336 STATE BOARD OF AGRICXXLTURE 



SOIL REQUIREMENTS 



The potato crop grows best in soils that are loose and friable. In heavy, 

 stiff soils the tubers are likely to be ill-shaped and of poor quality. Sandy 

 loam, gravelly loam, or silt loam soils that are well drained and rich in organic 

 matter make suitable soils for the potato crop. Potatoes will not do well in a 

 cold, wet soil. Thorough drainage is essential. 



A good potato soil should be retentive of moisture. Decaying organic 

 matter or humus in a soil acts as a sponge and increases the soil's moisture- 

 holding capacity. Most of the potato soils in the state are lacking in or- 

 ganic matter and cannot retain enough moisture through the growing season 

 to produce a good yield of potatoes. The organic content of the soils should 

 be increased by applying stable manure, and by following a systematic crop 

 rotation in which such crops as alfalfa, clover or sweet clover occupy the 

 land for a period of two years or more in the rotation. Many growers find it 

 profitable to plow under the second cutting of clover or alfalfa for potatoes. 



ROTATION OF CROPS 



Potatoes are a good crop to include in a standard rotation where soil and 

 chmatic conditions are suitable for their development. The thorough culti- 

 vation that is given potatoes kills the weeds and grass, and leaves the soil in 

 good condition for succeeding crops. 



The best yields are obtained when potatoes follow alfalfa or clover in the 

 rotation. Alfalfa and clover sods decay rapidly when plowed under, thus 

 liberating nitrogen, phosphoric acid, and potash, which become available for 

 the potato plants, while the decaying organic matter aids in retaining soil 

 moisture. Timothy and other grass sods are often infested with insects, such 

 as grubs and wireworms, which seriously damage a potato crop that follows 

 them in rotation. Furthermore, the grass sods do not furnish as much plant 

 food as do the alfalfa and clover sods. 



It is not a good practice to plant potatoes on the same land more often than 

 once in four or five years. A long rotation that includes alfalfa and the 

 clovers is important for bettering soil fertility and moisture conditions. A 

 long rotation also aids in controlling such potato diseases as Fusarium wilt, 

 scab and black scurf that live in the soil. 



The rotation to be adopted will be determined largely by soil and climatic 

 conditions, and by the type of farming that is being practiced. Potato 

 growers should determine what crops are best adapted to their farms, and 

 then should maintain a definite crop rotation system. 



The following rotations are suggested : 



A. First year — clover; second year — potatoes; third year — barley, oats, or 

 rye seeded to clover. 



B. First year — barley, rye, or wheat seeded to alfalfa; second year — alfalfa; 

 third year — alfalfa; fourth year — alfalfa; fifth year — potatoes, corn, or beans; 

 sixth year — barley, rye, or wheat seeded to alfalfa. 



C. First year — potatoes; second year— barley, oats, or rye seeded to 

 swee|; plpver; third year — sweet clover; fourth ye^^r — potatoes, pr pom, 



