49 

 TABLE XXVI. 



The addition of the nitrogenous manures to the others 

 reduced the percentage of sugar in the roots, especially in 

 the case of nitrate of soda ; but the increase in the weight 

 of the crop more than counterbalanced this, so that the 

 weight of sugar per acre is increased. The largest quantity 

 of sugar per acre is produced by farmyard manure and 

 ammonia salts ; being 340 Ibs. greater than the highest 

 produce of sugar obtained with nitrate of soda viz., that 

 from nitrate, farmyard manure, and superphosphate. Even 

 the smaller quantity of sugar produced by ammonia salts, 

 farmyard manure, and superphosphate, was still no Ibs. 

 per acre higher than the best yield from nitrate of soda. 



We may conclude, therefore, from this that with farm- 

 yard manure ammonia salts produce more feeding mate- 

 rial per acre than nitrate of soda, though the weight of the 

 crop may be less. 



Without farmyard manure, the opposite is the case ; 

 nitrate giving the largest amount of food per acre. The 

 following table shows the percentage and quantity per acre 

 of sugar, on the average of the plots at Rothamsted dressed 

 with superphosphate and sulphate of potash, and with a 

 complete mineral manuring, the minerals alone, and with 

 nitrogenous manures in addition : 



TABLE XXVII. 



MANURES. 



St'GAK. 



Per Cent. Per Acre. 



The figures given are the averages of four years 1877-80. 

 This shows clearly the superiority of nitrate of soda for 

 mangels where no farmyard manure is used ; for the pro- 

 duce of sugar per acre is 253 Ibs. greater than from ammonia 



