Agricultural Science Review, Vol. 4

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Excerpt from Agricultural Science Review, Vol. 4: Second Quarter 1966Since ancient times the humus of the soil had been considered as synonymous with its fertility and was often spoken of as the fat of the land. How ever, its exact chemical nature and its role in plant nutrition were only vaguely understood. In the early part of the 19th century, with the beginnings of our knowledge of modern chemistry, all organic substances were looked upon as simple in composition, similar to inorganic materials. Humus was considered to be made up of a few dark-colored compounds, designated as humic acids. More recently, it was recognized that humus is a natural body and that its formation, as well as its nature and abundance, depend upon the character of the surface vegetation, the treatment of the soil, and the various environmental conditions, such as cli mate and topography. Even if humus is not the major and direct source of nutrients for plants, it was shown to represent an accumulation of various chemical elements and compounds that are essen tial for the growth of higher plants. These ele ments become available to plants when the humus is decomposed through the action of the numerous soil-inhabiting microbes.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.