AgriculhLval Chemistry — Turnips. 



507 



It may be objected that the average weiofht of bulbs as stated 

 above is in itself small, and that the differences exhibited are 

 too slight to be relied upon as showing a result. We would beg 

 to say, however, that the estimations were taken from the whole 

 of the bulbs that were weighed in each case, amounting to nearly 

 2000, and that we believe they may be depended upon for our 

 present purpose. 



It will be remembered that with mineral manures alone there 

 were, on an average, rather more than 19,000 plants per acre, 

 but a glance at the results just given will show how uniformly the 

 direct supply by the drill of " organic manures " tended to lessen 

 the number. Again, it has been seen that the highest average 

 weight of bulbs (indicating the degree of development) was, by 

 purely mineral manures, 1'47 lbs., by sulphate of ammonia I'OS, 

 and by rape-cake alone 1*08 lb. The fact that these conditions 

 of manuring, employed singly, fall far short of their effects when 

 combined, helps us to form some judgment as to the point at 

 which the one or another class of constituents seems to fail, 

 either in quantity or in adaptation to the wants of the plant. 



Taking the lots 8, 9, and 10, we find the largest number of 

 plants where the proportion of mineral supply to that of rape- 

 cake is the greatest, and the smallest number where the rape-cake 

 is relatively in excess. The weight of bulbs is least where the 

 mineral matters are most in defect, and greatest where neither 

 condition was to the other so prominent as in the other two cases. 



Again, taking Nos. 12, 13, 14, and 15, in which superphos- 

 phate of lime was united with both rape-cake and ammoniacal 

 salt, the largest weight of bulb in the entire series of the season 

 is found to be in that case where, with a fair supply of each, no 

 one of the several manures predominated so much as in either of 

 the three other instances just mentioned, 



Were we to place unconditional reliance upon mere supply of 

 constituents for actual conversion into the substance of the plant, we 

 should expect that the farm-yard dung would give, in every 

 respect, the best crop in the series ; but agency, as distinguished 

 from mere supply, seems to constitute a most important item, 

 affecting the development of those truly artificial conditions of 

 growth which the cultivation of the turnip, lor feeding and ma- 

 nuring purposes, so pre-eminently implies. In the farm-yard 

 dung we had undoubtedly the largest provision of nitrogenous, and 

 especially of carbonaceous matter, and it may be supposed that 

 it also brought to the soil such an abundance of all the mineral 

 substances as would be contained in a much larger crop than was 

 produced by it. 



The results arranged below will sufficiently prove that, how- 

 ever liberal the supply of all required constituents, the health 



