ROOT-CROPS. 45 



is, without nitrogenous supply, with the least luxuriance, and 

 the smallest and ripest roots, the mean for plots 6 and 4 

 amounting to 12.97 per cent. On the other hand, in Series 

 4, with the highest nitrogenous manure, the greatest luxuri- 

 ance, and the least maturity, the percentage is only 10.66. 

 Comparison of the percentages of dry matter and of sugar 

 show that the sugar constituted about or more than two- 

 thirds of the total dry or solid substance of the root. As 

 a rule, where nitrogenous manure was used there was a some- 

 what higher percentage of sugar with than without potash 

 supply. There was also generally a somewhat higher per- 

 centage over the three years of direct nitrogenous supply than 

 over the succeeding two years. 



Eeferring to the second division of the table, which shows Manuring 

 the amounts of sugar per acre under the different conditions ffi s ^f 

 as to manuring, it is seen that over the three years the mean 

 produce of plots 6 and 4 with potash was, without nitro- 

 genous manure 1704 lb. ; with nitrate in addition 4635 lb. ; 

 with ammonium-salts 4063 lb. ; with ammonium-salts and 

 rape-cake 5279 lb. ; and with rape-cake 4788 lb. In other 

 words, with little more than three-fourths of a ton of sugar 

 per acre with the mineral manure alone, there was, with 

 nitrogenous manure in addition — when as ammonium-salts 

 more than If ton, with nitrate more than 2 tons 1 cwt., with 

 rape-cake nearly 2 tons 3 cwt., and with rape-cake and am- 

 monium-salts more than 2 tons 7 cwt., of sugar produced per 

 acre. Over the subsequent two years, without further nitro- 

 genous supply, there was, however, generally about, or not 

 much more than, half as much sugar yielded. 



The third division of the table shows that with superphos- Superphos- 

 phate and potash as the mineral manure, there was over the ph ^^' nd 

 three years an average annual increase of sugar yielded, per 

 acre, due to the nitrogenous supply, of 2931 lb. by the 

 nitrate, of 2359 lb. by the ammonium-salts, of 3575 lb. by 

 the ammonium-salts and rape-cake, and of 3084 lb. by the 

 rape-cake. Over the succeeding two years, however, the in- 

 creased production of sugar, due to the nitrogenous residue, 

 was, with the nitrate less than one-fifth, with the ammonium- 

 salts rather more than one-fifth, with the ammonium-salts 

 and rape-cake more than one-third, and with the rape-cake 

 alone less than one-fourth, as much as over the three years 

 with the direct supply of nitrogen. 



Upon the whole, therefore, it is evident that even with a Depend- 

 full supply of mineral manure the produce of sugar was e J^J^ f 

 small, and that the increased production of that non-nitro- nitrogen. 

 genous substance was dependent on the available supply of 

 nitrogen within the soil. Examination of the table will 



