June 20, 1895. 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
543 
NITROGENOUS MANURES AND THEIR EFFECT. 
There are ten elements absolutely essential for the production 
of plants. These are nitrogen, hydrogen, oxygen, carbon, sulphur, 
phosphorus, potassium, calcium, magnesium, and iron. It is to 
the first-named element (nitrogen) that I wish to call attention, 
and I will endeavour to show how important it is that we should 
become well acquainted with it. Nitrogen was discovered by 
Rutherford in 1772, and is a colourless inert gas, riightly soluble 
in water. It occurs free in the atmosphere, of which it constitntes 
79 per cent, or 11 lbs. to every inch of the earth’s surface. The 
nitrogen and oxygen of the atmosphere combine under the influence 
of electric discharges, nitrous acid being formed, which is converted 
into nitric acid by the action of ozone or peroxide of hydrogen. 
It forms several compounds useful to those engaged in horti¬ 
cultural and agricultural pursuits. Ammonia is a compound of 
nitrogen and hydrogen. 
Owing to the complicated changes of nitrogen in the soil, it is 
of the utmost importance that we should study the natural sources 
of its loss and gain there if we wish to become well acquainted 
with the^ difficult question of soil fertility. How does the soil 
obtain nitrogen in a natural way? The presence of organic 
nitrogen which is found in the soil has been formed by the decay 
of vegetable and animal matter. It is also brought down in rain as 
organic nitrogen, ammonia nitrates, and nitrites. The amount 
obtained in this way was determined at Rothamsted to be 4^ lbs. 
per acre per annum. But this varies in different parts of the 
country. It i«< estimated that an acre of fertile soil contains from 
■6000 to 30,000 lbs. of nitrogen in the first 18 inches, but the 
larger half is in the first 9 inches, and the quantity decreases the 
deeper we go, 96 per cent, of it being present as organic matter. 
From the above it seems that we have an inexhaustible supply 
of nitrogen in the soil, when our most exhaustible crops (Turnips) 
only remove about 150 lbs. per acre. But probably not more than 
5 per cent, of the nitrogen in the soil is in the form of nitrates, 
and thus available as plant food. Fallow land always contains a 
much higher percentage of nitrates than land under crop ; for 
instance, the first 27 inches of soil over an area of one acre of 
fallow contains from 33 to GO lbs. of nitrates ; land under crop 
only contains from 5 to 14 lbs. in the same bulk of soil. This 
shows hoar quickly the nitrates are taken up by a growing crop. 
These nitrates are most abundantly formed during the late 
summer and early autumn months, when the soil is warm, 
especially after cereal and other summer crops are removed. 
Nitrates, it should be remembered, are very soluble in water, and 
if light sandy soils are allowed to remain bare during the winter 
a very large proportion of this valuable manure will be washed out 
by the heavy rains. To prevent this loss some kind of winter 
crops should be grown, as these take up the nitrates. If the crops 
are of no other use they can be dug in during the early spring, and 
will then form a good organic manure which is beneficial to light 
sandy soils, as it helps to make them more retentive. 
I have stated that our most exhaustive crops remove about 
150 lbs. of nitrogen per acre, and from experiments at Rothamstead 
it was found that from 35 to 45 lbs. of nitrates per acre were 
washed out of the soil into the drains per annum, making the total 
loss of nitrogen about 157 lbs. per acre in one year. Gardeners 
must bear in mind that this loss goes on the same in garden soils, 
and therefore to keep it in a fertile condition we must replace 
this loss by the application of some nitrogenous manure, such as 
the following. 
Ammonium Sulphate. —This is a compound of ammonium and 
sulphuric acid. It contains 20 per cent, of nitrogen, equal to 25 per 
cent, ammonia. This is the most concentrated of all nitrogenous 
manures, and is very soluble in water. 
Potassium Nitrate. —This is a compound of potash and nitric 
acid, and usually contains 13 per cent, of nitrogen, equal to 
16 per cent, ammonia. It also contains about 45 per cent, of 
potash. It is a very valuable manure. Any gardener can increase 
the supply by the following process :—Make a compost heap of 
vegetable matter, such as garden refuse, and mix with it a fair 
proportion of wood ashes and lime. The wood ashes, which are 
rich in potash, can be obtained by burning all fruit tree prunings 
and hedge trimmings. The lime added helps to decompose the 
organic matter and liberate the nitrogen, which then chemically 
combines with the lime ; but another change takes place by which 
the nitrogen leaves the lime and combines with the potash, thus 
forming potassium nitrate. The compost heap must be frequently 
turned «o that all parts become thoroughly oxidised. 
Sodium Nitrate, —This is a compound of soda and nitric acid, 
and contains about 15 per cent, of nitrogen, equal to 19 per cent, 
ammonia. It is very soluble in water, and contains its nitrogen in 
a form that can be immediately appropriated by plants. 
