March 28, 1903. 
the gardening world . 
269 
manurial substances, samples of the soil were taken after the 
land had grown fifty crops of wheat. On submitting these 
soils to chemical analysis, they showed most remarkable results. 
For our present purpose it will be sufficient to refer to four 
plots of land only, and to samples of the soil which were taken 
to 27 in. in depth. The following table shows the results : — 
Nitrogen applied a? 
Manure. 
Total Nit ogen 
in Soil to 
27 ins. deep. 
Soluble Nitrogen 
as 
Nitric Acid. 
Average produce 
obtained 
per acre. 
lb. 
lb. 
lb. 
1 . 
None. 
6,401 
19 
2,323 
2. 
43 lb. a. Ammo ia S .1 s.. 
6,540 
33 
3,962 
3 
86 1b. ,, 
6,614 
43 ■ 
5,823 l 
4. 
1:9 lb. „ „ .. 
6 848 
53 
6,849 
Each of the plots referred to in the foregoing table received 
a full supply of potash and phosphates. No. 1 received nothing 
else. Nos. 2, 3, and 4 received, in addition, 43 lb., 86 lb., and 
129 lb. of nitrogen, as ammonia salts, respectively. The second 
[By courtesy of Messrs. Dicksons. 
Nymphaea Gladstoniana is a fine Water Lily, with numerous 
petals which have rounded ends, are sweet-scented, and afloat have a 
massive appearance. [See page 273.) 
column of the table, however, shows that on analysis of the 
soil down to 27 in. in depth there was- very little difference in 
the total nitrogen found in the four plots, although no nitrogen 
whatever had been applied to the soil of No. 1, and very variable 
quantities to the three other plots. 
But when we turn to the third column, we find that the 
amount of soluble nitric nitrogen varied from 19 lb. to 56 lb. 
per acre respectively ; and that the amounts were exactly in 
proportion to what had been appdied for so many years to the 
surface-soil as manure. 
Calculating this nitric nitrogen to its equivalent of nitrate of 
soda, we find the amounts are 122 lb., 2b0 lb., 274 lb., and 
354 lb. per acre respectively. 
The last column of the table shows that the average crop of 
grain and straw ranges from 2,323 lb. with no nitrogen supply, , 
to 6,849 lb. per acre with the largest amount of available plant- 
food. That is to say, the crop harvested) is not in proportion to 
the total nitrogen in' the soil and subsoil, but is in proportion to 
that which is soluble and immediately available to the growing 
crops. 
The facts relating to’ nitrogen are all equally applicable to the 
elements of potash and phosphoric acid. 
These invaluable investigations illustrate this fact among 
others, that a crop or particular plant has to do not only with 
the supply of food in the soil ns a whole, but also with each 
of its ingredients separately. The total productive power of a 
soil cannot exceed its power to supply to the growing plant each 
and all the necessary food constituents. 
EXHAUSTION OF PLANT-FOOD. 
Practical experience teaches us that if crops are taken from 
the land year after year without fertilisers ot some kind being 
returned to it, the yields obtained will gradually decrease until 
the land can no longer be cultivated with profit. 
The decrease will be more or less rapid, according to the 
character of the soil and of the crops grown. Some soils are 
extremely rich, and their fertility is but slowly exhausted ; 
others have only a small store of fertility, and are soon im¬ 
poverished. In the same way, some crops are gross feeders, 
while others extract much less of the fertility elements. 
Speaking in a general way, it may be said that an abundance 
of nitrogen in, the soil produces vigorous growth ; that potash 
is necessary for the woody parts of plants and increases the 
fleshy portions of fruits, also assists in the formation of starch 
and sugar ; and that phosphoric acid is largely consumed in the 
production of seeds of all kinds. In other words, nitrogen 
favours vegetative properties in the plants we grow, while 
potash, phosphoric acid and lime favour maturation and ripe¬ 
ness. 
In order to produce the best results, these elements should be 
supplied to the soil if not already in it in an available form, in 
different proportions for different plants'. These proportions 
are not necessarily those which are found in the plants them¬ 
selves. While chemistry is. an important assistant in deter¬ 
mining what these proportions are, much more can be learned 
of them by the practical gardener by careful experiments with 
the different crops he has to grow. 
Ci.pyrighl oj Messrs. Kdicay and Son. 
Mrs. Gwyn-Lewis. This new Paeony is of dwarf habit, with 
white flowers, of great beauty, and of extremely pleasant fragrance. 
Seepage 271;) 
It is certain that most plants of the garden succeed best in a 
soil containing available food far in excess of that consumed in 
their growth. Lime 1 , as we know, is present in all fertile soils 
and in all plants, yet it is valued not as a plant-food in itself, but 
because of its use in making existing plant-food more available, 
and improving the mechanical condition of soils. 
(To be continued.) 
