FARMYARD MANURE 173 



plots only ; so that if the yields from the 

 plots that are duplicated do not deviate 

 from each other by more than 10 per cent., 

 the tests may be held to be sufficiently 

 reliable. In the above scheme of experi- 

 ments the plot that had best be repeated, 

 once or oftener, is plot 2. In the five-plot 

 test, therefore, we might have plot 2 (under 

 the designation of 2A) repeated after plot 5, 

 while in the larger scheme involving 10 plots, 

 plot 2 might with advantage be repeated, 

 not only after plot 5, but also after plot 10, 

 when it would be designated as 2s. 



The Board of Agriculture have issued a 

 pamphlet dealing with field experiments, 

 and this should be obtained by those desirous 

 of going further into the subject, especially 

 on co-operative lines. 



CHAPTER VIII 



FARMYARD MANURE 



ALTHOUGH we have so far confined OUT atten- 

 tion to artificial manures, farmyard manure 

 is really of greater importance than any, 

 for the reason that practically every farmer 



