190 HATCH EXPERIMENT STATION. [Jan. 



5. Field Experiments with Different Coimmercial 

 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. Pre- 

 vious to 1887 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 sys- 

 tematic exhaustion of its inherent resources of plant food. 

 For this reason no mauurial 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 im- 

 l)rove its mechanical condition ; during the same period a 

 crop was raised every year. These crops were selected, as 

 far as practicable, Avith the 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. 



In 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 nitrogen, 

 while the phosphoric acid was furnished in each case in the 

 form of a difierent connuercial phosphoric-acid-containing 

 article, namely, phosphatic slag, Mona guano, Florida phos- 

 phate. South Carolina phosphate, floats and dissolved bone- 

 black. The market cost of each of these articles in 1890 

 controlled the quantity applied, for each plat received the 

 same money value of its particular kind of phosphate. The 

 phosphatic slag, Mona guano, South Carolina phosphate, 

 floats 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 per acre and potash-magnesia sulphate at the 



