ARTIFICIAL MANURES IN THE GARDEN. 
473 
square yard, or 2 lb. per square rod, is equal to about 8 cwts. per 
acre: this may be taken as an outside quantity to use of the 
rich and active nitrogenous manures like sulphate of ammonia 
or nitrate of soda; of more slowly acting manures like the 
guanos, two or three times the q uantity may be used. 
For plants in pots it is better to use manures in solution : for 
example, nitrate of soda and superphosphate, or 1 oz.of sulphate of 
ammonia and 3 oz. of superphosphate dissolved in 10 gallons of 
water makes an excellent liquid manure for finishing, when buds 
are opening or fruit is swelling. If a compost is to be enriched, 
let the slowly acting forms of nitrogen, like the guanos or meat 
meal, be used with phosphates to correspond, and let the manure 
be mixed with the soil some time before the compost is wanted, 
for the early stages of the decomposition in the soil of these 
manures are injurious to tender rootlets. 
As to the nature of the manure required for this or that crop 
little can be said ; the gardener has not at his service the know¬ 
ledge that the farmer possesses of the specific requirements of 
his crops; it is only for the farm crops that systematic trials 
have been carried out, like the fifty-year-old experiments at 
Rothamsted, and the many other stations that have grown up in 
England and elsewhere. From these experiments and their 
extension by the practical experience of many years we now 
know with a reasonable degree of accuracy the specific require¬ 
ments of each crop on the farm, whether its manure should be 
mainly nitrogenous or mainly phosphatic, whether potash is 
wanted or no ; whereas we have nothing but general grounds 
upon which to distinguish between the requirements of a 
Cabbage or an Apple tree, an Onion or a Rose. It is little use 
analysing the plant to get this information : the proportions of 
nitrogen, phosphoric acid, and potash in a plant are not the 
proportions in which these substances should be supplied in 
order to best feed the plant. What is present in the smallest 
proportions is often the particular substance the plant most 
wants ; it is only present in small proportions because the plant 
finds a special difficulty in getting it from the soil. As an 
instance of this common fallacy of supposing the composition of 
a plant’s ash gives any guide to its manuring, swedes may be 
taken : one acre of average swedes removes from the soil 98 lb. 
of nitrogen, 33 lb. of phosphoric acid, and 149 lb. of potash. 
