6o FUNDAMENTALS OF AGRICULTURE. 



mentation sets in and acids are formed which act upon 

 the unavailable plant food and renders it available. 

 During the process of decay humus is formed which 

 has a tendency of making heavy soils (like clay soils) 

 loose, and light sandy soils more binding. It increases 

 soil warmth and renders the moisture conditions of 

 the soil more satisfactory. 



Lasting Qualities of Farm Manure. Manure is 

 one of the most efficient fertilizers for the farmer to 

 use. It has wonderful lasting qualities; one good 

 application will last for several years. The Rotham- 



A MANURE SPREADER. 



stead Experiment Station of England has made valu- 

 able experiments with manure as a fertilizer on barley 

 to show its almost permanent effect. The experiment 

 is as follows: The first plot received an application 

 of 14 tons of farm manure per acre for 20 years 

 (1852-71), and since that time has been left unma- 

 nured. Another plot has been left unmanured during 

 the entire period since 1852. The yield on the first 

 plot for 20 years after the application of manure was 

 discontinued, was 30 bushels per acre, while the unma- 

 nured plot where nothing was applied gave an average 

 yield of 13 bushels per acre. 



Marl. This material is an earth. It is sometimes 



