THE TROPICAL AGRICULTURIST. [December r, 1887. 
THE ART OF MANUB NG. 
In the year 1852, Mr., now Sir J. B. Lawes, a 
manufacturer of artificial ma uures in England sowed 
some barley in a field, which was divided into several 
floti. Some of these plots received no manure of 
any kind ; one received farmyard manure at the 
rate of 14 tons per acre; auother received super- 
phosphate of lime at the rate of 3§ cwt. per acre ; 
another received a mixed manure at the rate of per 
acre of 3£ cwt-. of superphosphate of lime and 200 
lb. of ammoniacal salts ; and several others received 
dressings of various manures, artificial or otherwise. 
And for twenty years continuously barley was grown 
on all these plots, eaoh ot which for all these twenty 
years received substantially the same treatment in 
regard to manuring as it had received in tbe first 
year. The following statement shows the average 
anuml yield of dressed grain per acre gr.wn on 
lour of those plots during the five years, 1862-56 
the next five years, 1857-61 ; the third five years 
1862-66 : and the last five years, 1867 71 :— 
1852-56 18*7-61 1862-66 1867-71 
Bushels. Bushels. Bushe s. Bushels. 
Without manure 27J 20§ 20* 15f 
With 14 tons farm- 
yard manure 41f 48£ 55g 49£ 
With 3§ cwt. super- 
phospaate 31J 24§ 25g 20| 
With 3J cwt. super- 
phosphate and 200 
lb. ammonical salts 43J 481-7 53* 43J 
Or, taking the whole twenty years, the average 
annual yield without manure was 21 bushels per 
acre of dressed corn; with 14 tons of farm-yard 
manure, 48J bushels ; with 3£ cwt. of superphosphate 
of lime, 25£ bushels; and with the same quantity 
of superphosphate, together with 200 lb. of ammonia 
salts, 47 bushels. These figures are so striking in 
themse'ves that comment upon them seems a'most 
superfluous. They illustrate in a very forcible wa;' 
what can be done by proper manuring. In every 
agricultural country attention must, sooner or later, 
he turned in all seriousness to the subject of manuring, 
by which we mean scientific manuring, or manuring 
by method. The first settlers in a new country can 
grow their 50 and 60 bushels to the acre year after 
year without troubling themselves about how crops 
grew, or from whence the fertile soil obtains its 
virtue. And it is well, no doubt, for the first settlers 
that this should be so. Their difficulties in selecting 
land and opening up new country are very great ; 
and the ready fertility of the virgin soil may be 
looked upo.i as in some sort a compensation for the 
labours of fir.-t settlement. But this ready fertility 
does not continue long. In five or six years the 
crops begin to show signs of decreasing, and in 
two or three decades the 50 or 60 bushels of the 
lii st years have come down to 15 or 20. 
This has been the case in Victoria, as in every 
other newly opened up country. Even the rich 
volcanic soils of this colony, so noted in the early 
days for their productiveness, now yield only half 
of what they used to do. In America we hear o c 
how formerly famous crops were grown on the newly 
cleared lands with no more attention than just 
scratching the surface and putting in the seed, but 
as the lands first opened up became exhausted, settlers 
had to move further and further inwards, until at 
last their distance from the seaboard became a set- 
off Hgainst the fertility of their laud, and since then 
they have had to study the art of systematic manuring. 
The same thing has been seen more recently iu 
the coffee plantations of India, Ceylon, aud Brazil ; 
and coffee growing in the two former countries may 
now be regarded as almost a defunct industry. 
