364 QUEENSLAND AGRICULTURAL JOURNAL. [1 Nov., 1898. 
Leguminous plants furnish the humus required by the soil, and at the 
same time gather nitrogen from the atmosphere in sufficient quantities. In 
this way nitrogen is obtained more cheaply than by any other means, and it is, 
moreover, more valuable in this form than in stable-emanure. When green 
manuring is employed, potash and phosphoric acid should be provided 
artificially by means of potash-phosphate fertilisation. 
“Leguminous plants promote the formation of dew, keep the earth moist, 
prevent the growth of weeds, loosen the soil, and supply nitrogen to it, 
accelerate the decomposition of the mineral ingredients contained in the young 
grain, increase the amount of humus, and properly regulate the fermentation 
of the soil.” (Dr. Stutzer.) 
Green manuring ensures the best results on light and sandy soils. 
Leguminous plants should be sown in the beginning of the rainy season, 
and ploughed under about two months later. 
‘Among the leguminous plants suitable for the tropics may be mentioned 
indigo, earthnuts, soja-beans, and cow-peas (Dolychos). 
A's mentioned above, leguminous plants are fertilised with potash and 
phosphoric acid, and these ingredients are also beneficial to succeeding crops. 
The natural fertilisers previously referred to do not satisfy the demand, 
for, aside from the limited production of one or the other of them, not one 
contains the plant-food ingredients in sufficient proportions, and consequently 
the addition of so-called “artificial fertilisers’’ is necessary. It is to these 
» that the planter must turn at the present day. 
B.—ARTIFICIAL FERTILISERS. 
All of the plant-food ingredients mentioned can be purchased separately 
in the form of artificial fertilisers, and in an available state, so that the varying 
needs of different soils and plants may be cared for. 
J. Nrrrocenovus FERrinisens. 
1. Nitrate of soda contains nitrogen in the easily soluble form of nitric 
acid, which is immediately absorbed by the plant, and is therefore very effective. 
2. The nitrogen in sulphate of ammonia is also very soluble, but must be 
converted into effective nitric acid in the soil; the change goes on quite rapidly 
in hot climates and calcarcous soils, so that the efficacy of sulphate of ammonia 
is almost equal to that of nitrate of soda. 
3. The nitrogen in dried blood, horn-meal, wool-dust, &c., must be 
converted into ammonia by putrefaction, and then into nitric acid; these 
fertilisers, therefore, act slowly, but their effect is more lasting. ‘To this class 
belong the above-mentioned oil-cakes, tankage, bone-meal, guano, &e. 
As decomposition takes place much more rapidly in tropical regions than 
in temperate zones, the organic nitrogen supplied is proportionally of greater 
yalue, and will yield the best results, especially when applied to plants which, 
like sugar-cane, coffee, tea, &c., have a long period of growth. 
Investigations conducted by Prof. Wagner, of Darmstadt, have shown that 
nitrogen is most available in the form of nitrates. To illustrate: If the 
availability of nitrate of soda be taken as 100, then that of various other 
nitrogenous fertilisers will be as follows :— 
Nitrate of soda... ae ert an 700 pe eeLOU, 
Sulphate of ammonia... ues ed or ax | ELD 
Dried blood, horn-meal, oil-cakes in a green (not yet 
decomposed) state ... ie a0 re (ho) 
Steamed, finely powdered bone-meal, fish-scrap, tankage 60 
Stable manure... ib von yy ot 000 5 
Wool-dust ee Fi a oR ee ma 30) 
Ground leather ... : see oy : ogi AY) 
The above figures may vary somewhat in tropical regions, as the more 
casily decomposed organic fertilisers are quicker in their action, especially in 
the case of oil-cakes. 
