December i, 1882.] THE TROPICAL AGRICULTURIST. 



475 



hearing. lu the Uuited States a farmer, on coming across 

 any views, or statements on the subject of agriculture that 

 are new to him, asks himself the question, are these true ; 

 and, if so, what benefit can I derive from them ? In Great 

 Britain, from the conflicting interests of the owner of the 

 land, and the occupier who pays an annual rent for the 

 right to cultivate it, the teachings of science are likely 

 to be praised or blamed aerordiugly as they affect the 

 interests of the owner rather than those of the cultivator 

 of the soil. A few years ago, wheu public attention was 

 directed to the vast increase in the amount of agricultural 

 produce sent from the States to England, there were 

 many who put forward the view that, by a more liberal 

 application of capital to the soil, we could grow all the 

 wheat required to feed our population. Under these circum- 

 stances I thought it my duty to caution tenant farmers 

 agauist paying too much attention to statements which 

 were uttered by those who had no experience in either 

 practical or scientific agriculture. I accordingly delivered 

 a lecture before a farmers' club, in which I endeavored 

 to show, by the teaching of my own experiments, that 

 a higher system of farmnig was not so certain a remedy 

 for falling prices as some wished them to believe. 



In a letter recently published in a paper devoted to 

 field sports, which I have been informed is much read 

 by the owners of land, a writer, who signs himself 

 " Agricola, " makes the following observations : — " Certain 

 pamphlets of Mr. Lawes have done intolerable miscliief 

 in giving a false coloring to the service higher farming 

 might render in enabling British farmers to tide over the 

 present crisis,'' and he goes on to say that we have the 

 counterblasts of M. Georges Ville to send all unsubstantial 

 utterances beyond the domain of rational consideration ! 

 If in speaking of the immense influence which such 

 nitrogenous manures as Ammonia, or Nitric Acid produce 

 upon the growth of our ordinary cereal crops, I had pointed 

 out that, owing to the high price of these substances, it 

 was by no means certain the increase in produce would 

 pay for their apphcation ; and consequently it would be 

 desirable for the United States farmer to exercise some 

 caution in their use, I think it is hardly possible to 

 believe, that any one in the Sto,tes could suppose such a 

 caution would be productive of evil. 



In another case I was rather amused at a correspondence 

 which I lately noticed between M.Georges Vilie and .some 

 one who had called his attention to my views with regard 

 to the sources of the Nitrogen in vegetation, which were 

 altogether antagonistic to those entertained by M. Ville. 

 M. Ville, in his answer, .stated that he had heard of the exis- 

 tence of a pamphlet on the subject, but that hewas so much 

 engaged in showing how Foreign Corapetitiou could be 

 I>est overcome, that he bad not time to look into it, but 

 that he would do so, in order to. see whether it would 

 be necessary for him to answer it himself, or whether he 

 should leave the task to one of his pupils. 



With regard to the subject of Nitrogen, the views I 

 am disposed to entertain may be briefly summarized as 

 follows : — (I) That the soil and not the atmosphere is 

 the main source of the Nitrogen which we find iu our 

 crops. (2) That iu the apphcation of manures containing 

 Nitrogen, more or less loss of that substance is always 

 incurred ; and consequently, if the object is to obtain any 

 given amount of Nitrogen in the produce, the application 

 in the form of manure must be largely in excess of the 

 amount required. In everything relating to the competition 

 between Europe and the United States ; between the 

 vaste stores of untouched fertility of the one, and the 

 comparatively exhausted stock of the other, the question 

 of Nitrogen is one of paramoimt importance. I am not 

 aware myself of any writer, practical or scientific, who has 

 accepted as a fact, or even entertained the idea, thatiu 

 the application of Nitrogen in purchased manures a con- 

 siderable loss is incurred. This loss in a substance of so 

 costly a nature is a matter of great economic importance. 

 The view generaUy held, I believe, is that no loss takes 

 place, and further that by a small application of Nitrogen, 

 a farmer not only recovers in the crop all that he has 

 applied in the manure, but a good deal more. This, 

 according to M. Ville, is the economic function nf our 

 root crops, which, when well supplied with minerals, and 

 a small amount of Ammonia, get what more they require 

 of this element from the atmo.sphere. The following are 



the views of this writer with regard to a rotation ■' 

 " That some crops demand all the Nitrogen they require 

 to be supplied to them ; others require a small" amount, 

 which enables them to obtain a good deal in addition 

 from the atmosphere ; while others again can obtain the 

 whole of the Nitrogen they need from the atmosphere." 

