Gypsum amendment of arable fields as a water protection measure – farmers’ experience, phosphorus reduction potential and associated costs drawn from a large scale pilot

We organized a large-scale pilot on gypsum amendment of arable fields in southwest Finland, along the River Savijoki to examine its effects on phosphorus loads and aquatic environment, and to assess its feasibility as a water protection measure. This paper reports findings on the feasibility aspects of gypsum amendment covering logistics and costs of spreading, abatement potential and farmers’ experience. We found that farmers perceived gypsum amendment positively and the costs of reducing phosphorus are low relative to other measures available in agriculture. Gypsum amendment suits well to 0.5 million hectares of arable land in southern Finland. Gypsum could potentially contribute considerably to the achievement of phosphorus reduction targets of the Baltic Sea Action Plan if applied in all countries having clay soils.