Agricultural Chemistry — Turnips. 



563 



is an admirable manure for the turnip as a substitute for farm- 

 yard dung^ ; it may be employed in conjunction with superphos- 

 phate of lime —the former being sown broadcast, and the latter 

 drilled with the seed. Peruvian guano, which contains a large 

 quantity of ammonia as well as phosphates, is found to be a much 

 more certain manure for turnips in Scotland, where the fall of 

 rain is large, than in those parts of England where it is much 

 less. Indeed the natural agencies of season are much more 

 favourable to the growth of turnips in Scotland and the north 

 and west of England than in the eastern counties, where the ap- 

 plication of skill and capital, upon a soil well suited to the plant, 

 has gained for them a high reputation. In the south of England, 

 and wherever the comparatively small amount of rain that falls 

 renders the production of the turnip-crop uncertain, the cultiva- 

 tion of the man^old-wurzel mi2:ht be extended with considerable 

 advantage : it can be sown sufficiently early in the spring to enable 

 it to extend its roots deep in the soil before the dry weather sets 

 in, it is not liable to injury from insects, and it is capable of pro- 

 ducing a larger amount of solid food than any other crop in a 

 rotation. The objection raised against it as an exhausting crop 

 arises partly from the small amount of produce which it yields 

 from a given weight of manure compared with turnips ; but as 

 the percentage of dry matter is greater, the objection may not be 

 valid. The following Table shows the amount of dry matter 

 contained in various root- crops grown this season upon Rotham- 

 sted Farm under ordinary cultivation: — 



Percentage of dry matter in Long Red Mangold-wurzel . 12-7 



ditto, ditto, Yellow Globe ditto . . 11'34 



ditto, ditto, Common Swede (name unknown). 12*2 



ditto, ditto, Skirving's Swede, purple top . 9*4 



ditto, ditto, ditto, ditto, green top . 9*4 



ditto, ditto, Green common Turnip . , 7*9 



ditto, ditto, Norfolk White . . . . 7-83 



We see by this table that 10 tons of mangold-wurzel contain as 

 much dry matter as 15 tons of white turnips, and that the differ- 

 ence in bulk between a crop of Skirving's, compared with one of 

 the older sorts of swedes, is due to the difference in the pro- 

 portion of the water. That the soil on this farm, although not a 

 turnip soil, is capable of producing good root-crops, W7z<fe?' a proper 

 supply of manure, may be inferred from the fact that this year, 

 which is anything but a good turnip season, an acre of swedes 

 was weighed, the bulbs of which gave 20 tons 10 cwt. Number 

 of plants per acre, 20,120; average weight, 2 lbs. 3 oz. Ten of 

 the largest were found to weigh 112 lbs. 



We found in our experiments that the usual percentage of 

 nitrogen could be nearly doubled by the use of ammoniacal 

 manures ; but we do not recommend the general direct use of 



