PRACTICAL INFERENCES. 127 



without manure to 8 tons with superphosphate, and 9 to 12 

 tons with superphosphate combined with nitrogenous 

 manure, such as. ammonia or rape cake. Sugar beet pro- 

 duced when unmanured, from 7 to 8 tons per acre in the 

 earlier to 5 tons in the later years, but 18 tons with farm- 

 yard manure; nitrogenous manures increased the yield 

 largely, but superphosphate was of no use to the beet and 

 mangel. With mangel, the produce on the unmanured plot 

 was from 1 to 6 tons per acre (average 4'6 tons), as com- 

 pared with 19 tons with farmyard manure (or on the average 

 14 tons). Potatoes varied from about half a ton on the 

 unmanured, or about 2 tons on the average, to 4 to 5 tons 

 with farmyard manure, and to 6 to 7 tons with mixed mineral 

 and ammonia. The tendency to disease, however, increases 

 with the higher manuring, in larger proportion than does 

 the produce. 



The data of science on the effect of manures must, how- 

 ever, only be taken as indications by the practical farmer, 

 who must be guided by financial considerations and local 

 conditions, in determining what it is best for him to do 

 under particular circumstances at any given time. 



An interesting circumstance may here be mentioned, 

 viz : that many of our cultivated plants, such as cabbages 

 and mangold wurzel, have sprung from wild plants growing 

 by the sea, and are hence especially benefited by the use of 

 salt as a manure. Onions, the growth of which is also 

 favoured by salt, probably originated from a wild stock 

 growing in salt desert regions. 



Fallow. The good effects of this may be judged from 

 the results of some Eothamsted experiments, in which 

 the produce of wheat is recorded, after bare fallow com- 



