58 



EXPERIMENTS UPON WHEAT 



the potash in the soil of this plot. The plot receiving farm- 

 yard manure gives corn of about the same size and weight 

 per bushel, and also the same proportion of corn to straw, as 

 Plot 7, which receives a medium amount of ammonium-salts. 



Turning now to the influence of season on the wheat crop, 

 Table XX. shows the yield of both grain and straw, the 

 weight per bushel, and the proportion of grain to straw, in 

 1879, a typical wet year, and in 1893, an exceptionally dry one ; 

 the corresponding averages for the whole sixty-one years being 

 put alongside for comparison. Table XXI. shows the 

 monthly rainfall for the same periods, during the harvest-year 

 from 1st September to the following August 31st. 



TABLE XXI. Rainfall at Rothamsted (Large Gauge). Com- 

 parison of a wet and a dry harvest-year with the average 

 over 60 years (1852-3 to 1911-12). 



It will be seen that for the crop of 1879 there was a total 

 rainfall of 41 inches, of which 23*8 inches fell in the last six 

 months, as against 8'3 inches out of a total of 241 inches for 

 the corresponding periods of the harvest-year of 1892-3. 

 While the amount of grain produced is not so very different in 

 the two years, the wet year grew a far bigger crop of straw, 

 so that the grain weighed little more than one-third of the 

 straw, whereas in the dry year grain and straw weighed about 

 the same. The weight per bushel of the grain is very much 



