Assessment of land use land cover change and soil physico-chemical properties in semenbench district, southwest ethiopia

Abstract

Land use land cover changes have been recognized as the main factors in the process of soil resource degradation in south western Ethiopia. The aim of this study was to determine the land use and land cover change in the year of 1986, 2001and 2018, and to assess soil physico-chemical properties at different land use types in Semen Bench district. The primary data obtain Landsat satellite image (Landsat data): Thematic Mapper (TM) 1986, Enhanced Thematic Mapper Plus (ETM+) 2001 and Thematic Mapper (TM) 2018 obtained from USGS. Soil samples were collected from three land uses, namely forestland, agro forestry and crop land at 0–30cm depth. The satellite image of Landsat TM for 1986,Landsat ETM+for 2001 and LandsatTM for 2018 were analyzed using EARDAS IMAGINE 2015.Supervised classification method using the decision rule of maximum likelihood classifier algorithm was used to classify LULC map. Accuracy assessment in this study was made using the original images and interview with elders who live in the study area for 1986, 2001 and field observation and Google Earth image used for the 2018 study period. Eighteen soil samples were taken at a depth of 0-30cm from three land uses (agro forestry, crop land, and forestlands) of one kebele with six replicationsand one way Analysis of variance (ANOVA) were used to test the difference among land uses. The overall classification accuracy for the period of 1986, 2001 and 2018 was 90%, 87.5% and 90% with kappa coefficient of 0.87, 0.83 and 0.87 respectively. The result of this study indicated the strong agreement as the value is greater than 0.8. LULC change detection of the periods of 1986 to 2018 showed there were changes in several LULC classes. The net change of land cover class from 1986 to 2018 revealed to agro forestry and settlement were consecutively increased by 47.1% and 2.86% while forest land and cropland were decreased by 19.98% and 30.02% respectively. The soil physico-chemical properties result showedthere were significant differences (P <0.05) in between land use types. Soil OC, pH,OM,TN,AK,AP,EC ,CEC, exchangeable base and bulk density) were significantly different (P<0.05). Generally, the result showed land use change has adverse influence on soil physico-chemical properties. Therefore, sustainable conservation of natural forest and integrated soil management system are recommended to maintain forest resources and soil quality.