observed under Eucalyptus camaldulensis over three consecutive years. Therefore, farmers practicing maize intercropping with Eucalyptus camaldulensis in a hedgerow arrangement with sufficient spacing (8 m) between hedgerows can potentially obtain both wood and food from the same unit of land. Nevertheless, appropriate management practices are essential to minimize competition between trees and annual crops, as both are crucial for farmers’ livelihoods.