SOME INFORMATION AND SUGGESTIONS CONCERNING THE 



USE OF PHOSPHORUS. 



Bulletin No. 284 

 M. M. McCooL, G. M. Grantham, C. E. Millar. 



INTRODUCTION. 



Plu)S]>liorns is known to have been nsed in Europe as early as Kir):', 

 for soil improvement. In this country its benefits were early recop;ni/.e(l 

 and llie amount applied to the soil has steadih^ increased until it is 

 made use of with safe margins of profit in all tlie older agriculluvnl 

 regions. Moreover, it has been found to be profitable on some of the more 

 recently developed lands. Of course, there are several explanations for 

 its wide popularity. 



This report discusses terms used, forms in which phosphorus may be 

 purchased; its effect on crop growth and on the soil; the time, manner 

 and amount to apply; removal of phosphorus from Michigan farms; 

 the amount of commercial fjhosphate required to make good this loss; 

 soil composition; and some results obtained from the judicious use of 

 phosphorus. 



Terms Used. It is rather unfortunate, since it confuses some, that 

 several terms are used in referring to this valuable element of plant- 

 food. These are used somewhat loosely, but strictly speaking they convey 

 a definite meaning to tlie chemist or to tliose who have some knowlerlge 

 of chemistry. It is sometimes spoken of as phosfdiorus, as i)hos]>horic 

 acid, and as phosphate. 



When it is stated, for example, that a substance contains 4.1 per cent 

 of phosphorus it means the same thing as when it is said that it contains 

 10 per cent j)liosphoric acid. Thus, in order to express the phosphorus 

 content of a substance as an equivalent amount of phos]ihoric acid i( 

 must be multiplied by 2.8 and in order to express the phos])horic acid 

 content of a substance as an equivalent amount of phosphorus it must be 

 multiplied by .44. Many farmers use the term phosphate in a very general 

 or broad sense, all kinds of fertilizers, those containing only phosphorus 

 as well as mixed goods, being spoken of as phosphates. The term phos- 

 phate as used in this report refers to one or all of the three carriers 

 spoken of below. 



Carriers of Phosphorus. There are llii-ee ]»hosphates or carriers of 

 l)liosphorus, aside fr-om mixed goods, wliicli are worthy of mcntiou so 

 far as Micliigan agriculture is coucei-ned, namely: raw rock ])liosp]ia1e, 

 bone meal, and acid phosphate. 



Raw rock phos])hate or "floats" is found in natural deposits and has 

 been extensively mined in South Carolina. Florida and Tennessee. Other 

 deposits are also known to exist in Alal)ama, North Carolina, Nevada, 

 Pennsylvania, Arkansas, Idaho. Wyoming, TTtab and Montaiia. The phos- 

 pboriis orrurrijig in tlijs carrier is slow acting wbeii applied to the soil 

 and eojiseqnently it shoid<l be added in large quantities. 



