EXPERIMENTS WITH FERTILIZERS. 



PROF. WALTER BALENTINE. 



In accordance with the recommendations of the Station Council, 

 the experiments on the availability of phosphoric acid in finely 

 ground phosphatic rocks have been continued by using South 

 Carolina rock and Caribbean Sea guano, in field and pot 

 experiments. 



The South Carolina rock was selected for the work on account 

 of its being a crude material which is a standard article in the 

 fertilizer trade. The Caribbean Sea guano was a phosphate of 

 iron and alumina, and was used in the experiments because it 

 seemed to be desirable to obtain further information in regard to 

 the action of this class of phosphates on crops. 



The crude phosphates used in both field and pot experiments 

 were finely ground, the South Carolina rock carrying 27.2 per cent, 

 phosphoric acid and the Caribbean Sea guano 37.5 per cent. 

 The soluble phosphoric acid was furnished by acid South Carolina 

 rock having 13.3 per cent, available and 3.1 per cent, insoluble 

 phosphoric acid. 



FiELB Experiments by Farmers. 

 For the field experiments sets of fertilizers were prepared in 

 duplicate to be applied to plots of one-tenth of an acre. Two 

 plots were to receive acid South Carolina rock at the rate of 500 

 pounds per acre, with ammonium sulphate at the rate of 150 pounds 

 and muriate of potash at the rate of 100 pounds per acre. The 

 two plots thus manured would receive a liberal supply of available 

 plant food. 



3 A 



