Nitrogen, Phosphorus and Organic Matter

The Danish Research Programme on Nitrogen, Phosphorus and Organic Matter (NPO) was where the original work on Daisy was carried out. The original purpose of Daisy was to predict nitrogen leaching. That Daisy could also predict crop yield and a water balance were side effects of this. The NPO Programme was very significant as it lead directly to the "Action Plan on the Aquatic Environment" which, together with its successors, have played a large role in Danish environmental policy and management.

The original version of Daisy was documented in The Danish National Agency of Environmental Protection report number A10, which may still be the single most complete scientific description of Daisy.