106 EXPERIMENT STATION RECORD. 



the foundation which accumulated investigation has laid for this 

 better understanding of the nature of the questions studied is one 

 of the important products -which the public rarely appreciates. It 

 has modified the method of attack and the kind of information 

 sought. 



We no longer study soil fertility ; we study some special phase of 

 the problem, and the exact manner in which it affects the composite 

 condition designated as fertility. Neither do we study summer 

 fallowing for itself, but we seek out and study the factors which 

 are vitally involved in it. To determine merely that so many more 

 bushels of wheat were produced where the field was summer fal- 

 lowed is a demonstration at the present stage, and not an experiment 

 designed for getting new information. Studies in nitrification and 

 ammonification were carried on assiduouslj^ for several years before 

 the accuracy of the methods of study began to be questioned or the 

 care realized which should be exercised in drawing deductions from 

 the results. Investigators have come to feel that the meaning and 

 correlation of nitrification with other processes must be fundamen- 

 tally examined before a deeper understanding of its relation to meth- 

 ods of practice can be reached. 



The study of fertilizers and their use has followed much the same 

 course as that of soils. At first it was confined largely to analysis 

 of the materials and tests to show their effects upon various crops 

 in the field. The results obtained from these field tests were often 

 so extremely variable, however, as to make them difficult to under- 

 stand and to necessitate more exact methods and the determination 

 of limiting conditions. From these the work led naturally to studies 

 of the principles of the use of fertilizers, the relations of fertilizing 

 materials in the soil, their availability to plants, and the fertilizer 

 requirements of various crops. 



Fertilizer investigations have, therefore, in recent 3'ears taken a 

 quite different direction from the earlier work and are largely con- 

 cerned with narrowly restricted, specific studies. The result has been 

 to inject more caution into extension teaching regarding the use of 

 fertilizers, and to regard new results with some measure of doubt 

 until they are sufficiently confirmed. The broad basis for the intelli- 

 gent use of fertilizers has been laid in the work of the past twenty- 

 five years, and the present question is one of economic and wise use 

 as applied to a given farming system or region. 



The early work of the stations on field crops included an immense 

 number of practical experiments on crops of all kinds, together with 

 special investigations relating to them. The feeding value, cultural 

 methods, fertilizer requirements, improvement by breeding, adapta- 

 tion, and tlio merits of varieties were studied with every farm crop 

 grown commercially in the country. This furnished a broad basis 



