6 The Bulletin. 



alone. Potash added to phosphoric acid gave small increases over 

 phosphoric acid alone, while nitrogen and potash combined with 

 phosphoric acid gave increases over phosphoric acid alone, but with- 

 out profit. For the production of peas, phosphoric acid alone pro- 

 duced increased yields ; nitrogen combined with phosphoric acid 

 added slightly to the increase of phosphoric acid alone, as did 

 potash also. Potash and nitrogen combined with phosphoric acid 

 did not produce larger yields than nitrogen and phosphoric acid 

 alone, showing that potash had but little effect in increasing the 

 yield of peas. 



The experiments show that phosphoric acid is the most important 

 constituent for use on this soil in increasing the yield and adding to 

 the profit in growing cowpeas. 



5. The amount of nitrogen in the normal fertilizer (300 pounds 

 per acre) used in the pea experiment was 1 per cent. Varying this 

 amount from ^ per cent to 3 per cent did not, on the whole, taking 

 the yield of peas and hay together, show any decided advantage for 

 large amounts of nitrogen. 



6. The amount of potash in the normal fertilizer (300 pounds 

 per acre) application was 4 per cent. Increasing the amount of 

 potash up to 9 per cent in the mixture gave, as a whole, a decrease 

 in yields and profits. This further emphasizes the fact that this 

 soil not only does not need potash in the growth of peas, but if 

 added in large quantities it will be at a loss. 



7. The amount of phosphoric acid in the normal fertilizer (300 

 pounds per acre) application was 8 per cent. Reducing this quan- 

 tity by one-half and increasing it by two and thrfee times the normal 

 quantity, showed decided increases in the yields of both peas and 

 hay for the larger quantities, emphasizing, in the most emphatic 

 way, the need of this soil for phosphoric acid for the production of 

 cowpeas. The most profitable yields on any of the plats were ob- 

 tained from those receiving large amounts of phosphoric acid. The 

 amounts of phosphoric acid in the mixtures which gave the largest 

 profits varied between 342 and 514 pounds of 14 per cent acid 

 phosphate. 



8. Taken as a whole, the tests with lime did not show that this 

 soil needs this constituent especially in the growth of peas. 



