ll'OBL'RX EXPERIMENTS 45 



from the commencement of the experiment been applied as a 

 top-dressing, usually at the end of April or beginning of 

 May. 



In Table XI \ve give the produce of wheat during twenty 

 years on the group of plots with which we are at present 

 concerned. (See page 46.) 



The figures show that there has been some falling off in 

 the produce on all the plots in the second ten years as com- 

 pared with the first, this falling off is however smallest on the 

 plots receiving ammonia salts. As at Rothamsted, the em- 

 ployment of superphosphate and alkalies greatly increases 

 the return yielded by the ammonia. The superphosphate and 

 alkalies, used by themselves on plot 4, produce no increase of 

 crop, but added to 183 Ibs. of ammonia salts they raise the 

 crop from 23-8 bushels (plot 2) to 30-2 bushels (plot 5), and 

 in fact, as the two right hand columns show, nearly double the 

 rate of increase obtained. 



The great characteristic of these Woburn results is the 

 very good returns obtained for the quantity of ammonia 

 applied. As the quantity of ammonia salts employed per acre 

 has been somewhat less than that used in later years at Roth- 

 amsted, we shall best compare the results at these stations by 

 looking in each case at the return obtained for i cwt. of 

 standard sulphate of ammonia applied. At Rothamsted the 

 i cwt. of sulphate of ammonia, when applied to the best 

 advantage, yielded an average of 5 bushels of wheat. In the 

 three best seasons during 40 years the average return was 8-3 

 bushels. In the best season of all, 1863, the return on plot 6, 

 was ii bushels of wheat per cwt. of sulphate of ammonia. 

 At \Yoburn, however, the average return on plot 5, during 

 20 years, is 8-5 bushels per cwt. of sulphate, or rather 

 better than that reached at Rothamsted in the three best 

 seasons. If we now pick out the results of the best seasons 

 at Woburn, we find that in 1882 the return from i cwt. of 

 sulphate of ammonia on plot 5 was 11-3 bushels ; in 1884, 13-7 

 bushels; in 1889, 13 bushels; and in 1894 tne return reached 

 the extraordinary figure of 23 bushels. Both the average 

 return, and the returns obtained in fine seasons, are thus far 



