226 



SOILS AND FERTILIZERS 



If the mixed horse and cow manure together with litter, 

 similar to that referred to in section 280, be made the 

 basis of the calculation, the evaluation would be $1.60. Dilu- 

 tion of the plant-food materials due to the litter tends to 

 reduce the value. 



284. Agricultural evaluation of manures. — The com- 

 mercial value may be quite different from the agricul- 

 tural value, which is calculated from the increased crop 

 production resulting from the use of the manure. This 

 will vary with different soils, but even on similar soils it 

 will vary with different manures. The following table gives 

 the results of an experiment in which treated and untreated 

 manures were evaluated commercially and were then applied 

 to the land. The value of the increased crops in a three 

 years' rotation was then calculated in terms of financial 

 return to the ton of manure applied : 



Table 49. — Commercial and Agricultural Evaluation op 



Manures 



285. Deterioration of farm manure. — There is always a 

 loss in the value of farm manure on standing. The ways 

 in which this is brought about are: (1) fermentation; (2) 

 leaching. The first of these is a natural process, common 

 to all farm manure on standing, and not occasioned by any 

 outside agencies. The second is due to the running off of 



