DEPTH OF PLANTING 275 



of Bovee was attained with 15 bushels of seed per acre, while Carmen 

 No. 3 required 25 bushels for maximum yield. 



We may then sum up the main factors affecting rate of plant- 

 ing as : 



(1) Fertility of the soil. 



(2) Favorableness of climate for potatoes. 



(3) Variety used. 



(4) Time of planting. 



Whole vs. Cut Seed. Small whole seed is frequently used for 

 planting, as they are culls from the marketable potatoes and much 

 cheaper. Several experiments comparing whole and cut seed of 

 equal size have usually shown an advantage for the whole seed, 

 though results are variable and the advantage is usually not large 

 under ordinary favorable conditions. 



The greatest advantage for whole seed is found in the South, 

 where the early crop is planted in midwinter in cold ground where 

 cut seed is likely to rot. With whole seed only the most vigorous 

 buds at the seed end grow, which is also an advantage under unfavor- 

 able conditions. For these reasons large quantities of cull potatoes 

 from Northern crop are used as seed in the West Indies and South 

 Atlantic States for winter planting. In this case the cull seed was 

 grown from large potatoes each year and is quite different from the 

 continuous use of culls year after year from the same crop, as this 

 results in slow degeneration of the stock. 



Some growers, however, make a regular practice of growing small 

 whole seed by planting large potatoes very thick. Such seed is very 

 desirable and is preferred for early crop to cut seed. 



For the main crop in the North, planted at a favorable time, cut 

 seed from large tubers is to be preferred. 



Time of Planting. In the Corn Belt and southward, planting 

 is early in order to get as much growth as possible before the heat of 

 midsummer. In the North, planting is late to utilize the cool fall 

 weather. For example, in the Corn Belt, planting is general in 

 March and early April, while in New York, the main crop is planted 

 about June first. 



Depth of Planting. The principal considerations are the 



