CHAPTER VI 
LEGUMINOUS CROPS 
Nitrogen is no more essential to the growth of corn than 
certain other elements but it is the one required in the largest 
amount and is the most easily lost from the soil. Throughout 
the Corn Belt it is more often the lack of nitrogen than of 
any other clement which limits crop production. When this 
supply of nitrogen is low it must be restored before paying 
grain crops can be grown on the land. 
The object in growing leguminous crops is to restore 
economically the nitrogen which has heen used up hy the 
preceding grain crops. Many so-called worn out soils are 
worn out only in the sense that the humus (decaying vege- 
table matter) in them has been used up by the grain crops 
and clean culture which they received. When this nitrogen 
and humus has been restored by the growing of several legu- 
minous crops, many farms are made as productive as they 
were when first broken up. 
Leguminous crops such as clover, soy beans, cowpeas, 
vetches, alfalfa, sweet clover, ete., have the power of taking 
pure nitrogen from the air and storing it in the roots through 
the nitrogen-fixing bacteria in the root nodules. At the same 
time it must be remembered that all the nitrogen in the 
legumes is not stored in the roots but that a considerable part 
is distributed through the stem and leaves. If, then, hay is 
removed, all the nitrogen in the stems and leaves is also 
removed. By removing all the soy hean or cowpea hay it is 
believed that nitrogen is actually taken from the soil rather 
than added. It naturally follows that if the nitrogen con- 
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