 This explanation appears so simple and clear that it seems 

 quite .a pity to say anything that coulrt throw a doubt 

 upon its acciu"acy. I will now endeavour to show what 

 loss of the Nitrogen iu the manure has taken place in 

 our own experiments on the growth of potatoes at 

 Kotham.sted. In order to measure the effect of Nitrogen, 

 and also ascertain whelbir nny, and it so what amount 

 of loss has taken place, our plan has been to grow the 

 crop continuously with mineral manures alone. ^\'e con- 

 sider that by this means the crop avails itself of all the 

 sources of Nitrogen at its disposal, whether they be 

 derived from the soil or the atmosphere. AVhei'i, in 

 addition to the same minerals, Nitrogen in some soluble 

 form is applied to the potatoes in another experiment, 

 we consider that the increase in the crop over that grown 

 by minerals alone, is due to the Nitrogen of that manure ; 

 and, further, if we deduct the amount of Nitrogen in the 

 crop grown by minerals alone, from the amount con- 

 tained iu the crop grown by minerals and Nitrogen, the 

 residue, when compared with the amount of Nitrogen 

 applied in the manure, will give us the measure of the 

 loss. I must observe, however, that this experiment 

 requires to be continued for a good many years before 

 any safe conclusions can be drawn ; first, because of the 

 great influence of favorable or unfavorable seasons ; and 

 secondly, because it is only by the aid of time that we 

 can ascertain whether the Nitrogen applied, but not re- 

 covered iu one crop, is available for those which succeed. 

 The more favourable is the season for the growth of a 

 crop, the better will the crop be able to avail itself of 

 the stores of manure furnished by the soil and atmosphere. 

 At Itothamsted, the season just passed was very favorable 

 for the growth of potatoes, I therefore select this year's 

 crop, not as indicating what might be the average loss of 

 Nitrogen applied in manure, but to show how very serious 

 may be the loss, even under exceptionally favorable con- 

 ditions. The following table gives the number of bushels 

 of potatoes of 50 lb. each ; — 

 Table. 



Bushels per Acj^e. 



(1) Pota.sh, Soda, Magnesia, Superphosphate 2G5 



(2) The same as (1) with 4001b. Salts of Ammonia ... 484 

 Gain by addition of Ammonia 219 



It is quite evident that the mineral manm-es enabled 

 the potatoes to gather up a large amount of Nitrogen ; 

 and that further growth was only arrested for want 

 of more Nitrogen, is evident by the much larger 

 crop grown when a manure containing that substance 

 was used ; this fact is still further confirmed by the 

 analyses of the potatoes grown by mineral mauures alone, 

 which show a very low percentage of Nitrogen. Assum- 

 ing that the ordinary potatoes in a dry state contain one 

 per cent of Nitrogen, these potatoes contained one-sixth 

 less than that amount, and it is probable that under such 

 conditions no further growth was possible. 



"We now come to the loss of Nitrogen. The 400 lb. of 

 Sulphate and Muriate of Ammonia are estimated to furnish 

 about 85 lb. of Nitrogen ; taking the potatoes grown by 

 mineral manm-es alone at 26 lb., we find in those grown 

 by Ammonia and minerals GQ lb., or an increase of 40 lb.; 

 but as we supplied 85 lb. in the manure, we have recov- 

 ered son.-thing less than 50 per cent of the amount sup- 

 plied, and this, too, under the influence of an unusually 

 favorable season ! Taking an average of seasons, it would 

 be much nearer the truth to say that not more than one- 

 third of the Nitrogen supplied is recovered in the crop. 

 Potatoes contain 25 per cent of ilry matter in every 100 

 lb. ; if we take a bushel to weigh 50 lb., 8 bushels will 

 weigh 4('0 lb. : which amount is equivalent to 100 lb. of dry 

 matter, and will contain 1 lb. of Nitrogen. 



To obtain this 1 lb. of Nitrogen in the produce, we find 

 it necessary to apply 3 lb. in the manure, and as the Ni- 

 trogen costs about 25 cents per lb., this large difference 

 between the amount supplied and that recovered becomes 

 a very serious consideration. 



