66 PRACTICAL CORN CULTURE 
wheat one year and clover one year. As we have said be- 
fore, the straw should be returned to the land if the beans are 
hulled. The clover is often worth more for pasture than it 
would be if allowed to rot down as a humus and fertilizer. 
If the clover seed is hulled the straw should of course be 
returned to the land. If the clover fields are not needed 
for pasture it is a good plan to cut the first crop early and let 
it lay to enrich the land. This early cutting of the first crop 
will often double the yield of seed in the second crop. 
Humus 
Humus may be defined as decaying vegetable matter. It 
varies in composition and quantity in different soils. The 
productive capacity of land is measured largely by its phys- 
ical conditions and the physical condition depends largely 
upon the amount of humus and nitrogen in the soil. When 
old land is packed and breaks up cloddy it is often due to the 
fact that the humus has been exhausted. While the grain 
crops are dependent on several elements it is usually the 
supply of nitrogen which limits the crop production. All 
the nitrogen used in the growing of corn crops is taken from 
the humus in the soil, while the legumes get a certain amount 
from the air. 
Since the grain crops are dependent on humus, it can 
readily be seen that every effort should be made to restore 
as much humus to the soil as is taken out by the crops and 
the rapid decay which results from open culture. Vegetable 
or animal trash of any kind will make humus, although some 
kinds, like clover hay, and stable manure will make a great 
deal more than will straw, corn stalks or leaves. 
The drouth-resisting qualities of a soil depend largely 
upon the amount of humus in it. 
