4 



On Agricultural Chemistry. 



Prussia, has published the results of many analyses of soils. The 

 truth is, that little is as yet known of what a soil either is or ought 

 to be, in a chemical point of view ; but when we call to mind the 

 investigations of Professor Mulder, in relation to the organic 

 acids found in soils, and of Mr. Way and others, as to the chemical 

 and physical properties of soils, in relation to the atmosphere, 

 and to saline substances exposed to their action in solution, we 

 may at least anticipate for chemistry that she will ere long throw 

 important light on this interesting but intricate subject. 



In our field experiments, then, we have been satisfied with pre- 

 serving specimens of the soils which were to be the subjects of 

 them, and have sought to ascertain their deficiency, in regard to 

 the production of different crops, by means which we conceive to 

 be not only far more manageable, but in every way more con- 

 clusive and satisfactory in their result. 



To illustrate — What is termed a rotation of crops is at least of 

 such universality in the farming of Great Britain, that any investi- 

 gation in relation to the agriculture of that country may safely be 

 grounded on the supposition of its adoption. Let us, then, direct 

 attention for a moment to some of the chief features of rotation. 

 What is called a course of rotation is the period of years which 

 includes the circle of all the different crops grown in that rotation 

 or alternation. The crops which thus succeed each other, and 

 constitute a rotation, may be two, three, four, or more, varying 

 with the nature of the soil and the judgment of the farmer ; but, 

 whatever course be adopted, no individual crop • — wheat, for 

 example — is grown immediately succeeding one of the same de- 

 scription, but it is sown again only after some other crops have 

 been grown, and at such a period of the rotation, indeed, as by 

 experience it is known that the soil will, by direct manure or 

 other means, have recovered its capability of producing a profit- 

 able quantity of the crop in question. 



On carefully considering these established and well-known facts 

 of agriculture, it appeared to us that, by taking soils either at the 

 end of the rotation, or at least at that period of it when in the 

 ordinary course of farming farm-yard-manure would be added 

 before any further crop would be grown, should then have 

 the soils in what may be termed a normal, or, perhaps better still, 

 a practically and agriculturally exhausted state. 



Now, if it is found, in the experience of the farmer, that land 

 of any given quality with which he is well acquainted, will not 

 when in this condition of -practical exhaustion yield the quantity 

 he usually obtains from it of any particular crop, but that after 

 applying farm-yard manure it will do so, it is evident that if 

 we supply to different plots of this exhausted land the constituents 

 of farm-yard manure, both individually and combined, and if 



