510 BULLETIN OF THE BUSSEY INSTITUTION. 
Square £ barley. 
Of fish scrap . . . 8100 grms. X 162 = 502.200 kilos. = 11054 Ibs. 
», Sulphate of potash 463. ,, X162== 75.000; ,, == 165 ,, 
The cost per acre would have been :— 
1106 lbs. fish scrap . . . . . . @$18.00 perton $9.95 
165 ,, sulphate of potash . . . @ 0.03 4.95 
$14.90 
As was naturally to be expected no one among the various commer- 
cial fertilizers employed in these experiments. exhibited any note- 
worthy superiority to its fellows. The mixtures that contained nitrate. 
of. soda appear to have given rather better crops on the whole than 
those which contained sulphate of ammonia. It will be remarked that 
this result consists with what has been said on 307 as to the advantage 
of using mixtures of several kinds of nitrogenous fertilizers; for each 
of the superphosphates that were used in my experiments contained a 
small quantity.of ammonium. salts ready formed, besides nitrogenous 
matters capable of forming ammonia, and the last remark will apply 
to the bone meals also. The addition of the nitrate of soda had con- 
sequently the effect of increasing the resources of the crops. The 
plants that grew upon those squares of land which received the nitrate 
manifestly. had access to a greater variety of food than their competi-. 
tors. With this exception, and possibly that of the wood-ashes also, 
there was no indication that either of the fertilizers served any useful 
purpose other than to supply the amount of phosphoric acid, or of 
potash or of nitrogen, which analysis had shown to be contained in it. 
When used in fit proportion, in conjunction with suitable quantities of 
the other kinds of ‘plant food, each and all of the materials employed 
seem to be useful in proportion as they can supply one or another of 
the above-mentioned desiderata. Since the question of cost was not 
considered in choosing the fertilizers for these experiments most of the 
mixtures might be greatly improved upon in that respect, as has been 
already sugggested on pages 307 and 809. In point of fact, no effort 
was made to contrive the best possible mixture, even for the experi- 
mental field, much less to devise a mixture that should be generally 
applicable. 
Most, if not all, of the mixtures used, were probably very much 
richer in one or another of the elements of plant food, than they need 
