126 RESULTS WITH TURNIPS 



ration is much less. Ammonia salts, by themselves, do not 

 greatly increase the proportion of water, but when the quantity 

 of nitrogenous manure is doubled by the addition of rape cake 

 to the ammonia salts the effect becomes more marked. 



The proportion of ash tends to rise with ammoniacal 

 manuring, more so in the case of turnips than of swedes ; it 

 also rises where alkalies are applied. The application of 

 alkali salts at Rothamsted w T as a 'very liberal one. Any in- 

 crease of ash diminishes of course the proportion of organic 

 matter available as food. 



The nitrogenous manures considerably increase the pro- 

 portion of nitrogenous matter in the root, the alterations 

 produced are best seen in the results obtained in the case of 

 swedes. Here again the supply of potash tends to limit such 

 changes in composition by enabling the plant to produce a 

 larger quantity of organic matter. 



In the four-course rotation at Rothamsted the swedes 

 are grown, as we have already mentioned, on one plot with 

 superphosphate and alkalies alone, and on another plot with 

 the same manures plus a liberal dressing of ammonia salts and 

 rape cake. As the first named plot has received no nitrogenous 

 manure for a great many years the swedes are produced w r ith 

 a minimum supply of nitrogen ; the contrast in the composi- 

 tion of the roots grown on the two plots is thus very marked. 

 The average of nine crops shows 88*7 per cent, of water in the 

 superphosphate swedes, and 89*4 per cent in the highly 

 manured roots. The percentage of nitrogen in the dry matter 

 w r as i -89 in the superphosphate sw r edes, and 2-32 in those re- 

 ceiving ammonia salts and rape cake in addition. In a season 

 of great production the percentages of nitrogen in the roots 

 are much lower ; in 1880 the percentage of nitrogen in the dry 

 matter of the superphosphate swedes was 0-984, and in the 

 highly manured roots 1*539. 



The condition of the nitrogen in the roots is of great im- 

 portance in relation to their feeding value. The albuminoids 

 are the only nitrogenous bodies capable of forming flesh, the 

 amides are useful for little more than the production of heat 

 and muscular work. The superphosphate swedes grown at 



