290 DRY-FARMING 
farm days farmers feared that under conditions 
of low rainfall, the stubble or straw plowed under 
would not decay, but would leave the soil in a loose 
dry condition unfavorable for the growth of plants. 
During the last fifteen years it has been abundantly 
demonstrated that if the correct methods of dry 
farming are followed, so that a fair balance of water 
is always found in the soil, even in the fall, the heavy, 
thick header stubble may be plowed into the soil 
with the certainty that it will decay and thus enrich 
the soil. The header stubble contains a very large 
proportion of the nitrogen that the crop has taken 
from the soil and more than half of the potash and 
phosphoric acid. Plowing under the header stubble 
returns all this material to the soil. Moreover, the 
bulk of the stubble is carbon taken from the air. 
This decays, forming various acid substances which 
act on the soil grains to set free the fertility which 
they contain. At the end of the process of decay 
humus is formed, which is not only a storehouse of 
plant-food, but effective in maintaining a good 
physical condition of the soil. The introduction of 
the header in dry-farming was one of the big steps 
in making the practice certain and profitable. 
Finally, it must be admitted that there are a great 
many more or less poorly understood or unknown 
forces at work in all soils which aid in the mainte- 
nance of soil-fertility. Chief among these are the low 
forms of life known as: bacteria. Many of these, 
