GROUP OF HARVEY SOILS. 
27 
available potassium are grown that fertilizers containing this 
element need be used. 
Nitrogen and organic matter .—Nitrogen exists in the soil al¬ 
most entirely in combination with organic or vegetable matter. 
In this soil the vegetable matter is relatively low and should be 
increased. The accumulation of organic matter high in nitro¬ 
gen 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 sys¬ 
tem of farming is followed on this type of soil should involve a 
rotation one member of which is a legume. 
Lime and soil acidity .—This soil was originally laid down in 
an extension of Lake Superior as a sediment and in this a con¬ 
siderable amount of lime carbonate was deposited. This water- 
deposited soil was then worked over by the ice during the gla¬ 
cial period. Since this time the lime has been dissolved out of 
portions of the soil to a considerable extent, but other parts, less 
pervious to the water or containing large amounts of lime, still 
retain considerable quantities of this material. As a result these 
soils have become acid in patches, but as a whole are not acid 
and the subsoil still generally contains considerable lime. This 
is particularly favorable to the growth of clover and alfalfa, 
but where sorrel or other plants show the development of acidity 
lime should be used especially for alfalfa. 
Drainage .—Where the surface of these soils is level, as is very 
frequently the case the question of drainage is one of impor¬ 
tance. Over practically all level areas tile drains could be in¬ 
stalled to advantage. Thorough drainage will make these soils 
warm up earlier in the spring, insure better tilth and increased 
yields. 
