COLLATERAL READING 153 



Conservation of Soil Resources. Farmers' Bulletin, No. 342, pp 

 6-10. 



The Maintenance of Fertility. Ohio Bulletin, No. 182. 



The Maintenance of Fertility (Barnyard Manure). Ohio Bulletin 

 No. 183. 



How to Determine the Fertilizer Requirements of Ohio Soils- 

 Ohio Circular No. 79. 



The Fertility in Illinois Soils. Illinois Bulletin No. 123. 



Cyclopedia of American Agriculture. Vol. I, pp. 454-513 



Soils, by S. W. Fletcher. 



The Fertility of the Land, by I. P. Roberts 



Soils and Fertilizers, by Harry Snyder. 



Fertilizers, by E. B. Voorhees. 



SUPPLEMENTARY NOTE TO PAGE 138 



Since the humus of soils has so much influence on crop yields, the 

 amount of dry matter or humus-making material of the feed that is- 

 recovered in the manure is of great importance. In one test with a 

 horse, 47 per cent of the dry matter of the feed was recovered in the 

 manure. In a test with a steer, 55 per cent was recovered. The dry 

 matter of the manure is probably more valuable than the same amount 

 of material plowed under as straw or hay. It is safe to assume that 

 half of the humus-making material is recovered in the manure. 



If the manure is allowed to rot, some of this material is lost. In 

 several tests where it was exposed six months, about half of the dry 

 matter was lost. 



Just as it is usually wise to feed animals to get manure rather than 

 to depend entirely on comrnerical fertilizers, so it is usually wise to feed 

 animals to get humus rather than plow under crops. If the manure is- 

 properly handled we will still have about three-fourths of the nitrogen., 

 phosphoric acid and potash, and half of the humus-making material. 



