3i6 SYSTEMS OF MANURING CROPS [chap. 



only flourishes in an acid medium. Potash salts are 

 rarely used for the Swede crop, though, like other root- 

 crops storing up a good deal of carbohydrate, the Swede 

 will respond to liberal allowances of potash. On the 

 lighter soils, when farmyard manure is only scantily 

 used, it is undoubtedly wise to apply about 3 cwts. of 

 kainit while the land is being prepared for the seed- 

 bed. 



Of the other crops allied to Swedes, white turnips 

 require much the same treatment, except that the fish 

 guano may be omitted because they possess a shorter 

 period of growth, while the potash is more necessary. 

 Kohl rabi may have just the same treatment as Swedes, 

 as may thousand-headed kale and cabbage, with the 

 addition of more nitrogen. Cabbages in particular will 

 respond to enormous quantities of nitrogen ; in addition 

 to the farmyard manure or fish guano recommended 

 for the Swedes, up to 3 cwts. per acre of the mixture of 

 nitrate of soda and sulphate of ammonia may be used 

 in two or three top dressings. In market garden work 

 such active nitrogenous manure brings the cabbages 

 earlier to cutting and renders them tenderer, though 

 they are reputed in consequence not to travel so well to 

 distant markets. Stock feeders do not like cabbages or 

 any other root crop grown with an excessive amount of 

 nitrogen, especially of nitrate of soda ; the plant 

 material that has been forced in this fashion becomes 

 a poor or even a harmful food, but whether this is due 

 to the increased amount of nitrates in the plant or to 

 other compounds of nitrogen is as yet uncertain. 



Mangolds are often described as heavy feeders, by 

 which we may understand that the yield will go on 

 responding to very large additions of manure rather 

 than that the crop removes a specially large amount of 

 manurial constituents from the soil ; a fact which would 



