196 



Third- Sulphate of Potash of varying purity, containing 24 per cent, 

 to 50 per cent, of potash, is also a manufactured article. 



From these forms the others, carbonate and nitrate, are manufac- 

 tured. 



How SHALL Fertilisers be applied ? 



A rational discussion of the properties of each one of the three ingre- 

 dients of commercial fertilisers will enable us to intelligently appreciate 

 the proper methods of applying them. Nitrogen, the ingredient most 

 desired by cane plants, is the transitory one of commercial fertilisers. It 

 is to-day a gas, forming a part of the atmosphere ; tomorrow it is a solid 

 in the plant. It is now an ingredient of soil water, and is either ap- 

 propriated by plants, fixed by the soil or leached out into springs and 

 rivers, to be finally " in the dark bosom of the ocean buried," there to 

 be abstracted and appropriated by fish, which in time furnishes pabulum 

 for man or manure for plants. The idea of rest or permanence is for- 

 eign to the chemistry of this element, as to the atmosphere of which it 

 forms so large a part. Therefore, all nitrogenous manures should be 

 used with care and caution, especially those which contain actual ammo- 

 nia and soluble nitrates. Therefore, in using Nitrate of Soda, it should 

 be applied as a top dressing only on the growing crop, and at short in- 

 tervals in small quantities. Sulphate of ammonia is also liable to leach- 

 ing, but may be lost by excessive use, or application, at an improper 

 time. The organic nitrogenous fertilisers mentioned above must be 

 gradually oxidized and converted into nitrates as explained elsewhere 

 under " Nitrification," before they can become available as plant food. 

 Soil conditions determine largely the rate at which this nitrification takes 

 place, and excellent tilth with subsequent frequent and shallow cultivation 

 favour the rapid decomposition of organic nitrogenous fertilisers. Messrs. 

 Lawes and Gilbert have found that cotton seed meal formed, when ap- 

 plied to a soil not too dry, a slow but continuous supply of nitrates. 

 'I he oil present perhaps cripples the nitric ferment, and prevents too 

 rapid nitrifaction. As shown elsewhere, nearly all of its nitrogen is 

 available in one season. Dried blood is a quickly acting manure, re- 

 quiring only a slight covering in the soil for conversion into available 

 plant food. It may even be used as a top dressing. 



Taokage, so far as its content of blood goes, has similar properties. 

 The bone and meat portions, particularly the former, are much slower 

 of action. Fish scrap acts more slowly, and there is no evidence 

 that all its nitrogen ever becomes available. However, in the South, if 

 turned too deeply in a warm mellow soil with moderate humidity, the 

 results are fairly satisfactory. It cannot be profitably be used eittier as 

 a top dressing or when turned too deeply, since in both instances fer- 

 mentation is prevented ; nor will it yield good results in early spring 

 upon cold, damp, soils, but in warm sunshine it may do excellent ser- 

 vice upon both corn and cane. 



It has been shown elsewhere that soluble phosphates, soon after their 

 application to the soil, revert to insoluble forme. It was also shown 

 that before reversion, its solubility rendered its distribution througti the 

 soil more thorough and uniform, thus securing advantages not obtained 

 by other forms of phosphoric acid, in such soils the roots of crops grow 

 regularly, continuously, and rapidly, and not spasmodically and inters 



