Carbon sequestration in agricultural soils is accountable under Article 3.4 of the Kyoto protocol. In this report we present an inventory of relevant long-term experiments that can provide estimates of carbon sequestration in soils for activities in the Netherlands. Two main sources relevant to Dutch conditions were identified: archived information on several dozens of concluded experiments (TAGA) and a series of some thirty ongoing experiments run by different research groups. The information of this inventory is stored in an accessible data base (www.carboninsoil.alterra.nl). A strategy is proposed to make the information in TAGA that is available on paper forms only accessible in digital form for easy use and renewed analyses. This will provide an assessment of the carbon sequestration potential, an upper limit (carrying capacity) of soil carbon and estimate of uncertainty and variability in space and time without having to set up long-lasting, new and costly experiments.