Soil microbial communities in different rangeland management systems of a sandy savanna and clayey grassland ecosystem, South Africa

• Published in: Nutrient cycling in agroecosystems 2017-03, Vol.107 (2), p.227-245
• Main Authors: Kotzé, E., Sandhage-Hofmann, A., Amelung, W., Oomen, R. J., du Preez, C. C.
• Format: Article
• Language: English
• Subjects: Agriculture; Biological activity; Biomedical and Life Sciences; Commercial farms; Communities; Continuous grazing; Ecosystem management; Ecosystems; Enzymatic activity; Enzymes; Fatty acids; Grasslands; Grazing; Herbivores; Life Sciences; Maintenance; Management systems; Microbial activity; Microorganisms; Mineralization; Organic chemistry; Original Article; Parameter sensitivity; Phospholipids; Plant growth; Pressure; Range management; Rangelands; Rotational grazing; Sandy soils; Savannahs; Soil chemistry; Soil investigations; Soil nutrients; Soil properties; Soil structure; Soil texture; Soils; Structure-function relationships; Texture
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1007/s10705-017-9832-3

Soil nutrient supply in rangelands depends on the maintenance and performance of soil microbiological communities. In this study we investigated how different rangeland management systems affects the structure and function of soil microbial communities in the clayey grassland and sandy savanna ecosystems, South Africa. These ecosystems differ in climate, soil and vegetation, with the sandy savanna ecosystem being drier, and encroached by bush. Soils were sampled under continuous and rotational grazing systems along a gradient with increasing grazing pressure. Analyses comprised of enzyme activities and phospholipid fatty acids (PLFA). The results revealed that the clayey grassland ecosystem displayed elevated enzyme activities and PLFA contents compared with the drier, sandy savanna ecosystem, irrespective of the rangeland management practices, likely because soil texture played a significant role in maintaining microbial communities. However, when microbial activity was normalized to carbon, nitrogen and microbial biomass, specific enzyme activities were significantly higher in the sandy savanna ecosystem, indicating a more efficient functioning of microbes here. Furthermore, these microbial parameters were more sensitive to grazing pressure in the clayey grassland ecosystem than other chemical or physical soil properties, whereas in the sandy savanna ecosystem this was not the case. Decreasing the grazing pressure on rangeland, as, e.g., done by commercial farmers practicing rotational grazing, appeared to stimulate microbial performance and thus microbial mediated nutrient mineralization with positive consequences on plant growth.