EXPERIMENTS WITH REFERENCE TO THE POTATO DISEASE. 51 



Chalk, Salt, and Charcoal. — Table I. 23, 24, For these 

 two rows \ busliel of chalk was powdei'ed, then thoroughly 

 mixed with 1 lb. of common salt, being at the rate of 146 

 bushels of clialk and 2 cwt. of salt per acre. The salt and 

 charcoal were mixed with the soil previously to cutting out the 

 drills. Powdered charcoal to the depth of half an inch was put 

 in the bottoms of the drills, and on it the sets were placed. 

 The quantity of charcoal afforded was at the rate of 110 bushels 

 per acre. The growing foliage was paler than usual, like that 

 of some rows already noticed to which salt had been applied. 

 The average amount of sound produce from these two rows was 

 at the rate per acre of 1 ton 16 cwt. 104 lbs. less tlian that of 

 No. 22, the row next to them, which had nothing; but the 

 quantity diseased was nearly 12^ per cent, less than that of all 

 the rows having nothing. On the other hand, No. 22, one of 

 the rows which had nothing, was less diseased than one of those 

 to which the chalk, salt, and charcoal were applied, and this was 

 the adjoining row. 



Sulphate of Soda a7id Nitrate of Soda, — Table I. 25. These 

 substances were given as a top dressing. The quantities were 

 3 oz. of each to a row, being at the rate of 110 lbs. of sulphate 

 of soda and 110 lbs. of nitrate of soda to an acre. These were 

 mixed and scattered on the surface of the ground when the 

 plants were 6 inches high, care being taken to prevent the 

 salts coming in immediate contact with the stems and foliage. 

 The quantity of diseased produce was considerably greater than 

 in the adjoining rows. It was 7f per cent, more tlian in tlie row 

 next on the west, treated with chalk, salt, and charcoal, and fully 

 8 per cent, more than in the row next on the east side, to which 

 salt was applied. 



Salt successively applied. — Table I. 26, 27. 



1. Common salt was mixed with the soil before planting, i lb. 

 to a row. 



2. Common salt in solution with water was distributed on tlie 

 ground by means of a watering-pot, after the potatoes had 

 been planted a week, the quantity being ^ lb. to a row. 



3. Another ^ lb. of common salt was given as a top dressing, 

 scattered by hand on the surface of the ground, when the 

 plants were 6 to 8 inches high, just before the earthing up. 

 The quantity of salt applied as above was at the rate of 



2 cwt. 76 lbs. per acre each dressing, the whole amounting to 

 7 cwt. 89 lbs. per acre. The quantity diseased averaged nearly 

 7 per cent., not half so much as in the row adjoining to which 

 sulphate of soda and nitrate of soda were given. 



Sulphur. — Table I. 28. Flowers of sulphur, 4 oz. to a row, 

 was scattered over the plants when they were 8 inches high. 



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