42 Absorption of Phosphate of Lime; and 
barley experiments. It thus appears that phosphatic manures 
produce a more beneficial effect on barley than upon wheat, 
and ammoniacal manures a more striking effect upon the latter 
than upon the former. As Ixjth barley and wheat belong to 
the same natural family of plants, and barle}- does not contain 
more phosphoric acid than wheat, it mav be safely inferred from 
this fact, that the cause of the greater efficacy of phosphates 
for barley is intimately connected with the shorter period during 
which barley remains on the ground, m an actively-growing 
state. 
The later the barley-crop is put into the soil the more bene- 
ficial an application of superphosphate will be found. Such a 
dressing moreover has the additional advantage of encouraging 
early maturity, and producing a finer sample of grain ; whilst 
ammoniacal manures, on the contrarv, retard the ripening of the 
crop. 
In a warm climate or a good season, ammoniacal salts may 
be used with much greater propriety and more largely, other 
circumstances being equal, than in a colder country or in an 
ungenial season. For a similar reason, it is more dangerous to 
sow barley very late on soils highlv manured with nitrogenised 
animal fertilisers, than on poor land. In the former case the 
barley often does not get sufficient) v ripe to be of any use 
for malting ; whilst in the latter, very fair mal ting-barley is 
often obtained, contrary to all expectation. It thus appears 
that the ash analyses of our cultivated crops, do not bv them- 
selves afford a sufficiently trustworthy guide to the practical 
farmer in selecting that kind ot manure which is best applied to 
each crop. 
I should much regret to appear to undervalue the merits of 
those chemists whose labours have made us accpiainted with the 
composition of the ashes of plants. The recognition of the fact 
that the mineral matters composing the plant-ashes are not 
accidental but essential constituents, without which no plant can 
grow and come to perfection, has indisputably had a powerful 
influence on modern agriculture. The ash-analyses of plants 
unquestionably are useful in many respects, although they have 
not realised the hopes which manv persons entertained at one 
time. The composition of the ashes of a plant certainly does 
not in itself afford suflicient data to determine with anything like 
certainty, or even probability, which fertilising constituents or 
manuring mixtures should be aj)plied to the various crops usually 
cultivated in this country, in order to produce satisfactory results. 
Still a knowledge of the composition of the ashes of jilants gives 
us a salutary warning that our crops will remain but scanty, 
or become unhealthy, if the soil on which they are grown is 
