10 KF. A. CARLSON 
treatment of each plat, and of the cropping systems, is given in 
table 1: 
TABLE 1. Som TREATMENT AND CRopPpING SYSTEMS 
Soil treatment 
Plat Wee ee Cropping system 
7002 |Farm manure None Rotation without legume 
7008 |Farm manure Burnt lime Rotation without legume 
7003 |Farm manure None No vegetation 
7009 |Farm manure Burnt lime No vegetation 
7005 |Farm manure None Rotation with legume _ 
7011 |Farm manure Burnt lime Rotation with legume 
7006 |Farm manure None Oats, grass nine years 
7012 |Farm manure Burnt lime Oats, grass nine years 
7014 |Farm manure and K,SO,) None Rotation without legume 
7015 |Farm manure and K,.SO,) Burnt lime Rotation without legume 
The applications of farm manure were made in 1910, 1914, 
and 1918. The three applications were each at the rate of 10 
tons per acre, and were given to the plats that were never planted 
as well as to the cropped plats. The applications of potassium 
sulfate were made annually to plats 7014 and 7015 at the rate 
of 200 pounds per acre. In 1910 and 1915 burnt lime was ap- 
plied to plats 7008, 7009, 7011, 7012, and 7015, at the rate of 
3000 pounds per acre. 
The rotation without legume consisted of corn, oats, wheat, 
and grass two years. In the rotation with legume, clover was 
grown with grass for two years in the first half of the ten-years 
period, and during the second half of the ten-years period a 
legume was grown each year as follows: in 1915, soybeans with 
corn; in 1916, peas with oats; in 1917, vetch with wheat; in 
1918 and 1919, clover with grass. 
Plats 7003 and 7009 were never planted to any crop, and 
all vegetation was prevented from growing on them by hoeing. 
