ioo SCIENCE AND SOIL 



ultimate analysis of virgin soil from the Wisconsin Experiment 

 Station Farm at Madison, in the late glaciation, shows 3600 pounds 

 of nitrogen, 1500 pounds of phosphorus, and 36,300 pounds of 

 potassium, in 2 million pounds of surface soil. Where the same soil 

 had been heavily cropped in pot cultures (19 crops having been 

 removed) the nitrogen was reduced to 2200 pounds and the phos- 

 phorus to 1140 pounds, with no determinable change in total 

 potassium content. The analysis of another soil from the late 

 glaciation from northern Outagamie County showed 1400 pounds 

 of nitrogen and 2380 pounds of acid-soluble phosphorus. This 

 glaciation Professor Whitson regards as the best soil area in the 

 state. 



Residual sand from Jackson County contained 1000 pounds of 

 nitrogen, 870 of phosphorus, and 5100 of total potassium in 2 

 million of surface soil, and the glacial sand from Vilas County con- 

 tained 1000 pounds of nitrogen, 1580 pounds of phosphorus, and 

 30,000 pounds of potassium, indicating that the residual sand is 

 more largely quartz, while the glacial sand consists chiefly of sili- 

 cate minerals. (Compare with Tennessee soils.) 



Red clay from Ashland County contained 1400 pounds of acid- 

 soluble phosphorus in 2 million of soil; and peaty swamp soil from 

 Sauk County contained 32,000 of nitrogen, 1230 pounds of acid- 

 soluble phosphorus, and only 910 pounds of acid-soluble potassium, 

 in i million pounds of the surface soil. 



The acid-soluble plant food has been determined in many Minne- 

 sota soils (Snyder, Minnesota Bulletin 41), and a few analyses are 

 reported showing the total plant food in representative soils. 



The average prairie soil of the Red River Valley in northwestern 

 Minnesota contains 8200 pounds of nitrogen, 3340 pounds of phos- 

 phorus, and 45,100 pounds of potassium in the surface 2 million 

 pounds; and the average prairie soil in west-central Minnesota 

 contains 5300 pounds of nitrogen, 1760 pounds of phosphorus, 

 and 63,300 pounds of potassium. A general average for the soils 

 of the east-central part of the state is 5600 pounds of nitrogen, 

 2460 pounds of phosphorus, and 29,000 pounds of total potassium; 

 while the average southeastern Minnesota soils contain 4400 

 pounds of nitrogen, 1910 pounds of phosphorus, and 30,200 pounds 

 of potassium, in 2 million pounds of surface. 



