EXPERIMENT STATION BULLETINS. 665 



increase was greatest during the first five days and then rapidly dimin- 

 ished. At tlie end of 20 days the increase became ahnost iinpercepllhle 

 where only 10 tons of manure per acre had been applied but continued 

 to be distinct where 40 and 80 tons were employed. 



Wagner-^ conducted a somewhat similar field experimciit with differ- 

 ent kinds of manure and also some laboratory experiments. The field 

 tests showed that the application of heavy dressings of fresh manure of 

 horse, cow, sheep and hog, raised the temperature of the soil; the horse 

 manure increased it the most, the cow the least, and the sheep and hog 

 intermediately. 



Spragg" attempted to study the effect of farm yard manure of horse, 

 sheep, and cow under laboratory and field conditions. The data he 

 obtained show that the rise of temperature as a result of these applica- 

 tions is practically nil. 



Since our knowledge of this subject was very meager and since the 

 foregoing works as well as the statements found in various textbooks 

 are not concordant, it was deemed advisable to investigate the subject. 



The research consisted in studying the efl'ect of the decomposition of 

 diff"erent kinds of fresh manure upon the temperature of soils, under 

 laboratory or controlled conditions. The investigation was conducted in 

 the following manner: Four-gallon earthenware jars were insulated 

 on the inside with thick asbestos paper and on the outside with thick 

 hair felt. The asbestos on the inside of the jars was paraffined in order 

 to make it water proof. The reason for so insulating the jars w'as to 

 prevent the loss of heat by conduction from the sides and bottom and 

 thus imitate in a way natural conditions. In actual field conditions, 

 the loss of heat takes place from the surface soil. To each pot w^as then 

 added the same amount of a fine sandy soil, known as Jack pine sand. 

 From each jar was then taken equal w^eights of soil to correspond to a 

 depth of 6 inches. This soil was thoroughly mixed with the proper 

 amount and kind of manure and put back into the pot, and water added 

 to it to bring it to the required moisture content. Care was taken 

 to have the same percentage of moisture in the soils containing differ- 

 ent amounts of the same kind of manure. This, of course, necessitated 

 the making of corrections for the different amounts of w^ater contained 

 in the various proportions of manure. The correction was made only 

 within the various amounts of the same kind of manure and not among 

 the different kinds. The soils, therefore, containing the different kinds 

 of manure in the various proportions did not possess exactly the same 

 moisture content. In order to prevent evaporation as much as possible 

 the surface soil of each pot w-as also covered by a thick layer of quartz 

 sand. 



There were four experiments conducted. The first three dealt only 

 with horse manure and the fourth with horse, sheep, and cow manure. 

 Since the first three experiments were preliminary and the results ob- 

 tained are in the same order as the corresponding series in the fourth 

 experiment; also, for the sake of brevity, only the results of the latter 

 will be presented here. 



The three different kinds of manure, horse, sheep, and cow, were only 



21 Forsch. a. d. G. d. Agrik. Phy. V. : 373. 

 " Thesis. 1906, Mich. Agr. Coll. 



