"Cover crops are crops sown or planted in thick stands for the purpose of protecting and enriching the soil.... That the use of cover crops is a most efficient means for preventing soil erosion and increasing soil fertility is well known; yet this practice is not nearly so widely and extensively followed as it should be. The kinds of cover crops that should be used and the method of utilizing them to the best advantage varies in different regions, according to climatic conditions but almost everywhere cover cropping in some form can be profitably followed." -- p. 1. The bulletin considers cover crops as either legumes or non-legumes.