June 26, 1916 



Mineral Phosphates and Plant Nutrition 



503 



The data in Table XI show that dextrose .fails to be of any particular 

 advantage for rendering phosphorus available for the growth of rye and 

 clover. Even small quantities of this material killed clover. 



Table XI. — Dry matter prodticed by Tennessee brown rock phosphate and dextrose in 

 growing spring rye and red clover 



SERIES 5 



SERIES 6 



3- 

 4- 

 5- 

 6. 



7- 

 8. 



9- 



10. 



ft 20 



&20 

 ^20 

 *20 

 ^20 

 ^20 

 b 20 



b 20 



3- 

 2. 

 o 

 o 



o The clover in pots 19, 20, and 21 was dead on June 29. 1913. 



6 The clover in pots 17 to 24, inclusive, was dead in less than i month after planting. 



Rye and clover were replaced in series 7 (Table XII) by cowpeas, with 

 the feeling that the latter crop might respond more readily to various 

 treatments (PI. LXXVII). The cowpeas v/ere planted on July 4, 191 3, 

 and harv^ested on October 2, 191 3. 



The cowpeas grown in series 7 show clearly that so small a quantity of 

 dextrose as 4.8 per cent was injurious to plant growth. Where dextrose 

 was applied, smaller quantities of phosphorus were assimilated, due, no 

 doubt, to the injury of the plant by the acids formed from decomposing 

 dextrose. However, the percentage of phosphorus increased as the 

 quantity of the fermentable substance was increased. 



