USE OF PHOSPHORUS IN DIFFERENT FORMS 267 



"The crops of 1894 and 1895 were Indian corn and oats, respectively. 

 In the autumn of 1895 the land was replowed and seeded to clover and grass, 



as follows: 



SEED PER ACRE 



Timothy 12 quarts 



Red top 6 pounds 



Medium red clover . . 12 pounds 



"Owing chiefly to the dryness of the soil, a stand of clover was not secured, 

 and medium red clover was sown again, the next April, at the same rate. 



"On account of the fact that some of the phosphates contained soluble 

 phosphorus while others were pratically insoluble in water, all of the more 

 insoluble phosphates were sown broadcast after plowing, and were then thor- 

 oughly harrowed into the soil before seeding. These applications were made 

 sufficiently large to cover the crop requirements for three years that the land 

 was expected to be left in grass. It was planned to divide the application of 

 soluble phosphates into three parts, one third to be applied annually as a top 

 dressing, in the spring, together with the nitrogenous and potassic manures 

 which have been applied annually at like rates to all of the plots in both series. 

 Owing to the change in the plan of the experiment in 1898, the land was left for 

 an additional year in grass. In the spring of 1899 such quantities of phosphates 

 were applied as were supposed, based upon their composition, to equalize 

 the amount of phosphorus upon all the plots. It was discovered, however, in 

 1902, that the assistant to whom the calculations were intrusted in 1899 omitted 

 to take into account the applications of the insoluble phosphates which had 

 been made in the autumn of 1896, and owing to this oversight the complete 

 equalization of the phosphorus was not finally accomplished until the spring 

 of 1902. The total amount of phosphorus which was applied per plot (two 

 fifteenths acre) to all excepting the two check plots, from 1894 to 1902 inclu- 

 sive, amounted to 43 pounds, or to 322^ pounds per acre. " 



Thus, from 1894 to 1898, the experiments are a comparison of 

 equal money values of different phosphates; from 1899 to 1901 the 

 common raw phosphate plots contained about one third more 

 applied phosphorus than the soluble phosphorus plots, about one 

 fifth more than the bone-meal and slag plots, and slightly more 

 than the aluminum phosphate plots. 



The entire experiment was carried on over two series of plots, 

 one series having been given one ton of burned lime per acre in 

 1894, while the other series remained unlimed. 



In 1901, fourteen different kinds of plants were grown, from 3 to 

 8 rows of each having been planted across all of the plots in both 

 series. In Tables 44 and 45 are given the number of pounds har- 

 vested of the different kinds of produce. 



