26 
SOIL SURVEY OF OUTAGAMIE COUNTY. 
crops using unusually large amounts of available potassium are 
grown that fertilizers containing this element need be used. 
Nitrogen is chiefly responsible for the dark green, healthy 
color and rapid growth of corn or other crops on well manured 
land. It is important to have sufficient amounts in the soil, but 
when in excess it is detrimental to some crops. The quality 
of the grain may be injured by too much nitrogen. When the 
grain lodges the kernels do not fully mature. 
Virgin soils contain large amounts of nitrogen but if they 
are cropped continuously to such crops as corn, oats and tim¬ 
othy without the addition of fertilizer material containing nitro¬ 
gen the nitrogen supply is gradually exhausted and the yields 
are reduced. 
Nitrogen exists in the soil almost entirely in combination with 
organic or vegetable matter. In the light colored soils the vege¬ 
table matter is relatively low and should be increased. The 
accumulation of organic matter high in nitrogen is most readily 
brought about through the growth of legumes such as clover, 
alfalfa or soy beans. These may either be turned under as green 
manuring crops in which case all of the nitrogen collected from 
the atmosphere is returned to the soil and made available to 
succeeding crops, or they may be fed to animals and the manure 
returned to the soil so that a portion at least of the nitrogen 
gathered from the atmosphere is returned to the land to add 
to the supply already there. Whatever system of farming i r 
followed on these soils should include a rotation one member of 
which is a legume. 
Certain crops such as potatoes and vegetables are frequently 
grown by farmers who do not keep much livestock and who do 
not rotate these crops with legumes. In such cases fertilizers 
containing nitrogen and potash, as well as phosphorus may be 
used. Mixed fertilizers are, therefore, manufactured and offered 
for sale. The composition of these fertilizers is indicated by a 
formula. A 2-10-4 fertilizer, for instance, is one containing 2% 
of ammonia, or nearly 2% of nitrogen, 10% of phosphoric acid 
and 4% of potash. 
When nitrogen and potash are needed as well as phosphoric 
acid, there is some advantage in using these mixed fertilizers. 
But when the farmer needs to use only a phosphate fertilizer, 
purchasing a mixed fertilizer means that he is buying not only 
