1 Dec., 1898.] QUEENSLAND AGRICULTURAL JOURNAD. 44:3 
PHOSPHORIC ACID. 
The effect of phosphoric acid fertilisation upon the quantity and quality 
of tobacco has not yet been definitely determined. The results obtained, 
especially as regards the burning quality of tobacco, are in several instances 
diametrically opposed. Experiments indicate that a general rule for the 
application of phosphoric acid cannot be established; the quantity of this 
ingredient, however, and the form in which it should be applied, must depend 
upon the local conditions of the soil, and especially upon the percentage of 
phosphoric acid which the latter contains. Prof. Nessler has found, as the 
results of many experiments, that the injurious effect of chlorine is relatively 
insignificant as compared to that of phosphoric acid. Prof, Cserhati, on the 
other hand, holds that it is only in exceptional cases that phosphoric acid 
injures the burning quality, and then but to a comparatively small degree ; 
whereas there are numerous instances in which fertilisers containing phos- 
phoric acid improye the burning quality and increase the yield under favourable 
circumstances. ¢ 
Due attention must be given to the application of phosphoric acid, as it 
is well known that this ingredient hastens maturity. Moreover, its application 
is important because of the mutual effect which most of the plant-food 
ingredients have upon the development and growth of plants. Mixtures 
intended for tobacco should include phosphoric acid in amounts correspondin 
approximately to the analyses given above. ‘The changes necéssitated by loca 
conditions can only be determined by experimenting. 
As the absorption of phosphoric acid by the tobacco-plant extends almost 
uniformly over the growing season, no essential differences resulting from the 
application of acid phosphate and Thomas’ slag have hitherto been noticed. 
Both of these materials are preferable to bone-meal and Peruy. guano as 
sources of phosphoric acid, and the cheaper of the two former should be used. 
POTASH. ‘ : 
The great importance of potash fertilisation for tobacco is clearly 
demonstrated by the large quantity of potash removed from the soil by this 
plant. The beneficial effect of potash is more marked upon the quality than it 
is upon the quantity, though good results cannot be expected in either 
particular, unless sufficient quantities of nitrogen, phosphoric acid, and lime 
are, at the same time, placed at the disposal of the plant. Fertilisation with 
potash alone will not, therefore, be apt to produce satisfactory results. 
Excellence of burning quality usually corresponds to a high percentage of 
potash and a low percentage of chlorine. or this reason, fertilisers containing 
chlorine should be avoided; potash salts, like muriate of potash, kainit, &c., 
should not be applied to tobacco, the proper forms ot potash and potash- 
magnesia to be used for this plant being the sulphates, phosphates, and 
carbonates. 
No definite recommendations can be made as regards the particular 
form to apply, because the results of various experiments, conducted for the 
purpose of solving this question, quite frequently produce contradictory results. 
In this connection due consideration must be given to local conditions. 
The best burning-quality results when the potash contained in the tobacco-leaf 
is combined with organic acids. It is, therefore, advisable to apply the potash 
salts as early as possible, in order that they may be converted into carbonates 
and humates. 
Light sandy soils require larger quantities of potash than loamy and clayey 
soils; the latter are not very suitable for the cultivation of tobacco. 
Cottonseed-husk ashes, as well as wood ashes, are very good sources of 
potash for tobacco. The commercial supply of these materials 1s, however, 
limited ; they are also often leached, and, besides, the amount of potash they 
contain does not correspond to the prices demanded for them, The ploughing 
under of tobacco-stems also furnishes some potash to the soil, though not 
enough to satisfy the needs of the plant, 
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