J. B. LAWES AND JUSTUS VON LIEBIG. 



271 



the nitrogen and ammonia they require, from the atr 

 mosphere and rain-water. Mr. Lawes thinks it not 

 improbable that the other cereals commonly culti\'a- 

 ted require, like wheat, a much larger quantity of 

 ammonia for their maximum growth that they can 

 obtain from rain and air; and that, as these generally 

 command a high price, and farmers wish to raise them 

 as frequently as possible, every available means should 

 be used to increase the supply of ammonia on the 

 farm. But, as Liebig denies that these experiments 

 lead to any such conclusions, let us briefly glance at 

 the principal points. 



Three fields, with the general character of the soil 

 and previous treatment as much alike as possible, 

 were set apart for these experiments, some 17 years 

 ago. Four crops were grown without any manure, 

 and removed from the fields before the experiments 

 proper commenced. One or more plots in each field 

 was always left without any manure, and the otliere 

 received a variety of the various organic and inor- 

 ganic fertilizing substances. The first year, on the 

 wheat field, uumanured plot yielded 16 bushels per 

 acre. 14 tons farm-yard manure, on a plot adjoin- 

 ing, '22 bushels. The ashes of 14 tons farm-yard 

 manure, 16 bushels. Mean of 9 plots, dressed with 

 artificial mineral manures, 16^ bushels. Mean of 3 

 olots with artificial mineral manures, and 65 lbs each 

 ■jf sulphate of ammonia, 21 bushels per acre. 



With turnips, the first year, the unmanured plot 



.•jave 4 1-5 tons of bulbs peracre; 12 tons farm-yard 



nanure, 9| tons. 56 lbs. sulphate of ammonia, less 



han 7 tons. 4 J cwt superphospate of lime, 12.J tons. 



From these few experiments, which we select from 



.. large number giving similar results, it will be seen 



hat even the first year shows a great difference be- 



ween the mauurial requirements of the wheat and 



urnips. On wheat, a heavy dressing of superphos- 



hate of lime, phosphates of magnesia and potash, 



nd silicate of potash, gave an increase over the nn- 



aanured plot of only three pecks per acre; while on 



IK urnips, the superphosphate of lime trebled the crop. 



he 56 lbs of sulphate of ammonia per acre, which 



id such a good eBect on wheat, had little effect on 



\il arnips, giving only about half as large a crop as the 



J aperphosphate of lime. 



The second year, the same unmanured wheat plot 

 ave 23 bushels per acre; 14 tons farm-yard manure, 

 2 bushels; and 168 lbs. each of sulphate and muri- 

 te of ammonia, 33 1-11 bushels. One plot, which 

 !ceived the previous year superphosphate of lime 

 ithout benefit, was this year left without any ma- 



nure, and the yield was 22J bushels, or half a bushel 

 less than the plot continuously unmanured. 



The same unmanured plot the second year, on tur- 

 nips, produced 2 1-5 tons of bulbs per acre; 5 cwt. 

 superphosphate of lime, BJ tons; 4 cwt superphos- 

 phate of lime, with 56 lbs. sulphate of ammonia, 5 J 

 tons. 



It is remarkable that while on the unmanured wheat 

 plot the second year, the yield was 23 bushels, the crop 

 on the unmanured turnip plot was only 2 1-5 tons of 

 bulbs per acre; and while sulphate of ammonia is 

 again so beneficial on wheat, it has no influence on 

 turnips; on the other hand, superphosphate of lime 

 which is attended with little or no increase on wheat, 

 gives a great increase of turnips — four times as much 

 as the unmanured plot! 



The third year, the same continuously unmanured 

 wheat plot yielded 173 bushels per acre. On anoth- 

 er plot, from which, the previous year, a large crop 

 was taken by the use of ammonia salts, but which 

 was this year left unmanured, the yield was a little 

 over 17 J bushels. This is again nearly identical with 

 the plot continuously unmanured, and shows conclu- 

 sively that the ammonia is all assimilated the first 

 year. Does it not, also, on the other hand, discoun- 

 tenance the popular notion that ammonia is a stimu- 

 lant, acting on the plant as alcohol on the animal or- 

 ganism? 224 lbs. sulphate of ammonia alone, gave 

 27i bushels. The ash of 3 loads of wheat straw 

 gave 19 bushels; the ash of 3 loads of wheat straa?,- 

 and 224 lbs. sulphate of ammonia, 27 bushels, neaily- 

 identical with the yield obtained from the same- 

 amount of ammonia alone. 448 lbs. of Liebig's. 

 wheat manure gave 20J bushels, while the same 

 amount of Liebig's wheat manure, and 112: lbs. 

 each of sulphate and muriate of ammonia, gave 29 

 bushels. 14 tons farm-yard manure gave 27^ bush- 

 els, or precisely the same amount as that obtained , 

 from 2 cwt of ammonia salts alone. 



The third year the same unmanured' turnip plot 

 produced only 13i cwt. of bulbs per acre; 6 cwt of' 

 sulphate of ammonia, 3 1-5 tons; 534 lbs. superphos- 

 phate of lime, nearly 13 tons; 3 cwt of sulphate: of^ 

 ammonia, in addition to the same amount of super- fl' 

 phosphate, gave no more, but rather less than the 

 superphosphate alone; 11 cwt. of superphosphate of 

 lime gave 14J tons; the same amount of superphos- 

 phate, with 3 cwt of sulphate of ammonia in addi- 

 tion, gave 14J tons. We may here remark — and we 

 call particular attention to it as showing that it is. 

 the phosphoric and not the sulphuric acid to which 

 superphosphate of lime owes its efficacy as a manure; 



