The impact of grassland management on biogeochemical cycles involving carbon, nitrogen and phosphorus

Grassland introduction into intensively managed agricultural landscapes may enhance soil organic matter (SOM) content and ecosystem services. However, the magnitude of this effect depends on grassland management practices, and their influence on the soil system. The aim of this paper is to highlight these impacts and their consequences for SOM dynamics and element cycling. We focused in particular on the effect of different grassland management practices in terms of grazing regime, fertilization, and species choice. While carbon, nitrogen and phosphorus cycles are more strongly coupled under grassland as compared to permanent cropping, uncoupling of elemental cycles may occur through management intensification. Grazing regime, fertilization and species choice affect elemental coupling and SOM turnover via organic matter input and rhizosphere activity to different extent, thereby resulting in contrasting SOM storage. Grazing may be more beneficial for SOM contents compared to mowing up to a certain animal density depending on soil type and pedoclimatic context. SOM storage may be increased in some cases through specific fertilizer additions, whereas in others no change was observed. Species choice, e.g. high diversity or introduction of legumes, influence element budgets and soil nutrient availability through plant physiological constraints as well as intra-or interspecific interactions. The effect of different plant species mixtures on soil parameters has rarely been elucidated. We conclude that the impact of grassland management practices on SOM of different soil types and the resulting ecosystem services, such as C and nutrient storage need further research in contrasting pedoclimatic contexts. More studies on the controls of belowground biogeochemical cycling of elements are necessary in order to fully understand and manage belowground processes via aboveground plant communities.