BARLEY. 91 



is not in favour of the view that there is variation in the 

 proportion of the potash to the fixed and ripened non- 

 nitrogenous constituents, with the formation of which it is 

 probably to a great extent associated. 



The effects of exhaustion, or of full supply, of constituents, Amount of 

 are more strikingly still brought out by a study of the figures ^Znup 

 showing the amounts of potash taken up and retained per per acre. 

 acre by the above-ground growth, without and with the 

 supply of it. Thus the average amounts of potash per acre 

 per annum, in the entire crop (grain and straw together) 

 were, over the four successive periods without supply of it — 

 35.6, 30.9, 19.5, and 15.7 lb.; and with full supply they were, 

 over the same periods — 53.7, 63.7, 51.5, and 44.8 lb. That 

 is to say there was, without supply, less than half as much 

 potash annually stored up in the crop over the last as over 

 the first ten years of the forty. On the other hand, with full 

 supply, there was over the second period more than, and over 

 the third about the same amount as, over the first period, but 

 there was less over the fourth. Further, there was, over the 

 first period about one and a-half time, over the second more 

 than twice, over the third more than two and a-half, and 

 over the fourth nearly three times, as much potash in the 

 total crop with as without supply. Lastly, over the forty 

 years there was, without supply of potash an average of only 

 25.4 lb., but with it 53.4 lb. of potash per acre per annum in 

 the crop. 



Yet with these enormous differences in the amounts taken Potash ac- 

 up and retained by the entire above-ground growth in the c ^ r ^ ted 

 different cases, there was proportionally very much less grain. 

 difference in the amounts accumulated in the grain. Thus, 

 over the first period, the amounts in the grain were, over the 

 first period — without supply 13.1 lb., and with it 13.8 lb. ; 

 over the second — without supply 14.5 lb., and with it 15.3 

 lb.; over the third — without supply 11.5 lb., and with 

 supply, 13.7 lb. ; and over the fourth period — without supply 

 9.7 lb., and with supply 12.8 lb. Lastly, over the total period 

 of forty years the amounts were — without supply 12.2 lb., 

 and with supply 13.9 lb. 



It is thus seen that over each period there was rather less 

 in the grain without than with supply, but that the deficiency 

 was not material until the third period — that is, until after 

 twenty years without supply in the one case, and twenty 

 years with it in the other. 



In reference to these results, it will be of interest to con- Amount of 

 sider what were the actual amounts of produce— grain, straw, Produce. 

 and total — on each of the two plots, over the successive 



