224 THE FIRST BOOK OF FARMING 



means that most of the farm goes into cotton. A 

 small patch of corn is planted for the stock, which 

 are apt to suffer from a lack of variety in food. 



The same is true with reference to home supplies. 

 Very few vegetables are grown for the table and 

 there is little milk, butter or eggs for home use or 

 exchange for groceries or drygoods at the store. 



Thus we see that the continuous growing of cot- 

 ton on the soil, year after year, has a bad effect on 

 conditions necessary to its best growth and develop- 

 ment and also on the economics of the farm. 



These facts are true to a greater or less degree 

 in the case of nearly all of the farm crops. The 

 grain crops are often considered as humus makers 

 because of the stubble turned under, but Professor 

 Snyder, of Minnesota, found that five years' con- 

 tinuous culture of wheat resulted in an annual loss 

 of 171 pounds of nitrogen per acre, of which only 

 24.5 was taken by the crop, the remaining 146.5 

 pounds were lost through a waste or organic matter. 



THE ROTATION OF CROPS 



Now, suppose that instead of growing cotton on 

 the same soil year after year, we select four crops 

 cotton, corn, oats and cowpea and grow them in 

 regular order, a rotation practiced in some parts of 

 the South. 



We will divide the farm into three fields and num- 

 ber them i, 2 and 3, and will plant these crops as 

 indicated by the following diagrams: 



