RAatvTE OF HUMIFICATION OF MANURES. 
lave Jal, (Guna. 
It has been recognized for a long time that organic matter is an important 
constituent of the soil, but as to Just what way it aids in crop production, 
there seems to be considerable difference of opinion. Some maintain that it is 
valuable only for the plant food it carries, while others value it more espec- 
jially for the plant food in the soil which may be made available by its decom- 
position. The following paragraph from the Iowa Station, found in the 
September, 1915, Journal of the American Chemical Society expresses the 
sentiment of many soil investigators as to the value of humus, and the rate 
of humification. “‘The organic matter extracted by alkali is of no very differ- 
ent character than the organic matter of the soils as a whole. This together 
with the fact proved by Fraps and Hammer, Texas Bul. 129, that upon add- 
ing organic matter to soil, at the end of a years time there is no more material 
extracted with diluted ammonia than at the beginning of the period, proves 
quite conclusively that the determination of the amount of humus as found by 
the various methods is of no particular value in the study of a soil.’”’ This 
statement seems rather unreasonable to the author of this article, since the 
elements that are of value as fertilizers are locked up in most farm manures, 
green manures, cotton seed meal, ete., as complex compounds and hence are 
unavailable to the growing plant which must have its food supplied in a very 
simple form. In well rotted manures these complex molecules are largely 
broken down to simpler substances containing the same elements, but with a 
different arrangement in the molecule. They are quite soluble in water and 
if not leached by rains are very effective as a fertilizer compared with fresh 
manure. : 
Therefore, since fertility is so closely related to the unlocking of these 
complex plant molecules in the manures, an effort was made to measure the 
rate of humification of the more common ones. 
PLAN oF PROCEDURE. 
A clay soil was chosen that was very deficient in organic matter and was, 
therefore, humus-hungry. With this soil were mixed different manures so 
