CROP ROTATION AND SOII^ IMPROVEMENT 273 



and without clover.^ When these same crops were rotated with 

 each other and with clover, the cost of the fertilizer averaged only 

 four to five cents per bushel of increase. 



Proper Order of Cropping. — ^Much depends upon the order in 

 which crops are grown. Usually cultivated or intertilled crops are 

 followed by small grains, which in tmrn, are followed by hay or 

 pasture. Sod is commonly planted to some cultivated crop. 



Aside from this order, it is important to know what cultivated 

 crop is best to follow a certain other cultivated crop; or when two 

 grain crops are grown in succession, which one should follow the 

 other for best results. The growing of deep rooted plants after 

 shallow feeders has already been suggested as an important con- 

 sideration. In Central Kansas the growing of aKaha (where it can 

 be grown) leaves the ground so dry that it is usually not wise to 

 grow corn after alfalfa, but rather an early maturing variety of 

 sorghum instead. On rich bottom lands in this section, where 

 the moisture supply is usually good, corn may follow the spring 

 cutting of aKalfa. Other facts concerning the proper sequences 

 of crops have been mentioned in a preceding paragraph, page 267. 

 Crop Rotation and Soil Improvement. — Crop rotation alone, 

 even when clover is included, will not maintain yields, perma- 

 nently. After awhile the clover fails, and as a result farming fails. 

 Whenever a cropping system is planned to maintain or increase 

 crop production it is essential that a definite soil-enriching plan 

 be established at the same time. In some cases, clover and green- 

 manuring crops are of the greatest immediate importance to 

 increase and maintain the nitrogen supply and the organic matter. 

 This seems to be true in the greater portion of the Great Plains 

 area. Most soils, however, respond best and are unproved the 

 quickest when a carefully planned cropping system is established 

 which embraces some definite plan involving the use of lime, 

 manure, legumes and special fertilizers. These soil-improvement 

 materials make possible successful crop rotation, and rotation, in 

 turn, makes possible the most profitable returns from the use of 

 lime, manure and fertilizers. 



It is recognized that a short rotation is usually the most 

 effective in soil improvement, largely because of the growing of 

 more clover and the more frequent appHcation of manure and 

 fertilizers. The advantage of a short rotation in soil improvement 

 is illustrated in the next table. These results were secured at the 



1 The Monthly Bulletin, Ohio Station, June, 1918. 

 18 



