42 MISC. PUBLICATION 3 69, U. S. DEPT. OF AGRICULTURE 



modified by the use of fertilizers has been known since the earliest soil 

 fertility studies were made, and, in fact, plant composition has often 

 been used as a guide for determining the nutrient requirements of a 

 soil. One of the first and most comprehensive investigations of this 

 nature ever undertaken is that of Lawes and Gilbert (332) in 1884. 

 They analyzed 92 wheat-grain and the same number of wheat-straw 

 samples collected over a period of years. Every sample was from a 

 crop of known history of growth, as to soil, season, and manuring. 

 Nine different fertilizer treatments were investigated, and much 

 valuable information was obtained concerning yields and crop quality. 

 They concluded, for example, that 



the proportion of both potassium and phosphorus in the grain, which if normally 

 ripened is assumed to be a comparatively uniform product, varies very con- 

 siderably according to season; whilst at any rate as between the grain grown with 

 farmyard manure and that grown without manure, the mean proportion over the 

 sixteen years differs but little. The grain grown under the influence of ammonium 

 salts alone shows not only a wide range in the proportions of both potassium and 

 phosphorus according to season, but much lower mean amount than either with 

 farmyard manure or without manure. 



Among other early workers in this field of investigation was Robert 

 Peter (454), wno m 1884 reported that calcium sulfate applied to a 

 Kentucky soil caused an increase in the calcium and potassium con- 

 tent of the hemp plant. Anderson (9) in Alabama, Lechartier (334) 

 in France, and Godlewski (213) in Austria were also pioneers in this 

 work of determining the composition of plants grown in fertilized and 

 unfertilized soils. Hills made quite extensive investigations, in 

 1898, of the composition of potatoes and of corn and corn stover grown 

 in Vermont soils with and without fertilizers (271, 272). His data do 

 not show any marked differences in the composition of the plants when 

 different fertilizer elements or combinations of these elements were 

 applied to either a sandy loam or a clay loam soil. Similar results on 

 potatoes were reported by Davidson (1 42) in 1898 in connection with 

 his work in Virginia. 



NITROGEN, PHOSPHORUS, AND POTASSIUM 



It does not seem necessary to consider in detail the great number of 

 experiments that dealt with the change in the nitrogen, phosphorus, 

 and potassium contents of plants when these plants were grown in 

 differently fertilized soils. Few of the investigations included observa- 

 tion on soils, climate, or other pertinent factors, and they are, therefore, 

 of little value in any general interpretation. For the most part, there- 

 fore, only those fertility experiments of rather recent date that deal with 

 well-identified soils, and those that deal with the specific effects of each, 

 or definite combinations of the elements, on the mineral composition 

 of the plant, will be discussed. 



Nolte (438) reported in 1923 that fertilization with potash, either 

 with or without phosphates, did not materially modify the composition 

 of the grain or straw of barley, field beans, or field bean straw, or beets 

 or beet leaves, when these crops were grown in soils of quite different 

 character in Germany. 



Price (472) in 1923 reported a 500-percent increase in the calcium 

 content and a 300-percent increase in the phosphorus content of the 

 first cutting of alfalfa hay when he applied 2 tons of limestone per acre. 