The necessity of adding liberally to the soil the 
mnt:rials which are taken nut of it in the form of 
crops, is of course widely recognised in Victoria, and 
it is well illustrated in the figures above given. The 
soil which in 1852-56 ga^e, counting good and bad 
; ' :> '.us, an average annual crop of 27-J- bushels of 
"arli y t . the acre, twenty years later gave an average 
Myld of very little more' than half that amount, 
namely, 15J bushels. It is a very common custom iu 
Victoria, when a soil shows itself exhausted, to apply 
bone dust ; but the uselessness of bone dust when used 
alone cannot be better shown than by a refereuce to 
the above figures. Si: J. B. Lawes used the bone 
dust in the form of superphosphate of lime, in which 
form it acts more quickly and gives an earlier return 
for the money expended in purchasing it, than does 
the unmodified bone dust. Of this superphosphate 
he used 3£ cwt. to the acre — certainly a lib ral enough 
supply. But what was the result? An increased yield 
on the average of oily 4£ bushels to the acre ; not 
sufficient indeed, to pay the cost of the manure if reck- 
oned at Victorian rates. The 3J cwt. of super- 
phosphate u-td by Sir J. B. Lawes may be reckoned 
as equal t;o 3 cwt. of the superphosphate supplied in 
Victoria. Now 3 cwt. of superpho.-phate, at 7s per cwt.. 
would involv • an expenditure of 21s, aud the total 
cost of this manure when applied to the grouud may 
be put down as 24<. The return for this 24s worth 
of manure was 4| bushels of barley, which, reckoned, 
at 3s 6d per bushel, would give a money return of 
16s 9d. There would, of course, be a small extra 
quantity of straw and chaff, as well as refuse corn ; 
but still there would be a loss of 6s or 7s, and by 
referring to the above figures it will be seen that the 
land was being exhausted with the use of super- 
phosphate alone just as rapidly as without any manure. 
Here, then, we have a striking comment upou the 
action of those Victorian farmers who use bone dust, 
and bone dust alone. There is no wonder that their 
land deteriorates, that their grain crops are poor, that 
their grass is thin and patchy. The bone dust supplies 
phosphates, but it is no use supplying phosphates 
unless other soil constituents, which may be deficient, 
are also supplied. Tons of phosphates might be 
supplied, and yet no greater crops obtained. The 
two constituents in which soils become soouest ex- 
hausted are phosphates and ammonia. Sometimes, 
also, they become exhausted in potash and lime, and 
more rarely in magnesia and in silica. The soil in 
which the above experiments were made was evidently 
in want of ammonia, as well as of phosphate ; and 
when 200 lb, of ammoniacal salts were mixed with the 
superphosphate of lime, the effect was simply wonder- 
ful. With just this 5 cwt. of mixed chemical manures, 
the crops were more than double what were obtained 
from the unmanured land, and nearly double of what 
were obtained by the use of superphosphate alone. 
They were, in fact, very nearly equal to what were 
produced by the regular use of 14 tons of farm- 
yard manure. 
The use of the superphosphate alone we saw resulted 
in a loss. Now, let us «ee what were the financial 
results of the experiment with tbe mixed superphosphate 
and ammonical salts. The cost of the superphosphate, as 
before, would be 21s ; and the cost of 200 lb. of sulphate 
of ammonia, at 16s per cwt., tbe price at which it can 
he obtained in Melbourne, would be 28s 6(1 ; making 
a total cost of £2 9s 6d, or reckoning the cost of 
carriage, and other expenses, say £2 15s, put down 
on the land. The average increased yield through 
twenty years due to this expenditure was 26 bushels of 
barley, which, reckoned at 3s 61 per bushel, would 
mean an increased revenue of £4 lis, leaving the 
handsome profit of £1 16s per acre, or 66 per cent 
on the cost of the manure, without taking into 
aceouii 1 ; the increased yield of straw, chatf, and refuse 
grain; and. moreover, it is to be observed that 
whereas the unmanured land and that manured 
wi:h superphosphate alone were becoming tapidly 
exhausted at the end of the twenty years, as 
shown by the yields in 1867-71, the plots treated 
with the mixed phosphate and ammoniacal manure 
gave as good a yield at the end of the twenty years 
as it did at first. 
Tbe practical lesson of all this is that the use of 
one kind of manure alone can be of no use where 
the soil requires two or more kinds. Therefore, let 
those fanners who have used bone dust or super- 
phosphate alone with disappointing results mix it with 
sulphate of ammonia, and," if that is not enough, 
with potash salt also. The results, providing the seasons 
