SECRETARY'S REPORT. 43 



that every rootlet readily finds its appropriate food, and so the 

 plants thrive to perfection ; or it may be such that, though capa- 

 ble of being brought to light by the action of chemical reagents, 

 they may be, for all practical purposes, locked up from the little 

 rootlets, utterly unavailable, and so the plants starve. A proper 

 combination of elements in a soil is but one among other neces- 

 sary conditions of fertility. 



This subject is so fairly and ably treated in a paper, by Dr. 

 John D. Easter, in the transactions of the United States Agri- 

 cultural Society, that no apology is deemed necessary for its 

 insertion here : 



" I propose, in this paper, to consider the true use of chemi- 

 cal analysis of soils, and some of the requisites of a valuable 

 analysis. 



As it is from the soil that plants derive the principal part of 

 their constituent elements, the presence in the soil of these ele- 

 ments, in forms in which they may be absorbed by the rootlets 

 of the plants and assimilated in their cells, is indispensable to 

 their perfect growth. Where the want of fertility arises from 

 the absence of one or more of these constituents, or to their 

 being locked up in combinations in which plants cannot use 

 them, chemical analysis is perfectly competent to detect the 

 cause of the evil and point out its remedy. 



But the growth of plants is influenced by a multitude of other 

 circumstances to which chemical analysis can furnish no clue. 

 A soil may abound in all the elements of a very fertile one, and 

 yet be perfectly barren. The soil of the great Colorado desert 

 in California, which I have recently analysed, furnishes a good 

 example of this. It possesses in abundance every element 

 necessary to extreme fertility, but it is entirely barren from the 

 want of water. 



The reverse of this also frequently occurs. The chemist 

 receives a specimen of soil, in the chemical constitution of 

 which he can detect no deficiency, and in his laboratory, he can 

 assign no cause for its alleged unproductivenes. An examin- 

 ation of the locality probably shows him that it is underlaid 

 by a stiff tenacious subsoil, which retains an excess of water, 

 and no provision has been made for drainage. 



