30 BULLETIN 995, U. S. DEPARTMENT OF AGRICULTURE. 



should be applied. Under certain conditions commercial fertilizers 

 do not seem to be effective. This may be due to the fact that 

 the fertilizer elements are not used in the proper proportions, or it 

 may be due to the physical condition of the soil. The greatest 

 benefits are obtained from commercial fertilizers when the soil is 

 well supplied with humus. There should, of course, be a suffi- 

 cient supply of moisture in the soil to dissolve and hold in solution 

 the plant foods .that are already present or that may be supplied in 

 the form of a commercial fertilizer. The benefits arising from the 

 use of fertilizers, whether stable manure, green crops, or mineral com- 

 pounds, are frequently noticeable over a period of several years: 

 hence, in estimating the value of a fertilizer the results of several 

 seasons' crops should be taken into account. 



CROP ROTATION. 



Occasionally a farm is found on which beets are grown on the same 

 field year after }^ear. While' this seems to give satisfactory results 

 for a time in some instances, it is in general a poor method and one 

 that can not be recommended, since it tends to encourage the de- 

 velopment of certain sugar-beet pests which eventually render the 

 crop unprofitable. The rotation practiced in the various sugar-beet 

 areas must necessarily depend upon the crops that do best or are 

 most profitable in these several localities, as well as upon the crop 

 and live-stock requirements of the farm. In some areas, for example, 

 the Irish potato is a profitable crop and forms an important link 

 in a system of rotation with sugar beets. In other areas the Irish 

 potato is not successful, and in such sections it would be a waste of 

 time and money to undertake to utilize it in rotation with sugar 

 beets. Again, there are areas in which the muskmelon is very satis- 

 factory and rotates well with sugar beets or other crops; in other 

 parts of the sugar-beet territory the muskmelon can not be grown 

 with success. In planning the rotation, therefore, one must have 

 in mind not only the crops that will rotate well with sugar beets, 

 but also the success of those crops independently. The grower must 

 also consider the practicability of handling such crops from the 

 standpoint of his returns: for example, in some sugar-beet areas 

 alfalfa gives good yields, but because the hauls are so long the 

 value of the alfalfa under normal conditions is not sufficient to pay 

 the transportation charges and leave a reasonable profit. Therefore, 

 unless there is an abundance of live stock to utilize the alfalfa locally 

 or unless it is needed as a soil improver, it is not a satisfactory rota- 

 tion crop in certain localities in spite of the fact that it produces 

 satisfactory yields. Our studies of the various sugar-beet sections 

 indicate that live stock is an important factor in crop rotation on the 

 sugar-beet farms. As already indicated, certain crops can be grown 



