QUESTION OF THE SOURCES OF THE NITROGEN OF VEGETATION. 
49 
these data, the losses or gains of nitrogen by the soil, during the different periods 
under the influence of the different manures and crops, were calculated. 
M. Dehekain further gives the results of numerous determinations of carbon in the 
soils, and shows that woth a loss of nitrogen there is also a loss of carbon; and that 
where in the case of the growth of sainfoin, the nitrogen in the surface soil increased, 
there was not a reduction in the carbon. 
In his flrst paper M. Deherain summarises his conclusions as follows:— 
1. The soil of each experimental plot lost nitrogen from 1875 to 1878 and 1879, 
when it had grown green maize or potatoes; it also lost when beet was grown. 
2. The loss much exceeded the amount due to the removal of the crop. 
3. The loss was very sensible even when the soil received abundance of manure, 
and it continued from 1878 or 1879 to 1881, when the soil grew maize, or potatoes 
followed by wheat. 
4. When, from 1879 to 1881. sainfoin was substituted for beet, not only was loss 
no longer manifested, but the nitrogen of the soil augmented, and at the same time 
abundant crops of sainfoin were obtained, which contained large quantities of 
nitrogen. 
5. This nitrogen has not come from the deeper layers of the soil, for these showed 
an equal, or even rather greater richness in 1881 than in 1879. 
With regard to the actual amounts of loss or gain of nitrogen found in M. Deherain’s 
experiments, the losses especially are extremely large, as the following results will 
show :— 
When farm-yard manure was applied, in very heavy dressings for three years in 
succession, in amount estimated to supply 400 kilog. nitrogen per hectare per annum 
357 lbs. per acre per annum), there was, when green maize was grown, a loss of 
nitrogen by the soil, besides that removed in the crops, amounting to 288 kilog. per 
hectare (= 257 lbs. per acre) per annum, over the 3 years of the application; when 
potatoes were grown there was a loss of 242 kilog. per hectare (= 216 lbs. per acre) 
per annum; and when, with the same manuring for 3 years, beet was grown for 3 
years and maize for ane year, there was an average annual loss over the 4 years of 
679 kilog. nitrogen per hectare (= 606 lbs. per acre). 
When nitrate of soda, supplying 192 kilog. nitrogen per hectare (= l7l lbs. per 
acre) per annum, was applied, the annual loss of nitrogen was, when maize fodder w^as 
grown, 401 kilog. per hectare (= 359 lbs. per acre); when potatoes, 436 kilog. per 
hectare (= 389 lbs. per acre); and when beet was grown for 3 years and maize for 
one year, the average annual loss of nitrogen by the soil over the four years, besides 
that removed in the crop, was 557 kilog. per hectare (= 498 lbs. per acre). 
When ammonium sulphate was used, supplying annually 252 kilog. nitrogen per 
hectare (= 225 lbs. per acre), the annual losses were—after the green maize 
359 kilog. per hectare (= 321 lbs. per acre), after the potatoes 555 kilog. 
MDCCCLXXXIX.-B. 
H 
