This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The word "manure" has now come to mean any substance that is placed on or in the soil with the object of fertilizing or enriching it in plant food. Originally the word meant "working with the hand", having been derived from the two French words main, the hand, and oeuvre, work. There is a vast depth of meaning in the word "manure", if the French derivation of it is accepted. Long before botanical or agricultural science enabled man to understand the nature of his plants, and what they required as food, the peasant who tilled his ground by hand was manuring or " manoeuvring " it in the real sense of the word. And even to this day, "working" the soil - turning it up and exposing it to the weather - is one of the cheapest and best, if not the quickest, methods of adding fertility to the soil.
Since, however, the great and illustrious Baron Justus von Liebig (b. 1803, d. 1873) propounded his theories on agricultural chemistry some seventy years ago, a vast change has taken place in the methods of manuring. The chemist has stepped in, and as a result of his laboratory experiments he has told the gardener and the farmer, but chiefly the latter, what manures he must use if -he would wish to obtain the best results from his soil. A vast industry has arisen in the shape of chemical or artificial manure manufacture, and thousands have become impressed with the idea that their salvation as cultivators depends entirely upon the amount of "artificials" they apply to their soil. Indeed, there is very great danger of the art of cultivation being lost altogether amongst the agricultural community, and even amongst many market gardeners.
Cultivators of the soil should always remember the very old story of the dying man who on his deathbed told his sons that they would find gold deeply buried in the farm, and they had only to dig deep enough to obtain it. At first the sons mistook their father's meaning, and it was not until they had turned up the soil of the farm to a great depth, and noticed the magnificent crops that followed, that they began to realize the true meaning of their father's words. The gold came, not as they expected, from the soil itself, but from the sales of their farm produce.
If they had not tilled the ground deeply the gold would not have been forthcoming in any shape or form.
This story conveys an excellent moral for all cultivators, and it embodies the true principles of manuring - principles that are strictly in accordance with all we have learned about the composition of soils and manures from the best scientific authorities.
Experiments at Rothamsted and elsewhere clearly prove that the soil does contain vast supplies of some of the most important plant foods, such as nitrogen, phosphates, potash, lime, magnesia, soda, iron, chlorine, silica, etc. But what none of these experiments teach is that these foods can be liberated and made available for the use of our various crops by cultivation or "handworking" the soil.
After all, it must be remembered that the agricultural chemist is not a cultivator, although he may deduce from the chemical analysis of a certain soil, or a certain plant, that such and such foods are required, and that it is only necessary to supply them by means of some artificial manure, and the plant will proceed to carry out its functions, and be perfectly happy ever after.
If this were really the case, the art of manuring would be reduced to the simplest mechanical process. A certain soil is found by analysis to be lacking or deficient in one or more foods that we know to be essential for the welfare of a certain crop. Therefore sprinkle over the soil - or dig it in - a manure which is known to contain the necessary foods, and all will be well - at least it was thought so at first by Liebig and others. The quantity of special fertilizer must be carefully regulated, otherwise the plants, instead of growing, will probably die. Indeed the difficulty as to regulating the quantities to be applied has only been overcome by frequent experiment, and after plants had been killed by overdoses.
This is practically the basis upon which modern manuring is practised. Either the soil is dosed with special manures, or certain crops are given special manures, almost irrespective as to their growth, or as to the nature and condition of the soil in which they are growing.
If these principles of manuring were sound, our cereal and root crops ought to show a vast increase in yield and quality since farmers have taken to using artificial fertilizers in such large quantities. But our crops of wheat, oats, barley, rye, potatoes, turnips, beet, mangels, Swedes, etc, appear to be no greater on the average per acre now than they have ever been. Here and there, of course, are to be found exceptions that prove the truth of the statement, but it will generally be found that these exceptions are due more to good cultivation - to the working, and cleansing, and purifying of the soil - than to the extensive use of artificial fertilizers.
This view receives confirmation from Prof. Snyder, of the University of Minnesota, in his book on Soils and Fertilizers. He says: "Scant crops are as frequently due to the want of proper tillage as to the absence of plant food. Poor cultivation results in getting the soil out of condition; then instead of thoroughly preparing the land, commercial fertilizers are resorted to, and the conclusion is reached that the soil is exhausted, when in reality it is suffering for the want of cultivation, for a dressing of land plaster, for farm manures, or for a change of crops. There is no question but what better tillage, better care and use of farm manures, culture of clover, and systematic rotation of crops would result in greatly reducing the amount annually spent for commercial fertilizers without reducing the yield of crops, as well as securing larger returns for the fertilizers used. In general, the better the cultivation the less the amount of commercial fertilizer required for average farm crops. Cultivation cannot, however, entirely take the place of fertilizers".
The reader must not imagine that artificial manures are being abused. From practical experience the writer knows their virtues very well, but the point he wishes to drive home is that artificial manures, unless used carefully and judiciously, are more likely to ruin a cultivator than to add to his bank balance. They have their uses undoubtedly, and as adjuncts to natural manures and cultivation they can be made to play a most important part. Many experimenters and growers are beginning to realize this now, and they take care to use a proper mixture of natural and artificial manures.