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THE FARMER'S MAGAZINE. 



manuring would lead. In order to verify and define the 

 more obvious conclusions of superficial observation on 

 some of the points here in question, the summer of 1846 

 was mainly devoted to the examination of the compara- 

 tive underground ranges of the various crops of our rota- 

 tions. In reference to the results of the experiments 

 then made, it may be mentioned, that the relatively great 

 depth and extent to which several of the leguminous 

 crops, and also wheat and oats, penetrated, were very 

 remarkable. In defect of drawings of the specimens 

 then traced out, rough sketches taken in the case of 

 some recent experiments, in which, with another object 

 in view, wheat and barley had been grown side by side, 

 under somewhat artificial conditions, in pots, illustrated 

 the strikingly different distribution of the roots of these 

 two plants. The barley threw only a single fibrile to 

 the bottom of the pot. The wheat, on the other liand, 

 sent out such a mass of ramifications, that the whole of 

 the surface of the dish in which its pot rested was covered 

 with a thick net-work of roots ; as also was the bottom, 

 and, to a great extent, the sides of the inside of the pot 

 itself. The contrast here manifested is, indeed, pretty 

 characteristic of the two plants as grown in our fields. 



Further on this point: — "When considering the 

 results of field experiments on wheat, we have directed 

 attention to the fact, that the success of the autumn-sown 

 crop was greatly dependent upon the progress of the 

 under-ground development during the early months of 

 growth. It was held that this was very much favoured, 

 other things being equal, by a liberalsupply of available 

 nitrogen within the soil, and that thus, the range of col- 

 leclion of the fibrous feeders of the plant was so extended 

 as to render available, when needed in the after-stages 

 of growth of the plant, the mineral constituents of a 

 much larger area of the soil than otherwise would be the 

 case. Very different are the usual conditions of the 

 growth of barley. Instead of winter-growth, and a com- 

 pressed soil, tending to increased depth and area of root- 

 distribution, we sow our barley in the spring, work the 

 staple shallow, and keep it as light and open as possible. 

 Under these circumstances of short time, rapid growth, 

 and comparatively limited depth and area of root- 

 development, we find the direct supply of some of the 

 rarer, but essential mineral constituents of our soils, 

 much more efficient with the barley crop than with 

 wheat. 



" The mechanical conditions of soil, and the season of 

 growth of the barley crop, are in many respects more 

 like those required by the turnip ; and they are calcu- 

 lated to favour the distribution of a large amount of 

 fibrous root near the surface, rather than any consider- 

 able development in the lower layers. In our paper on 

 ' Turnip Culture,'* it was shown how much this distri- 

 bution of surface root-fibres was increased by the use of 

 superphosphate of lime. The same is the case with bar- 

 ley. It is obvious, that with this multiplication and 

 more thickly-distributed net-work of root-fibres, the 

 greater must be the resources of the plant within its 

 comparatively limited period and area of growth. Thus 

 it is, that the increased supply of certain important con- 



* Journal of the Royal Agricultural Society', Vj!. viii., 1817. 



slituents within a limited area, enables the plant to 

 provide itself more freely and rapidly with others it may 

 require." Again — 



" Still referring to the action and province of mineral 

 manures applied to our crops grown on cultivated land, 

 it has been shown on former occasions that, in a soil 

 brought to what may be termed a condition of agricul- 

 tural exhaustion— that is, at the end of a rotation, 

 when in the ordinary course of things it would receive 

 manure of some kind — the autumn-sown wheat was not 

 increased in produce by the direct application of mineral 

 manures, until so many crops had been taken from the 

 land as to exhaust it of mineral constituents more than 

 would happen under nearly a century of ordinary rota- 

 tion and home-manuring. It has now been shown, that 

 a very similar soil, certainly not more exhausted in an 

 agricultural sense, gave an increase in the produce of 

 barley, even on the first year's application of mineral 

 manures. Collateral experiments in the same field, as 

 well as those in other fields of very different, yet to a 

 certain extent known history of relative exhaustion or 

 fertility, showed, however, that mineral manures were 

 competent to yield, under these conditions of agri- 

 cultural exhaustion, but a small amount of increase 

 when compared with that obtained by nitrogenous 

 manures. The evidence has also led to the conclusion, 

 that the mineral manures, if at all, yielded increase in 

 an extremely limited degree, unless there were available 

 nitrogen accumulated by some means within the soil ; 

 in fact, that the increase of produce, other things being 

 equal, was more in proportion to such available nitrogen 

 within the soil, than to any other supplied condition. 

 It has, however, recently been maintained in the Journal 

 of the Royal Agricultural Society, that our cha- 

 racteristic nitrogenous manures cannot De said to be 

 active in proportion to the nitrogen they contain." 



In the paper referred to,* Baron Liebig states, that 

 ammonia alone, or nitric acid alone, has never been 

 used in agricultural experiments. His conclusion is , 

 that the acids in combination with ammonia in ammo- 

 niacal salts, and the bases in combination with nitric 

 acid in the nitrates, have had their share in the resulls 

 obtained by the use of these salts. He also further 

 quotes experimental evidence to show, that the value of 

 manures cannot depend upon the amount of their 

 nitrogen, but must depend upon the substances com- 

 bined with the nitrogen. 



In regard to the first mentioned statement, which was 

 one of fact, it might be observed, that the results of 

 experiments made at Rothamsted had been published, 

 in which ammonia in combination with only carbonic 

 acid had been employed. Mr. Pjiscy had also given the 

 results of trials, in which nitric acid, soda, and potash, 

 were each separately applied to grass. Of these results 

 Mr. Pusey said : "In both trials the nitric acid acted 

 decidedly. The alkalies, neither of them produced 

 even a trace of eJect on the colour or on the growth of 

 the grass." And again, "The question being whether 

 in saltpetre the alkalies or the acid contain the active 

 principle, we have found upon a given soil the alkalies 



* Ibid, vol. xvii., part I. 



