The role of Chomo grass (Brachiaria humidicola) and exclosures in restoring soil organic matter, total nitrogen, and associated functions in degraded lands in Ethiopia

摘要

Establishment of native plant species on degraded environments, followed by a period of exclosure, is a practice increasingly used in southwestern parts of Ethiopia for land restoration and soil and water conservation purposes. To assess its effectiveness, and the complementary benefits of combining establishment of Chomo grass (Brachiaria humidicola) with land exclosure for restoration of degraded lands have been studied. Soil samples were collected in two soil depth (0-10 cm and 10-30 cm) from open sites, from 4-, 8-, and 15-year-old exclosures, and three different land cover types (open land with bare soil, grasslands, and wood/bush lands). Soil organic carbon (SOC) and total nitrogen (TN) increased in open land with bare soils to 15 years old and wood/bush land-based exclosures. The mean SOC in wood/bush land-based exclosure soils was 16.4 t ha(-1) and 26 t ha(-1) higher than grasslands and bare lands, respectively. The protection of degraded lands from direct animal interference coupled with establishment of Chomo grass appears to be effective in restoring SOC and TN. Therefore, the exclosure and Chomo grass sowing practices and functions have improved vegetation recovery, soil fertility, and water retention capacity. In addition to the restoration enhancement effect of Chomo grass, the grass has been used as the source of livestock feed through cut-and-carry system by the local community. Therefore, integration of exclosure with ecologically adaptive Chomo grass planting appears to enhance the restoration of degraded lands and may bring the land back to its previous better status for livestock feed and crop production.