AbstractA description is given of a PVC‐container installation which allows the determination of plant yield as well as the measurement of water flow. The single containers with 600–700 kg soil are transportable by means of a fork‐lift truck or similar vehicle. Information is given on the insulation and the heating unit (overwintering) of the container as well as on the elimination of border effects, fluctuations in soil temperature etc. An example of practical use, a trial with 48 units with the aim of evaluating the BNF (closed system) of faba beans in a rotation, is described. Detailed instructions (English, French, German) for constructing the container unit are available from the au