482 NATURE AND PROPERTIES OF SOILS 



is a mere statement of the percentages of NH 3 , P 2 5 and K 2 0, 

 as, for example, a 2 — 8 — 2. 1 This, however, is too brief for a 

 guaranteed analysis on goods exposed for sale, as it gives no 

 idea whatsoever regarding the solubility of the materials. As 

 might be expected, there is a wide range in the character of 

 the guarantees required by the various states. For example, 

 some states insist on the statement of the percentage of both 

 nitrogen and ammonia, while others insist only on the percent- 

 age of nitrogen. Some require the soluble, the reverted, and 

 the total phosphoric acid, while others require only the soluble 

 and the reverted. As to potash, in some cases the soluble 

 must be stated, while in other cases the total must be given. 2 

 In general, a guarantee should show not only the amount 

 of the various constituents but also their form or availability. 

 The following outline analysis is excellent in this respect : 



Percentage of NH 3 as nitrate. Percentage of P 2 5 soluble 



Percentage of NH 3 as ammonia. in water. 



Percentage of NH 3 total. Percentage of P 2 6 reverted. 



Percentage of K 2 water soluble. Percentage of P 2 5 as 



Percentage of K 2 as chloride. insoluble. 



272. The buying of mixed goods. — The successful buying 

 of mixed fertilizers on the retail market depends on two 

 things: (1) the selection of a composition suitable to soil and 

 crop with carriers of known value; and (2) the purchase of 

 high-grade goods. The farmer who observes these points will 

 at least have purchased successfully. Whether he obtains a 



J In the South, the order is different. An 8-3-2 means 8 per cent, of 

 P 2 5 , 3 per cent, of NH 3 and 2 per cent, of K 2 0. 



a Below is the guarantee of a complete fertilizer : 



Nitrogen 4.2% 



Equal to ammonia 5.0 



Soluble P 2 5 4.0 



Reverted P 2 5 2.0 



Available P 2 5 6.0 



Insoluble P 2 5 1.0 



Total P 2 5 7.0 



Water soluble K 2 3.0 



