Grassland renovation has important consequences for C and N cycling and losses

Abstract

AbstractSward degradation is a serious threat to the functioning of agricultural grassland and the provision of ecosystem services. Renovation measures are frequently applied to restore degraded swards. The success is highly variable, and substantial trade‐offs can be related to the process of renovation. This paper starts with a general classification of renovation measures and then investigates the processes that are directly related to renovation and lead to a change in botanical composition and affect soil functions and C and N fluxes. These processes are strongly interrelated and dependent on site, climate, and management condition as well as on the timescale. The more an existing and degraded sward is deliberately disturbed prior to a renovation measure, for example, by ploughing, the stronger will be the change in sward composition, and the stronger will be the potential yield and quality advantage. However, the risk of a release of soil organic C and N emissions to the environment will also increase. These emissions will usually decrease in time, but so will the positive effects on sward composition. This demonstrates that the renovation of swards is normally the second best solution and a proper and well‐adapted grassland utilization and management should be adopted to avoid degradation in the first place.