THE I'ARMER'S MAGAZINE. 



377 



much more stiikingly. In boLli fields, indeed, the 

 amount of available nitrogen supplied to the soil ruled 

 the amount of produce very much more strikingly than 

 did the supply of the nece-sary mineral constituents of 

 the crop. In growing barley in rolatlon, on land pre- 

 viously brought to that comparative state of exhaustion, 

 in which, under ordinary cultivation with home manuring 

 and ordinary cropping, the conclusion of a course will 

 leave it, the unmanured produce of barley throughout 

 three subsequent courses of an entirely unmanured ro- 

 tation was considerably greater than that where barley 

 was grown year after year ; and it was still further in 

 excess of that obtained after a series of unmanured 

 turnip crops." 



" Here then is a striking effect upon the produce of 

 barley by growing it in a rotation — even unmanured — 

 of turnips, barley, clover, wheat. When the turnips in 

 such a rotation were grown by superphosphate of lime, 

 and by it larger crops of the roots removed than with- 

 out manure, the produce of barley was less than after 

 the unmanured turnips. Here too, then, the produce of 

 barley is diminished after unusual exhaustion by turnip- 

 cropping. But either the consumption of the super- 

 phosphatcd turnips on the land, the residue of a mixed 

 mineral and nitrogenous manure after turnips grown by 

 it liad been carted off, or the consumption of these 

 turnips on the land, greatly increased the subsequent 

 produce of barley above that of the turnip-exhausted 

 rotation land. It could certainly not be the restoration 

 of mineral matters, to which, in these cases the increased 

 produce of barley was mainly due ; for the increase was 

 greater by the consumption on the land of the merely 

 superphosphated turnips, than by the residue of far 

 richer mineral (and organic) manure where the turnips 

 grown by it had been removed, taking away but a small 

 proportion of the supplied minerals ; and it was greater 

 still where these highly-manured turnips were fed on 

 the land, and returned to it a considerable amount of 

 nitrogen, in addition to the already relative excessive 

 amount of minerals. It was seen too, in the other 

 fields, that mineral manures were quite unavailing to 

 give even moderate crops of barley, unless there were 

 available nitrogen within the soil," 



" It may be fairly concluded that a characteristic 

 effect of alternating the other crops with the barley, has 

 been to leave more available nitrogen from some source, 

 within the reach of the roots of the latter, than when 

 either this same crop was grown continuously in succes- 

 sion, or when a number of successive turnip-crops were 

 previously removed from the land. Barley then, like 

 wheat, requires characteristically wliat may be termed a 

 nitrogenous condition of soil. It cannot, however, 

 under ordinary circumstances, bear such large amounts 

 of nitrogen supplied as wheat ; though what it does re- 

 quire, from the habit of the plant, and its usual limited 

 period of growth, should be more confined to the upper 

 layers of soil. For these reasons, barley may often be 

 taken with advantage after a previous white crop, by a 

 spring dressing merely, of chiefly nitrogenous manure. 

 In auoh cases the direct addition of mineral manures, 

 especially those containing phosphates, will have a more 



striking effect than upon the winter-sown wheat. The 

 effect of such mineral manures is not only to increase 

 the general growth, but to bring the crop more rapidly 

 to maturity. The more frequent alternative is, that 

 barley ia taken after a root-crop, in part or entirely fed 

 on the land. The appropriateness of this course for 

 barley rather than for wheat, besides the advantage 

 arising from the season of the yearat which the land is 

 generally clear for the corn, rests mainly on the fact, 

 that the manure by folding, with the subsequent light 

 working of the land, is more confined to the superficial 

 layers of soil, in which, comparatively, the roots of the 

 barley play more freely. 



"A disadvantage of growing barley after the folding 

 of sheep on turnips is, that with high farming the land 

 is apt to be thus left in too high a condition for the crop 

 to succeed well in the average of seasons; whilst, on the 

 heavier lands, there is frequently much injury done to 

 the texture, rendering it difficult to get the fine tilth so 

 essential to the favourable growth of barley. 



" Of direct portable manures for barley, Peruvian 

 guano, or salts of ammonia, or nitrate of soda — either of 

 them with a small quantity of superphosphate of liuie— 

 are the best. Rape- cake is also a good manure for bar- 

 ley, but it is generally too high in relative price. These 

 manures, as well as purely mineral manures, are most 

 advantageously applied before, or at the time of sowing, 

 so as to be somewhat distributed through the surface 

 soil by the mechanical operations. As a mere top-dress- 

 ing nitrate of soda is the best. Of the more exclusively 

 nitrogenous manures — salts of ammonia and nitrate of 

 soda — the nitrate acts somewhat more rapidly for a given 

 amountof nitrogen supplied. The action of the purely 

 nitrogenous manures is economised by admixture with a 

 small quantity of superphosphate of lime, or other 

 appropriate mineral manure. Other thmgs being equal, 

 the later the barley is sown, the less should be the pro- 

 portion of nitrogen in the manure, and the greater that 

 of mineral constituents; otherwise the crop is liable to 

 be too luxuriant; and with a limited range of root in 

 the soil, it will probably not find mineral constituents 

 rapidly enough in the later stages of growth, for a favour- 

 able development and maturini; of the seed." 



Some additional remarks are here appropriate, on the 

 observed more marked effects of direct mineral manures 

 on the barley than on the jt»Aea< crop. A consideration 

 of the distinctive habits and usual circumstances of 

 growth in our rotations, of these two nevertheless much 

 allied crops will be found to throw some light on the 

 point alluded to. 



The necessity of considering the various habits and 

 conformation of the different crops of our rotations in 

 relation to their resources of growth was prominently 

 insisted upon in previous papers, in the Journal of the 

 Royal Agricultural Society, more than ten years ago. 

 Such considerations, the bearings of which are among 

 the first lessons taught by the progress of field experi- 

 ments, tend materially to modify the conclusions to 

 which a more purely chemical view of the offices and 

 province of the various constituents in a system of 



