88 BULLETIN 355, U. S. DEPARTMENT OF AGRICULTURE. 
mercial fertilizers. In fruit farming, it is generally necessary for soil 
improvement to grow legume crops to return to the soil as well as to 
add the mineral elements which are low in the soil by using fertilizers. 
In grain farming, if fertility is to be maintained or increased, the 
grain, including small seed, may be sold, but all roughage, including 
cornstalks and straw from grain and seed, should be returned to the 
soil; besides, a legume crop like red clover should be grown once in 
three or four years as a green manure to furnish vegetable matter 
and nitrogen to the soil, while mineral elements not plentiful in the 
soil should be regularly added to provide for what is removed from 
the sale of grain. It should be remembered also that phosphorus 
is removed from the farm in large quantity in grain farming. In 
live-stock farming, where the manure is well cared for and returned 
to the soil without much loss, the humus and nitrogen content of the 
soil can be built up where sufficient leguminous crops are grown in 
the rotation to furnish the feed of this kind necessary for the best 
results with the live stock. However, it will still be necessary 
to return some mineral elements, especially phosphorus, in order 
to increase the fertility of the soil. 
EXERCISES, LESSON XII. 
ROTATION PROBLEMS. 
1. Plan a system of crop rotation on an 80-acre sandy farm, potatoes being the main 
crop. 
2. Plan a rotation for farming on a 120-acre sandy farm. The following crops are to 
be grown each year as far as possible: Corn, 25 acres; rye, 12 acres; oats, 15 acres; 
clover, 25 acres; alfalfa, 10 acres; potatoes, 4 acres; tomatoes, 2 acres; and melons, 2 
acres. Five acres are allowed for buildings, etc., and 20 acres for pasture. 
3. Describe a plan for treating the soil in problem 2 — use of manure (200 tons), 
commercial fertilizers, liming, and inoculation. 
4. Suppose the sand on one of the forties in problem 2 is subject to blowing by the 
wind, will that make any change in the plan for rotation? Work out a plan of crop 
rotation under these conditions. 
5. Suggest a plan for rotation on a sandy soil on which potatoes, tomatoes, melons, 
and onions are the principal market crops. 
6. Plan a rotation on a southern sandy plantation of 200 acres where peanuts are an 
important crop. Other crops grown are cotton and corn. (Ref. No. 7, pp. 695-710.) 
7. A man owns the W. \ and the SE. \ of the SW. \ of a section of land. Locate 
this land in the section. 
8. All of this land in problem 7 is level and under cultivation. Each year he 
raises 40 acres of corn, 20 acres of clover, 20 acres of timothy, and 40 acres of oats in a 
3-year rotation. Outline his system of rotation. 
9. A farmer has a farm including the SE. \ of the NW. \\ the SW. \ of the NE. £; 
the NW. \ of the SE. \; and the NE. \ of the SW. £ of a section. His farm buildings, 
orchard, and garden take out 5 acres in the NW. corner of the NW. \ of the SE. \. 
This land is all level, silt loam. In order to meet his requirements he wants to raise 
each year 40 acres of corn, 40 acres of hay (30 of clover and 10 of timothy), 30 acres of 
oats, 10 acres of barley, 5 acres of potatoes, and 30 acres of pasture. Plan a system of 
crop rotation. 
