J. H. Gilbert— Points in connection with Vegetation. 189 



It is quite evident that in the case of the gramineous crops, 

 wheat and barley, which contain a comparatively low per- 

 centage of nitrogen, and assimilate a comparatively small 



beet, there was a greatly increased amount of carbon assimi- 

 lated by the addition of nitrogenous manure alone. In the 

 case of the wheat, there is much more effect from a given 

 amount of nitrogen supplied as nitrate, which is always applied 

 in the spring, than from an equal quantity as ammonia salts, 

 which are applied in the autumn, and are subject to winter 

 drainage. There is also more effect from ammonia-salts 

 applied to barley than to wheat ; the application being made 

 for the former in the spring and for the latter in the autumn. 

 There is again more effect 'from the nitrate than from the 

 ammonia-salts when applied to sugar-beet, the application 

 being made in both cases at the same date, in the spring. 



On the other hand, the effect of the nitrogenous manure 

 upon the highly nitrogenous bean crop is seen to be, compara- 



In reference to this point, it should be observed that there 

 has been this greatly increased assimilation of carbon in the 

 wheat and in the barley for more than twenty years, without 

 the addition of any carbon to the soil. It is indeed certain 

 that, in the existing condition of our soils, the increased growth 

 of our staple and starch-yielding grains is greatly dependent 

 on a supply of nitrogen to the soil. It is equally certain that 

 the increased production of sugar in the gramineous sugar- 

 cane, in the tropics, is likewise greatly dependent or. the supply 

 of nitrogen to the soil. 



In reference to the great increase in the assimilation of car- 

 bon in the sugar-beet by the use of purely nitrogenous 

 manures, it may be of interest to observe that over the three 

 years of the experiments with sugar-beet, the increased produc- 

 tion of sugar per acre per annum was about 20 cwts. by the 

 use of 82 lbs. of nitrogen per acre per annum as ammonia-salts, 

 and about 28 cwts. by the use of 82 lbs. of nitrogen as nitrate 

 of soda. 



It is then our characteristic-all \ star< i md sag 

 traps that are the most chara ' "1 by _ the 



application of nitrogenous manures; while our high v nitro- 

 genous leguminous crops are comparatively little beuehted by 



Proportion of nitrogen of manure got bach by the increase of 

 crops. —But now let us consider what is the proportion of the 

 nitroiren supplied in manure that we get back in the increase 

 of the crops * by » te llse « , , 



In Table IX is shown the amount of nitrogen recovered, and 



