Offered Papers Theme B: Grassland and the Environment
Description
Dairy farming in humid, subtropical parts of South Africa is based on permanent kikuyu grass (Pennisetum clandestinum) swards. However, there is a shortage of feed during the winter because low temperatures limit kikuyu growth. As a result, annual pastures incorporating temperate grasses, are grown for winter feed production. The grasses used are typically annual ryegrass (Lolium multiflorum) and sometimes perennial ryegrass (Lolium perenne). Kikuyu is so invasive in the locality that it becomes dominant within a few years, even if the field is sown to perennial ryegrass. For that reason, the swards are usually incorporated using a rotary cultivator, each summer and resown. Concern has arisen in recent years about soil degradation that is possibly occurring under annually-tilled pastures. Observations have suggested that with time, production has progressively declined and this is suspected to be related to soil degradation, particularly a decrease in organic matter content and a loss of related soil microbial and physical properties. The purpose of this study was to compare the effects of permanent pasture and annually-tilled ryegrass pasture on soil organic matter content, size and activity of the microbial biomass and aggregate stability.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Soil Quality Under Permanent and Annual Pastures: Its Implications for Soil Microbial Activity and Nutrient Turnover
Dairy farming in humid, subtropical parts of South Africa is based on permanent kikuyu grass (Pennisetum clandestinum) swards. However, there is a shortage of feed during the winter because low temperatures limit kikuyu growth. As a result, annual pastures incorporating temperate grasses, are grown for winter feed production. The grasses used are typically annual ryegrass (Lolium multiflorum) and sometimes perennial ryegrass (Lolium perenne). Kikuyu is so invasive in the locality that it becomes dominant within a few years, even if the field is sown to perennial ryegrass. For that reason, the swards are usually incorporated using a rotary cultivator, each summer and resown. Concern has arisen in recent years about soil degradation that is possibly occurring under annually-tilled pastures. Observations have suggested that with time, production has progressively declined and this is suspected to be related to soil degradation, particularly a decrease in organic matter content and a loss of related soil microbial and physical properties. The purpose of this study was to compare the effects of permanent pasture and annually-tilled ryegrass pasture on soil organic matter content, size and activity of the microbial biomass and aggregate stability.
