the web OB EIBE—THE soie 
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They become part of the soil, they are buried and decay, 
and as they decay the bacteria change them into stuff 
called “nitrates” which enrich the soil. 
Even the soil is full of Nature’s magic! 
When the farmer complains that his crops will not 
thrive because his soil needs humus , he means it has not 
enough of this decaying green matter, and his crops are 
starving for want of proper food. He has to go and 
buy some humus which has been prepared by men, or 
he must let his fields lie idle, without sowing seeds for 
a year or two, so that’the bacteria may have a chance to 
work on the decaying green things ready at hand. 
How does the farmer know when he has found good 
soil? He knows by the color, and by the weight; he 
makes sure also that his fields will have a chance to get 
plenty of water, because he realizes, as you do, that of 
all things, plants most need water. Water not only feeds 
the plant, but it helps dissolve the soil-food and to carry 
it through the soil and up the roots into the living stem 
or trunk. Too much water, of course, like too much of 
anything, is bad for plants. A flooded field will kill the 
farmer’s wheat by closing up the pore-spaces or air¬ 
spaces in the soil; even roots must have air or they will 
suffocate. The flooded field, however, would not kill 
our oak, because our oak is strong enough to stand a 
great deal of hardship. 
