The soil fertility and leaf nutrient status in enset gardens in different altitude zones of the Gamo highlands, Ethiopia and inferences for Xanthomonas wilt prevalence

Abstract

Abstract. Enset (Ensete ventricosum) is a productive, drought-tolerant and multipurpose food security crop grown in the densely populated Ethiopian highlands. Its production suffers from poor soil fertility management and a bacterial wilt disease caused by the pathogen Xanthomonas campestris pv. musacearum. The aim of this study was to assess soil-plant-nutrient variation within enset home gardens over three different altitudes (ranging from 2000–3000 masl) in the Chencha catchment of the Gamo highlands and investigate whether this variation affects disease prevalence. Plant available P, Ca and Mg significantly increase with decreasing elevation but significantly decline with distance from the house. In addition, soil pH, conductivity, total organic carbon (TOC), total N, available K, Mn and Fe levels significantly decline with distance from the house. This indicates that soil fertility factors are influenced by both agro-ecology and farmers' management practices. Moreover, most nutrients reach very high levels in the garden whereas the more distant outfields are severely nutrient deprived. Plant nutrient levels are not correlated to soil nutrient levels except for N. Twenty two percent of the studied farms are symptomatic for bacterial wilt and its prevalence increases with decreasing elevation. Symptomatic gardens have a higher soil pH and available P, K and Ca levels. We conclude that soil fertility management in enset gardens should be optimized in relation to agro-ecological conditions and that both elevation and soil nutrient status need to be considered when developing strategies to curb the current Xanthomonas wilt epidemic.