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WISCONSIN STATE AGRICULTURAL SOCIETY. 
PRACTICAL MANAGEMENT OF SANDY LAND. 
Prize Essay. 
BY HOIST. J. G. KNAPP, MADISON. 
Lying in the center of Wisconsin is the largest development 
of the lower silurian, or Potsdam sand-stone, known in North 
America, if not in the world. These rocks are too porous to 
contain minerals in economical quantities, and frequently too 
friable to be of value as building stone. In many places, the 
surface to great depths consists of loose sands, liable to be 
drifted by the winds, and if cleared of vegetation may become 
dunes and uninhabitable. The thin soil is nearly destitute of 
the important elements for vegetable growth, such as potassa, 
sodium, phosphorus, lime, and humus. Crystalized silex 
abounds, forming almost the entire surface. The native forms 
of vegetation show the scarcity of these essential elements to 
plant growth; and where the cultivation of farm crops has 
been undertaken, their dwarfed condition makes the deficiency 
most glaring. Geologists concede that this region has been 
exposed to the action of the rains, snows and air, since the 
distant epoch when the lower magnesian lime rocks were formed 
beneath the upper silurian sea. The currents of fresh w r ater 
passing ever these sands during this vast cycle have carried off 
the salts and soil, and with the sediment filled the basins of the 
Mississippi and its tributuries; the vast ice-fields of the glacial 
period spread over them,ground down the soft rocks,and scraped 
the crystals into the valleys and plains as far south as central 
Illinois, innumerable years of sparse vegetation have not been 
equal to the task of making a soil over these ancient dunes. 
