29 



QUESTIONS OFTEN ANSWERED BY THE ANALYSIS OF SOILS. 



The results of soil analysis frequently give, decided and satisfactory 

 answers, according to Dr. Voelcker,* to the following questions : 



(1) Whether or not barrenness is caused by the presence of an injurious substance, 

 such as sulphate of iron or sulphide of iron, occurring in peaty and clayey soils ? 



(2) Whether soils contain common salt, lauds flooded by sea water, nitrates or other 

 soluble salts, that are useful to vegetation in a highly diluted state, but injurious 

 when they occur in land too abundantly? 



(3) Whether barrenness is caused by the absence or deficiency of lime, phosphoric 

 acid, or other important elements of plant food? 



(4) Whether clays are absolutely barren, and not likely to be materially improved 

 by cultivation, or whether they coutain the necessary elements of fertility in an un_ 

 available state, and are capable of being rendered fertile by subsoiliug, deep cultiva- 

 tion, steam plowing, and similar mechanical means? 



(5) Whether or not clays are usefully burnt and used in that state as manure ? 



(6) Whether or not the land will be improved by liming? 



(7) Whether it is better to apply lime, or marl, or clay, on a particular soil ? 



(8) Whether special manures, such as superphosphates or ammoniacal salts, can be 

 used of course, discreetly without permanently injuring the land ; or whether the 

 farmer should rather depend upon the liberal application of farm-yard manure, that 

 he may restore to the land all the elements of fertility removed in the crops? 



(9) What kind of artificial manures are best suited to soils of various compositions? 



According to the same authority ,t chemical analysis cannot supply 

 any definite information in regard to barrenness of soil on the following 

 questions : 



(1) Whether barrenness is caused by defective drainage? 



(2) To what extent sterility is affected by a bad physical condition of the land ? 



(3) How far unproduc'iveiiess is affected by the climate ? 



(4) That a soil is barren simply because there is too little of it ; or 



(5) That it is unproductive simply because a thin surface soil rests on a stiff clay 

 subsoil of great depth ? 



(6) What is the relative productiveness of different soils? 



OBJECTS AND INTERPRETATION OF SOIL ANALYSIS. 



For a very full discussion of the objects and interpretation of soil anal- 

 ysis the reader is referred to an article on this subject in the American 

 Journal of Science vol. 22, pp. 183-197, by Prof. B. W. Hilgard, as well 

 as the report on U 8oil Investigation," by the same author, contained 

 in the " General Discussion of the Cotton Production of the United 

 States, 77 Tenth Census of the United States, 1880, Vol. V, pp. 67-81, of 

 whicli the following is a summary : 



The claim of soil analysis to practical utility has always rested ou the general .suit- 

 position that, "other things being equal, productiveness is, or should be, sensibly 

 proportional to the amount of available plant food within reach of the roots during 

 the period of the plant's development; " provided, of course, that such supply does 

 not exceed the maximum of that which the plant can utilize when the surplus simply 

 remains inert. This statement is, either tacitly or expressly, admitted by all those 



' Jouru. Royal Agric. Soc., vol. xiv, p. 338. 



t Jouru. Royal Agric. Soc., vol. 1, 1865, p. 12L). 



