Effects of integrated soil and water conservation measures on soil aggregate stability, soil organic matter and soil organic carbon stock of smallholder farmlands in semi-arid Northern Ethiopia

Abstract

Soil and water conservation (SWC) measures such as stone bunds and trenches integrated with fodder species (ISWC) have been implemented to tackle soil erosion in Ethiopian highlands. However, effects of ISWC measures on soil aggregate stability (SAS) and soil organic carbon stocks (SOCS) have been less studied. Fifteen disturbed composite and 15 undisturbed soil samples were collected from cropland sites treated with ISWC measures, SWC structures alone and no SWC measures (NSWC). Results revealed that mean values of stability index (SI) and stability quotient (SQ) are: 15 and 712 for sites with ISWC measures, 8 and 268 for sites with SWC structures alone and 6 and 187 for sites with NSWC measures. The SOCS (t ha-1) and SOM contents are: 12.7 and 1.7% for sites with ISWC, 8.0 and 1.2% for SWC alone and 6.3 and 0.7% for NSWC. SI, SQ SOCS and SOM content are significantly higher (p0.05) in SI, SQ and SOCS, between sites with SWC alone and NSWC. This study strongly suggests that, application of ISWC measures has considerable potential to enhance SAS, SOCS and SOM content.

Keywords

• soil organic matter content
• soil aggregate stability
• soil organic carbon stock
• integrated soil and water conservation measures and cropland