Peruvian Guano. —This manure varies from 1 to 12 per cent. 
of nitrogen. It is a more general manure than the preceding, as it 
contains nitrogen in three forms. 1, As organic nitrogen ; 2, am¬ 
monia ; 3, nitrates, and is, therefore, a more lasting manure. 
Dried Blood. — Blood contains nitrogen equal to from 12 to 
16 per cent, ammonia, but it is slower in action than any of the 
above manures, as it has to undergo decomposition before it is 
available as plant food. 
Fish Guano. —This is also a slow acting manure. It contains 
nitrogen equal to from 8 to 10 per cent, ammonia. 
Farmyard Manure. —This is the most general of all manures. 
One ton contains from 9 to 15 lbs. of nitrogen, besides other 
valuable manurial ingredients, such as potash and phosphoric acid. 
Animal Urine. —One ton of this from horse stables contains 
36 lbs. of nitrogen ; from cows, 30 lbs.; and from sheep, 38 lbs. 
Most gardeners can get a good supply of stable manure, and many 
persons have noticed the black streams draining away from it. If 
the value of the fertilising ingredients of this liquid contain was 
better known it would not be allowed to waste as it does. This is 
the analysis of it in 100 parts. Water, 82 per cent., and dry sub¬ 
stance 18 per cent. The dry substance is made up as follows :— 
Ash 
• • • • 
... 107 
Magnesia 
« • • 
... 0 4 
Nitrogen... 
• •• • 
... 15 
Phosplioric acid 
• • • 
0-1 
Potash ... 
• •• • 
... 4-9 
Sulphuric acid ... 
• •• 
... 0'7 
Lime 
• •• 
... 0-3 
Silica . 
• •• 
... 02 
It will be seen by this analysis that the liquid contains, in 
addition to nitrogen, five of the mineral ingredients that are 
essential for the production of a healthy growing plant ; the one 
not mentioned is iron, but plants only require a trace of this 
ingredient. And it is usually present in soils. It must be borne 
in mind that all the manures mentioned, except the sodium nitrate, 
the potassium nitrate, and part of the Peruvian guano had to 
undergo a process, next to be dealt with, before they can become 
available as plant food. 
Nitrification. —This is effected in the soil by two micro-organisms 
(Bacteria). The first, known as the nitrous organism, converts 
ammonia into nitrons acid ; the second, the nitric organism, con¬ 
verts the nitrous acid into nitric acid. 
Carbon as organic matter must be present for the existence of 
these micro-organisms. Air, heat, and moisture are the three things 
that promote nitrification. It is very feeble at a temp, of 40° F., and 
ceases at 32° F. It is, therefore, necessary that the soil should be 
well drained. If the soil is waterlogged the air is shut out, and 
nitrification ceases, the nitrates present becoming denitrified, with 
the result that the nitrogen is set free. We must understand that 
nitrification takes place exactly the same in the soil of the smallest 
pot, under the gardener’s care, as it does in any prepared border, 
or in the open field. If the soil in pots become waterlogged nitri¬ 
fication ceases, and if allowed to remain long in this condition the 
roots will perish. 
Basic Condition of Soils. —Sufficient lime and potash must be 
present as carbonates or sulphates for the nitrates when formed to 
combine with, nitrate of lime and nitrate of potash then being 
formed, and these are the two sources from which all plants obtain 
their nitrogen from the soil. If any soil is not in a good basic 
condition it cannot be fertile. 
How Plants Obtain Their Nitrogen. —The dry substance of 
plants usually contain from 2 to 3 per cent, of nitrogen, and 
they all (except the leguminous plants) obtain it from the soil 
principally as nitrates. Some gardeners still favour the idea that 
the foliage of plants has the power of absorbing nitrogen as 
ammonia from the air, but the most eminent botanists in England 
and on the Continent have concluded that the quantity obtained 
by plants in this way is so small as not to be worth considering. 
We may deduce from this that damping down houses, when 
closing in the afternoon, with liquid manure, as practised by 
some gardeners, does not benefit the plants so much as they 
think. Some, however, consider that the fumes of ammonia are 
injurious to red spider and other insect pests. 
Leguminous Plants. —Peas, Beans, and Clover belong to this 
family. These plants have some power, not yeo properly under¬ 
stood, of absorbing the free nitrogen from the atmosphere. Dr. 
Paul Sorauer, in his popular treatise on the “ Physiology of 
Plants ” (1895), says, “ As far as our scientific knowledge goes, 
the leguminous plants can subsist on the nitrogen they take from 
the atmosphere, while cereal crops, fruit trees, and indeed all other 
phanerogams, must obtain this substance in some soluble form from 
the soil. Nitrates seem to be the most suitable form of salt from 
which plants obtain their nitrogen. Ammonia, which can probably 
be absorbed in minute quantities even in a gaseous state, is less 
suitable.” It is a fact that leguminous plants can be grown in a 
soil devoid of nitrogen. These plants do not rob the soil of this 
element, but act as purveyors of it to the soil. 
Why is Good Loam so Valuable f —The first 9 inches of an old 
