408 



THE FARMER'S MAGAZINE. 



Fichtnf-r, .Mally, ani Holbleng, the frontiers have been opened 

 to the iinportAtioQ of giiauo, and nitrate of soda, and the pre- 

 paratiou of farm-yard manure has been subjected to great im- 

 provements. Drainage gains partisans. Societies are estab- 

 lished for the fatting of cattle ; the merinos shew symptoms of 

 occupying the fold at the expense of the common breeds, and 

 the porcine race is improved by well-judged crossings. For- 

 ester societies, and schools are established in almost all the 

 provinces of the monarchy, and itinerant foresters convey to 

 them instruction in the best methods. Lastly, engineers 

 skilful in the art of cultivating the meadows, travel through 

 the country, and lend their aid in the clearing of the lands and 

 in the drainage of the marshes. Id a word, the elevated rate 

 of agricultural produce, or at least, the remunerative price that 

 they obtain, offers a sufficient premium to the efforts of the 

 husbandman, to engage them to launch themselves without 

 hesitation in the course of progress. Eugene Marie. 



THE ANNUAL YIELD OF NITROGEN 

 PER ACRE IN DIFFERENT CROPS. 



By J. B. La WES, F.R.S., F.C.S., and J, H. Gilbert, 

 Ph.D., F.C.S. 



[Read at the British Association for the Advancement of 

 Science, Leeds. Section B., September 28th, 1858.] 



Abstract. 



In a paper given last year at the Dublin meeting, on the 

 question of the Assimilation of Free Nitrogen by Plants, and 

 some allied points, the authors had stated in general terras, 

 that the amount of nitrogen yielded per acre, per annum, in 

 different crops — even when unmanured — was considerably 

 beyond that annually coming down, in the forms of ammonia 

 and nitric acid, in the yet measured and analyzed aqueous 

 deposits from the atmosphere. The investigations then re- 

 ferred to were still in progress ; and a desirable introduction 

 to the record of the results would obviously be to illustrate 

 by reference to direct experiment that which had been before 

 only assumed regarding the yield of nitrogen in our different 

 crops. To this end, had been determined the annual produce 

 of nitrogen per acre, in the case of various crops, which were 

 respectively grown for many years consecutively on the same 

 laud, namely, wheat fourteen years, barley six years, meadow 

 hay three years, clover three years out of four, beans eleven 

 years, and turnips eight years. In the majority of the 

 instances referred to, the yield of nitrogen had been estimated, 

 both for the crop grown without manure of any kind, and for 

 thst with purely mineral manure — that is, excluding any arti- 

 ficial supply of nitrogen. It was the object of the present 

 communication to give a summary view of some of the facts 

 thus brought to light. 



Beans and clover were shown to yield several times as much 

 nitrogen per acre as wheat or barley. Yet the growth of the 

 leguminous ctops, carrying off so much nitrogen as they did, 

 was still one of the bett preparations for the growth of wheat ; 

 whilst fallow fan important effect of which was the accumu- 

 lation within the soil of the available nitrogen of two years 

 into one), and adding nilrorjenous manures, had, each, much 

 the same effect in increaeing the produce of the cereal crops. 



Other experimental results were adduced, which illustrated 

 the fact that four years of wheat, alternated with fallow, had 

 given as much nitrogen in the eight years as eight crops of 

 wheat grown consecutively. Again, four crops of wheat, 

 grown in alternation with heans, had given nearly the same 



amount of nitrogen per acre as the four crops grown in alter- 

 nation with fallow ; consequently, also much about the same 

 as the eight crops of wheat grown consecutively. In the case 

 of the alternation with beans therefore, the whole of the 

 nitrogen obtained in the beans themselves was over and above 

 that which was obtained during the same series of years in 

 wheat alone— whether it was grown consecutively or in alter- 

 nation with fallow. 



Interesting questions arose, therefore, as to the varying 

 sources, or powers of accumulation, of nitrogen in the case of 

 crops so characteristically differing from one another as those 

 above referred to. 



It had been found, that the leguminous crops which yielded 

 in their produce such a comparatively large amount of nitrogen, 

 over a given area of laud, were not specially benefited by the 

 direct application of the more purely nitrogenous manures. 

 The cereal crops, on the other hand, whose acreage yield of 

 nitrogen under equal circumstances was comparatively so small, 

 were very much increased by the use of direct nitrogenous 

 manures. But it was found that, over a series of years, 

 only about 4-lOtha. of the nitrogen annually supplied in ma" 

 nure for wheat or barley (in the form of ammonia-salt or ni- 

 trates) were recovered in the immediate increase of crop. Was 

 any considerable proportion of the unrecovered amount drained 

 away and lost ? Was the supplied nitrogenous compound 

 transformed in the soil, and nitrogen in some form evaporated* 

 Did a portion remain in some fixed and unavailable state of 

 combination in the sod ? Was ammonia, or free nitrogen, 

 given off during the growth of the plant ? Or, how far was 

 there an unfavourable distribution, and state of combination, 

 within the soil, of the nitrogenous m&tters applied directly for 

 the cereal crops — tho.>e, such as the leguminous crops, which 

 assimilated so much more, gathering with greater facility, and 

 from a different area of soil, and leaving a sufficient available 

 nitrogenous residue within the range of collection of a succeed- 

 ing cereal crop ? These questions, among others which their 

 solution more or leas involved, required further elucidation 

 before some of the most prominent of agricultural facta could 

 be satisfactorily explained. 



Comparing the amount of nitrogen yielded in the different 

 crops, when grown without nitrogenous manures as above re- 

 ferred to, with the amount falling in the measured aqueous 

 deposits, as ammonia and nitric-acid, it appeared, taking the 

 average result of the analysis of three years' rain, that all the 

 crops yielded considerably more, and some very much more, 

 than so came down to the soil. The same was the case when 

 several of the crops had been grown in an ordinary rotation 

 with one another, but without manure, through two or three 

 successive courses. Was this observed excess in the yield 

 over the yet measured source at all materially due merely 

 to exhaustion of previously accumulated nitrogenous com- 

 pounds within the soil ? Was it probably attributable chiefly 

 to the absorption of ammonia or nitric-acid from the air, by 

 the plant itself or by the soil ? Was there any notable/orma- 

 lion of ammonia or nitric acid, from the free nitrogen of the at- 

 mosphere? or, did plants generally, or some iu particular, assi- 

 milate this free nitrogen ? 



As already intimated, some of the points which had been 

 alluded to, were at the present time under investigation ; 

 the authors having, in this, the able assistance of Dr. Pugh. 

 Others, it might be hoped, would receive elucidation in the 

 course of time. There of course still remained the wider 

 question of the orginal source, and of the distribution and 

 circulation, of combined nitrogen, in the soil, in animal and 

 vegetable life on the earth's surface, and in the atmosphere 

 above it. 



