1 Nov., 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 367 
4. Carbonate of potash-magnesia does not contain any chlorine or sulphur, 
thus bringing the potash to the plants in a directly available form. This fact 
is of importance in the case of delicate plants or such as require large amounts 
of potash during the primary stage of growth. 
IV. Ferrintsens conraryine Two or Tres Pranr-roop INGREDIENTS. 
1. Nitrate of potash is obtained from East India under the name of 
“Bengal saltpetre”’; it can also be manufactured by converting muriate of 
potash and nitrate of soda, and the manufactured product is considerably purer 
and of higher grade. Nitrate of potash contains both nitrogen and potash, is 
comparatively pure, but rather expensive. 
2. Phosphate of potash is a similar product, also containing two of the 
essential plant-food ingredients—viz., potash and phosphoric acid. These two 
materials are valuable chiefly on account of their highly concentrated contents 
of plant-food ; the use of these materials, therefore, leads to. a considerable 
saving in freight charges. 
3. Peruvian guano, fish guano, and tankage contain chiefly nitrogen and 
phosphoric acid; they therefore require an addition of potash in order to 
produce good effects. 
VY. Cancarrous Frrririsers. 
According to Prof. Maercker,* a soil containing less than 0:25 per cent. 
of lime will always respond favourably to lime fertilisation ; one containing 
from 0'25 per cent. to 0°5 per cent. will probably do so, and the application of 
lime has produced good results even on soils containing more than 05 per 
cent. of this material. 
A sufficient supply of lime in the soil is of the utmost importance, as it 
not only is a valuable plant-food ingredient, but also improves the physical 
condition of the soil. Should the soil be deficient in lime, the planter should 
not fail to supply this ingredient artificially. x 
Sour and heavy soils are neutralised and loosened by lime, and are thus 
more easily worked, and produce better yields. Furthermore, lime hastens the 
process of decomposition going on within the soil, causing the more rapid con- 
version of humus into carbonic acid, and accelerating the formation of nitrate. 
Lime is of much importance in assisting in the decomposition of potash salts, 
but this action will deplete the soil of its supply of lime; 220 lb. of potash 
galts convert and force into the lower depths of the soil about an equal 
quantity of lime. 
Among calcareous fertilisers the following deserve mention: 
1. Marl, which contains from 10 to 70 per cent. of carbonate of lime, 
according to the nature of the substance, so that the amount of marl required 
depends upon the percentage of carbonate of lime it contains. In order that 
lime may produce the best effect, 2,000 lb. to 5,000 1b. of carbonate of lime 
must be applied to the acre. Recently, finely ground limestone has been applied 
with success to light soils. 
2. Freshly burnt lime consists of quicklime which absorbs moisture from 
the atmosphere and then falls to a fine powder. The material acts much more 
vigorously in the soil than carbonate of lime, and is therefore to be preferred, 
especially on heavy soils. 2,000 Ib. to 3,500 1b. of slaked lime will satisfy the 
needs of the soil for from four to eight years. In the case of light soils, it is 
more advantageous to apply smaller quantities at shorter intervals. 
3. Plaster or sulphate of lime does not produce a very favourable eftect 
upon the soil. As this material only dissolves certain plant-food ingredients 
in the soil, it is only natural that its application should be but temporarily or — 
partially successful. 
* Prof. Maercker, Die Kalidiingung, Berlin 1893. p, 32, 
