Publication Date
1985
Location
Kyoto Japan
Description
The self-regenerating annual legumes mainly the medics (Medicago spp.) and subterranean clover (Trifolium spp.) are vital for maintaining the nitrogen economy of some 40 million hectares of crop and pasture land in Australia. However, new pests and diseases and poor management practices have caused serious decline of these annual legumes in many districts. In recent years a research program to identify the main factors causing legume decline has been started at the Waite Agricultural Research Institute. This research involves (i) studies of seed-seedling dynamics of the annual species of medics in the cereal-livestock zone (350-500mm annual rainfall) where legumes· are affected by grazing, tillage and cropping, and (ii) studies of seed-seedling dynamics of the annual species of subterranean clover in the higher rainfall pasture areas (600-900mm annual rainfall) on undisturbed longer-term pastures. Farm surveys have confirmed that 80% of fields sampled following the cropping phase of the rotation have insufficient medic seed reserve to ensure good medic pastures. In a five-year stocking rate experiment where Merino wethers continuously grazed at five stocking rates, there were marked changes in botanical composition - barley grass dominance at the lowest stocking-rate, capeweed dominance at intermediate stocking rates and cluster clover/winter grass dominance at the highest stocking rate. Each stocking rate generated a mini-ecosystem. Differences in botanical composition could be explained on the basis of differential seed production and seed consumption/digestibility by sheep. Persistence of subterranean clover was related to the cumulative hard seed reserve.
Citation
Carter, E D. and Lake, A, "Seed, Seedling and Species Dynamics of Grazed Annual Pastures in South Australia" (1985). IGC Proceedings (1985-2023). 79.
(URL: https://uknowledge.uky.edu/igc/1985/ses6/79)
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Seed, Seedling and Species Dynamics of Grazed Annual Pastures in South Australia
Kyoto Japan
The self-regenerating annual legumes mainly the medics (Medicago spp.) and subterranean clover (Trifolium spp.) are vital for maintaining the nitrogen economy of some 40 million hectares of crop and pasture land in Australia. However, new pests and diseases and poor management practices have caused serious decline of these annual legumes in many districts. In recent years a research program to identify the main factors causing legume decline has been started at the Waite Agricultural Research Institute. This research involves (i) studies of seed-seedling dynamics of the annual species of medics in the cereal-livestock zone (350-500mm annual rainfall) where legumes· are affected by grazing, tillage and cropping, and (ii) studies of seed-seedling dynamics of the annual species of subterranean clover in the higher rainfall pasture areas (600-900mm annual rainfall) on undisturbed longer-term pastures. Farm surveys have confirmed that 80% of fields sampled following the cropping phase of the rotation have insufficient medic seed reserve to ensure good medic pastures. In a five-year stocking rate experiment where Merino wethers continuously grazed at five stocking rates, there were marked changes in botanical composition - barley grass dominance at the lowest stocking-rate, capeweed dominance at intermediate stocking rates and cluster clover/winter grass dominance at the highest stocking rate. Each stocking rate generated a mini-ecosystem. Differences in botanical composition could be explained on the basis of differential seed production and seed consumption/digestibility by sheep. Persistence of subterranean clover was related to the cumulative hard seed reserve.
