Ecological recycling agriculture can reduce inorganic nitrogen losses - model results from three Finnish catchments

Protection measures are needed to control nutrient leaching from agriculture to the Baltic Sea. Ecological Recycling Agriculture (ERA) is based on local nutrient resources, integrating animal and crop production on farms or in their proximity. In Finland, three agricultural study catchments were chosen to demonstrate environmental impacts of ERA. Inorganic nitrogen (N) leaching from the catchments was simulated with INCA-N model in prevailing and ERA farming conditions. Lepsämänjoki catchment is a crop production area, in the Yläneenjoki catchment animal husbandry is common and in the Lestijoki catchment the main production line is dairy production. A theoretical crop rotation was developed to represent ERA cultivation consisting of leys, cereals and mixture of cereals and pea. N fixation, mineralization and manure were sources of N. INCA-N was calibrated in the catchments using present cultivation practices. Next, crop parameters were modified to describe ERA cultivation. The model results showed that ERA has potential to decrease N losses: the highest inorganic stream N concentrations and average annual inorganic N losses from agricultural fields decreased, compared to those resulting from present production relying on inorganic fertilizers. Therefore, ERA may serve as one of the measures to achieve the N reduction targets set for agriculture in the Baltic Sea Action Plan.