| Popis: |
Dairy, and more generally ruminant production, is based on grass, fodder crops, and often concentrates that bring additional necessary nutrients. During the transition from the soil–plant system to the animal, the major biochemical change is the uncoupling of carbon and phosphorus from nitrogen, resulting in dung rich in C and P, urine rich in N and K, or a mixture in the form of manures (slurry, solid manure, compost, etc.). In all these animal returns, C, N, P, and K are more or less labile (from organic to mineral forms) and have the potential to contribute to nutrient losses, recycling, or storage in plant or soil compartments. The dynamics and fate of nutrients depends on their intrinsic properties, as well as on biophysical and management factors (feeding system, animal and herd management, manure management, grassland botanical composition, fertilization, stocking rates) that drive variability and diversity in the size and form of CNPK pools and fluxes, as well as their distribution in space. Here, we explore the nutrient cycle/cascade at different steps (from air–soil to plant–animal to the full air-soil-plant-water-animal system) and at different organizational and spatial scales, i.e., animal and field versus farm or territories. We suggest that a multiscale and multicriteria comparison of the performances of contrasted production systems is necessary to design more sustainable production systems and identify ways to optimize both production and environmental ecosystem services. |
