The aim of the project Biobased Fertilisers Achterhoek (‘Kunstmestvrije Achterhoek’ in Dutch) was to make fertilisation practices more sustainable through use of locally available nutrients that are derived from renewable sources. The project is part of the Sixth Action Programme of the Netherlands which serves the Nitrates Directive. One of the objectives was to determine the nitrogen fertiliser replacement value of biobased fertilising products that are made from animal manure. A second objective was to assess the risk of nitrogen leaching from these biobased fertilising products. These objectives were implemented by WUR- Wageningen Environmental Research in a monitoring programme which included field experiments carried out on grassland and on arable land with silage maize. This document reports the results of a second field experiment on grassland which was conducted in 2021. These results have indicated that the biobased nitrogen fertilisers tested could serve as a replacement for mineral nitrogen fertiliser.