Does high-density grazing mimic grazing patterns of game?

In their paper on high-density grazing in Southern Africa, professors Angelinus Franke and Elmarie Kotzé from the Department of Soil, Crop and Climate Sciences at the University of the Free State say high-density grazing systems may not accurately reflect natural ecosystems. Roelof Bezuidenhout reports.

- Roelof Bezuidenhout

The massive herds of grazers on the African savannahs and grasslands, and the large herds of bison that once roamed the plains of North America, continuously on the move in search of fresh feed and relentlessly chased by pack hunters, provide fascinating images of nature.

But to what extent can high-density grazing (HDG) be regarded as a true representation of grazing patterns in natural ecosystems? HDG aims to regenerate veld by improving soil and vegetation productivity and diversity. It's often taken for granted that HDG leads to favourable environmental outcomes like enhanced on-farm biodiversity because of its relationship with nature.

More recently, HDG systems have been promoted in the regenerative agriculture movement and as a tool to mitigate climate change through soil carbon sequestration.

ENVIRONMENTAL CONSIDERATIONS AND GRAZING BEHAVIOUR

While HDG in semi-arid grasslands may increase organic matter in the upper part of the soil profile, it may also result in soil compaction, reduced soil aggregate stability, and decreased soil moisture.

Further, the impact of grazing on soil organic carbon levels is site-specific and affected by precipitation, temperature, and soil texture.

To study the relationship between grazing systems and climate change mitigation, the additional methane and nitrous oxide emissions arising from increased livestock densities should also be taken into account.