106 
Artificial Manures for Swedes. 
We thus see that well-made superphosphate was by far the 
most economical manure in these experimental trials, and the 
" economical manure " the worst of all ; for whilst 1 ton of increase 
raised with the agency of superphosphate of lime Avas obtained 
with an expenditure of 4s. 'dd., 1 ton of increase raised v;ith 
" economical manure " would cost no less than 21. 9s. 6jC?. for 
the manure. 
It is worthy of observation that the land in the preceding year 
was not manured with farm-yard manure, nor indeed with any 
manure whatever, and we thus see that with superphosphate 
alone a better crop of swedes may be raised than with guano. 
It will be seen that guano produced nearly 2 tons less of swedes 
per acre than home-made superphosphate, a difference which, 
considering the small crop furnished by the unmanured land, is 
considerable. Peruvian guano alone, indeed, should not, as is 
so often the case, be employed for root-crops, for when employed 
in small quantities the per-centage of phosphates contained in it 
is not adequate to enlarge the roots sufficiently, and when used 
in large quantities it is apt to produce an excess of leaves, which 
is generally the case with all manures containing like guano a 
large amount of nitrogenized constituents. Had the experiments 
been tried on wheat instead of swedes, there can be little doubt 
but that the results would have been different, and guano, in all 
probability, would have carried off the palm, for it is on the 
cereals and upon grass-land that highly nitrogenized manures 
like guano, soot, blood, &c., produce the most beneficial effects. 
Next to superphosphate made fi'om bones, the mixture of dis- 
solved coprolites and guano gave the greatest increase, the crop 
weighing 12 tons 16 cwts. 16 lbs. per acre ; whilst dissolved 
coprolites employed alone furnished 11 tons 12 cwts. per acre. 
This is an exceedingly interesting result, for it shows that a 
purely mineral pliosphatic manure, even when applied in a form 
in which it can readily be assimilated by plants, does not pro- 
duce, at least on a poor soil, so large a crop as a mixture in 
which a portion of the mineral phosphate is replaced by a manure, 
which, like guano, is rich in nitrogenized constituents. A small 
amount of an ammoniacal manure, or a fertilizer rich in organic 
matters, readily furnishing ammonia on decomposition, appears 
to be sufficient to secure the assimilation of the mineral phos- 
phate ; for it will be observed, by glancing at the experiment in 
which a mixture of soot, guano, superphosphate, and dissolved 
coprolites was used, that if the amount of organic fertilizing 
matters in a mixture is increased at the expense of its phosphatic 
constituents, the produce will be reduced. Thus this mixture, in 
which a portion of superphosphate was replaced by soot and 
guano, both containing much ammonia, or furnishing it on decom- 
