<A MONTHLY. ^ 
XXIII. 
COLOMBO, DECEMBER 1st, 1903, 
No. 6. 
THE LOSS OF SOIL FERTILITY 
HE loss of fertility from the soil 
occurs in varions ways, but the 
characteristics of soils have 
much influence on the loss, and 
something also depends upon 
the kind of manure or fertilizer 
used. One result of an inquiry 
regarding the mineral fertili. 
zers used at the Rothamsted Experimental Farms, in 
England, says American Fertilizer, is to show that 
neither potash nor phosphoric acid, when present 
in excess of immediate reqniremsnts, is liable 
to escape from the soil or to sink to a depth 
bayond the reash of pUot roots, and that if such 
should happen the qaantity would be very small. 
When birnyard manure is med, both the potash and 
phosphoric acid contained in the manure have been 
found to descend in mire liberal quantities and to a 
greater depth inti the snb-soil, than when applied in 
the form of fertilizers. The excess phosphoric acid 
a,nA potash derived from superphosphate and potash 
Salts respectively accumulate in the first nine inohes 
of the soil, but are less soluble thxn the sama substan- 
ces supplied in barnyard manure. The accumulations 
of phosphodo acid are less flxe'l, but, and consequently 
mora available, when alkiline salts hive baen applied 
with suparphojphate, and it is also the case that p jtash 
salts are similarly affjcted in a beneflciil sense, when 
there are accompanying applications of phosphate and 
nitrogenous substances. It has, therefore, been de- 
monstrated that the loss from the soil is not as great 
as has been supposed, and that the soil has the power 
to retain the larger share of soluble plant foods near 
the surface, if it is not exceedingly porous. 
THE EFFECT OP THE I! \lNFALt. 
Dai-iog the entire year the amount of water which ' 
falls upon a field is very large, and soluble substances 
are consequently dissolved, especially as the actual 
amount of water used by crops, compared with that 
which fails is small. Therains would soon deplete the soil 
of its soluble mineral mitter but for the power of the soil 
fo retsin potash and other sabstanoes. For that reason 
some soils are more valuable than others. The nitrates 
in soils are more easily carried away than potash or 
phosphoric acid, hence it is possible that the loss in the 
fOrm of nitrates may bo large, especially during very 
vvet weather. When the soil is dry, evaporation 
brings to the surface some of the nitrates carried down 
by the rains, and growing crops also prevent loss by 
protecting the soil, or by appropriating the plant 
foods. It is well known also that some soils absorb 
gases from the air, hence some of the ammonia lost 
from the soil is recovered in that manner, and the 
power of ordinary land plaster to absorb gases has 
enabled some farmers to gain fertility to their soils by 
its use; while ammonia is largely brought down by 
rains to the soil, the result being that it is converted 
into nitric acid. In the soil there is a large and abun- 
dant supply of plant foods, but they do not exist in 
forms which permit of their use except in limited 
supply. This is a provision of nature to prevent ex- 
haustion of the soil, for if the plant foods in the soil 
were easily rendered soluble the soil would long ago 
have been deprived of them. But they are in the soil, 
and ready for use when demanded ; but the soil will 
not give up these foods except when certain natural 
laws have been complied with, even the farmer cannot 
rob the soil by taking therefrom more than a fair 
proportion unless he pays the cost of so doing to an 
amount which is realiy prohibitory to a certain extent. 
COMPENSATION FOR EXCESSIVE CBOPPINa. 
When a farmer exhausts a soil by excessive cropping, 
and without returning something as compensation there- 
for, he simply deprives the soil of its soluble portions, 
but even the poorest soil will have left, for a future 
reserve, its vsst stores of insoluble pi an t foods. 
The farmer who uses manure and fertilizer thereby 
g»ins from the soil more than he applies because the 
materials which he adds to the soil serve to render 
soluble the inert plant foods existing in the soil ; and 
•s it takes capital to make money in business, so it 
takes manure and fertilizers to make the soil moro 
subservient to the demands of the farmer. Every 
dollar expended for plant food to be applied to the soil 
is an investment which in the future is sure to bring 
good retarng, because of the abundancs of raw mate- 
rials existing in the soil ready for use when proper 
