lo Sf.pt., 191-'.] W I/cat and its Citllivation. 547 



ingredient may be ,'(])i)lied, under his conditions, as well as the most profit- 

 able rate at which it may be applied. 



Classification of Manures. 



Manures may be divided into two general classes. Those which supply 

 the soil with elements in which the soil is deficient are called Direct 

 manures; whilst those which act by improving the physical and biological 

 condition of the soil rather than bv augmenting the supply of plant food 

 are called Indirect manures. Again, Direct manures may supplv all the 

 elements of plant food, in which case they may be called General manures ; 

 or they may contain one dominating plant food ingredient such as phos- 

 phorus, potash, or nitrogen, in which case they may be called Special 

 manures. Finally, the Indirect manures may be either vegetable in 

 character, such as green manures, or mineral, such as lime, gypsum, salt. 



The following tabulated statement may assist in making the matter 

 clear : — 



fi. Nitrogenous 

 (-Special \2. Phosphatic 

 (Direct J '■3. Potassic 



! [(ieneral — Farmyard manure 



. J Mmeral — Lime, gypsum 

 [ Indirect^ Vegetable — Green manures 



We will consider these seriatim : — 



Nitrogenous Manures. 



The most striking and fundamental difference between the manurial 

 practice of Europe and that of Australia is that, in the Old World, 

 nitrogenous manures are all important, whilst in Australia they are generallv- 

 unneces.sary and unprofitable. In European agriculture, the controlling, 

 factor for successful cropping is the amount of available nitrogen present 

 in the soil. In Australia, assuming the rainfall be sufficient, the limiting; 

 factor in crop production is the amount of available phosphoric acid. 



The importance of this distinction is obvious. The cereal farmer of 

 the Old World must supply the all-important nitrogen, either through the 

 medium of costly nitrogenous manures, or by providing a regular scheme 

 of rotation in which leguminous crops play an important part. 



The cereal farmer of Australia finds expensive and costly nitrogenou.s- 

 manures, like nitrate of soda and sulphate of ammonia, quite unnecessary, 

 and he is thereby saved the great expense incidental to their application. 



His manure bill amounts to 2s. 6d. to 4s. 6d. per acre, and this amount 

 is expended on the purchase of soluble phosphates. 



117/ V XitrogCHOus Manures are Unnecessary. 



Whv is it that nitrogenous manures are unnecessary, and even unpro- 

 fital)le.' in the wheat areas of the State? At fir.st sight, oiie might be 

 inclined to the belief that our soils were richer in supplies of nitrogen than 

 those of Europe. Examination of typical .soils in the wheat areas, how- 

 ever, prove that such is not the case. 



Many instances might be quoted of Australian .soils which have proved' 

 unresponsive to the application of nitrates, even though they would be 

 regarded as lamentably deficient in total nitrogen if judged by European- 

 standards of fertility. 



The .soils in our wheat areas have not been under cultivation for such 

 a length of time as to reduce the supply of available nitrogen below the 



