880 ANNUAL REPORT OF THE Off. I>oc. 



SUMMARY OF THE MAINE STATION EXPERIMENTS. 



1. Plants differ iu their ability to feed upon crude phosphates. 



2. Turnips, rutabagas, caulitlowers and kohlrabi gave nearly as 

 good returns with the Florida rock as with the acid rock. 



8. In every other case the good effect of the acid rock was very 

 marked. 



4. In most cases the crude Florida rock yielded better returns 

 than the Redonda. 



5. Barley, corn and oats seem to require an acid (soluble) phos- 

 phate. 



6. When early maturity is desired, the acid rock can profitably be 

 used. 



7. The largely increased production obtained by the use of the acid 

 rock will often determine the success of the crop. 



8. The solubility of a phosphate in ammonium citrate is not always 

 the correct measure of its actual value to the plant. 



TESTS MADE BY THE CORNELL UNIVERSITY EXPERIMENT STATION. 



In the winter of 1900-1901 some experiments were conducted at 

 the Cornell Experiment Station upon the relative ability of various 

 orders of plants to utJize different sources and forms of phos- 

 phoric acid. These tests were conducted in a green-house and 

 the plants grown in box pots. The soil in which the plants were 

 grown was a white quartz sand prepared by grinding quartz rock. 

 The soil or medium furnished practically no plant food, so that 

 it was necessary to furnish an artificial supply of the essential 

 plant foods. All conditions were made exactly similar except as to 

 the kind of phosphoric acid supplied. The actual amount of phos- 

 phoric acid supplied the different boxes was the same, but the 

 sources were different. 



The following table gives the variety of plants used, the source of 

 })hosphoric acid supplied and the results obtained: 



