188 J. H. Gilbert— Points in connection with Vegetation. 



The fact of the comparatively little, or at least uncertain action 

 of directly applied nitrates on the growth of the Leguminos©, 

 would seem to be inconsistent with the supposition that it is 

 the nitric acid in such a surface soil that has given it its special 

 adaptation for the growth of clover for so many years — unless. 

 indeed, it be the case, that it is much more available to such 

 crops when in combination with some bases than with others. 



The next point to consider is, whether there are any facts in 

 favor of the supposition that clover, and leguminous crops 

 generally, acquire any material proportion of their nitrogen in 

 lower layers, and in a more extended range of the soil, than 

 the Graminese. As an element in the discussion of this ques- 

 tion, it will be well in the first place to call attention to the 

 effects of direct nitrogenous manures, such as ammonia-salt, or 

 nitrates, on the growth of some of our crops. 



In Table VIII is shown the estimated amounts of carbon, 

 yielded per acre per annum, in wheat over twenty years, in 

 barley over twenty years, in sugar-beet over three' years, ami 

 in beans over eight years; each with a complex mineral 

 manure alone, and each with the same mineral manure and 

 given quantities of nitrogen in addition, supplied in some cases 

 in the form of ammonia-salts, and in others as nitrate. The 

 gain of carbon by the use of the nitrogenous manure is also 





Wheat 20 years, 1852-1871. 







Comply MirMafan 



re 



i 



si 













IComplex Mir 





re 





1 H38 1 1 















Snga 



-Beet S year,, \m\-l%n. 





Icomplex Mir 



eral Mam 



re 





1 H36 i 1 



Complex Mir 



! -2 r.... 

















B- ■ , 



^,.1862^1864-1870 





(Complex Mir 













■- 



nitrogen, as nitrate 



1 992 | J66J 



