ROTATIONS FOR WHEAT 87 
growing is wheat—clover—corn. The clover seed is sown with or 
in the wheat. If the climate is rather severe spring sowing of 
the clover in the wheat is practised. Clover is harvested the year 
following the wheat harvest. Usually two cuts are secured, one 
in June, the other in August or September. This leaves a good 
cover crop which is plowed under the following spring for corn. 
The most popular four-year rotation for wheat is wheat—clover 
Fic. 56.—Distribution of winter wheat (above), and spring wheat (below), each dot rep- 
resenting 10,000 acres. (U.S. D. A.) 
—grass—corn. The grass and clover are usually sown together 
in the wheat field and the grass remains one year after the clover 
harvest, otherwise the rotation is similar to the three-year rotation 
already described. The grass sod turned under is very favorable 
for the growth of corn. 
In far too much of the intensive wheat-growing area wheat 
follows wheat for several years in succession. Experiments have 
proved that the results are very unsatisfactory. Yields are decreased 
even when manure and fertilizers are applied.