The Farm That Won't Wear Out by Cyril G. (Cyril George) Hopkins
page 37 of 55 (67%)
page 37 of 55 (67%)
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residues and ordinary farm manures. In the decomposition of these
organic materials sour or acid products are formed. Thus vinegar, containing acetic acid, is formed from the fermentation of apple juice, hard cider being an intermediate product. Sweet, chopped, immature field corn becomes sour silage in the silo, lactic, acetic, carbonic and other acids being formed. By a similar process cabbage is turned into sauerkraut. Likewise sweet milk becomes sour, with the formation of lactic acid. Oxalic, citric, tartaric, succinic, malic, gallic and tannic are other well-known organic acids. Some of these are contained in the sap or juice of certain plants, and these or others are formed when crop residues are decomposed in the soil. In the ultimate decomposition of organic matter the carbon appears in the form of carbon dioxid which when combined with water forms carbonic acid. Though this is a very weak acid, its solvent action is very important. But, in addition to the various organic acids and carbonic acid, we have also to consider the formation of nitric acid in connection with the decomposition of organic manures. Nitric acid is one of the strongest known, and in solvent power it is excelled by no single acid. The nitrogen contained in crop residues and other organic manures is chiefly in chemical combination with carbon, oxygen and hydrogen, much of it in insoluble protein compounds. Normally this organic nitrogen is transformed in the soil, first into ammonia nitrogen, next into nitrite nitrogen, and lastly into nitrate nitrogen, these three transformations being effected by biochemical action produced by different kinds of living microscopic organisms called bacteria. Though detectable amounts of free nitric acid do not accumulate during this process of nitrification, the soluble |
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