"This very useful booklet is packed with information about using chromatography. Many examples are given of tests and trials to determine the quality of soils and compost, but also of select crop plants. This classic is an informative and scientific work by Ehrenfried Pfeiffer, an early biodynamic pioneer. A critical part of the serious biodynamic practitioners library. Color chromatograms help the reader visualize the application. Contents include: The art and science of composting A qualitative chromatographic method for the determination of biological factors Studies of vitamin preparations Chromatograms of grain and flour"