182 BULLETIN OF THE BUSSEY INSTITUTION. 
best possible manure for all graminaceous crops — wheat, barley, maize, oats, 
sugar-cane, rice, pasture, grass — is a mixture of superphosphate of lime and 
nitrate of soda. Three hundred pounds of superphosphate of lime and 275 
pounds of nitrate of soda applied every year to one acre of ordinary English 
land has for twenty consecutive years given a produce annually of six quarters 
of barley. Fourteen tons of farm-yard dung applied annually over the same 
period has given the same produce of barley. Superphosphate of lime is a 
special chemical manufacture which can be made cheaper on a Jarge than on 
a small scale, and therefore farmers ought to purchase it cheaper than they 
can make it; but it is better to make up their own compound manures, pur- 
chasing their nitrate of soda or salts of ammonia. It is not advisable to sow 
artificial manure with beans, peas, tares, or other leguminous plants. Corn 
[i.e. grain] and root crops will take all the artificial manure which the farmer 
can afford to pay for. Superphosphate of lime should always be placed under 
the soil, either by drilling or harrowing in when the seed is sown. Nitrate of 
soda may,be sown in the same way, or it may be sown broadcast when the 
crop isup. ‘The increase in the growth of the cereal crop is much more de- 
pendent upon the nitrogen supplied than on the phosphoric acid. Potash is 
generally found in sufficient quantities in soils, and the artificial supply is not 
required. J. B. Lawes. 
I have no doubt but that if there were any widespread, intelligent 
demand for high-grade superphosphates in this country, these fertil- 
izers could be manufactured here and sold at a profit for less money 
than it would cost to import them; but in point of fact there is no 
such demand, and there never will be until the consumer has learnt 
in one way or another that it would be for his advantage to procure 
such materials, and to avoid those that cost more than they are 
worth. It is precisely for the purpose of diffusing sound knowledge, 
and of exciting a just demand, that the foreign superphosphates 
should be imported by our societies. It is idle to expect the Ameri- 
can manufacturers of fertilizers to materially change their methods 
and processes so long as they can find a ready market for inferior 
products, that can be manufactured at comparatively small cost and 
sold at high prices. 
The publication of Mr. Lawes’s letter soon after its arrival in this 
country, in the spring of 1873, led to various adverse criticisms, some 
of which were manifestly unjust. It was objected that Mr. Lawes’s 
estimate of the cost of raising phosphate-rock must be incorrect, 
since experience had taught that the material could not be bought in 
