66 



THE ROTH.piSTED EXPERIMENTS. 



Different 

 forms of 

 nitrogen in 

 mangels 

 and tur- 



Upon the whole, so far as the evidence at command 

 enables us to judge, there is in mangels — with their more 

 extended root-range, greater power of accumulation, more 

 luxuriant growth, and frequent greater immaturity when 

 taken up — a somewhat less proportion of the total nitrogen in 

 the albuminoid condition than in either common turnips or 

 swedes. There is also probably in mangels a less propor- 

 tion of amide nitrogen, and pretty certainly a larger propor- 

 tion of nitrogen as nitric acid, and in other forms. 



Approximate average percentage of Dry Matter and of 

 Sugar in various Boots. 



It has been stated that roo t-crops, as grown for stock-food, 

 are essentially sugar crops. 



Not only, however, do the various descriptions of roots 

 differ much in composition one from another, but the compo- 

 sition of one and the same description will vary very greatly 

 under different conditions of growth and of maturity of the 

 roots accordingly. It will, nevertheless, be useful to give 

 such an estimate as the evidence at command permits of the 

 approximate average percentages of dry matter, and of sugar, 

 in different descriptions of feeding roots. 



TABLE 20. — Estimates of the Approximate Average Percen- 

 tages of Dry Matter and of Sugar in different descrip- 

 tions of Roots. 



Sugar in Thus, then, even in common turnips, one-half or more of 



root-crops. ^ ^ Q ^ go j^ ma ^ er f fa e roo £ s ma y \y e SU g ar . Of the 



total dry matter of Swedish turnips a larger proportion, and 



of that of mangels a larger proportion still, will be sugar ; 



indeed in well -matured mangels about two -thirds of the 



total solid matter may be sugar. 

 Albumin- It may be assumed that in the cereal grains the proportion 

 oid-ratioin f albuminoid matter to the non-nitrogenous food material 

 roots. (starch, &c.) averages about as 1 to 6 (more or less) ; and 



that this is a proportion which is, as a rule, fairly favourable 



