EXPEBIMKNTS ON CLOVKR-80ILB. 151 



"In ttcparulc purlioiis u£ ihc liircf lasers uf soil, tbr propuriious 

 jf iiilruj;fu Mid phospliDric acid cuiiluiiieii iu ciicli layer of six 

 iiiclied, were delcrmiued aiid fouud U> be as follows : 



isuU drUil at 212 dty. Falir, 

 Ixt six 2</ six '6d mx 

 inc/ifji. inr/us. iiichts. 



Percentage of phospboric acid 'M'J A'-A .1?- 



Nilrn;,au l.»>'- .tH'2 .004 



K(juiil li> auiiuouia l'.»8 .112 .078 



" lu the upiHT si.\ iiKbcs, us will be seen, tbe percenUiije of botb 

 pbospborie acid and nitrogen, was larger than iu the two follow- 

 ing layers, wbile tbe proportion <»f nitrogen in tbe six iiiebes of sur- 

 face soil, was niucb larger than in iIk- next six incbes; and in Ibe 

 tliird s(Htion, containing no visible particles of root tilires, only 

 very little nitrogen occurred. 



■' In Ibeir natural slate, tbe tbree layers of soil contained : 



1st xix 2</ six 3</ .til 

 inrhe.^. inrhes. inr/iejt. 



Moisture 17.lt; 18.24 lt;.«2 



PlK.sphi.ric acid I'.W .109 .143 



Nitn.p.n VM .075 .053 



Equal to ammonia Itii .091 .064 



lbs. lbs. lbs. 



Weight of one foot square of soil tX) 01 <J3 



"Calculated per acre, tbe absolute weiglit of one acre of tbis 

 land, six incbes deep, weigbs : 



TJjs. 



let six inches 2,618,600 



2d six inches 2,657,160 



3d six inches 2,746,280 



"No great error, therefore, will be made, if we assume in the 

 sulxsequent calculations, that six incbes of this soil weigbs two and 

 one-balf millions of pounds per acre. 



" An acre of land, according to tbe preceding determinations, 

 contains : 



1«/ six incites, 2cl six incfie.'i, Zd six inches^ 

 Lbs. Lbs. Lbs. 



Phosphoric acid 4,950 2,?25 8,575 



NitroiTcn 3..350 1.875 1,325 



Equal to ammonia 4,0.'jO 2.275 1.600 



" Tbe proportion of phosphoric acid in six inches of surface soil, 

 it will be seen, amounted to ;d)out two-tcntbs per cent ; a propor- 

 tion of tbe whole soil, so small that it may appear insufficient 

 for tbe production of a good corn-crop. However, when calcu- 

 lated to tlie acre, we find that six incbes of surface soil in an acre of 

 land, actually contain over two tons of phosphoric acid. An aver- 

 age crop of wheat, assumed to be 25 bushels of grain, at CO lbs. per 



