COST OF A CEOP OF CORN. 81 



two per cent., or 1.12 lbs. to the bushel by Boussingault and 

 Pay en. 



These three, — potash, iihosphoric acid and nitrogen, with 

 the possibihty of magnesia in a very few cases, — are the valu- 

 able elements removed with the grain. As there is a super- 

 abundant supply of the other elements used by the crop, we 

 need not consider them in this inquiry. 



In investigating the fertility removed by the cob and the 

 fodder, it will be necessary here to determine the size of the 

 crop. The average of eighty-six reports gives eighty-one 

 bushels per acre. This gives 19.067 lbs. of potash, 31.3875 

 lbs. of phosphoric acid, and 90.72 lbs. of nitrogen removed 

 from the acre by the grain. The proportion of the cob to the 

 merchantable grain is about 25 per cent. As the mean of tive 

 trials in October and November, we have 28^ per cent., and 

 the mean of nine trials, four of which were in the winter, was 

 about 20 per cent. The cob contains 1.4675 per cent, of ash 

 as the mean of five trials. Of this ash 0.4564 per cent, is 

 potash and 0.05 per cent, is phosphoric acid. I am unable to 

 find any determination of the nitrogen. The 25 per cent., or 

 1,134 lbs. of cob, removes then 0.0759 lb. of potash and 

 0.008 11). of phosphoric acid from one acre. 



A careful analysis of the statements gives the average 

 amount of fodder or corn-straw, grown with one crop of 

 eighty-one bushels, as 7,204 lbs. This is the average of four- 

 teen reports, and as it is in accordance with the result of ex- 

 periments on a smaller scale, which give the proportion of 

 straw to corn as somewhere in the relation of 80 or 90 lbs. of 

 fodder to the bushel of grain, I think it must be substantially 

 correct. 



Two analyses of the straw give as the mean amount of ash 

 at 4.4 per cent., of which 18.16 percent, is potash, and 14.08 

 per cent, phosphoric acid. The nitrogen has been determined 

 by Boussingault as 0.54 per cent. The crop has then re- 

 moved, — 



Total, 400.29 76.705 76.0255 129.62 



11 



