March 1, 1898.] 
Supplement to the “ Tropical AgricuUuriet.^'* 
65f 
manures, their action on the quality, and especially 
the flavour of produce, the relation of different 
manures to soils of different characters, and to the 
nature of the climate, particularly temperature and 
rainfall. All these are questions for the Agricultural 
Chemist to study on the spot, and it will be to the 
advantage of the agriculturist as well as the 
manure merchant to see that they are solved by 
a competent authority. It will not do for any one 
to dogmatise in the face of the many apparently 
paradoxical facts that have to be carefully con- 
sidered, and as carefully worked out in practice, 
before he can attempt to offer an opinion on so com- 
plicated a question. It is enough for us to re- 
member what has been already hinted at, viz., that 
the action of a manure depends not only on its 
own inherent qualities, but on the soil, the condi- 
tions of temperature and rainfall, as well ns the 
character of the plant to which it is to be applied. 
POTASH AND ITS FUNCTIONS IN AGRI- 
CULTURE. 
The following is a brief summary of an ex- 
haustive paper on the above subject by the Chief 
of the Division of Chemistry in the United Stales 
Department of Agriculture : — 
1. The potash used in fertilizers and found in 
the soil has been derived from the decay of 
minerals containing it as an ingredient, and 
chiefly from feldspars. 
2. During the progress of weathering, a por- 
tion of the potash in original rocks becomes 
soluble and is lost by lixiviation. As a rule, 
about 25 per cent of the potash finds its way by 
this means into the streams and seas. 
3. There is usually a less percentage of potash 
in the finer particles of soil than in the coarser 
particles, and this is due to the fact that the 
solvent action of water is more strongly exerted 
upon the finer particles. 
4. The potash is quite evenly distributed both 
, in the soil and subsoil, there being only a sliglitly 
greater proportion in the deeper layers, doubt- 
less to the fact that they have not been so 
thoroughly leached. 
5. The solubility of potash in the soil is very 
different for different solvents, the least for the 
weak organic acids and greatest for the strong 
mineral acids. Hot hydrochloric acid extracts 
from the soil about 20 per cent of its total potash 
content, which is about thirty-two times as much 
as is removed by a 1 per cent citric acid solution. 
6. A fertile virgin soil contains about 2 per 
cent of total potash, or about 70,000 pounds per 
acre taken to the depth of 1 foot. A crop re- 
moving 60 pounds of potash a year could be 
grown consecutively for about one thousand four 
hundred years on such a soil before exhausting 
all the potash which it contains. 
7. The soil retains a certain quantity of fer- 
tilizing material with such tenacity as to render 
it practically impossible for plants to withdraw 
the whole of it, thus protecting tiie future against 
the rapacity of the present. 
8. The quantity of potash removed by various 
crops per annum varies greatly. The largest quan- 
tities are removed by beets, and the smallest 
quantities by cereals and cotton. Beets may re- 
move as much as 100 pounds per acre, cereals about 
30 pounds, and cotton about 2-3 pounds for the 
average crops as produced in this country. In 
Germany, beets grown for forage remove often 
over 200 pounds of potash per acre from the soil, 
clover hay about 74 pounds, and tobacco thO 
same quantity. 
9. Tobacco contains a larger proportion of 
potash than any^ other common crop, viz , about 
40 parts per thousand of the dry leaves. Forage 
beets contain 35, potatoes 20, sugar beets Id, 
clover hay 19, beans 13, and cereal-s 5 parts per 
thousand. 
10. There is about four times as much potash 
in the straw of cereals as in the grains, while in 
peas and beans the proportion is about ns two to one. 
11. A soil which yields about O'Ol per cent of 
potash to a 1 per cent citric acid solution, and con- 
tains about 0'30 per cent soluble in hydrochloric 
acid does not usually need a potash fertilizer. 
12. The potash salts which supply the com- 
mercial potash fertilizers of the world have been 
deposited as the result of the evaporation of 
saline lakes charged with potassic materials. 
13. The commercial potash of the world is 
derived almost exclusively from the neighbour- 
hood of Stassfurt, in Germany. The quantity of 
crude salts annually mined is about three-quarters of 
a million tons, worth nearly three million dollars. 
14. The high-grade commercial salts used for 
fertilizing purposes are manufactured from the 
crude salts, and are to be preferred when ship- 
ments are made to great distances and at high 
rates of freight. 
15. The principal crude potash salt.s used for 
fertilizing purposes are kainite containing 12 o per 
centof potash, and caruallitecontaining9-9 percent. 
16. Tobacco waste, cotton seed hulls, and 
wood ashes also furnish important quantities of 
potash for fertilizing purposes. 
17. Recovered marsh or swamp lands and 
lands containing large quantities of sand need, 
almost universally, potash fertilizer. The per- 
centage of potash in soils usually rises with their 
content of clay. 
18. The maximum effect from feitilization 
with potash is secured only when other plant 
foods are supplied in such a way as to make a 
well-balanced ration, and where proper methods 
of culture are employed. 
19. Lime is an important adjunct to potash 
fertilization,'^and, asa rule, should be added to ajsoil 
in large quantities wherever potash is applied. * 
20. Tlie best kind of potash fertilizer is deter- 
mined by local conditions, freights, and the 
nature of the soil and the crop. Fertilizers con- 
taining considerable quantities of chlorine should 
never be applied to vineyards and tobacco fields. 
21. In intensive pot or garden culture, where 
highly-concentrated plant foods are desired, and 
where the cost of the fertilizer is unimportant, 
potash may be applied in the form of phosphate 
or nitrate. 
22. In some soil potash salts, in common with 
other saline bodies, produce injurious effects by 
reason of theii’i hygroscopic nature, attracting 
moisture, and, on drying, producing a cementation 
of the soil, which renders it impervious to water 
*nd impenetrable by the rootlets of plants. 
