186 J. H. Gilbert— Points in connection iviih Vegetation. 



The action assumed by Mulder and Deherain, if it have 

 place at all in soils in their natm .1 < » idition vould be sup- 

 posed, and is assumed, by Deherain, to occur in layers suf- 

 deep to be poor i'n oxygen. In the lower layers of 

 the soil there is, however, a deficiency of carbonaceous organic 

 matter also. Again, if such formation of ammonia do°take 

 place, it is probable that some at any rate of it must be oxi- 

 dized into nitric acid; a condition which, on the other hand, 

 implies an atmosphere not poor in oxygen. Thus, numerous 

 results of analysis of the drainage water from manv of the ex- 

 i, to which further reference will 

 be made presently, show that nearly the whole of the combined 

 nitrogen m the drainage collected at a depth of about thirty 

 inches, exists as nitrates and nitrites; which, obviously, would 

 hardly be the case if the solution passed through a considera- 

 ble layer of soil, the interstices of which contained an atmos- 

 phere poor in, or destitute of, oxygen. 



Again, assuming such formation of ammonia to take place in 

 the upper layers of the soil, where there is the most organic 

 matter, and much oxidation of it, the supposition would be 

 that the conditions would favor oxidation rather than the for- 

 mation of ammonia from free nitrogen ; and the fact of the 

 formation of a good deal of nitric acid by the oxidation of 

 nitrogenous organic matter, or ammonia, in the surface soil, 

 is sufficiently established. 



Further, if it were to the action assumed by Mulder and 

 Deherain taking place in the upper layers of the soil that we 

 owe the supplies of combined nitrogen available to leguminous 

 and other . [late so much more of it over a 



given area than the Graminea?, the question may be asked — 

 why cannot the Graminea? avail themselves of this superficial 

 supply? On this point it mav be mentioned that, on some 

 parts of the experimental wheat and barley fields at Kotham- 

 Q ore has been applied year after year, for a 

 quarter of a century or more, in quantity contaii a perhaps 

 six or seven times as much nitrogen as is removed in the in- 

 crease of crop, and that thus the percentage of nitrogen in the 

 surface soil has been more than doubled. Yet, as large a pro- 

 duce of barley, and a larger produce of wheat, is annually 

 obtained by the use of very much smaller quantities of nitrogen, 

 as ammonia-salts or nitrate. It would thus appear that the ni- 

 trogen of the farm-yard manure was only available to the cereals 

 transformation into ammi [, Unfortu- 



nately, we are not at present able to adduce direct experimental 

 evidence as to the condition in which the large amount of ineffi- 

 cient nitrogen exists in the soil, or as to whether a leguminous 

 crop would or would not grow luxuriantly in it, but there is 



