1911.] PUBLIC DOCUMENT — No. 31. 347 



Judging from such results most of the soils can at least be 

 classed as normal from a chemical standpoint, some of them 

 good and a few rich. Practically all of them are quite suit- 

 able for crop production if properly handled. One, however, 

 would not care to say, from a chemical analysis alone, whether 

 any one of them was suited to a particular crop, so many other 

 conditions entering into the problem. Brooks, in Circular No. 

 29 of this station, has made this matter clear, as follows: — 



1. The Crop Adaptation. — While the chemical condition of a soil 

 is not altogether without influence in determining the crops to which 

 it is suited, this, as a rule, at least within such range of soil variation 

 as exists in this State, plays a much less important part than mechani- 

 cal and phj'sical peculiarities. The crops to which a soil is suited 

 are determined chiefly by its drainage, its capacity to hold and to 

 conduct water, its temperature and its aeration, and these in turn 

 are determined by the mechanical structure of the soil and sub-soil. 

 Variations in the proportions of gravel, sand, silt and clay, and not 

 in chemical comiiosition, cause the usual differences in these respects. 

 The varying proportions of these, therefore, usually determine the 

 crops to which a soil is suited. 



2. Fertilizer Requirements. — The results of a chemical analy.sis of 

 a soil do not, as a rule, afford a satisfactory basis for determining 

 manurial requirements. The chemist, it is true, can determine what 

 the soil contains, but no ordinary analysis determines with exactness 

 what proportion of the several elements present is in available form 

 for the crop. Indeed, there is no such thing as a constant ratio of 

 availability. While one crop finds in a given soil all the plant food 

 it requires, another may find a shortage of one or more elements. 

 Further, on the very same field one crop may find an insufficient amount 

 of potash ; another may find enough potash for normal growth, but 

 insufficient phosjihoric acid; while a third may suffer only from an 

 insufficient supply of nitrogen. 



Most of our soils are of mixed rock origin, and, as a rule, i^ossess 

 similar general chemical charactei'istics, providing they have been 

 farmed under usual conditions. The manurial and fertilizer require- 

 ments are determined more largely in most soils by the crop than by 

 IDeculiarities in the chemical condition of the soil. 



3. Crop Diseases. — The chemical composition of the soil may in 

 some instances exercise a controlling influence in determining a con- 

 dition of health or disease, and is never unimportant from the stand- 

 point of vigorous, normal and healthy growth; but in the ease of 

 most diseases, the immediately active cause is the presence of a parasitic 

 fungus, and this fungus is usually capable of fixing itself upon the 



