102 



THE EOTHAMSTED EXPERIMENTS. 



nitrogenous manure, on soil very poor in available nitrogen, 

 so far as accumulations due to recent applications of nitro- 

 genous manure are concerned. 



TABLE 32. — Nitrogen per acre per annum, in various Crops 



GROWN AT EOTHAMSTED, WITH MINERAL BUT WITHOUT NITRO- 

 GENOUS Manure. 



* 13 years, 2 years failed. 



+ 9 years beans, 1 year wheat, 2 years fallow. 



J 6 years clover, 1 year wheat, 3 years barley, 12 years fallow. 



Yield of Turning now to the yield of nitrogen in the root-crops — 



rooUropT turnips, sugar-beet, and mangel-wurzel — it may be mentioned 

 that prior to the period referred to in the table, turnips had 

 been grown for a number of years, and had yielded 42 lb. of 

 nitrogen per acre per annum, due to the accumulations from 

 " comparatively recent nitrogenous manuring. But it is seen 

 that after these accumulations had been reduced, Swedish 

 turnips gave, over 15 years, an average of only 18.5 lb.; 

 sugar-beet over the next 5 years, an average of only 14.7 lb.; 

 and mangel-wurzel over the succeeding 10 years, an average 

 of only 14.0 lb. of nitrogen per acre per annum. Or, reckoned 



