The effects of land management on soil fertility and nutrient balance in Kecha and Laguna micro watersheds, Amhara Region, Northwestern, Ethiopia

Abstract

Poor soil fertility status due to erosion, intensive farming, and leaching of nutrients causes food insecurity in Ethiopia. Hence, estimating soil fertility status using different measurements is very essential to secure food insecurity. The aim of this study was to determine the effects of land management on soil fertility using a nutrient balance approach at Kecha and Laguna micro watersheds in 2016. Plant nutrient losses were estimated through measuring discharge and sediment loads coming from the treated (Kecha) and untreated (Laguna) catchments. A total of 40 bulk sediment and water samples were collected on a monthly basis. The inputs used in the two catchments, inorganic fertilizer and organic manure, were quantified through interviews using a semi-structured questionnaire. Plant samples were collected from 92 plots for determining grain yield (OUT1) and straw biomass (OUT2). Other inputs and outputs were calculated using a transfer function. From sediment, grain and straw samples, NPK contents were determined. The nutrient balances were found to be −89.37, −23.66 and −124.75 NPK kg/ha, and −112.41, −20.62 and −130.26 NPK for Kecha and Laguna, respectively. The main paths for these negative balances were residue removal and soil losses. Higher nutrient losses were observed in Laguna than Kecha watershed; this may be due to lack of soil management practices, crop rotation and planting of leguminous plants. Therefore, soil management practices should be done to reduce these higher losses of plant nutrients, and maintain crop residues in the farm so that nutrient recycling and better soil fertility can be achieved.