per acre, and an adjoining field, where rotation was practiced, made a 

 yield of over seventy bushels per acre. Another demonstration 

 extended over a period of seventeen years gave a yield of eleven bushels 

 of corn the last five years, but where rotation was adopted on an 

 adjoining field, the jdeld was seventy-five bushels per acre. Scores of 

 like instances can be mentioned. 



We know that flax cannot be profitably grown on the same land two 

 or more years in succession because of a root wilt, and potatoes rarely do 

 well when they succeed themselves on account of scab, fungi, rot, etc. 



We know that land becomes wheat, oats, barley and clover-sick to the 

 extent of being discarded as "worn out," when in reality the land sim- 

 ply refuses to produce because of mismanagement. 



Deep-rooting plants should be followed by those which have shallow 

 roots; for instance, alfalfa and clover roots grow many feet into the sub- 

 soils; they secure water and food far below the reach of other plants. 

 We know that legumes have the power to take nitrogen out of the air, 

 not only to provide for their own wants, but leave a surplus in the soil. 

 Such crops should be followed by one which requires an abundance of 

 nitrogen and does not send roots as deep. Corn always produces more 

 abundantly when it follows a legume, because it requires a large quantity 

 of nitrogen and secures most of its food from the seed-bed. Wheat and 

 other grain crops obtain their food nearer the surface, and their plant 

 food requirements are somewhat different from corn and clover; hence, 

 wheat yield is increased when it follows corn. 



Crops which encourage the growth of weeds, such as grains, should not 

 succeed each other, but follow a hoed crop. Crops which are liable to be 

 infested with insects should not succeed each other; likewise crops which 

 develop fungi, scab and rot, such as potatoes and other root crops, 

 should not be repeated on the same land each year. Grain crops are apt 

 to lodge if not planted on compact soils, and root crops do well only 

 when planted in loose ground. Again, root crops such as turnips and 

 beets should follow crops which have been heavily manured and the soil 

 is of such texture that they can easily penetrate it. 



In every rotation, some one of the legumes, preferably the lucerne or 

 clover, should be grown. 



Lucerne or Alfalfa 



The roots of the lucerne penetrate very deep. It is not uncommon 

 for them to attain a length of from twelve to eighteen feet, and one fifty 

 feet long, in a preserved state, is in the museum at Berne. 



Clover 



Clover roots do not penetrate so deep as the lucerne, rarely going 

 more than three and one-half to four and one-half feet, but they are very 

 abundant. 



