May 2, 1904. J Supplement to the '^Tropical AgriciiUurist." 
793 
has been known that discharges of lightning 
parsing through the air are able to fix free 
nirrogeii, and beginning with this as a basis, 
some very satisfactory results have been obtained 
by the ui-e of electricity. With a power suffi- 
ciently cheap and with perfect machinery, there 
seems good reason to believe that in the near 
future it will be possible to place upon the 
market a manufactured nitrate of soda or nitrate 
of potash that will be superior in quality to the 
deposits found in South America, and that will 
also be reasonable enough in price to compete 
with the natural product. 
Fortunately, there are still other means by 
which nitrogen gas may be made available for plant 
food, and that, too, without requiring the introduc- 
tion of a commercial product, which must always 
be rather expensive, whatever degree of perfection 
may be reached in the mechanical operation of the 
process. Ever since the earliest dnys of agricul- 
tural science it has been noticed that certain land, 
if allowed to stand fallow for a considerable length 
of time, would gain in nitrates without any visible 
addition having been made. It is now known 
that one of the principal means of this increase 
in nitrogen content is due to a few forms of soil 
bacteria which have the power of fixing the free 
nitrogen from the air and rendering it available 
for plant food. These organisms have been 
isolated and cultivated artificially, and great hopes 
were held at one time that it would be possible to 
inoculate land with these cultures and thus bring 
about a large inciease in the nitrogenous salts 
without the aid of any manure or mineral ferti- 
lizer. Under certain conditions these bacteria 
seemed able to do a Inrge amount of work, and 
there are experiments on record where the crops 
raised from plots inoculated with nitrogen-fixing 
organisms were much greater than crops from 
uninoculated land. Unfortunately, these results 
were not always constant, and such a large per- 
centage of failures had to be reported, that from 
a practical standpoint the use of such cultures 
is now considered worthless, A matter of such 
vast importance to agriculture, however, should 
not be neglected simply because of first failures. 
It is quite possible that as we become better 
acquainted with the habits of these bacteria and 
learn the conditions which are most favorable to 
fixing nitrogen, and the causes which prevent 
this operation from going on at all times, we 
shall be able to discover some means of using 
these nitrogen gatherers in practical farming. 
— Year Book V.S. Departmeut of Agriculture. 
{To be continned.) 
THE FOOD OF CROPS, 
H. W. Potts, Hawkesbury College. 
The main object in a farmer's avocation is to 
convert soil and atmosphere into suitable food for 
man and domestic animals. The boundless stores 
of fertility in earth and air have to be intelligent- 
ly utilised iu producing wheat or oats from his 
paddock, fruit from bis orchard, milk, butter, and 
cheese from his cow, beef or mutton for his 
butcher, wool for his clothier, and labour from his 
farm animal?. Chemistry has not yet reached 
that point at which the elements can be adroitly 
combined to artificially manufacture food. We 
still, as in the days of yore, depend on nature's 
inscrutable laboratory, combined with man's 
guidance and intelligence, to bring forth our vast 
food supplies. Nature is our good chemist, and 
life or organic movement is the mainspring of all 
development in plants or animals. Plant life and 
animal life contribute in the most perplexing 
unions to provide us with our daily bread? But 
many of nature's hitherto inviolable secrets have 
of late years been disclosed, and we are beginning 
to recognise that it is an essential factor to 
success in farming to utilise the information given 
to us by the researches of our chemists and 
bacteriologisls. A great part of the material from 
which food is produced is obtained from the vast 
supplies of nitrogen and other nourishing gases in 
the air we breathe, but the important part of it is 
derived directly from the soil. Whilst the 
atmosphere provides adequate supplies this is not 
the case with the soil. The soil, when analysed, 
will be found to furnish a supply of plant-food, 
which has lain, in many instances, dormant since 
creation. This, hoveever, is limited. Examples 
are numerous also to show that plunt-life has 
pursued an unbroken course of growth for 
centuries without loss of health and vigour. A 
prominent writer states : "The processes of nature 
are such that the same material can be used over 
and over again as food, passing from plant to 
animal and from animal to plant in an endless 
cycle, and as long as the energy of sunlight falls 
upon the surface of the earth to keep food supply 
in motion through this cycle, so long is it possible 
for the fertility of the soil to continue undimin- 
ished. It is upon the continuance of this food 
circulation that agriculture is dependent." The 
fertility of soil depends on its containing all the 
organic and inorganic substances needed for the 
nutrition of plants in soluble or available form. 
The most vital factors in soil are bacteria. With 
every crop a portion of plant food is removed. 
A part is returned from the air; another . part, 
however, is lost for ever if not returned by man. 
If all the ingredients of the crop are given back to 
the land its fertility remains undiminished. Such 
restitution is effected by bacteria, cultivation, 
manure and favourable climatic conditions. We 
cannot escape the law of restitution. To dis- 
regard this means failure of crops. The study of 
the cycle of nature's food is important. We find 
the chemical constituents of the soil and the 
atmosphere are the predominating ingredients of 
man, animals and plants. The decay or rotting 
of all animals and plants returns to the soil those 
elements which go to fertilise it and provide food 
for future plant growth. In this change the 
study of the functions of bacteria is involved. 
The soil is full of living organisms, bacteria and 
fungi. Where warmth, moisture and ample food 
supplies prevail they are more prolific and more 
active. The very superficial layers of the earth are 
extremely rich in bacteria, the number varying 
according to conditions — 10,000 to many millions 
per gramme. In sandy soil the number is small. 
