128 HATCH EXPERIMENT STATION. [Jan. 



3. Field Experiments with Different Commercial 

 Phosphates, to study the Economy of using the 

 Cheaper Natural Phosphates or the More 

 Costly Acidulated Phosphates. {Field F.) 



The field selected for this purpose is 300 feet long and 137 

 feet wide, running on a level from east to west. Previous 

 to L887 it was used as a meadow, which was well worn out 

 at that time, yielding but a scanty crop of English hay. 

 During the autumn of 1887 the sod was turned under and 

 left in that state over winter. It was decided to prepare the 

 field for special experiments with phosphoric acid by a 

 systematic exhaustion of its inherent resources of plant food. 

 For this reason no manurial matter of any description was 

 applied during the years 1887, 1888 and 1889. 



The soil, a fair, sandy loam, was carefully prepared every 

 year by ploughing during the fall and in the spring, to 

 improve its mechanical condition to the full extent of exist- 

 ing circumstances. During the same period a crop was 

 raised every year. These crops were selected, as far as 

 practicable, with a view to exhaust the supply of phosphoric 

 acid in particular. Corn, Hungarian grass and leguminous 

 crops (cow-pea, vetch and serradella) followed each other in 

 the order stated. 



1890. — The field was subdivided into five plats, running 

 from east to west, each 21 feet wide, with a space of 8 feet 

 between adjoining plats. The manurial material applied to 

 each of these five plats contained, in every instance, the 

 same form and the same quantity of potassium oxide and of 

 nitrogen, while the phosphoric acid was furnished in each 

 case in the form of a different commercial phosphoric-acid- 

 containing article, namely, phosphatic slag, Mona guano, 

 Florida phosphate, South Carolina phosphate (floats) and 

 dissolved bone-black. The market cost of each of these 

 articles controlled the quantity applied, for each plat received 

 the same money value in its particular kind of phosphate. 

 The phosphatic slag, Mona guano, South Carolina phosphate 

 and Florida phosphate were applied at the rate of 850 pounds 

 per acre, dissolved bone-black at the rate of 500 pounds per 

 acre. Nitrate of soda was applied at the rate of 250 pounds 



