Abstract
The R3-RAM56 long-term experiment in Ultuna, Sweden has tracked the effect of organic and inorganic amendments on agricultural crop and soil properties for the past almost 70 years. Aboveground crop biomass has been collected annually since the beginning of the experiment, while topsoil samples were collected three times in the first twenty years and every other year since 1963. We report crop yields and nutrient content, as well as carbon, nitrogen, and micronutrient content for soils and amendments. The data presented here provides the backbone for numerous published studies in international peer-reviewed journals, and provides a useful time series for calibrating models of soil carbon and nitrogen stocks under varying agricultural management practices in relation to soil amendments.