THE ORANGE IN CALIFORNIA — FERTILIZATION. 141 



ops; and the same principle is recognized in the practical 

 rtilizatiou of the root crops with fertilizers that include 

 liefly potash, while for grain a combination of nitrogen and 

 losphoric acid is usually given and found most profitable. 

 Supplying Deficiencies.— The reason why in many cases the 

 turn of one or two of these fertilizing ingredients can be 

 nitted from the replacement is that the soil itself frequently 

 ntains a larger proportion of one or several of these same 

 gradients in a form available to plants; that, moreover, these 

 gredients, usually occurring in the soil chiefly in a diflBcult 

 luble condition, are gradually set free by the "fallowing" 

 :tion of the atmosphere from their insoluble combinations, 



as to become available to plants; and that if the soil is 

 iturally rich in one or more of these ingredients, the return 



such ingredient may be omitted, either after a fallow or after 

 crop that has drawn but lightly upon it. Thus, after a root 

 op phosphoric acid may usuallj' be omitted from fertilization, if 

 e soil is known to be (naturally or artificially) rich in phos- 

 loric acid; and the same, of course, is true of potash and 

 trogen in other cases. In so doing, the husbandman draws 

 )on the natural resources of the land, availing himself of the 

 [vantages of a rich soil; but those who cultivate soils nat- 

 'ally poor may be compelled to return in every case each one 



the three or four ingredients needed for and commonly used 



fertilization. 



Wasteful Practice. — Were the immediate return of everything 

 at the crop takes away necessary on every soil, the possessor 



rich land would have no advantage over the owner of poor 

 nd, for as soon as the first flush of fertility is exhausted in 

 6 virgin soil, both would be equally obliged to supply the full 

 Qount of ingredients withdrawn from the soil by each crop. 

 it the experience of centuries has shown that such integral 

 placement is altogether unnecessary on very many lands, and, 



a result, the use of a " complete " fertilizer is in Europe a 

 re exception, save as regards stable manure. Farmers buy 

 e individual ingredients as furnished in commerce, according 



the supposed requirements of the land, as deduced either 

 )m its previous history or from the known richness of the 

 il in either one or the other ingredient in question. 



