Wim and John van den Hengel have an organic dairy farm with an area of 21 ha. In addition, they make hay on 10 ha of natural grassland from the Utrecht Landscape. With this, they feed 40 dairy cows and accompanying young stock. In 2002 they started farm composting to better feed the grassland. In 2009 the Van den Hengel Family started a pilot project with rock flour. The intention is to supplement the minerals, of which there is a shortage in the soil, with natural rock flour mixed with the compost. The ultimate goal is to produce food with the minerals it should contain.