EFFECTS OF DIFFERENT LAND-USE LAND-COVER TYPES AND SLOPE POSITION ON SELECTED PHYSICO-CHEMICAL SOIL PROPERTIES AND SOIL QUALITY IN MAYA-GUDDOO SUBWATERSHED OF MAYA-CITY, EASTERN ETHIOPIA

Abstract

Soil is a vital resource for agricultural production and environmental sustainability. Soils in SSA suffer from nutrient depletion, leading to low agricultural productivity. The soils in Hararghe are highly degraded due to intensive and continuous cultivation. Gathering fundamental information about soil properties under different LULC types is so vital to guide management techniques and address the problems of declining soil fertility and quality. This study assessed the influence of LULC types and slope position on selected physico-chemical soil properties and soil quality in Maya-Guddoo subwatershed of Maya-City, Eastern Ethiopia. To achieve this, a total of 27 surface composite soil samples (0-20 cm depth) were collected from cultivated, Khat and grazing LULC types across slope positions. For each composite sample, 8-10 sub-samples were randomly collected using the quadrant method. Key soil properties were analyzed by following the standard laboratory procedures. The soil quality was assessed using a SQI from the selected indicators in the MDS. A linear scoring approach was utilized, being categorized as more is better, less is better, or optimal is better for each indicator. Data were analyzed using a two-way factorial ANOVA in R software to assess the main and interaction effects on soil properties. Tukey's HSD test (p<0.05) was used to further analyze significant effects in pairwise comparisons. The findings indicate significant differences for most soil parameters. However, the PBS showed non-significant variation. Additionally, silt and AWHC among LULC types and TN across slope positions showed nonsignificant difference. Grazing LC type on lower slopes, exhibited the highest values of clay content (40.33%), TP (57.09%), FC (38.00%), AWHC (17.54%), OM (4.91%), TN (0.24%), and most exchangeable bases and micronutrients. In contrast, cultivated LU types at upper slope displayed the lowest values of clay content (21.33%), OM (1.95%) and TN (0.09%). Khat LU types presented mixed results, with higher AV.P (23.41mg/kg) and MC (28.57%) at lower and middle slopes but variable values for other indicators depending on slope positions. The soil under Khat and grazing LULC types exhibited comparable SQI values of 0.65 and 0.64, respectively, while the soil under cultivated LU type showed the lowest SQI of 0.62. Among the slope positions, the highest SQI (0.67) was recorded at middle slope followed by the lower slope (0.65), whereas the upper slope had the lowest SQI (0.59). Notably, the middle slope of Khat LU type exhibited the highest soil quality. The study concludes that the LULC types and slope position significantly influence the soil fertility and quality. To lessen soil degradation, especially on upper slopes and intensively farmed areas, sustainable land management techniques like contour-based strip cropping and biochar-compost blends, reduced tillage and organic matter incorporation are recommended. These results offer vital information for improving agricultural productivity in the area and conserving soil. Mandatory residue retention and nitrogen-fixing hedgerows should be implemented in Khat fields to improve soil fertility and quality. In pasturelands, rotational grazing can greatly enhance soil structure and water retention.