Textbook in PDF format This publication, Keys to Soil Taxonomy, 13th edition, 2022, incorporates the amendments approved by the regional and national conferences of the National Cooperative Soil Survey since the publication of the last edition of the Keys in 2014. The authors of the Keys to Soil Taxonomy are identified as the "Soil Survey Staff." This term is meant to include all of the soil classifiers in the National Cooperative Soil Survey program and in the international community who have made significant contributions to the improvement of the taxonomic system