Mixtures of Nitrogenous and Mineral Manures. 161 



represented, yet, with, the ammonia- salts and mineral manure 

 together, both Festuca ovina and Agrostis were much less 

 prominent, Holcus and Dactylis were nearly as much so, 

 and Poa pratensis (smooth- stalked meadow-grass) was the 

 most prominent of all. The character of development of the 

 grasses was, moreover, totally different, there being a great 

 tendency to form stem and seed and to mature. Under 

 these conditions a much larger proportion of the supplied 

 nitrogen was taken up than when the ammonia-salts were 

 used alone. As it is probable that, even when used in con- 

 junction with the mineral manure, not much more than half 

 the supplied nitrogen was taken up, the reduction in produce 

 over the second ten years would not seem to be connected 

 with a deficiency of available nitrogen. The reduction in 

 the amount of mineral matter taken up was greater than in 

 that of the nitrogen, and yet calculation shows that more, 

 and generally much more, of each constituent, excepting, 

 of course, silica, was applied each year than was removed in 

 the crop, so that there would be a constantly increasing 

 residue accumulated during the later years in all cases in 

 which there was no material loss by drainage. As will 

 presently appear, however, when the same mineral manures 

 were used with an increased amount of ammonia-salts, 

 a larger amount of each of the mineral constituents, 

 excepting lime, was taken up. 



The reduced assimilation of both nitrogen and most of the 

 mineral constituents over the second period was probably 

 less connected with any real deficiency of either within the 

 soil, in a condition capable of being yielded up, than with 

 the description of plants favoured, and the character both of 

 their underground and their above-ground development. 



8. 400$. Ammonia-salts, with Mixed Mineral Manure 

 containing Potash, and 2000Z6. cut Wheat Straw : Plot 13. 

 The only difference between this and the preceding case is 

 the addition of 20001b. of cut wheat straw per acre per 

 annum, the object being to supply silica and carbonaceous. 



M 



