PURCHASE AND USE OF FERTILIZERS 



313 



In a pot experiment on oats and millet the treated nitrogenous 

 material had an availability of 66 compared with that of nitrate 

 of soda as 100, cottonseed meal 47, hair waste 29, garbage tank- 

 age 28, and peat 4. 



Guarantee of Fertilizer. A fertilizer is valuable on account 

 of the quantity and kind of plant food it contains. The manu- 

 facturer buys on analysis, that is, he pays on the basis of the 

 chemist's analysis of a fair sample of the shipment. The in- 

 dividual farmer, or one who purchases on a small scale, cannot 

 afford to pay for a chemical analysis and can tell little or nothing 

 about the substance by inspection. Hence the laws of most States 

 in which fertilizers are used, provide for a guarantee of com- 

 position, penalties for failure to deliver guaranteed ingredients, 

 and officials who are charged with the inspection and analysis of 

 fertilizers. The simplest guarantee consists of a statement of the 

 guaranteed minimum percentages of the available or total phos- 

 phoric acid, the nitrogen, and the potash. The total phosphoric 

 acid is guaranteed only with respect to bone meal or rock phos- 

 phate, which contain little "available" according to chemical 

 methods. 



In some States, the term ammonia is used instead of nitrogen, 

 and in one or two States, phosphorus and potassium instead of 

 phosphoric acid and potash. Otherwise the latter terms are used 

 the world over. A a varying guarantee, such as "2 to 3 per cent, 

 potash," is allowed in some States, but is not desirable. Other 

 States require a guarantee of water-soluble and reverted phos- 

 phoric acid. The use of the terms "potash as sulphate" etc., 

 allowed in some States, is confusing to the average purchaser. 

 21 



