FOREIGN AND MISCELLANEOUS NOTICES. 



numerous experiments on the practical ap- 

 plication of those manures, might probably 

 be expressed as follows. A dozen years ago 

 it was stated by Likbig and his followers 

 that the great object of all artificial manures 

 "was to supply certain inorganic matters to 

 growing plants. It was asserted that soils 

 became exhausted from the abstraction of 

 potash, phosphoric acid, and soluble silica, 

 and it was therefore said that manures were 

 chiefly valuable in proportion to the quanti- 

 ty of those substances which they contain- 

 ed. The experience of the last few j'^ears 

 has, however, shown that this is not really 

 the case, for the most careful and satisfacto- 

 ry experiments have proved, that soils are 

 veryseldom wanting in the inorganic elements 

 of plants, such as phosphoric acid and alka- 

 lies; but that they are often deficient in ni- 

 trogen, in a state capable of being assimilat- 

 ed by plants. In other words, that ammo- 

 nia and nitric acid are far more important 

 components of manure than phosphoric acid 

 or alkalies. 



That LiEBiG did, at one time, attribute 

 very great importance to the earthy and al- 

 kaline parts of manure, no one will deny; 

 and, indeed, it is evidently proved, by the 

 fact that he even became the originator of a 

 patent mineral manure, which, as Payen 

 remarks, has for the most part been found 

 of comparatively little real value. If, how- 

 ever, it is acknowledged on the one hand, 

 that the value of these inorganic manures 

 has been over-rated, it must, however, at the 

 same time be admitted that there are cir- 

 cumstances under which they produce very 

 remarkable effects; and that even though it 

 is proved that they are not the only things 

 necessary to the growth of plants, or the 

 only things which the cultivator has to add 

 to the soil, it does not, therefore, follow that 

 they are of no value at all ; and we ought to 

 take care that in acknowledging our error, 

 we do not fall into the opposite extreme. 



It has been all along known, that the very 

 best manures were those which contained a 

 mixture of organic and inorganic matters; 

 substances such as common farm-j'ard ma- 

 nure, consisting of decomposed and decom- 

 posing animal and vegetable materials, inti- 

 mately mixed together. The error which 

 has been committed consisted in the attempt 

 to comi)are perfectly different and opposite 

 things; and to decide which of the two was 

 the most important. The alkalies and phos- 

 phoric acid are, no doubt, quite essential to 

 the growth and well-being of plants; but so 

 e ammonia, nitric acid, and the vari- 

 ious other sources of nitrogen. To attempt 



to compare the two kinds of food, is pretty 

 much as though we were to try and compare 

 together meat and bread, as articles of ani- 

 mal food; both are valuable, and the two 

 taken together are more valuable than either 

 taken alone. So it is with plants; it is of no 

 use attempting to determine whether ammo- 

 nia or alkaline phosphates are the most im- 

 portant, as constituents of manure; they 

 serve very different objects in the nutrition 

 of plants, and when the one is required, it 

 is certainl}'- idle to attempt to supply its 

 place b}' giving more of the other. 



There are a number of curious experiments 

 which have at times been quoted, as proving 

 that the organic part of common yard ma- 

 nure is of no value; and that its virtue con- 

 sists entirely in the inorganic salts which it 

 contains. Thus, for example, it has been 

 stated, that on manuring two equal pieces 

 of ground, the one with a certain weight of 

 good farm-3'ard manure, and the other with 

 the ashes of an equal quantity of the same 

 manure, no difference could be subsequently 

 observed between the crops raised on the two 

 fields. The truth of this, again, has been 

 called in question by other experiments, the 

 results of which were just the reverse; and 

 those who attempted to draw general con- 

 clusions from the two experiments, were 

 at last fairly puzzled how to reconcile two 

 apparently diametrically opposite state- 

 ments. The real cause of the difficulty, 

 however, was simple enough; it arose mere- 

 ly from the attempt to compare together dis- 

 similar things, which, from their very na- 

 ture, could not fairly be contrasted with one 

 another. If we admit that which is now 

 pretty well generally acknowledged, name- 

 ly, that all plants, in addition to certain 

 other substances, require both ammonia and 

 also alkaline phosphates, it is very easy to 

 perceive, not only that a manure containing 

 both those substances must be generally val- 

 uable, and therefore more certain in its ef- 

 fects than a manure which contains only one 

 or the other; but also that such a manure 

 would act in a very different manner on dif- 

 ferent soils, and applied to different plants. 

 For example, good farm-yard manure, ap- 

 plied to a soil rich in earthy phosphates, 

 and abounding in bone earth, will, never- 

 theless, be found to do good and cause the 

 plants cultivated in it to grow with increas- 

 ed vigor and luxuriance; not because of the 

 phosphoric acid which it contains, but chief- 

 ly from the presence of a certain quantity 

 of ammonia, nitric acid, and matters capa- 

 ble of yielding those substances by their pu- 

 trefaction. Nevertheless, the same manure 



