No. 6. DEPARTMENT OF AGRICULTURE. 851 



EXPERIAfENTS AT THE PENNSYLVANIA STATION, WITH SOLUBLE, 

 REVERTED AND INSOLUBLE PHOSPHORIC ACID. 



These experiments had for their object the testing of the value 

 of the dilTerent forms of phosphoric acid in actual crop production, 

 as coiiii)ared with their cost in the market. These experiments were 

 phiuned by Dr. W. H. Jordan, now director of the New York Agri 

 cultural Experiment Station at Geneva, and have been in progress 

 since 1883 or nearly twentv vears. 



The soil of the plots used in this test is a so-called limestone 

 clay, formed from the decomposition of the surrounding and under- 

 lying rock, which is very largely magnesia and limestone. It has 

 the general appearance of a clay loam. Previous to the adoption 

 of this land to the experiments under consideration, it was farmed 

 under the general four or five years' rotation of that section, which 

 includes turning under a good sod every four or five years, and 

 thus the land contained a fair amount of organic matter. The 

 plots were laid out in the spring of 1883. In 1871) and 1881 the land 

 ■was in grass (clover and timothy) and in 1882 in potatoes. No man- 

 ure was applied to either crop. The first year the plots were seeded 

 to oats and no fertilizer of any kind was applied, so that some idea 

 could be gained as to the uniformity of the land. In the general 

 work the four year's rotation, common to that part of the State, 

 was adopted, viz: oats, wheat, grass, corn. The fertilizer was ap- 

 plied but twice in the rotation just previous to seeding to wheat 

 and planting to corn. 



The last report made upon the results of these tests is contained 

 in the annual report of the Pennsylvania Experiment Station for 

 1895, and covers the v.ork for twelve years, or throe rotations. The 

 kind and amount of fertilizer applied is shown in I he followiui: tabh't 



