190 



THE FARMER'S MAGAZINE. 



Now, the best interpretation whicli can be given of 

 this somewhat vague conclusion (and which no doubt 

 applies to the nitrogenous contra-distinguished from the 

 mineral manures) will be to place the effects of the two 

 sets in juxtaposition — 



Table V. Produce 

 per acre, 

 b. p. 

 Ex. 8. — Produce of lOOlbs. each sulphate and mu- 

 riate of ammonia, mean of second period 36 



Ex. 5, 4, 6. — Average produce of the three ex- 

 periments forming the mineral series 29 3 



Superiority of the nitrogenous manure No. 8 over 



the mineral series 6 1 



Ex. 13. — Produce of 2001bs. each sulphate aud 

 muriate of ammonia, mean of second period. ... 44 



Ex. 5, 4. 6.~Average produce of the three expe- 

 riraeuts forming the mineral series 29 



Superiority of the nitrogenous manure No. 13 

 over the mineral series. .. . 15 



But although these ammoniacal manures, Nos. 8 and 

 13, compared with the mineral series, evince a marked 

 superiority, yet, when contrasted with the true gauge 

 (No. 17), No. 8 shows a deficiency of 14 b., and No. 13 



of 3 b. If p.; and still more important is it to remark 

 that both belong to the secularly decreasing instances ; 

 thus— 



Table VI. 



Ex. 8. Ex. 13. 



b. p. b. p. 

 Produce of the two experiments severally 



in the first period of three years .... 41 47 1 

 Produce of the two experiments severally 



in the second period of three years , . 36 44 3 



Secular decrease per acre per annum. ... 50 22 



Here, indeed, is exhibited a very "striking effect;" 

 but it is the effect of ultimate exhaustion, induced by 

 the use of a species of manure all but entirely destitute 

 of any mineral element of plant nutrition, and seem- 

 ingly acting only as an unnatural and eventually de- 

 pressive stimulant. 



Again, it is asserted by the experimenters — 

 " That by the annual supply of nitrogenous manures 

 alone (nitrate of soda or ammoniacal salts), larger suc- 

 cessive crops both of corn and straw wefc obtained than 

 by the annual use ot 14 tons of farmyard manure with 

 all its minerals, and certainly more nitrogen than either 

 the nitrate or ammoniacal salts employed by its side," 

 This is most erroneous, as is shown below— 



Here, then, it is shown that were the average of six 

 years to be a proper criterion, the difference either way 

 is too immaterial to be regarded. On the other hand, 

 tested by the more appropriate mean furnished by the 

 second moiety of that period, the superiority is unequi- 

 vocally in favour of the farmyard manure, amounting, as 

 it does, to all but 21b. per acre per annum of greater 

 yield. 



But what at once demonstrates that any fair compa- 

 rison of these four nitrogenous manures with farmyard 

 manure is impossible, is this — that, excepting the ano- 

 malous instance No. 12, they all belong in very striking 

 degrees to the decreasing class of the experiments, the 

 trial with farmyard manure belonging, on the other 

 hand, to the increasing list. On referring to Table V. 

 of the former paper, it will be seen that in No. 13 the 

 secular annual decrease per acre is 2 bush. 2 pecks ; in 

 No. 7, 3 bush. ; and in No. 8, it is no less than 5 bush. 

 Per contra to Wns, thtre is a secular increase ejected 

 by the farmyard manure of all but 2 bush, per acre per 

 annum. 



Again, reverting to the summary of conclusions pre- 

 sented by the experimentalists themselves, we find this 

 other proposition : 



" That, within certain limits, even on this compara- 

 tively exhausted soil (and it would probably be more 



nearly so on soils in ordinary condition for the crop), 

 nitrate of soda, ammoniacal salts, and rapecake all in- 

 crease the produce of barley, approximately, in propor- 

 tion to the amounts of nitrogfu they respectively 

 supplied. Their comparative effects will, however, 

 vary somewhat according to season, the nitrate being 

 generally more rapid in its action." 



And again it is said : 



" That the effect of a given amount of nitrogen, if not 

 excessive, will be considerably increased by the addition of 

 certain mineral manures, especially those containing 

 phosphates. The action of the mineral manures is very 

 much increased under such circumstances — that is, their 

 application gives very much more increase when there 

 is present a liberal supply of available nitrogen within 

 the soil, than when there is not." 



It is impossible to assent to these propositions; and, 

 indeed, the reverse of them is true, as shall be proved 

 by means of the following tabulation : 



Table VIII., showing — Ist.Thatasecular decrease of produce 

 prevailed amougst the instances of manuring in which ni- 

 trogenous salts were used ; 2ndly, Thst this decrease was 

 greatest where the proportion of nitroj^eQ m-.s largest; and 

 3rdly, That the annual acreable produce was most where 

 the nitrogen was proportionally least, 



