THE BEET-SUGAR INDUSTRY IN THE UNITED STATES, 27 
vation and the satisfactory crops that the tillable area is capable 
of producing when properly fertilized and tilled. Furthermore, a 
considerable portion of the stable manure produced on most sugar- 
beet farms is wasted or rendered only partially effective either by 
not giving it proper care or by the method in which it is handled in 
connection with crop production. In addition to the humus con- 
tained in stable manure considerable quantities of plant food are 
present, which if properly handled add to the fertility of the soil. 
This plant food is largely soluble ; consequently the leaching process 
to which the stable manure is in most cases subjected, owing to the 
fact that it is usually exposed to rains and snows, frequently causes 
much of the fertility to be lost. Again, stable manure is often 
spread upon the fields and left exposed to the weather, until a large 
part of the volatile plant foods have passed off into the atmosphere. 
Much of the nitrogen is often lost in this manner. The best results 
in utilizing stable manure in connection with sugar-beet production 
are obtained by applying the manure to the crop preceding the beet 
crop ; this allows the manure to be thoroughly worked into the soil. 
It is a common practice in many localities where manure spreaders 
are not used to haul the manure from the feed yard or stable at times 
when there is no urgent work to be done and to dump it in piles, to be 
spread at some convenient time before the ground is plowed. This 
is a wasteful method, especially if the piles are left for some days 
or weeks without spreading, often resulting in much loss of valuable 
material through leaching. However, this method is preferable to 
spreading the manure and leaving it on the surface of the ground 
exposed to the action of the sun and wind. If the manure is spread 
and the ground can not be plowed immediately, it should be disked 
whenever practicable; that is, if the ground is not frozen. Fortu- 
nately the manure spreader is becoming more and more common, and 
where the number of live stock on the farm warrants it there is 
probably no other implement of greater value to the farmer. The 
full value of the spreader is not realized, however, unless the manure 
is plowed under or worked into the soil immediately after spreading. 
Green crops. — Green crops plowed under provide another source of 
humus for soil improvement. Any vegetable matter plowed under and 
worked into the soil will add humus, though certain crops are more 
valuable for this purpose than others because of the plant food as 
well as the vegetable matter which they contain. The so-called legu- 
minous crops, such as peas, beans, clover, and alfalfa, are among 
the best for supplying humus to the soil. These crops should be 
plowed under in the fall, so that they will have abundant opportu- 
nity to decay before the growing season begins the following year. 
In irrigated countries the ground should be irrigated thoroughly, if 
necessary, before plowing, so that there will be sufficient moisture 
