ioo8 The New Nitrogenous Fertilisers, [march, 



2 to 5, cyanamide occupies the lowest place, as again it does 

 in the other series 6 to io, and this looks as though cyanamide 

 might be a little less effective than the other fertilisers. The 

 differences, however, are within the range of the experimental 

 error, and the only conclusion that it is safe to draw until 

 the experiments have been extended, is that when such a 

 quantity as 50 lb. of nitrogen per acre is employed, all the 

 fertilisers are equally effective in producing grain. Of course, 

 on the Rothamsted soil, which contains a sufficiency of 

 carbonate of lime, the quicklime, which is often so valuable 

 a constituent of the cyanamide, is without effect, and the 

 fertiliser acts as a source of nitrogen only. 



As regards the proportion of offal corn, sulphate of 

 ammonia and cyanamide have done rather better than either 

 of the nitrates, yielding only about 10 per cent, of offal corn 

 against 13 ; this also is in accord with previous experience. 

 The weight per bushel shows but little variation, except 

 in the case of one bad sample grown with nitrate of soda, 

 which, for some unexplained cause, gives a result much 

 below that of any other plot. For reasons that have already 

 been explained, the straw returns possess little value, but 

 they would seem to confirm the impression formed by the eye 

 during the growing period that the plots receiving nitrates, 

 either of soda or lime, yield the greater amount of straw. 



It will thus be seen that the experimental plots were not 

 numerous enough to enable one to determine in a single 

 season the magnitude of the difference, if any, between the 

 four nitrogenous fertilisers selected for comparative trial. 



One sees, however, that if any difference does exist between 

 the effectiveness, nitrogen for nitrogen, of nitrate of soda and 

 nitrate of lime, or of sulphate of ammonia and cyanamide, 

 it will be only a difference of 10 per cent, or less. That being 

 the case, it should be the character of the soil and the relative 

 price of the fertilisers per unit of nitrogen, which should 

 dictate the choice between them. The Rothamsted soil has 

 no special peculiarity, and suits any of these fertilisers in- 

 differently, but on other soils — very light sands, heavy clays, 

 soils very short of lime — secondary considerations, which do 

 not come into play in these experiments, will make one or 

 other of these fertilisers the preferable manure. 



