Agriculture of Maine Volume 45; Annual Report of the Secretary of the Maine Board of Agriculture (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 Excerpt: ...in the soil. The fertility of a soil is measured by its power to produce crops. A soil may have many hundreds of pounds of plant food per acre, and still be unfertile, while another may contain little plant food, but may have that little in an available form and thus be productive, i. e., fertile. Usually manures are applied to soils for the double purpose of supplying plant food in an available form and unlocking the unavailable compounds already in the soil. The direct manurial value of fertilizing materials of the same class can be accurately measured by chemical analysis. Sometimes as the results of field and pot experiments it is also possible to extend this comparison of analyses to materials of unlike nature. In general, however, it is not enough to know the pounds of nitrogen, phosphoric acid and potash in a given manure, but we must by actual experiment with the living plant find out how much of these materials is available to the plant. In studying the manurial value of the three classes of fertilizing materials discussed in this bulletin, these facts must be kept in mind. For example, in comparing a "muck" with 22 pounds of nitrogen in 100 pounds of dry matter with stable manure with only i$4 pounds of nitrogen in the same weight, a great mistake would be made in thinking the muck a better fertilizer than the manure. The nitrogen of the muck is largely unavailable as plant food until it hai been treated by composting, exposure to the air, etc., while the stable manure contains in itself the ferments necessary to render its nitrogen available to the growing plant. In like manner the phosphoric acid of a superphosphate is in a form ready to be assimilated by the growing plant, while that of wood ashes may be practically insoluble and only...