"Missouri Agricultural Experiment Station Bulletin 734, An Explanation of Theory and Methods of Soil Testing by E. R. Graham (1) was published in 1959. It served for years as a guide. In 1977 Extension Circular 923, Soil Testing in Missouri, was published to replace Station Bulletin 734. Changes in soil testing methods that occurred since 1977 necessitated the first revision of EC923 in 1983. That revision replaced the procedures used in the county labs. This second revision adds several procedures for nutrient analyses not previously conducted by the laboratory. It also revises a couple of previously used analyses (soil organic matter and extractable zinc)."--Preface
