150 Transactions, —Miscellaneous, 
keeps a flock of sheep to feed off his turnips. He has probably, also, a town 
or large village iu his vicinity, from which he ean purchase house-manure ; 
and, under the system of high farming, other manures are brought to him 
from all parts of the world. 
It probably would not pay in a new country to go into the elaborate 
system of farming which is practised in an old one. Much may, however, 
be done in this direction ; and if we contrast the farm work of Otago with 
that of the rest of the colony, we will see that it can be done to advantage. 
It may be that most of the wheat crops now grown in New Zealand are 
only preparatory to laying the land down in grass. In that case there is 
little harm done. The land is not exhausted, and after being for some 
years under grass, may be again broken up and cropped; but what I 
propose to consider is whether we can hit upon an economical plan of 
continuing grain-cropping without a rest under grass. 
There is nothing new in what I propose to state. It is only a reitera- 
tion of well-known facts, but facts which, strange to say, are seldom known 
to the farmer. He knows that his land is liable to exhaustion, but of the. 
constituents which are taken away in the grain removed, or of how to 
replace them, he is generally ignorant. 
The chief constituents of a grain crop which are carried away with the 
grain are only three in number—viz., phosphate of lime, potash, and 
nitrogen. The two former, when once exhausted, cannot be replaced 
except by earrying them to the ground, or by the slow process of the land 
lying fallow, or in grass, until fresh supplies which may still remain in the 
soil shall be released, and put in a condition to furnish food to plants. 
With regard to nitrogen, there is an ample supply in the atmosphere, 
and, if I remember right, Liebig originally held that no nitrogenous 
man‘ires were necessary, but afterwards, considering the effect of guano 
and of muck, changed his views on this point, and eame to the conclusion 
that the nitrogen of the atmosphere in, I suppose, the form of ammonia, 
did not assimilate with sufficient rapidity to obviate the necessity for 
nitrogenous manures, and that therefore these manures must be provided. 
Now, leaving aside for the time the question of the supply of phosphate 
of lime and of potash, let us consider how the supply of nitrogen may be 
most readily brought about. No doubt the simplest plan would be to pur- 
chase and apply Peruvian guano, but I wish to arrive at the result without 
an outlay of money. If we go back to the time of the Romans we find that 
they supplied nitrogen by growing and ploughing in lupins. Now any of the 
bean tribe will answer for the purpose, these plants being rich in nitrogen, 
and, when ploughed in, the decomposition which is set up places the 
nitrogen in a state to be assimilated by plants, 
