MINERAL COMPOSITION OF CROPS 27 



phosphorus content than tobaccos grown in light soils. Some rela- 

 tionship was also established between the "available" lime in the soils 

 and the calcium content of the plant. 



Robinson, Steinkoenig, and Miller (495) in 1917 made a number of 

 analyses of plants collected on different soils. Their analytical work 

 is the most complete that has ever been published in this field, but, 

 unfortunately, comparisons of the different samples cannot always be 

 made in order to determine differences in soil properties, because the 

 stage of growth of the plants differs. Specific references to most of 

 their analyses are given in the appendix, and an examination of their 

 data reveals interesting variations in some of the minor element con- 

 tents of the plants studied. Thus, the manganese content of wheat 

 grown in the Durham soil is very high as compared with that of wheat 

 grown in the Penn silt loam, but the manganese content of the Dur- 

 ham soil is about one-eighth of that of the Penn soil. The magnesium 

 content of the red clover grown in a Penn silt loam was higher than 

 that of the clover grown in a Hagerstown loam, although the relative 

 magnesium contents of the two soils are the reverse of that of the 

 plants. Similar results are shown for the manganese, strontium, and 

 aluminum contents of this plant. Both soils are classified as gray- 

 brown podzolic soils, but the Penn silt loam is developed from shale 

 while the Hagerstown loam is developed from limestone. It is evident 

 from these data that no direct relationship necessarily exists between 

 any single characteristic of the soil and any characteristic of the plant. 



These authors also studied the occurrence of a number of unusual 

 elements such as rubidium, which was not detected at all in the wheat 

 plant from a Penn silt loam, whereas 2.7 p. p. m. was found in the 

 plant from the Durham loam. In other samples of vegetation these 

 authors found caesium in plants grown in two soils known to contain 

 caesium beryls, whereas they reported that most of the vegetation 

 did not contain this element. Chromium was occasionally found, 

 though in very small amounts. Vanadium was detected in only 

 six instances, and then only in traces. 



Maschhaupt (397) determined the composition of summer barley, 

 field beets, oats, two varieties of winter barley, potatoes, and rye 

 grown in rotation in several Dutch soils from 1909 to 1922. His 

 soils, transported from their original environment, included peat 

 soils, loams, and clays and lay adjacent to one another but separated 

 by concrete walls. He reported that the influence of soil type on 

 the content of nitrogen and the ash constituents was greater on grain 

 straw, potato leaves and beet leaves than on the grain itself, beet 

 roots, or potato tubers. The silica content of the straws from the 

 clay soil were nearly five times as high as those of the straws grown 

 in a "heidebode," and significant variations were noted in the phos- 

 phorus contents of potatoes and the calcium contents of beets grown 

 in different soils. 



Carefully sampled and prepared specimens of crabgrass (Digitaria 

 sanguinalis (L.) Scop.) obtained from a garden soil and from a lime- 

 stone roadway were analyzed by Buckner (96) in 1919. The samples 

 grown on the roadway soil contained about 50 percent more calcium 

 and more phosphorus and magnesium in the ash than did the other 

 samples, but calculated on the dry basis rather than on the ash, the 



