32 



THE ROTHAMSTED EXPERIMENTS. 



Produce 

 from dung 

 alone and 

 from dung 

 and other 

 manures. 



Table 9 ex- 

 plained. 



Artificial 

 manures. 



Produce 

 from min- 

 eral man- 

 ures alone 

 and with 

 addition of 

 nitrogenous 

 manures. 



in suitable soils and localities, will yield nearly, and some- 

 times quite, 20 per cent of sugar! 



For brevity, and as such heavy manuring is not adopted 

 for the growth of beet for the manufacture of sugar, the 

 results obtained with farmyard manure will not be given 

 in any detail. It may, however, be observed that over the 

 three years of the application, the average produce per acre 

 of roots of farmyard manure alone was about 16 tons, which 

 was raised to nearly 24 tons by the annual addition of 86 lb. 

 of nitrogen per acre as nitrate of soda ; to about 22 tons by 

 the same quantity of nitrogen as ammonium-salts ; to nearly 

 25 tons by 98 lb. of nitrogen as rape-cake ; and to more than 

 25 tons by 184 lb. as rape-cake and ammonium-salts together. 

 These facts are sufficient to show how powerful a feeder and 

 grower is the sugar-beet when liberally manured ; and that, 

 provided other supplies are not deficient, nitrogenous man- 

 ures very greatly increase the produce. 



The following Table (9, p. 33) shows the average produce 

 of sugar-beet ; in detail roots only, and in the summary roots 

 and leaves, over the three years, the two years, and the five 

 years, under three conditions of mineral manuring, each 

 alone, and each cross-dressed as indicated, by various nitro- 

 genous manures. 



The table shows that when superphosphate was used either 

 without nitrogenous manure or with nitrate of soda, the pro- 

 duce was as great as when potash was applied in addition ; 

 but when the nitrogen was applied as ammonium-salts, am- 

 monium-salts and rape-cake, or rape-cake, the addition of 

 potash to the superphosphate shows more effect. And it will 

 be seen further on, that in the case of the mangels in subse- 

 quent years, the effect of the potash was very much more 

 marked — that is, when under the continuous use of super- 

 phosphate without potash, the potash of the soil had doubt- 

 less become more and more exhausted. That the deficiency 

 of produce is much less marked where the superphosphate 

 is applied with nitrate of soda than where with ammonium- 

 salts or rape-cake, is probably due to the roots of the plant 

 penetrating more deeply under the influence of the more 

 soluble and more rapidly distributed nitrate with its more 

 readily available nitrogen — thus securing a better command 

 of the supplies of potash (and other constituents) in the lower 

 layers of the soil and subsoil. 



Turning to the summary at the foot of the table, which 

 gives the average results over the three years for plots 6 and 

 4 (with potash supply) both without and with nitrogenous 

 manures, it is seen that whilst the mineral manures alone 

 give an average of less than 6 tons of roots, the addition of 



