Assessment of the economic value of cattle slurry and biogas digestate used on grassland
¹Institute of Economics and Social Sciences, Estonian University of Life Sciences,
Kreutzwaldi 1, EE51014 Tartu, Estonia
²Institute of Agricultural and Environmental Sciences, Estonian University of Life
Sciences, Kreutzwaldi 64, EE51014 Tartu, Estonia
Concentration of dairy production and development of manure handling technologies has led to large amounts of cattle slurry produced as a by-product. Slurry can be used directly for fertilisation or input for biogas production. As a result of added organic materials, the nutrient content of the by-product of anaerobic digestion (biogas digestate) differs from nutrient content of slurry. The data from the 2012 to 2014 field experiment designed to evaluate the use of local organic fertilisers on grassland were used for the current study. The objective of this research is to present an approach for the fair reflection of the economic value of organic fertilisers. The approach is based on substitution relationships between mineral and organic fertilisation on a certain yield level of grass dry matter production. The economic value was assessed based on the nutrient content of cattle slurry and biogas digestate, application costs, and the cost of mineral fertilisation. Two categories of economic value were calculated: the total and the actually realised value. The total economic value shows the potential value of nutrients available for plant production. The actual realised value is formed through the nutrient usage by plants. The economic value of the biogas digestate used in the experiments appeared to be higher than the value of slurry, due to the equal application of ammonium nitrogen (NH4-N), the higher content of potassium and lower application rates.