MINERAL COMPOSITION OF CROPS 39 



p. p. b. Bishop and Lawrenz (72) reported that they detected cobalt in 

 different species of plants, as well as in some species grown in certain 

 soils. Robinson, Whetstone, and Scribner (497) found most of the 

 rare earths in hickory leaves taken from a tree growing in a pegmatite 

 vein of the Moorefield Mine, Amelia, Va. Later unpublished work 

 by Robinson (18x) seems to indicate that this group of elements may 

 normally be present in the hickory tree wherever it may be found. 

 Dingwall, McKibbin, and Beans {155) reported, in 1934, that molyb- 

 denum was found in plants grown on one farm, while none was found 

 in those grown in any other soils. The molybdenum, they state, "may 

 have been present in the parent rock or it may have been carried 

 down with drainage waters." Dingwall and Beans (154) also 

 reported the presence of chromium in some plants grown in certain 

 localities. Nemec, Babicka, and Oborsky (433) recently claimed 

 to have found considerable quantities of gold in certain plants growing 

 in gold-bearing soil in Czechoslovakia. Their data indicate that 

 Eguisetum palustre L. accumulated gold to the extent of 610 gm. per 

 ton of plant ash. 



Effect of Soils on Botanical Composition of Herbage of Pastures 



In 1873, Muller (420) reasoned that pastures grazed by animals 

 suffering from nutritional diseases must, either positively through 

 poisoning or indirectly through mineral deficiencies, adversely affect 

 the animal. A botanical analysis of some pastures revealed no great 

 difference in the amount or quality of the different forage plants in 

 normal and abnormal pastures, but in other cases an unusual number 

 of undesirable plants such as "sauergrasern" and marsh plants were 

 found in abnormal pastures, whereas sweetgrasses and clovers pre- 

 vailed in the better pastures. Similar observations were made by 

 Lawes and Gilbert (333) in 1900 and by Armstrong (14) in England, 

 who found that white clover, ryegrass, crested dogstail, and florin 

 (Agrostis stolonifera L.) were most abundant on the best grazing lands. 

 The herbage of the inferior types of grassland in the same districts 

 consisted very largely of bentgrass (A. vulgaris With.) and various 

 weeds, while white clover and ryegrass were present in comparatively 

 small quantities. Woodman, Blunt, and Stewart (599) noted 

 seasonal variations in the botanical composition of pastures. 



Barnes (47) , in 1911, found that treating Ohio pastures with lime- 

 stone and acid phosphate was accompanied first by a marked increase 

 in percentage of legumes. This was later followed by a renewal of 

 the bluegrass sod, which, however, did not reach its optimum until 

 at least the end of the fourth summer after treatment. Brown 

 (89, 90) reported in 1933 that fertilization with phosphorus, lime, and 

 potassium, as compared with other systems of manuring, resulted in a 

 maximum increase of white clover in Connecticut pastures. 



Robinson (492), in his recent comprehensive investigations of 

 pasture flora and soil fertility in West Virginia, concluded that 



A comparison of samples from the same pastures shows that, in general, soils 

 supporting Kentucky bluegrass are higher in pH, percentage base saturation, total 

 exchangeable bases, available phosphorus, total nitrogen, and exchangeable 

 potassium, than are soils supporting Danthonia. Base exchange and available 

 phosphorus are the limiting factors, however. In the Hagerstown soil there is a 

 high correlation between the percentage of Kentucky bluegrass plus white clover 

 in the pasture and the amount of phosphorus in the soil. 



