494 



STATE BOARD OF AGRICULTURE. 



Fig. 4. — There is much land that does not produce crops, owing to the frequency of the surface 



drains that are formed by means of the plow. 



COMPOSITION OF THE CLAY LOAM 



Nitrogen and Organic Matter. The clay loam contains a large amount 

 of organic matter as is evidenced by the black color of the soil. Analyses 

 show from 9.19 per cent to 9.73 per cent of volatile matter which corresponds 

 approximately to organic matter. This is due to the swampy condition in 

 which these areas existed for many years thus a,llowing heavy growths of 

 vegetation to return to the soil. The nitrogen content corresponds with the 

 high content of organic matter, analyses showing from 5,800 to 6,416 pounds 

 per acre six inches as compared to 3,000 pounds in average black clay loam 

 soil. The dark green color of the growing crops and the general tendency 

 of small grains to lodge bear witness of the plentiful supply of this element. 



Phosphorus. This soil contains a medium amount of phosphorus, analysis 

 showing from 1,600 to 1,780 pounds per acre six inches. This type normally 

 should contain approximately 2,000 pounds of phosphorus per acre. Phos- 

 phate fertilizers when applied usually give excellent returns as might be 

 expected. Unlike the element nitrogen, phosphorus can not be drawn from 

 the air by certain crops and stored in the soil but must be added in either 

 manures or fertilizers. Owing to the slight deficiency of this vital element 

 it may be well said that phosphorus is the first limiting element of soil fer- 

 tility and its supply should be replenished at frequent intervals. 



Potassium. The element potassium is much more abundant in soils than 

 either nitrogen or phosphorus, normal soils containing approximately 30,000 

 pounds of this element in the surface layer. Analyses of the potassium 

 content of the clay loams show variations from 47,290 to 49,660 pounds per 

 acre of surface soil. Potash fertilizers have not given satisfactory results 

 except where sugar beets have been grown which indicates as does the analy- 

 sis, that this element is well supplied. 



Soil Acidity and Liming. Chemical analyses show that the greater part 

 of the subsoils contain carbonates and that the surface soils are alkaline or 

 sweet in reaction. Excellent crops of clover and alfalfa are being grown 



