Re-introduction of light grazing reduces soil erosion and soil respiration in a converted grassland on the Loess Plateau, China

Abstract

Prohibition of grazing has significantly reduced soil erosion and enhanced soil organic carbon (SOC) stock on the Loess Plateau. However, this practice has reduced livestock production and consequently decreased herders’ income in the region. In this study, light grazing was therefore re-introduced to investigate effects of converting cropland to grassland on soil erosion and CO2 emission under light grazing practice. The light grazing trials (10 adult sheep grazing to 7–8 cm of the initial grass height in 1530 m2 land area) were conducted, where soil loss, SOC erosion and CO2 emission were measured using 7Be technique and Li−COR Automated Soil CO2 Flux System. Soil and SOC erosion were 60% and 56% lower in the light grazed grassland and 46% and 29% lower in the un-grazed grassland when compared with cropland, respectively. Light grazing and un-grazing practices increased soil CO2 emission by 15% and 33% respectively, relative to cropland. The mechanisms to control soil erosion by light grazing and un-grazing practices were similar, and governed by grass root biomass and near surface vegetation coverage. However, light grazing had higher potential than un-grazing practices in reducing Soil and SOC erosion and CO2 emission. Our results highlight the potential of light grazing in reducing soil erosion in the “Grain for Green” grassland ecosystems to achieve the dual goals of ecological and economic gains, and sustainability in China and elsewhere.