

WHEAT. 185 



had been full annual supply. The evidence is clear, there- 

 fore, that the residue from potash applied before the com- 

 mencement of the 40 years had been available to the 

 succeeding crops. Indeed, according to calculations showing 

 the balance of supply and removal, it would seem that the 

 whole of the potash residues from the previous applications 

 to plots 12 and 14 were, at the end of the succeeding 40 

 years, approximately exhausted. It may be added that the Phosphoric 

 Bothamsted experiments afford somewhat similar evidence mid ' 

 in regard to phosphoric acid ; and both constituents seem to 

 be retained comparatively near the surface of the soil. 



It will be remembered that in the case of some of the Dyer's in- 

 experimental barley plots, we were enabled to correlate the i mr y- 

 results of the analyses of the ashes of the crops, with those 

 of determinations of potash in the soils, made by different 

 solvents by Dr Bernard Dyer (see Table 29, p. 89, and con- 

 text), and that the inquiry proved to be of very much 

 interest. It may be added that Dr Dyer is submitting 

 samples of the soils from the above four plots, among others, 

 in the experimental wheat-field, to similar investigation, and 

 the results will doubtless prove very instructive. 



Detailed examination of the other columns in the Table Potash in 

 (52) relating to the potash, will show that there is much less ^™^ d 

 difference in the amounts of it in the grain of the different wheat. 

 plots than in that of the straw. Thus, excluding plot 11, 

 where there was no supply, and the produce suffered con- 

 siderably even early in the 40 years, it is seen that the aver- 

 age amounts of potash per acre per annum in the grain were, 

 on plots 12 and 14, with only residual supply, 10.1 and 10.3 

 lb., against only 10.8 lb. on plot 13 with full supply. The 

 average annual amounts in the straw were, however, 25.0 

 and 26.5 lb., with residual supply, against 39.6 lb. on plot 13 

 with full annual supply. It would thus seem that whilst 

 the plant is in its vegetative stages, it takes up potash largely 

 in proportion to the available supply of it — and it may be in 

 excess of actual requirement if there be abundant supply; 

 whilst, if there be no actual deficiency, the composition of 

 the final product — the seed, is essentially uniform. 



Eeferring to the columns relating to soda, it is seen that Soda and 

 considerably smaller amounts were found in the produce of P° tash - 

 wheat than in that of barley. But, as in the case of the 

 barley, the quantities of soda per acre in the total crop 

 were greater where there was a marked deficiency of potash 

 than where soda was actually supplied ; whilst the smallest 

 amounts were where the supply of potash was the greatest. 

 Probably the greater amount of soda taken up by the barley 

 than by the wheat is connected with the less root-range, and 



