JANUARY, 1912 CIRCULAR No. 12 



CORNELL UNIVERSITY 



AGRICULTURAL EXPERIMENT STATION OF 

 THE COLLEGE OF AGRICULTURE 



Department of Soil Technology 



THE CHEMICAL ANALYSIS OF SOIL 



E. O. FippiN 



The large number of requests for analyses of samples of soils sent by 

 residents of the State, has made it advisable to put in printed form a state- 

 ment of the policy of the College in this matter. There appears to be 

 a general belief on the part of persons not familiar with the technic 

 of soil investigation, that a chemical analysis of a soil is in itself a reliable 

 guide to the fertilizer needs of that soil, to the kind of crops adapted to 

 the soil, and to its treatment generally. Unfortunately this is not the 

 case. It is our policy, therefore, not to make chemical analyses of samples 

 collected by other than our own agents. 



The insufhciency of a chemical analysis of the soil when unaccompanied 

 by other careful studies, the unreliability of samples collected by persons 

 not trained in the work, and the limited facilities of the College, make 

 the analysis of miscellaneous soil samples an unprofitable expenditure of 

 public money. 



THE INSUFFICIENCY OF CHEMICAL ANALYSIS 



I. Chemical composition of soils and plants. — Chemical analysis \\dll 

 determine the total constituents, or some proportional amount of them, 

 which a soil contains. The total amount of plant food constituents in 

 the normal soil is large in comparison with the amount removed by an 

 average crop. Plants use ten elements in their growth and seven of them 

 are obtained from the soil; the soil elements are iron, sulfur, magnesium, 

 calcium, potassium, phosphorus, and nitrogen. Water and the carbon 

 dioxid of the air furnish the other three elements — hydrogen, oxygen, 

 and carbon. 



Potassium, phosphorus, and nitrogen have been termed the fertilizer 

 constituents because the addition of these most generally serves to give 

 increased crop growth. The object of a chemical analysis of samples of 

 soil is to determine whether any of these are present in insufficient amounts. 

 The following table shows the amount of the most important plant food 



constituents in a normal soil in pounds per acre of soil one foot deep: 



[717] 



