42 



EXPEKIMKXT STATION. 



[Jan . 



Potatoes. — Averagi Yields per Acre (Bushels). 



Potash Salt. 



Large. 



Small. 



No potash (plots 1, 9, 17, 25, 33), . 

 Kainit (plots 2, 10, 18, 26, 34), 

 High-grade sulfate (plots 3, 11, 19, 27, 35), 

 Low-grade sulfate (plots 4, 12, 20, 28, 36), 

 Muriate of potash (plots 5, 13, 21, 29, 37), 

 Nitrate (plots 6, 14, 22, 30, 38), 

 Carbonate (plots 7, 15, -.'3, 31, 39), . 

 Silicate (plots 8, 16, 24, 32,40), 



168.93 

 '--.'11.47 

 234.73 

 245.90 

 236.57 

 235.07 

 223.13 

 223.73 



20.90 

 11.77 

 1.-..47 

 14.97 

 19.53 

 15.67 

 21.87 

 18.83 



The no-potash plots this last year gave a yield much inferior 

 to that produced on the plots receiving potash. The highest 

 average yield was produced on the low-grade sulfate of potash : 

 the lowest on the kainit. The differences between the different 

 potash salts, exclusive of the kainit, are, however, relatively 

 small. The full table showing the rates of yield per plot shows 

 that there was considerable rot on about one-half of the plots. 

 Dr. Stone failed to discover Phytophthera infestans on the 

 foliage. The rot did not set in until the heavy rains of autumn. 

 The variation in the proportion of decayed tubers in the different 

 plots appears to be duo to a difference in moisture conditions. 

 There seems to be no well-defined influence on the propor- 

 tion of decayed tubers which can be attributed to the potash 

 salt employed. This year, as last, the foliage of the vines 

 on the no-potash plots died much earlier than on any of the 

 plots receiving potash. This premature death of the foliage 

 may, however, have been due simply to lack of vigor consequent 

 upon deficiency of potash in the soil, as Dr. Stone failed to 

 find the characteristic fungi causing either the early or the late 

 blight. It is probable, however, that in seasons with climatic 

 conditions more favorable to the blight fungi they would attack 

 the relatively weak foliage of plants growing where potash is 

 deficient more seriously than they would the more vigorous 

 foliage of better-nourished plants. 



