The Bulletin 99 



ommend an application of 800 to 1,000 pounds per acre every three or 

 four years. It should be remembered, however, that as a general 

 thing, for immediate returns, acid phosphate used in the proper way 

 and in optimum quantity will usually be found to supply phosphoric 

 acid in the form that will afford the largest profit per acre, although 

 the phosphoric acid in the acid phosphate will cost two to three times 

 as much per pound as that derived from finely ground phosphate rock. 



NITROGEN. 



Most of the cultivated soils of the Piedmont Eegion are very deficient 

 in organic matter, and therefore lack nitrogen, as organic matter is the 

 principal source of nitrogen in the soil. This source of supply is not 

 sufficient as is shown by the plat results. Other than organic matter 

 there are three sources from which to obtain nitrogen: commercial 

 fertilizers, farm manure, and the free nitrogen of the air. 



There are many nitrogenous materials used as fertilizer, but they are 

 all expensive. Especially is this true for the Piedmont Region, since 

 most of the general farm crops are heavy feeders on nitrogen. In the 

 eastern part of the State where cotton is much more important commer- 

 cial carriers of nitrogen can usually be used with profit. Where cotton 

 is grown in the Piedmont Section, ordinarily here too the commercial 

 forms of nitrogen may be used in fertilizing most soils and have them 

 prove profitable. Where grains and grasses are grown chiefly, however, 

 other sources will have to be depended upon largely. Staljle manure 

 furnishes one of the most desirable sources, as there are large amounts 

 of organic matter in it as well as nitrogen, and at the same time con- 

 siderable quantities of phosphoric acid and potash. Still, it is not a 

 well-balanced fertilizer for these soils unless fortified with additional 

 phosphoric acid. Valuable as it is, however, the supply of organic 

 matter and nitrogen in the soils throughout this section cannot be built 

 up through the use of manure alone, because in the production and hand- 

 ling of manure there is a great loss of the element nitrogen. 



The only other available source is that contained in the air. Here we 

 find the supply which must be largely depended upon in the permanent 

 increase of the supply of this element in the soils of the Piedmont Sec- 

 tion. Most crops, including the grain and grasses, are unable to draw 

 upon the inexhaustible supply, but there is a large class known as 

 legumes Avhich have this power. The clovers, peas and beans, as is 

 commonly kno-wn, are legumes. They furnish an economincal means of 

 maintaining and even upbuilding the supply of this most expensive ele- 

 ment of plant food in soils. It has tnithfully been said of them that 

 "They not only feed themselves, but pay for the privilege," meaning 

 that they not only secure nitrogen for their own growth but at the same 

 time furnish a profitable crop. 



POTASH. 



Of all the types of soils of the Piedmont Plateau Region of the State 

 thus far studied, the content of potash present in the surface soil is gen- 

 erally sufficient for growing maximum crops for a hundred years or 

 more. It is generally more a problem of making this supply available 



