270 



J. P. LA WES AND JUSTUS VON LIEBIG. 



the thirteenth annual crop is now g:rowing, and though 

 the soil is rather too heavy to be well adapted for 

 turnip culture, vet good crops are obtained, fully 

 equal, as we know from our own observation, to those 

 grown in the neighborhood, under the ordinary sys- 

 tem of rotation. So in Gcescroft, twelve crops of 

 beans have been grown in twelve years, and removed 

 from the soil, and yet as good crops are obtaiaed as 

 the farmers could desire. So of peas and tares. 

 Clover is an exception ; no matter how lavishly and 

 variously it is manured, clover will not flourish con- 

 t'nually on the same land. But with other crops, 

 Mr. Lawes has " solved the single problem worthy of 

 scientific agriculture." At the j^resent price of wheat 

 and ammonia, Mr. Lawes or any other intelligent 

 agriculturist can not only grow wheat continuously 

 on the same land, but can also grow it with a profit. 

 If his land, without manure, will produce In bushels 

 of wheat per acre, he can make it produce 30 bushels 

 by an application of from S12 to $15 worth of 

 manure. If wheat sells for 80 cents to $1 per bush- 

 el, such a system will not pay; if it is worth from $2 

 to $3 per bushel, nothing can be more profitable. 



LiEBiG says: " So to explain the action, and recom- 

 mend the use of ammonia salts ia the production of 

 wheat, as Mr. Lawes has done, appears to be mock- 

 ery of the present state of agriculture; for all the 

 salts of ammonia now manufactured in Europe, are 

 mot enough to supply the fields of the kingdom of 

 iSaxony with the quantities used by Mr. Lawes." 

 'This appears to us a very lame argument. What if 

 salts of ammonia are not now manufactured in sufH- 

 cient quantities? If farmers can obtain what they 

 want at present, shall they not use them? The am- 

 monia salts used in agriculture or commerce, are made 

 principally from the refuse liquor of the gas works; 

 and in nearly every city in Europe the greater por- 

 tion of this liquor runs to waste. lu this country, 

 we know of but one establishment where ammonia 

 salts are manufactared from gas liquor for agricultu- 

 ral purposes — that of M. De BeEO, of New York. 

 Shall we condemn the use of ammonic salts, because 

 they are not at present extensively manufactured, 

 while we have the means of increasing their produc- 

 tion to an almost unlimited extent? 



■But Mr. Lawes has not " recommended the use of 

 ammonic salts in the production of wheat" Mr. 

 Lawes tells u.?, indeed, that ammonia is specially 

 (needed for the production of wheat; but he has nev- 

 'Cr advised farmers to use ammonia salts at their pres- 

 iCnt price. He used them in his experiments because 

 lihey enabled him, for a special object, to apply ammo- 



nia free from the organic and mineral matter united 

 with it in barn-yard manure, guano, rape cake, <Src 

 These experiments led him to the conviction that am- 

 monia, in ordinary agriculture, is greatly needed on 

 all our wheat soils, but he has never recommended 

 farmers to imitate his example, and purchase expen- 

 sive ammonic salts. He points to cheaper sources of 

 it. AVhat these sources are, we shall see further on. 



Professor Ltebio, in some parts of his late work, 

 appeai-s to labor under the impression that Mr. Lawes 

 affirms that if ammonia be present in sufficient quan- 

 tity in the soil, the wheat plant can grow wilhont min- 

 erals. We cannot understand how any one could 

 arrive at such a conclusion from Mr. Lawes' writings. 

 Certainly he has never written any thing that we 

 have seen, which favors such an idea; while he has 

 repeatedly declared that the "growing plant must 

 have within its reach a sufficiency of the mineral con- 

 stituents of which it is to be built up." He also ful- 

 ly admits that the atmosphere and rain-water are ca- 

 pable of supplying plants with a considerable quan- 

 tity of ammonia. On these two main points, Liebio 

 and Lawes are agreed. In what, then, do they differ? 

 It is obvious that they do differ very essentially, but 

 in what exact particulars, it is hard to say, simply be- 

 cause it is impossible to determine what Liebio at 

 present teaches. From the general tenor of his 

 works, we conclude that he beheves, or did believe 

 among other things, that the manurial requirements 

 of a plant are represented by its ashes. In other 

 words,, that the proportion in which potash, phos- 

 phoric acid, kc, exist in the ashes of a plant, is the 

 best proportion for them to exist in the manure adap 

 ted for their growth. The ash of wheat contaijs 50 

 per cent, of phosphoric acid; that of turnips only IC 

 per cent.; therefore, a manure for wheat should con 

 tain five times as much phosphoric acid as a mannrt 

 for turnips. That Liebig and his followers have taughl 

 this doctrine, cannot be denied. Mr. Lawes' e.xperi 

 ment prove this idea erroneous. 



Liebig, we have shown, taught that if plants art 

 supplied with a sufficient quantity of their ash con 

 stituents, they will obtain all the ammonia they neei 

 from the atmo.«phere. Mr. L.iwEs' experiments shos 

 this partly right, and mostly wrong. They show tha' 

 wheat, which contains only a comparatively smal 

 quantity of nitrogen, (ammonia,) requires for a maxi 

 mum crop, very much more ammonia than the atmos 

 phere and rain can supply under the most favorable 

 conditions. On the other hand, they show that beani 

 peas, lares, and turnips, which contain much mori 

 nitrogen than wheat, are enabled to obtain nearly al 



