How far can cycles be closed in organic dairy farming?

Summary

Abstract - Dutch organic dairy farmers asked for a tool to get insight in the ecological sustainabilty of their farms. For that purpose, the area used for milk production outside the farm was calculated for 17 farmers. As expected, a high variation in external input was found, since diversity in farming was one of the selection criteria for involving the project.
Management factors as selling manure and crop rotation resulted in a smaller total area used per kg produced milk. A deep litter stable and a low clover percentage in the grassland fields caused on the other hand an increasment in total area used per kg milk and thereby a lower degree of closeness of nutrient cycles. The calculation of external hectares (ha) gave the farmers insight in the total area that they used for milk production. The degree of closeness varied per farm, which means that improvement on this issue is possible. A few Bioveem-farmers have almost closed their cycles; these farmers used no, or even a nega-tive amount of external ha. This means that closing nutrient cycles is possible in organic dairy farming. And that in some cases even space is created for other more demanding types of land use such arable farming.