Soil Quality Indices for Evaluating Smallholder Agricultural Land Uses in Northern Ethiopia

Abstract

Population growth and increasing resource demands in Ethiopia are stressing and degrading agricultural landscapes. Most Ethiopian soils are already exhausted by several decades of over exploitation and mismanagement. Since many agricultural sustainability issues are related to soil quality, its assessment is very important. We determined integrated soil quality indices (SQI) within the surface 0-15 cm depth increment for three agricultural land uses: rain fed cultivation (RF); agroforestry (AF) and irrigated crop production (IR). Each land use was replicated five times within a semi-arid watershed in eastern Tigray, Northern Ethiopia. Using the framework suggested by Karlen and Stott (1994); four soil functions regarding soil's ability to: (1) accommodate water entry (WE); (2) facilitate water movement and availability (WMA); (3) resist degradation (RD); and (4) supply nutrients for plant growth (PNS) were estimated for each land use. The result revealed that AF affected all soil quality functions positively more than the other land uses. Furthermore, the four soil quality functions were integrated into an overall SQI; and the values for the three land uses were in the order: 0.58 (AF) > 0.51 (IR) > 0.47 (RF). The dominant soil properties influencing the integrated SQI values were soil organic carbon (26.4%); water stable aggregation (20.0%); total porosity (16.0%); total nitrogen (11.2%); microbial biomass carbon (6.4%); and cation exchange capacity (6.4%). Collectively, those six indicators accounted for more than 80% of the overall SQI values. OPEN ACCESSSustainability 2015, 7 2323

Exclosures backed up with community-based soil and water conservation practices increased soil organic carbon stock and microbial biomass carbon distribution, in the northern highlands of Ethiopia

“…This caused for the loss of carbon in the form of carbon dioxide [60]. Similarly, Gelaw et al [61] in a nearby site found that environmental disturbance was the main cause for the decrease in microbial biomass carbon.…”

Soil Quality Evaluation Using the Soil Management Assessment Framework (SMAF) in Brazilian Oxisols with Contrasting Texture

“…The SMAF has also been successfully used in several other countries around the world [e.g., South Africa (Swanepoel et al, 2015), Ethiopia (Gelaw et al, 2015), Nepal (Kalu et al, 2015)]. The first SMAF application to Brazilian tropical soils was conducted by Cherubin et al (2016a), who verified that SMAF was effective for assessing SQ changes due to land-use change (LUC) for sugarcane expansion in the central-southern region.…”

A Soil Management Assessment Framework (SMAF) Evaluation of Brazilian Sugarcane Expansion on Soil Quality

“…In addition, SMAF has been tested in other countries around the world, including South Africa (Swanepoel et al, 2015), Ethiopia (Erkossa et al, 2007;Gelaw et al, 2015), and Nepal (Kalu et al, 2015). Data from Brazilian soils was limited in the development and validation of the SMAF, and to our knowledge, no other studies using SMAF as a tool for assessing the impacts of current management practices and land uses on SQ in Brazil have been published.…”