254 Missouri Agricultural Report. 



The positive or intrinsic value of farm manure lies in the 

 amounts of valuable plant food which it contains. It also possesses 

 an important indirect value as a soil stimulant, due to its power, as 

 it ferments and decays in contact with the soil, to liberate from 

 the soil plant food that would not otherwise become availabe so 

 quickly. There is still another distinct value in farm manure due to 

 the fact that it makes the soil more porous and spongy, and thus 

 increases the power of the soil to absorb and retain moisture and 

 to resist surface washing. In other words, this third value of farm 

 manure is due to improvement in physical condition. 



The value of farm manure for its physical improvement of the 

 soil is commonly fully appreciated and frequently even overesti- 

 mated by popular agricultural writers, while its value for the plant 

 food which it supplies and for that which it liberates from the soil 

 is sometimes almost ignored. 



There is no good excuse for erroneous teaching regarding 

 these different values, because there exists a vast amount of posi- 

 tive information, both from practical experience and from exact 

 scientific investigations. 



Thus, organic matter from peat beds hauled out and spread on 

 the land and incorporated with the soil produces no such effects on 

 crop yields as are produced by good farm manure. Why? Be- 

 cause the peat does not decay readily so as to furnish plant food, 

 either by its own decomposition or by liberating it from the soil; 

 and yet the peat has as great power as farm manure for physical 

 improvement of the soil. 



Manure made from clover hay and heavy grain rations has 

 much greater value than manure made from wheat straw. Why? 

 Is it because they affect the physical condition of the soil in differ- 

 ent ways? No. The great difference in value is due to the dif- 

 ference in plant food and in rapidity of decay. 



At the famous Agricultural Experiment Station at Rotham- 

 sted, England, on a field to which no manure and no plant food have 

 been applied, the average yield of wheat has been 13,1 bushels per 

 acre for more than half a century. 



Land treated with a heavy annual application of farm manure 

 has produced 35.7 bushels of wheat per acre as an average of 51 

 years. Another field treated with commercial plant food, without 

 organic matter, has produced 37.1 bushels of wheat per acre as an 

 average during the same time. The latter field received a little 

 less plant food than was furnished in the manure, thus furnishing 

 ample proof of the value of plant food supplied in manure, and 



