506 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 



bo more scientifu' in tlie I'uturo than in tlio past, with consequent 

 i^reater and surer returns for the money and hibor expended. 



An especially valual)le line of research has been the study of the 

 action or some of tlie compounds isolated from soils on plants, with- 

 out fertilizers and also with various ratios of fertilizers. In these 

 investi<]:ations it has been found that some of these isolated bodies 

 are decidedly harmful in their efTects on plant growth and that this 

 harmfulness consists not only in the dwarfino; or killing; of the plant, 

 but that the process of absorption of nutrients is very seriously 

 interfered with, so that even in the presence of larj^e amounts of 

 nutrient elements the plant can not obtain its full amount of nutrients 

 when the harmful body is present. It has further been found that 

 while the fertilizer salts ameliorate the harmful effect, they do not 

 entirely overcome it. The most interestino; factor of this work has 

 been the discovery that certain harmful compounds are overcome 

 most by the mainly nitroo:enous fertilizers, that others are influenced 

 most by potassic fertilizers, and still others are influenced most by 

 phosphatic fertilizers. 



The action of fertilizers on soils is a much contested question, but 

 the wei.2:ht of evidence is ajjainst the assumption that their effect 

 is due aitopjether to the added plant food. If so simple an explanation 

 were a true one, nearly a century of investio;ation of this problem by 

 scientists of all civilized nations would surely have produced greater 

 unanimity of opinion than now exists in regard to fertilization. 

 Tiioughtful investigators everywhere are finding that fertilizer salts 

 are influencing many factors which contribute toward plant produc- 

 tion besides the direct nutrient factor for the plant. It is this addi- 

 tional influence of fertilizers wdiich makes them doubly effective 

 when rightly used. To this influence of fertilizers on soil and bio- 

 logical conditions is due their capriciousness when applied on the 

 the theory of lacking plant food and any study which throws light 

 upon the mooted question is of direct help toward reaching that view 

 of soil fertility and soil fertilization which will eventually result in 

 a more definite system of fertilizer practice, to the end that surer 

 and safer returns shall be obtained from their use. This will tend to 

 extend fertilizer practice by making it more remunerative and 

 rational than in the past. 



SOIL-WATER INVESTIGATIONS. 



The soil-water investigations were continued in field and office 

 throughout the year. The later field w^ork has lain largely in Kansas, 

 Colorado, and California. Western Kansas (in wdiich a reconnois- 

 sance soil survey has just been completed) and eastern Colorado 

 form a typical part of the Great Plains sloping eastw^ard from an 

 average altitude of some 5,300 feet at the base of the Rockies to, say, 

 1,800 feet, or at the rate of 10 feet to the mile. The underlying 

 formations are largely Cretaceous sandstones and shales; these are 

 overlain by heavy deposits of sands, gravels, and loams w^hich form 

 the soils and subsoils. Both the Cretaceous formations and the 

 overlying deposits are pervious in varying degree, and throughout 

 the region ground water is found at a limited depth below the sur- 

 face; where the materials are sufficiently pervious to permit free 

 movement this ground w^ater supphes w^ells, and frequently where 



