12 



BARN FIELD 



The value of farmyard manure in growing mangels is evident, especially 

 when they are grown continuously on the same land. In favourable 

 seasons it is possible to obtain good crops by the aid of manures contain- 

 ing no organic matter, as seen in 1905 ; but in ordinary years the bad 

 texture of the soil which results, and its tendency to lose water on account 

 of the lack of humus, affect both the germination of the seed and the 

 growth of the plant in its early stages. 



Table YII. — Barn Field Mangel Ww^zel. Average produce of Boots 2)er acre 

 over 27 years (1876 to 1902). 



The addition of Potash to Plot 2 only began in 1895. 



Effect of Nitrogen 



To ascertain the effects of nitrogen, it is best to examine Strip 4, which 

 receives a complete mineral manure with different compounds of nitrogen. 

 Series A, which receive ammonium-salts, should also be compared with 

 Series N, receiving nitrate of soda. The general superiority of nitrate 

 of soda as a nitrogenous manure for mangels is most strikingly seen on 

 Plots 5, where potash is omitted. 



The diagram, Fig. 3, shows on the left hand the average results ob- 

 tained with the varying amounts and compounds of nitrogen on the Plots 4 

 in question, where there is an abundant supply of mineral manure. The 

 right-hand half of the diagram shows the effect of the same nitrogenous 

 manures when used in conjunction with dung instead of complete 

 minerals. 



The injurious effects of the very large amounts of nitrogen added to 

 some of the plots is very manifest wherever there is more nitrogen than the 

 plant can properly deal with. The leaves have a dark green appearance, 

 are much curled and crinkled, and show an increased tendency to variega- 

 tion, the chlorophyll collecting into dark green or almost black blotches 

 on the lighter background of the leaf. The leaf stalks are often much 

 more coldured, and become a bright orange yellow. 



On these plots the leaves do not ripen off and obtain the general 

 yellow flaccid appearance presented on the more healthy plots when the 

 crop is ready to lift ; instead, the outer leaves begin to die and shrivel up 

 quite early in October ; in some places they show numbers of dead spots 

 and burnt-looking patches round the edges of the leaf. 



