THE SOUTHERN PLANTER 



109 



cases, as well as the special conditions which 

 caused the increase in his experiments. 



If now it is true that G lbs. of ammonia were 



necessary to produce one bushel of extra yield, 

 and that of this ammonia 5 lbs. were lost (evapo- 

 rated through the plant), it must also be true 

 that 6 lbs. of ammonia were removed from the soil 

 of the unmanured plot, to produce every bushel 

 of ordinary yield, and of this ammonia 5 lbs. also 

 were lost to the soil by volatilization. 



" Since now the unmanured plot yielded in seven 

 years 123'! bushels of wheat, it follows that the 

 soil must have contained, or received from the 

 air or rains, G18f lbs. of pure ammonia, or 3850 

 lbs. of carbonate of ammonia (salts of hartshorn), 

 and that in seven years this quantity of ammonia 

 was rendered useless for future harvests by the 

 wheat culture. 



" Such a conclusion it is impossible to support 

 by any fact. What we know with certainty is, 

 that during sever* years 21 } lbs. of nitrogen were 

 annually removed from the soil of the unmanured 

 plot by the crop grown upon it, or 149 lbs. in total. 

 But how much ammonia was contained in the soil, 

 and was consumed in the production of 171 

 bushels of wheat, we know nothing about. 



" Since, now, Mr. Lawcs did not know how 

 ro^ch ammonia the wheat plant requires from 

 the soil in order to give one bushel of yield upon 

 the unmanured plot, how could he know that for 

 every bushel of increased yield (gain by ma- 

 nuring) precisely six pounds of ammonia were 

 necessary 1 „ 



" if it had accidentally occurred to Mr. Lawes 

 to manure his field with four, five, or 

 ammonia salts 

 those ca';o3 th 

 may with cert) 

 he might with 

 loss of amnion 

 of increased yi 

 " Or if Mr. 

 at the rate of 

 acre, and then, 

 solved bones a 

 he has not U 

 vested the sai 

 elusion that t 



ins l ead 

 viehl v 



of with si 



mci 

 aid 



jus 

 10 



.OS. 



•wt. or 



n.% } and if in 

 rased (as we 

 iappen) then 

 ■ert that the 

 every bushel 



mmonia salts 



Lawes had applie 

 2 or 1 cwt. instead of 8£ cwt. the 

 after previous manuring with dis- 

 nd silicate of potash (whose action 

 hen at all into account), had bar- 

 is-- increase of 8 bushels, his con 

 he jsoil suffers a loys of ammonia 

 wo ill d doubtless have been vastly modified. lie 

 has made the loas and not found it. The num- 

 ber 5 for the amount of ammonia, and the qiian 

 tity 1 bushel for the increa.'.ed yield, are not ex- 

 pressions for a natural relation between manure 

 and crops. The first does not express the weight, 

 of ammonia necessary to produce a maximum of 

 increase equal to l,and ascertained by a series of 

 observations, but is a mere stroke of fancy. It 

 never seems to have occur! ed to Mr. Lawes to 

 determine the minimum of ammonia which was 

 effective upon his field in producing maximum 

 crops." 



The pith of the controversy lies here; and 

 Liebig puts forth his whole strength. W c have 

 rarely met with a finer specimen of special 

 pleading. It is, however, the only portion ot 

 his lengthy paper jwhith is to the point. The 

 case against Mr. Lawes is stated in as strong a 

 Hgh| as possible, and no doubt many who read 

 only one side, will be deceived by the plausi- 

 ble sophistries of this greatest, ablest, and, we 



are sorry to add, most unscrupulous of contro- 

 versialists. He seems to "stick at nothing* 

 that will help him to make out a case. Never- 

 theless, we are glad that Dr. Wolff has suc- 

 ceeded in forcing him to attack Mr. Lawes* 

 main position. We have given Liebig's whole 

 argument, and will now briefly examine it. 



It is true, as Liebig states, that Mr. Lawefi? 

 soil yielded 1 7 bushels of wheat per acre an- 

 nually for seven years, without any manure ; 

 and we may add, indeed, for thirteen years. It 

 is also true that mineral manures — the ashes 

 of the wheat plant — alone, do not enable it to 

 produce any larger crop. It is further true 

 that 17 bushels "is almost an average crop of 

 wheat." On the other hand, it is also true 

 that where this same soil has been annually- 

 supplied with ammonia alone, much larger 

 crops have been obtained— on an average of 

 seven years, as Liebig admits, Half as much 

 again; and, we may add, last year (1854) as 

 much as 34^ busbfcls per acre were obtained; 

 and this, it must be observed, after ten suc- 

 cessive crops had been grown (and removed 

 from the soil) by the aid of ammonia alone. 

 The province of Agricultural Chemistry, Lie- 

 big tells us, is to produce more grain and more 

 meat, and not simply grain and meat, which 

 have been produced for centuries without her 

 aid. Yv T e fully agree to this; the object of ag- 

 riculture is not to maintain merely, but to in- 

 crease the productiveness of our fields'. How 

 can this be done? Liebig says truly that the 

 17 bushels of wheat annually grown on Mr. 

 Lawes' experimental field, by the aid of good 

 tuiage alone, is "almost an average crop.* 

 But the object cf Agricultural Chemistry, 

 according to Liebig, is to increase the produc- 

 tiveness of our fields. This Mr Lawes haa 

 done. Instead of 15 or 20 bushels of wheat 

 per acre, he has grown SO and 40 bushels, 

 and in 1854 as high as 55 bushels; and, in a 

 private letter recently received, Mr Lawes 

 informs us that some of the plots this year 

 (1855) more than double the unmanured plot, 

 the yield on which is still 17 bushels per acre. 



On this soil, by good tillage alone, 1 7 bushels 

 of wheat arc annually grown. The object is 

 to get a heavier crop. It was supposed thai 

 "as the crops on a field diminish or increase in 

 exact proportion to the diminution or increase 

 of the mineral substances conveyed to it in 

 manure," superphosphate of lime, potash, 

 soda, lime, magnesia, sulphuric acid, chlorine, 

 and soluble silica, or the ashes of the wheat 



plant, would increase the crpp ; but they did not. 

 Liebig's patent wheat manure was also tried 

 in vain. Uut ammonia, in whatever form used, 

 increased the crop. Six pounds of ammonia 



