Effects of Soil and Water Conservation and Slope Gradients on Selected Soil Physicochemical Properties at Chiri and Lankisa Micro-Watersheds, Ejere District, West Shoa, Ethiopia

Abstract

The study was conducted in Ejere district, Oromia region, Ethiopia, to assess the effects of soil and water conservation measures on selected soil physicochemical properties in the Chiri and Lankisa micro-watersheds. About 118 individual households were selected using simple random sampling techniques. Soil samples were taken from 12 purposively selected fields; six were conserved and six were not conserved. A total of 36 composite soil samples were collected from two micro-watersheds using an auger at a depth of 0–20 cm. Sampled soils were air-dried, grinded, and sieved to 2 mm to make them ready for all parameters and for total nitrogen and organic carbon sieving to 0.5 mm, and analyses were conducted at Batu Soil Research and Fertility Improvement Centre. Soil physical properties analysis methods: soil texture content, SMC, and soil BD were analyzed by using hydrometric, gravimetric, and core sampling methods, respectively. Soil chemical properties: soil pH by pH meter, EC by EC meter, available phosphorous by using the Olsen method, TN by Kjeldahl digestion method, SOC by Walkley-Black method, SOM by value SOC x 1.724, CEC was by extraction NH4OAC, and cation exchangeable (Na+ and K+) were by flame photometer, Ca2+ and Mg2+ by atomic absorption spectrophotometer. Farmers’ perceptions and challenges faced were analyzed through descriptive statistics like mean, percentage, frequency, and standard deviation. SAS (version 9.2) was used to analyze soil physicochemical properties using General Linear Model (GLM) procedures. Soil physicochemical properties measured values: sand (27.31 and 33.5%), silt (20.26 and 19.44%), clay (51.84 and 47.07%), SMC (9.18 and 6.20%), BD (1.117 and 1.238 gcm-3), pH (6.25 and 5.75), EC (0.0722 and 0.060 dS/m), Av. P (6.32 and 6.29 mg/kg), TN (0.150 and 0.123%), recorded from conserved and non-conserved farm plots, respectively. SOC (1.75 and 1.086%) and SOM (3.022 and 1.872%), CEC (37.5 and 30.69 Cmolckg-1) and Cation exchangeable were K+ (0.93 and 0.7), Na+ (1.257 and 0.996), Ca2+ (22.23 and 11.92) and Mg2+ (8.50 and 7.28) Cmolckg-1 from conserved and non-conserved farm plots, respectively. Mean values of soil physicochemical properties (P <0.05) for two land types and slope positions: sand, clay, silt, CEC, and exchangeability (Ca2+ and Mg2+) were significantly different, but EC and TN were not. For both land types, SMC and BD were significantly different (p <0.05) but not by slope position, and SOC, SOM, pH, Av. P, and exchangeable (Na+ and K+) were significantly different (p<0.05) with respect to slope location rather than land types. Therefore, the overall results showed that the SWC measures had a significant positive effect on the physicochemical properties of the soil in the study area