14 BARN FIELD 



The value of farmyard manure in growing mangolds 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 containing no organic matter, as seen in 1912; 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 VII. — Barn Field Mangolds. Average produce of Roots per acre 

 over .34 years (1876 to 1912).* 



1S85, 1901, and 1908 omitted. 



t 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 superi- 

 ority of nitrate of soda as a nitrogenous manure for mangolds is most 

 strikingly seen on Plots 5, where potash is omitted. 



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

 obtained 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 nitro- 

 genous 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 appear- 

 ance, are much curled and crinkled, and show an increased tendency to 

 variegation, the chlorophyll collecting into dark green or almost black 

 blotches on the lighter background of the leaf. The leaf-stalks are often 

 much more coloured, 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. 



