MINERAL COMPOSITION OF CROPS 23 



Theodore de Saussure, of Switzerland, in 1804 made the first approximate 

 analyses of the ashes of the leaves, stalks, bark, wood, straw, seeds, fruits, etc., of 

 79 different plant products, the results of which were assembled in the earliest 

 published tabulations of this character [(504)]. 



Saussure's work demonstrated the falsity of the old view that plants could 

 produce any of their mineral constituents by the transmuting action of vital 

 forces. His numerous experiments established the following facts: 



(1) The mineral constituents of plants are obtained in solution through the 

 roots from the soil. 



(2) Plants do not absorb mineral constituents in the same proportion in which 

 they occur in the soil solution, but they have a marked selective power, some 

 elements being assimilated in greater amounts than others. 



(3) Herbaceous plants assimilate more mineral matter and exhaust the soil 

 more markedly than do woody plants. 



(4) Different soils have a profound influence upon the quantity and composition 

 of the mineral constituents of the same species of plants. 



(7) The different organs of plants differ in the content and composition of their 

 mineral constituents. 



(8) The percentage of ash in herbaceous plants reaches its maximum before the 

 flowering stage and thereafter begins to decline. 



Carl Sprengel, a German agriculturalist, was the first (1838) to attempt an 

 enumeration of the various mineral elements of the soil that are necessary for the 

 normal growth of crops [{535)]. Because of the general occurrences of the 10 

 mineral elements, potassium, sodium, calcium, magnesium, iron, aluminum, 

 manganese, sulfur, phosphorus, and chlorine, in the ashes of all plants, he drew the 

 conclusion that the elements named were all essential for the growth of crops. 

 Sprengel also remarked that other mineral elements not yet discovered in plants, 

 as fluorine, bromine, iodine, lithium, and copper, even though occurring in minute 

 amounts, might also be necessary — a statement that foreshadowed modern investi- 

 gations of a century later upon the so-called trace or minor elements of soils and 

 crops. 



Sprengel maintained that in addition to the soil elements which promoted the 

 growth of plants, there were other elements, as lead, arsenic, and selenium, which 

 injured the growth of plants if they existed in combinations that were easily 

 soluble in water. He stated, however, that all plants were not affected alike by 

 these injurious elements, one species having a greater power of resistance than 

 another. Sprengel seems to have been the earliest to call attention to the possible 

 injurious effects of selenium upon the growth of plants. 



Of the early developments in the United States, Browne states that 

 "the first scientists to make studies of the correlation of differences in 

 American soils with the mineral constituents and nutritive value of 

 the crops were the State geologists." Among these men was Amos 

 Eaton, who "made an agricultural survey of Rensselaer County, N. Y., 

 as early as 1821. Hitchcock, Jackson, Emmons, Shepard, Owen, 

 Booth, and the other early State geologists made chemical analyses of 

 the soils and crops of their respective States." Browne continues: 



No writer has more clearly expressed the vital need of correlating the mutual 

 chemical relationships of soils and crops than has Jackson. In the Patent Office 

 Report on Agriculture for 1858 [(296)], Jackson published a comparative research 

 upon the relationship of the chemical composition of soils in Massachusetts and 

 Maryland to the chemical composition of the ash of the tobacco which was grown 

 thereon. The ash of Maryland tobacco was higher in magnesia and lower in lime 

 than the ash of the Massachusetts tobacco, a circumstance which led Jackson to 

 the conclusion that these bases might replace each other to a certain extent without 

 alteration in the healthy condition of the plant. He remarks that the limits of 

 such substitution can be determined only "by making a long series of analyses of 

 the same varieties of plants grown on peculiar soils, or on such as are artificially 

 prepared for the experiments." 



There are many factors that may operate to modify the mineral 

 composition of the plant. These would include differences in soils, 

 cultivation and the use of soil amendments, rainfall and other climatic 



