532 



Agricultural Chemistry — Turnips. 





Bulb per Acre, in 



Leaf per Acre, in 



Average 

 Weight of 

 Bulbs. 



Proportion 

 ■J Leaf to 

 1000 of 

 Bulb. 



12 tons farm-yard dung . 



12 tons farm-yard durig, j 

 and 3 cwt. sulpliate of/ 

 ammonia . . . .J 



\i' o' 3' g' 



11 IS 3 12 



Tons. cwts. cjrs IIds. 



7* 7" 3' 2' 



10 8 3 12 



1-61 

 1-45 



433 

 700 



was less, under the excessive supply of nitrogen ; the 4th, that 

 under the same circumstances the proportion of leaf to bulb was 

 increased by more than one-half. So far as supply of constituents 

 is concerned, we could select from the series of experiments 

 several instances where we may reasonably suppose that every 

 constituent, excepting carhon, existed more fully in quantity and 

 more favourably in combination than in the dung-, yet with its 

 larger carbonaceous supphj to the root we get the largest crop of 

 bulb in the series. The excess of nitrogenous manure, however, 

 is seen greatly to enhance the leaf-forming tendencies of the plant, 

 which it is true may probably aid carbonic acid accumulation 

 from the atmosphere, but at the same time gives a less profitable 

 appropriation of the resources within the soil ; and we shall after- 

 wards see it to be by no means clear that there is with a large 

 production of leaf a proportional gain of nitrogen from the atmos- 

 phere. 



-Admitting, then, that the organic manure required for the 

 growth of turnip hulhs should be carbonaceous rather than nitro- 

 genous, there is still evidence that, under the influence of a due 

 provision of nitrogen, the vitality or longevity of the plant is > 

 greatly increased ; and since the turnip crop is required to brave 

 the winter frost.s, an early and perfect ripening, such as would be 

 induced by a defect of nitrogen relatively to carbon, whilst it 

 might be coincident with a more rapnd bulb formation, would by 

 no means be a desideratum. We believe, however, that in the 

 ordinary course of farming, the special supply of nitrogen to the 

 turnip crop, by means of artificial manures, is seldom if ever ne- 

 cessary ; for there is no ample source of available carbon which 

 does not provide at the same time a considerable amount of 

 nitrogen. As therefore, in the case of wheat, we need not study 

 the supply of carbonaceous manures, so, in the case of turnips, it 

 comes to be unnecessary to devote special care to the provision of 

 nitrogen. In the one case the means adopted specially to secure 

 niti ogen to the soil, brings with it enough of carbon ; and in the 

 other the peculiarly carbonaceous manures are associated with 

 sufficient nitrogen. 



We have argued that for the growth of turnip-Z/«/^ a soil is 



