102 Report of Farmers' Institutes 



and raw Redonda the increase was $330 or less; and with the 

 other phosphates the increase varied from $44'2 with the dis- 

 solved rock to $590 with the double superphosphate. 



Phosphates in Massachusetts agriculture. (Mass 162.) Massa- 

 chusetts soils show a much less marked deficiency in phosphorus 

 than those of states in the corn belt, though the supply is usu- 

 ally not great enough to insure maximum crops. The cropping 

 systems generally employed in the state are not depleting the 

 soil of phosphorus since: (1) The products sold carry relatively 

 small amounts of phosphoric acid; (2) the grain and by prod- 

 ucts fed contain large amounts of phosphorus which makes its 

 way, with little loss, to the soil in farm manures; (3) com- 

 mercial fertilizers are freely used, especially in market garden- 

 ing, which contain large proportions of phosphorus; (4) phos- 

 phorus does not leach from the soil in any considerable amount. 



The use of phosphorus-containing materials as fertilizers is 

 generally profitable in the state; and the dissolved phosphates 

 have given larger returns and greater profits than the fine-ground 

 raw rock. Although 1,600 pounds to the acre of phosphoric acid 

 in the form of raw rock has been applied to a series of plats in 

 experiments extending over eighteen years, the plats are yielding 

 proportionately smaller crops, as compared with those on plats 

 receiving dissolved phosphates, than in the first years of the tests. 

 The dissolved phosphates appear to stimulate early and rapid 

 growth of both root and top; to lead to earlier and more per- 

 fect maturity, and, according to the work of other experimenters, 

 to increase tillering of grain and grasses ; to promote availability 

 of some other important soil constitutents ; to induce activity of 

 nitrifying organisms in the soil; and to stimulate micro-organ- 

 isms which assimilate nitrogen from the air. 



This bulletin is an important contribution to a very much dis- 

 cussed phase of agriculture, and should be studied before adoption 

 of methods recommended by western agronomists. 



Potassmm from the soil. (111. 182.) Investigations made in 

 pots, under carefully checked conditions, apparently indicate that 

 " potassium can be liberated as needed from the inexhaustible 

 supply naturally contained in the normal soils of Illinois." 

 Clover takes up from two to three times the amount of potassium 



