ROOT-CROPS. 59 



It will be of interest, therefore, to consider, as in the case of 

 the sugar-beet, both the percentage and the amounts of sugar 

 produced per acre in the mangel under the different condi- 

 tions of manuring. Table 18 (p. 60) gives particulars on 

 these points. Average results for four years are given, and 

 in each case for five selected plots, with different conditions 

 of mineral and nitrogenous supply. 



It is seen that the percentage of sugar is higher in the roots Sugar in 

 grown by farmyard manure alone than in those with nitro- ™%dnitro. 

 genous manures in addition. It is higher still when mineral genous 

 manures are used alone, but here, again, it is reduced by the manures ' 

 addition of nitrogenous manures. The fact is that the lower 

 the nitrogenous manuring the riper is the crop, and with this 

 there is the higher percentage of sugar ; and conversely, the 

 higher the nitrogenous manuring the more luxuriant the 

 growth, the less ripe the crop, and the lower the percentage 

 of sugar. 



Turning to the middle division of the table, it will be seen 

 that notwithstanding the lower percentage of sugar with 

 high nitrogenous supply, the quantity of sugar produced per 

 acre is greatly increased by such supply. Thus, referring to 

 the results with farmyard manure, which is used so largely 

 for the growth of the feeding-beet or mangel, it is seen that, 

 taking the average of four years, the annual produce of sugar 

 was — with the farmyard manure alone 2358 lb., with the 

 addition of nitrate of soda 2916 lb.,. of ammonium-salts 3409 

 lb., of rape-cake 3218 lb., and of ammonium-salts and rape- 

 cake 3445 lb. That is to say, the produce by farmyard 

 manure alone was rather more than 1 ton of sugar per acre, 

 which was raised in 2 out of the 4 series by about half a ton 

 by the addition of nitrogenous manure. 



Eeferring now to the effects of mineral manure without Sugar and 

 •and with nitrogenous supply, and taking the average of the ^f™e. 

 two plots 6 and 4, with full potash supply as well as super- 

 phosphate, it is seen that the mineral manure alone gives 

 957 lb., or less than half a ton of sugar per acre ; and that 

 with nitrogenous manures in addition the quantity is raised 

 to 2740 lb. by the nitrate, to 2487 lb. by the ammonium- 

 salts, to 2873 lb. by the rape-cake, and to 3312 lb. by the 

 ammonium-salts and the rape-cake together — that is, the 

 produce of sugar was raised to 2| and even to 3| times as 

 much by the addition of nitrogenous manure. In other 

 words, as shown in the third division of the table, the 

 increased produce of sugar by nitrogenous manure was 1783 

 lb. by the nitrate, 1530 lb. by the ammonium-salts, 1916 lb. 

 by the rape-cake, and 2355 lb., or more than a ton, by the 

 ammonium-salts and rape-cake together. Comparing these 



