Thirty-fourth Annual Convention. 



28f 



ductive, mainly because the soil is deficient in organic matter. 

 Grains of all kinds do poorly on these ''points." The supply of 

 nitrogen in the soil is contained only in the organic matter, and 

 the top soil contains much the larger part of this constituent. The 

 soils of the hilly and broken lands of the state were originally 

 somewhat deficient in organic matter, and consequently in nitro- 

 gen also; and if the scant supply is largely removed when the top 

 soil is washed away a very bad condition results. As an average, 

 the surface seven inches of our rolling hill lands contains only 

 2,000 pounds of nitrogen per acre, and the next seven inches 

 does not contain more than one-third as much, and the next still 

 less. If the 2,000 pounds of nitrogen per acre is not a sufficient 

 reserve from which enough may be liberated to grow large or 

 even fair crops, which is true, what can we expect from a soil 

 whose nitrogen content has been reduced by loss of organic mat- 

 ter from surface washing to one-third of the above amount. To 

 show the value of nitrogen to these soils, let us consider the re- 

 sults obtained in some pot culture experiments at the University 

 of Illinois upon soils of this kind. The first soil was taken from 

 washed hill land in Pulaski county and the second from broken 

 land in Henry county. The soils were placed in pots and differ- 

 ent elements of plant food added, except in one used as a check. 

 Wheat was grown in the Pulaski county series, oats in the other, 

 and when calculated to the acre basis the results were as given in 

 Table 3. 



Table 3.— Yields in Pot Cultures— Worn Hill Land. 



Pulaski Henry 



.Treatment county soil, county soil, 



wheat, bu. oats, bu. 

 per acre. per acre. 



None 8 21 



Potassium 9 23 



Phosphorus 9 31 



Nitrogen 69 225 



It must be remembered that these yields were obtained in 

 the greenhouse under perfect conditions. The experiment cer- 

 tainly tells that these soils need nitrogen, and one of the great 

 problems of the farmers on this kind of land is not only to main- 

 tain but to increase the supply of nitrogen in the soil. The only 

 practical way of doing this on an extensive scale is to add organic 

 matter, by growing legumes and turning them under. (See 

 Bulletin 115). 



