Assessment of agricultural water protection strategies at a catchment scale: case of Finland

Abstract

For decades, water quality monitoring programmes, agri-environment schemes and environmental permits for animal farms have targeted a decrease in agricultural loads. These have been supplemented with more recent policies related to nutrient recycling and a circular economy. However, eutrophication of surface water bodies remains a widespread problem. In this paper, we focus on the nutrient loading and recycling in the catchment of Eurajoki River, Finland. We statistically examine the generation of nutrient loading and its variation on a sub-catchment scale. We extend this examination to the factors behind the loading and estimate the impact of nutrient recycling on it. Our analysis reveals shortcomings in the availability and collection of data on the agricultural nutrient loadings and the parcel-specific data on the presence and application of manure and fertilisers. Nine sub-catchments were responsible for roughly half of the TP loading from the 46 sub-catchments studied. To reveal such hot spots and to better target agricultural water protection measures, we recommend short-term water quality sampling campaigns. Judging from our data, the rate of manure recycling is not high enough to reduce the regional P surplus to manageable levels. Therefore, we suggest facilitated collaboration between animal and crop farms to decrease the nutrient surplus. We also propose setting up a national database containing parcel-specific information, for example, on soil P content, manure and fertiliser application, agricultural practices and the presence of acid sulphate soils. We also suggest an independent soil fertility sampling to provide valid baseline soil P data for field parcels.