Botanical Composition Changes over Time and Pasture Persistence

Abstract

Regular measurements of botanical composition have shown large changes in the botanical composition in response to management impacts (both grazing management and levels of fertiliser inputs and sowing of pasture species). Overall, there has been maintenance of sown, deep-rooted, perennial species on farmlet A, largely through re-sowing. Short-term ryegrass pastures sown on two paddocks of farmlet A in two different years both failed to persist productively into the second year. The decline in sown, perennial grasses on farmlet B is severe and is associated with an increase in native perennial grasses. A similar but less pronounced trend has been seen on farmlet C. The legume percentage is low on all three farmlets but there is evidence to suggest that the legume percentage on farmlet A is more responsive to the brief periods of favourable rainfall over recent years. It is hypothesised that favourable seasons will have big effects on the subsequent maintenance of sown, fertilizer-responsive, perennial species, largely through improved nitrogen cycling via the legume.