Effect of soil and water conservation practices and slope gradient on organic carbon stocks micronutrients: A case study on Kulkullessa sub-watershed, Eastern Ethiopia

Abstract

Soil degradation in sub-Saharan Africa is a serious problem that causes declines in agricultural productivity linked to hunger and poverty. The study was conducted in the Kulkullessa sub-watershed of Goro Gutu District in Eastern Ethiopia to assess the effects of climate-smart soil and water conservation (SWC) practices and slope gradient on selected physicochemical properties of the soil and the soil’s organic carbon stocks. The farmland conserved by stone bund (SB), bench terrace (BT), and gras strip (GS) five years after construction with two slope gradients (15-20%) and (21-30%) was selected. Twenty-four composite soil samples were collected from a depth of 20 cm and tested in the Haramaya University soil laboratory. The study found that climate-smart SWC practices were very effective on the soil physicochemical properties and soil organic carbon stock (SOCS) of the study area. Similarly, the slope gradient brought considerable variation in soil physicochemical properties and soil organic carbon stock. On farmland that a bench terrace had preserved, the bulk density (BD) value was lower. The recorded value for total porosity on the farmland conserved by BT was also positively higher and significant (p ≤ 0.05). Likewise, the higher mean values for micronutrients and SOCS were recorded on farmlands conserved by SB, BT, and GS in contrast to the values recorded on non-conserved farmland (NCF) in the study area. Based on the study findings, climate-smart soil water and conservation practices have outstanding potential for improving soil physicochemical properties essential for agricultural crop production, climate change adaptation, and strengthening smallholder farmers’ resilience.