40 FERTILITY AND FERTILIZER HINTS 



Lasting Effect of Manure. — The lasting effect of manure is 

 shown by the experiments conducted at Rothamstead. A plot of 

 grass land received applications of 14 tons of manure per acre 

 for 8 consecutive years and then the applications were discontin- 

 ued. During the first year after the discontinuance of manure 

 the yield was twice that of an unmanured plot. Since that time 

 the yield on the manured plot has slowly decreased until at the 

 end of 40 years the excess has been about 15 per cent, greater 

 than the yield of the unmanured plot. 



An experiment was conducted with barley. Three plots were 

 employed. One plot received 14 tons of manure per acre since 

 1852, another received 14 tons of manure per acre for 20 years 

 and then the applications were stopped, and the third has been 

 unmanured since 1852. 



The experiment showed that the continuously manured plot 

 had the largest yields but the plot that was measured for 20 

 years is still producing crops at least 40 per cent, greater than 

 the unmanured plot. 



The results in these experiments would not be found to be so 

 apparent in actual farming, as the soils that were used for these 

 experiments were more exhausted than the farmer would use. 

 However, the results are interesting as they show the almost 

 permanent effect of farm manure on soils." 



6. The Care, Preservation and Use of Manure. — From the fore- 

 going pages it is very evident that the composition of manure 

 and the amounts produced by different kinds of animals are ex- 

 ceedingly variable. It is also tnown that a regular value for this 

 product cannot be estimated from its chemical composition. 



Waste of Manure. — In some sections of the United States farm 

 manure is dumped into streams, burned, buried in holes in the 

 ground, or allowed to remain in large piles in some uncultivated 

 place. The soils in many of such sections are fertile enough to 

 produce profitable crops but it seems very wasteful to throw 

 away such valuable fertilizer. 



Leaching. — When a manure heap is exposed to the washing of 

 rain and the solutions allowed to wash away, the value of the 

 manure is decreased. The soluble plant food elements are washed 



