Nutrient Cycling, Modelling and Management from Field to Catchment Scale

The changes in land use caused by antropogenic interventions, has increased the global pool of nutrients (Nitrogen and Phosphorus) in terrestrial and aquatic ecosystems. This report analyzes the behavior of the main nutrient biogeochemical cycles and the consequences of its alterations. It is remarkable the enhancement of some inputs and outputs to terrestrial and aquatic ecosystems and the increasing rate of nutrient loss from the soil to other reservoirs. From field to a catchment scale, the quality of fresh waters and its discharges to coastal environments have been deteriorated, emphasizing the increased trophic state and primary production with consequences such as acceleration of natural eutrophication processes of water bodies. Additionally, the effect of climate change in the balance of nitrogen and phosphorus is reviewed through the use of low complexity models to assess their inputs and outputs. Finally mitigation measures, to minimize nutrient losses from the soil, are explored and their efficiency is discussed. Even if many different ways to deal with the increasing input of nutrient to aquatic environments are presented, the main focus is put on the functioning of wetlands and buffer strips which have proven to be generally effective for the purpose. 2