530 BOAED OF AGRICULTURE [Jan. 



the particular character of the season, nor the quality of the 

 seed potatoes used, had any special relation to our results ; 

 but that some peculiar feature of the soil would ultimately 

 prove to be the cause of our trouble. 



Assuming that the presence of some injurious parasite in 

 our soil might be the first cause of the scab, it was decided 

 to devise some means by which its development would be 

 prevented. The following course was adopted : Three plats, 

 each forty-four by seventy feet, corresponding in location with 

 plats 1, 2 and 3 in our description of preceding years, were 

 assigned for the observation. 



Plat 1, located on the eastern side of the stated area, re- 

 ceived the same manure and in the same proportion as in the 

 preceding year (600 pounds of fine-ground bones and 580 

 pounds of potash-magnesia sulphate per acre). The plat 

 thus fertilized was subsequently subdivided into two equal 

 parts, of which one received broadcast a mixture of one-half 

 a pound of bi-sulphide of carbon and of ninety-five pounds 

 of air-slaked lime ; while the other half received broadcast a 

 mixture of one-half a pound of carbolic acid and of ninety- 

 rive pounds of air-slaked lime. 



In both instances the soil was subsequently slightly har- 

 rowed before the potatoes were planted. 



Plat 2, located between plats 1 and 3, received, as in 

 previous years, no fertilizer ; but one hundred and ninety 

 pounds of air-slaked lime were sown broadcast and har- 

 rowed in before planting. The application of lime was made 

 here to assist in discriminating between the influence of a 

 mere application of air-slaked lime, and that of a mixture of 

 either bisulphide of carbon or carbolic acid and air-slaked 

 lime. 



Plat 3, forming the western end of our experimental field, 

 received for manuring purposes, as in the preceding years, 

 fine-ground bones and muriate of potash, at the rate of 600 

 pounds of the former to 300 pounds of the latter per acre. 

 The fertilizer was applied broadcast and slightly harrowed 

 in. The plat thus prepared, in a similar way tc plat 1, was 



