I'llE FARMER'S MAGAZINE. 



375 



scarcely 19 bushels per acre per aunum of barley corn, 

 and little more than half a ton of straw — together, equal 

 to not a ton of dry substance of produce — will be ad- 

 mitted to be exceedingly small. The conclusion was, 

 that the condition of the land, after ten successive crops 

 of turnips had been removed, must have been, for barley 

 growth, at the lowest possible point. 



" That a liberal supply of mineral constituents distri- 

 buted through the soil cannot restore this exhausted 

 fertility is seen by the produce of barley after the 

 mineral-manured turnips. After ten years of turnips, 

 the last eight of which were grown by excessive supplies 

 of mineral manures, we have an annual average of Sllbs., 

 or 1 bushel of corn more, and 791bs. of straw less, 

 equal to 251bs. less total produce, than after the unma- 

 nured turnips." 



The question is then — " In what constituent, or con- 

 stituents, had these unraanured and mineral-manured 

 turnips exhausted the soil, in so far as the after produc- 

 tion of barley was concerned, to a point even far below 

 that arrived at in the other field by the previous growth 

 of one crop of wheat, one crop of barley with sulphate 

 of ammonia, and one crop unmanured — that is, three 

 white-straw crops in succession without mineral ma- 

 nure ?" 



A comparison of the produce of barley on the plots 

 where the turnips had been manured with nitrogenous as 

 well as mineral manures, with that where they had re- 

 ceived mineral manures alone, throws some light on this 

 point. Thus, where ammoniacal salts as well as mineral 

 manures had been supplied to the turnips, the succeed- 

 ing barley gave an average annual increase of about 2 

 bushels, or 102lbs., of corn, and 941bs. straw, over the 

 produce where the mineral manures alone had been ap- 

 plied. Where, in the rapecake, a larger amount of 

 nitrogen had been supplied to the turnips, there was an 

 average annual increase in the barley crop of 5t bushels 

 of dressed corn, or 3331bs. total corn, and 3811bs. of 

 straw. Lastly, where during six out of the ten years of 

 turnips their manure (in the form of both ammoniacal 

 salts and rapecake) supplied a still larger amount of 

 nitrogen, in addition to the mineral manures, the suc- 

 ceeding barley gave an average annual increase of nearly 

 5J bushels of dressed corn, or 315lbs. total corn, and 

 331Ib8. of straw, over the produce where there had been 

 mineral manures alone. 



" We had then, with a residue in the soil of merely 

 mineral manures, even a loss of produce of barley — due 

 to a greater growth, and consequent greater exhaustion 

 of other matters, by the turnip. We find, on the other 

 band, a perceptible gain in the barley wherever the 

 turnips had received either ammoniacal salts or rape- 

 cake as well as the mineral manures. Even here, how- 

 ever, the produce, with this nitrogenous and full mineral 

 residue in the soil, was not equal to the annual unma- 

 nured produce in the other field, where the barley was 

 growing continuously." 



" That the beneficial effect of the residue of the rape- 

 cake was not due to the mineral constituents it supplied, 

 may be judged by the fact, that the residue of the direct 

 mineral manures had not any such effect. It was un- 



doubtedly a residue of available nitrogen within the soil, 

 that gave the increase of produce of barley where the 

 ammoniacal salts or rape-cake had been employed for 

 the turnips. If this be admitted, we have in the facts 

 at once a beautiful illustration of the degree of reliance 

 upon nitrogen in the soil, of the turnip ciop, and of the 

 utter incapability of rich supplies of mineral constituents 

 in the soil, to be of any avail in yielding agricultural 

 quantities of barley, unless there be at the same time 

 within the soil a liberal amount of available nitrogen." 

 If further proof be wanted that the necessary mineral 

 constituents were in abundance, and available in this 

 turnip-exhausted soil for very full crops of barley, pro- 

 vided only available nitrogen were also within the reach 

 of the roots of the plants, it is to be found in the 

 results of experiments, in which, in one of the three 

 years of barley after turnips, one portion of the plot, 

 where the residue of the turnip mineral-manures alone 

 had been unavailing to increase the produce of barley, 

 now received about 82lbs. of nitrogen in the form of am- 

 moniacal salts, and another portion about the same 

 amount of nitrogen in nitrate of soda. They were as 

 follows : 



" In 1854, those portions of the mineral-manured 

 plots left without further manure gave 19i bushels. 

 But where now (in 1854), about 821bs. of nitrogen per 

 acre were added as ammoniacal salts,* we had, instead 

 of 195 bushels, ^2^- bushels of barley; and where the 

 same quantity of nitrogen was added as nitrate of soda,t 

 .'i4f bushels. The increase in the produce of straw was 

 in greater proportion still. By the addition of the am- 

 moniacal salts, the straw was raised from l,3971bs. per 

 acre to 4,3791bs. ; and by the nitrate of soda it was in- 

 creased to 4,7811bs. The total produce (corn and straw 

 together) , was thus from 3 to 3^ times as great by the simple 

 addition of ammoniacal salts or nitrate of soda." And 

 it may be observed, in passing, that here, as has been 

 noticed in other cases, the nitrate of soda was more 

 active than a quantity of ammoniacal salts containing an 

 assumed equal amount of nitrogen. 



" It is very remarkable too, that a'.thoujjh the pro- 

 duce after the mineral-manured turnips was little more 

 than half as much as the unmanured produce in the 

 field of continuous barley experiments, yet the addition 

 of a given amount of nitrogen gave very nearly iden- 

 tical results in both fields. Thus, after the mineral- 

 manured turnips, we had, with the ammonaical salts and 

 nitrate of soda respectively, 7,3771bs. and 8,0051bs. of 

 total produce (corn and straw together) ; and in the 

 field of continuous barley experiments we had, with the 

 same amount of nitrogen, given as ammoniacal salts 

 (without minerals), 7,5481bs., and as nitrate of soda 

 (second year without minerals), 7,4001bs. of total pro- 

 duce. Again, in the same field of continuous barley 

 experiments, the mean result of direct mineral manures 

 and ammoniacal salts together, was 8,3201bs. ; and that 

 of even more nitrogen given as rape- cake (itseU supply- 

 ing also mineral constituents, as well as carbonaceous 



* 2001b3. 9ulph»te aud 2001b8. muriate of ammonia of com* 

 mcrce. 

 t SSOlbs. commercial nitrate of soda. 



