Soil properties, C and N recovery after 20 years’ exclosure from grazing on a rough fescue grassland
Zhang B, Beck R, Willms W, Zhao M. Hao X. 2019. Soil physical properties, carbon and nitrogen recovery after 20 years’ exclosure from grazing on a rough fescue grassland. 2019 SSSA International Soils Meeting in San Diego, CA. Jan 5-9, 2019.
Résumé en langage clair
Native rangeland soil recovery is a very slow process and 20 years resting (grazing exclosure) is not sufficient for heavily grazed soil to recover.
Overgrazing changes soil physical and biological properties and affects grassland ecosystem function and services. Excluding livestock from grasslands to prevent further grazing activity are an effective strategy for allowing degraded soil to recover. In this study, two cattle grazing paddocks were selected; Paddock H has been stocked at 2.4 AUM ha-1 and Paddock VH at 4.8 AUM ha-1 since 1949. Within each paddock, three exclosures were installed at top, middle and bottom slope positions in spring 1998. Soil physical properties and carbon and nitrogen contents were assessed in 2017, 20 years after exclosure installations. In both paddocks, soil total porosity and saturated water content were higher and penetration resistance and bulk density lower inside than outside exclosures. Soil organic carbon, active carbon and total nitrogen contents were higher inside than outside exclosures for H paddock only, while values were similar inside and outside the exclosure for VH paddocks. Our results suggest soil physical properties showed some recovery over the 20 years for both stocking rates while soil carbon and nitrogen content recover is limited or undetectable as indicated by similar values inside and outside the exclosure for VH paddocks. Thus, the soil recovery is a very slow process and 20 years resting (grazing exclosure) is not sufficient for heavily soil to recover.