Effects of coffee certification on selected soil Physico-chemical properties under different Production systems in southwest Ethiopia

Abstract

Ethiopia is the origin of Arabica coffee and the 5th biggest coffee producing country in the world. Coffee is Ethiopia’s most significant export crop contributing for about 24 % of the country’s foreign currency income.In recent years, certification of agricultural products in Ethiopia increasingly gained attention of international certification agencies. More researchhas been conducted in relation to socio-economic impacts of certification of coffee but, researches in relation to impacts of coffee certification on soil property were not done.Therefore, this study wasconducted to analyze the effects of different coffee certification schemes on selected soil properties under different coffee production systems.To achieve the objectives: soil samples (0-30 cm depth) were randomly collected from70 plots (32 certified and 38 non-certified)including12 certified and 12 non-certified forest plots, 12 certified and 12 non-certified semi-forest plots and 8 certified and 14 non-certified garden coffeefrom three districts. The collected samples were analyzed for soil physico-chemical properties such as texture, soil moisture content(SMC), bulk density(BD), pH, electrical conductivity (EC)Cation exchange capacity (CEC), soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (Av.P)following soil laboratory analytical procedure at Jimma university soil laboratory.Comparison first was made between total certified and non-certified plots. The ANOVA result revealed there was significant(P≤0.05) difference between certified and noncertified coffee farms.Soils from non-certified farms had higher valuesof in clayand silt content, SMC, BD, EC, Av.P,CEC,SOCand TNas compared to certifiedones, whereassand content and pH values werenot significantly (p>0.05) different. The Second comparison was among totalcertified and non-certified plots within a district. Mostsoil properties including, clay and silt content, BD, pH, SOC, TN, Av.P and CEC were higher in noncertified than didRainforestcertified farms, whereasSMC and sand content were higher in Rainforest certified farmsand no difference observed in EC. Soil properties such as sand and silt contents and TN were higher in non-certified farms than didFairtrade certified plots, whereas clay content, SMC, EC and Av.P were higher in Fairtradecertified farms and no difference observed in BD, soil pH, SOC and CEC. The soil properties such as sand and silt content. BD, TN and Av.P were higher in non-certified farms than in organic certified farms. Whereas, clay and CEC were higher in organic certified and no difference in, SMC, pH, EC, and OC.The third comparison was between certified and non-certified plots by production system within the districts. Under forest system conditionSOC, TN andAv.pwas higher in non-certified farm in all types of certification. Similarly,under semi-forest SOC, TN, Av.p and CEC were higher in noncertified plotsin all certificationand SMC,Av.p, and CEC were higher in Fairtrade certified garden stands, whereas no differences were observed for the remaining parameters in all production systems. Generally, certification has no positive contribution for the improvement ofsoil physicochemical properties in the study area. This indicates that the principles of the three certification standards have not yet applied in the ground as intended