APPENDIX. 



ON THE COMPOSITION OF THE ASH OF THE WHEAT GRAIN AND WHEAT 

 STRAW GROWN AT ROTHAMSTED IN DIFFERENT SEASONS AND BY 

 DIFFERENT MANURES BY SIR J. B. LAWES AND J. H. GILBERT. 



Under this title Lawes and Gilbert have recently published the re- 

 sults of a study of the constituents of wheat which are derived from 

 the soil and of the conditions modifying their assimilation. It has 

 seemed desirable to present their conclusions here as an appendix to 

 the preceding report, and to remark upon their relations to the Amer- 

 ican plant. The following is therefore given in their own words :* 



SUMMARY AND CONCLUSIONS. 



The investigation comprises the analyses of 92 wheat-grain and 92 

 wheat-straw ashes, and, including 69 duplicates, the number of com- 

 plete ash analyses involved is 253. Every ash is of produce of known 

 history of growth as to soil, season, and manuring, all the specimens 

 having been grown in the experimental field at Kothamsted, which has 

 now yielded wheat for forty years in succession, 1844 to 1883, inclusive. 

 The results are arranged in three series. 



FIRST SERIES OF ANALYSES. 



1. This series includes results obtained under three very character- 

 istically different conditions as to manuring in each case for sixteen 

 consecutive seasons. The manuring conditions were : Plot 2, farm-yard 

 manure every year ; that is, with an excessive supply both of nitrogen 

 and of mineral or ash constituents. Plot 3, without manure every 

 year; that is, with exhaustion of both nitrogen and ash constituents. 

 Plot 10, with ammonium salts alone every year; that is, with an ex- 

 cess of supplied nitrogen, but with great relative deficiency of ash con- 

 stituents. The results thus illustrate the influence of fluctuations of 

 season from year to year, under known but very different conditions as 

 to manuring. 



2. There was a much greater range of variation in the percentages of 

 potash and phosphoric acid in the ashes both of grain and straw, due 

 to variations of season than to variation of manure. The range of 

 variation due to season was much the greater in the straw ashes, which 

 is explained by the fact that favorable or unfavorable seed forming and 

 ripening may supervene on conditions of high or of low luxuriance r 



* Journal of the Chemical Society, Vol. XLV, August, 1884. 



85 



