MINERAL COMPOSITION O'F CROPS 45 



stems accompanied potassium fertilization. They also found that 

 the potassium content of the juice paralleled the potassium applied 

 as fertilizer, whereas the phosphorus fertilization decreased the 

 potassium content in young, rapidly growing plants. 



Mather (398) claimed in 1929 that fertilization increased the 

 inorganic, but not the organic, phosphorus content of hays grown in 

 Minnesota and Canada. 



Murphy {422), working with the Kirkland sandy loam in Oklahoma, 

 in 1930, reported an increase of about 20 percent in the phosphorus 

 content of wheat grain when he applied superphosphates. Neither 

 the application of potash nor of nitrogen alone resulted in any change 

 in the phosphorus content of the grain. 



Hester and Shelton (267, 268, 269), investigating the relationship 

 between the replaceable bases in Virginia soils and the composition of 

 vegetable crops, concluded that a high absorption of calcium at 

 high pH value to the exclusion of the other ions (potassium in par- 

 ticular) was probably responsible for depressed yields. In general, 

 he observed that 



The presence of a large amount of a particular replaceable base in the soil colloidal 

 complex influenced the elemental composition of plant material even though the 

 yields were affected but little. A high replaceable calcium content suppressed 

 the absorption of potassium, nitrogen and magnesium; a high replaceable mag- 

 nesium content suppressed the absorption of potassium, calcium and nitrogen; 

 and a high potassium content suppressed the absorption of calcium, magnesium 

 and nitrogen. 



The investigations of Tyson (569) in 1930 of the relationship be- 

 tween soil conditions in Michigan and the chemical composition of 

 sugar beets indicated that the addition of potassium to unlimed plots 

 resulted in increased potassium content of the leaves and roots and 

 caused a decrease in the percentages of calcium, magnesium, sodium, 

 and phosphorus. Applications of calcium resulted in a decrease in 

 the potassium content and increased the phosphorus, sodium, and 

 calcium content. Applications of phosphorus caused an increase in 

 phosphorus and a decrease in potassium in the plant. 



Wimer (596), studying the composition of mature corn stover in 

 Illinois, reported in 1937 that 



The general tendency of limestone was to raise the nitrogen, phosphorus, potassium 

 and calcium contents of the stover and to increase the stover and grain yields. 

 The chief exceptions were in the stover yields on soils naturally well supplied 

 with carbonates, where the addition of limestone might be expected to have little 

 or no effect. 



Rock phosphate, when used in addition to residues (green manures) 

 and limestone, resulted in increased nitrogen and phosphorus contents 

 of the stover, but little or no change was observed in the contents of 

 potassium and calcium. The use of potassium resulted in an increase 

 in the potash content, a decrease in nitrogen and phosphorus, and no 

 change in the calcium content. 



Opitz, Rothsack, and Morgenroth (442), working with barley grown 

 in a German soil, stated in 1937 that the omission of phosphorus 

 from a complete fertilizer caused a reduction in the phosphorus content 

 of the plant, a slight increase in the potash, and a significant increase 

 in nitrogen. The omission of potassium resulted in a decrease in 

 potassium and a slight increase in nitrogen, but no material change in 

 phosphorus. Byczkowski (99), working with Polish soils, found that 



