and in the grain alone, of the plots last referred to, and some others 

 are given. 



TABLE VII. 



Potash and Phosphoric Acid in Grain, and in Total Produce. 

 Ten years, 1852-'61, and ten years, 1862-71. 



PER ACRE IN POUNDS. 



I will illustrate this point by referring only to the potash. Plots 3, loa, 

 lob, and n show a deficiency of potash in both grain and total prod- 

 uce compared with the amounts in the produce of plots 2, 12, 13, 14 and 

 7, on all of which there was a sufficiency, or more or less excess, of 

 potash available. On comparison of these results with the manuring 

 of the plots, we find that in every case the increase of potash in the 

 total crop depends either on a direct annual potash supply, or on a 

 residue from previous applications. The first ten years shows more 

 potash in the total produce with the direct supply (13 and 7) than with 

 the residue (12 and 14); but the amount in the grain is essentially 

 the same in each case. In the second ten years there is a greater 

 difference in the amounts of potash in the total produce between the 

 plots having the direct and those having only the residual supply; 

 whilst there is scarcely any difference in the amounts in the grain, but 

 such as it is, it is in accordance with the conditions of supply. Hence 

 it is evident that whilst the plant in its vegetative stages assimilates 

 according to the available supply, it may be in excess of actual need, 

 if there is no deficiency, the composition of the final product the 

 seed is essentially the same. 



We have thus traced the effects of exhaustion, of full manuring, and 

 of nitrogenous and non-nitrogenous manures on one particular soil. It 

 has been seen how very different is the effect of one and the same 

 manuring in different seasons, but the real extent of this variation is 

 more clearly brought out in Table VIII., which shows the best, the worst, 

 and the average produce, over a period of thirty-two years, under very 

 opposite conditions as to manuring. 



