84 Mineral Nutrition of Plants 



At one time it was believed that liming decreased the boron availa- 

 bility of soils. Subsequent work, however, indicates that if it does affect 

 availability, it is because of the relation to boron fixation by soils (5). 

 Other investigations have shown that boron fixed by soils under alka- 

 line soil conditions is readily released by acidification. 



TABLE I 



Distribution of Phosphorus Between Clay Surfaces and the Liquid Phase of a 

 Clay-Water System as a Function of pH, and Amounts of Phosphorus Added* 



*Adapted from Dean and Rubins (//). 

 fSodium hydroxide was added on the 28th day. 

 _ Cqh (solution) X ChsPo, (surface) 

 Coh (surface) X Ch 3 poi (solution) 



Robinson* has shown that crops grown on limed plots contained a 

 greater concentration of molybdenum than the crops from adjacent 

 unlimed plots. 



Soluble salts 



The concentration of phosphorus in the liquid phase of soils is 

 dominantly influenced by the concentration and kind of salts present. 

 The extent to which the concentration of phosphorus in the soil solu- 

 tion is increased by lowering the salt concentration can be demon- 

 strated by comparing the phosphatic concentration of successive in- 



*W. O. Robinson, private communication. 



