48 THE POTATO 



4. Nitrate of soda is very deliquescent, and if left 



mixed with other fertilizers is liable to render the 

 whole mass wet and pasty, and so difficult to 

 apply. Cottonseed-meal is a very useful source 

 for part of the nitrogen of mixtures. If it is nec- 

 essary to hold a quantity of nitrate of soda for a 

 time, it is advisable to empty it out of the bags, 

 as they are liable to ignite spontaneously. When 

 emptied do not leave the bags lying in a heap in 

 the corner of the barn. Store nitrate of soda in a 

 dry place. 



5. Kainit is also very deliquescent, and it is the worst 



potassic fertilizer to use in a mixture on this ac- 

 count. Sulphate or muriate of potash are better 

 for mixtures. 



Applying Fertilizers. When a horse planter is 

 used the fertilizer is usually distributed in the row at 

 the time of planting. The fertilizer may be sown 

 broadcast or in the rows as desired, but it should be 

 incorporated with the soil and not left on top. 



Water Requirement. It has been shown clearly 

 that the available water content of the soil exerts a 

 great influence upon the life of the potato plant, upon 

 its assimilation of plant-food, and upon the yield. At 

 the Wisconsin Experiment Station 1 it was found that 

 when two acre inches of water were added in two irri- 

 gations in one case the yield was increased 100 bushels 

 of salable potatoes per acre, thus showing that the 

 right amount of water at the right time is a very im- 

 portant factor in determining the yield. Whitson, 2 of 



i Wis. Report, 1899, p. 213. 2 Wis. Report, 1902, p. 190. 



