SUGAR IN MANGOLDS 117 



or with rape cake as the source of nitrogen are less watery 

 than those grown with nitrate of soda, rape cake producing 

 the richest roots for their size. As regards its effect both on 

 the magnitude and composition of the crop, 200 Ib. of nitrogen 

 in dung are less effective than 86 Ib. in nitrate of soda or 98 Ib. 

 in rape cake, and have about the same value as 86 Ib. of nitrogen 

 in ammonium-salts. 



It has already been noticed that the use of ammonium- 

 salts promotes an earlier maturity than does nitrate of soda ; 

 this is seen in the generally higher " quotient of purity " of the 

 " A " as compared with the " N " series. The glucose co- 

 efficient is correspondingly lower in the " A " series. Excess 

 of nitrogen has the same effect as the substitution of nitrate of 

 soda in lowering the quotient of purity and raising the glucose 

 coefficient. For instance, Plot 2 N gives a quotient of purity 

 of 55*5 as compared with 64'9 and 62'2 on Plots 4 N and 6 N, 

 which receive the same mineral manures but not the extra 

 nitrogen of the dung on Plot 2 N ; similarly, the glucose co- 

 efficient is 6 '5 on Plot 2 N and only 3'0 and 3 '4 on 4 N and 

 6 N. Again, all the plots on the AC series, receiving both 

 rape cake and ammonium-salts, show worse results as regards 

 purity than the corresponding plots on either the A or the C 

 series, which receive only one portion of the nitrogenous 

 manure on series AC. 



The dependence of sugar-formation upon potash is well 

 seen by comparing the weights of sugar per acre produced on 

 Plots 4 or 6, receiving potash, with the corresponding weights 

 from Plot 5, without potash ; or by comparing Plots 2, where 

 dung, nitrogenous manures, phosphates, and potash are applied, 

 with Plots 1, which receive dung and nitrogenous manures only. 

 To this latter statement the nitrate Plots 1 and 2 afford an 

 exception. As a rule, however, the percentage of sugar in the 

 root is little if at all increased by the use of potash ; the effect 

 comes from the increased crop, and is apparent in the amount 

 of sugar grown per acre. The quotient of purity is, however, 

 better on Plots 4 and 6, with potash, than on Plots 5, without 



