CHOICE OF POTASH AND PHOSPHATES 299 



soil causes considerable of the subsoil, which contains an abun- 

 dance of mineral elements, to become mixed with the soil through 

 plowing and harrowing. 



Nitrogen is present in all muck and peat soils in abundance. 

 For intensive crops like onions, cabbage and celery, fertilizers 

 containing nitrogen seem to be profitable, especially on new lands. 



Choice of Potash and Phosphates ; Their Application. Muriate 

 of potash is most commonly used. Sulfate of potash, a higher- 

 priced material, is thought by some to produce better quality in 

 crops like potatoes and onions, but this claim has not been verified. 

 On soils not previously fertilized, the usual application of muriate 

 or sulfate of potash consists of about 100 pounds per acre for grass 

 and small grains, 250 to 300 pounds per acre for corn and potatoes, 

 and about 400 pounds per acre for sugar beets, onions, etc. When 

 grown in rotation, the hay is not fertilized since it receives the 

 residual effect of previous applications. 



Of the phosphate fertilizers, acid phosphate is most commonly 

 used. On soils requiring phosphorus as a secondary need, initial 

 applications may be made at the rate of 200 pounds per acre for 

 small grains, and 400 to 600 per acre for corn and truck crops, 

 respectively. Soils especially in need of phosphorus should be 

 given special phosphate treatments. 



These fertilizers may be mixed and applied at any time. For 

 general soil improvement broadcast application is recommended. 

 It is best to mix the fertilizers with the soil through harrowing. 

 Subsequent applications may be made in somewhat less amounts, 

 especially when manure is used. 



It is more economical to buy muriate of potash and acid phos- 

 phate separately and mix them on the farm. A desirable mixture 

 for general use is obtained when these two fertilizers are mixed 

 in equal proportions. 



Rock phosphate applied directly to muck and peat and thor- 

 oughly mixed in the soil sometimes gives excellent results 

 (Fig. 200). 



Large amounts of mixed commercial fertilizers are used on 

 marsh lands'. Applications vary from 200 to 3QO pounds or more 

 per acre for crops like grain, and 500 to 1500 pounds or more per 

 acre for corn and truck crops, respectively. 



On lands previously cropped and fertilized, the application of 

 commercial fertilizers in the hill or drill for crops like corn gives 

 excellent results, especially when a mixture of muriate of potash 



