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



the amount of potassium absorbed by a plant was dependent upon 

 the anion of the salt used, the chloride being more readily assimilated 

 than the sulfate. 



Stale (537) in 1937 reported that phosphates alone increased yields 

 as much as did phosphorus and potassium together on certain glacial 

 soils in Switzerland that were rich in available potash. An increase 

 in the phosphorus content and a decrease in calcium content of hay 

 was observed with phosphate fertilization. No consistent effect was 

 noted on the magnesium and potassium contents. Potash alone 

 resulted in no increased yields, a marked increase in the potash con- 

 tent, and a decrease in the calcium and magnesium content of the 

 plant. No effect was observed on the phosphorus content of the plant. 



Increases in the phosphorus content of hays, as a result of fertiliza- 

 tion, have been reported bv several investigators in Minnesota (6), 

 Montana (98, 440), Florida (95), and Germany (321). Bishop (71) 

 obtained increases in the phosphorus content of a number of vegetables 

 (both leaves and roots) when phosphates were applied to Alabama 

 soils, but the increases in phosphorus in plants grown in some soils as a 

 result of fertilization were not large enough, in many cases, to produce 

 plants that contained as much phosphorus as did those grown in other 

 soils. Thus, a marked increase in the phosphorus content of turnip 

 tops was obtained by the use of 1,000 pounds of superphosphate per 

 acre of Oktibbeha soil, but still the phosphorus content did not equal 

 that of turnip leaves grown on the Eutaw soil without phosphorus 

 fertilization. 



The effect of the liming of soils has been studied by a number of 

 investigators. Gile and Ageton (209) in 1914 made extensive in- 

 vestigations of the effect of liming on the composition of crops grown 

 in Puerto Rican soils. They reported that 



The limestone apparently had no effect on the amount of nitrogen, potassium 

 and phosphorus contained in the various plants, but did increase slightly the total 

 carbon-free ash in all plants except rice. The calcium, magnesium and iron 

 contents were all modified, the iron content sometimes being greatly reduced. 



xlmes and Schollenberger (8) showed in 1924 that the effect of liming 

 on plant composition varied markedly with the soil. In general, 

 however, they noted a tendency for liming to result in a decreased 

 phosphorus content in the plant. Hjorth-Hansen (273) in 1931 

 reported that the contents of phosphorus, potassium, and calcium in 

 the plant were influenced to a great extent by a change of soil reaction 

 resulting from liming. The magnesium content remained quite 

 constant. 



Emmert (167) i investigating liming practices in Kentucky, reported 

 that the average percentages of the phosphorus and manganese in the 

 plants grown in the more acid soils were greater than the average of 

 those grown in the more nearly neutral soils, while Lott (358) found 

 that calcium carbonate greatly decreased the absorption of zinc by 

 plants. 



Carolus (108) in 1933 reported that even small amounts of limestone 

 increased the absorption of magnesium under conditions of excessive 

 rainfall in Virginia. The available magnesium content of soils under 

 such conditions is readily depleted by leaching, unless the soil con- 

 tains in its internal colloidal phase an abundance of organic matter. 

 Rendering the soil more alkaline with limestone results in an increase 

 in this necessary organic material.' 



