108 



THE ROTHAMSTED EXPERIMENTS. 



Yield of 

 carbon with 

 and with- 

 out nitro- 

 genous 

 manure. 



Yield of 

 carbohy- • 

 drates with 

 and with- 

 out nitro- 

 genous 

 manure. 



carbon per acre per annum, under the influence of a complex 

 mineral manure alone ; and that the amount was increased to 

 1590 lb. by the addition of 43 lb. of nitrogen as ammonium- 

 salts, to 2222 lb. by 86 lb. of nitrogen as ammonium-salts, and 

 to 2500 lb. by 86 lb. of nitrogen as sodium-nitrate. Accord- 

 ingly, as shown in the second column, the increased assimila- 

 tion of carbon was — by 43 lb. of nitrogen as ammonium-salts 

 602 lb., by 86 lb. as ammonium-salts 1234 lb., and by 86 lb. 

 as sodium-nitrate 1512 lb. 



Reckoned in the same way, the increased assimilation of 

 carbon in the barley was, for 43 lb. nitrogen as ammonium- 

 salts 950 lb. per acre — that is, one and a-half time as much 

 as by the same application in the case of wheat. 



In the sugar-beet, the roots only (the leaves being left on 

 the land), the increased assimilation of carbon was 1477 lb. 

 per acre by the application of 86 lb. nitrogen as ammonium- 

 salts, and 1908 lb. by 86 lb. nitrogen as sodium - nitrate. 

 There was, therefore, considerably more increased assimilation 

 of carbon, and accumulation of it in the roots of the sugar-beet, 

 than in the grain and straw of wheat, by the same applications 

 of nitrogenous manure. 



In mangel-wurzel roots (the leaves being returned to the 

 land), the increased assimilation of carbon was 1130 lb. by 

 86 lb. of nitrogen as ammonium-salts, and 1370 lb. by 86 lb. 

 as nitrate — that is, less than in the removed crops (grain and 

 straw) of wheat, and considerably less than in the removed 

 crops (the roots) of sugar-beet. 



In the potatoes, reckoned on the increased production of 

 tubers only (the tops being left on the land), the increased 

 yield of carbon by 86 lb. of nitrogen as ammonium-salts was 

 762 lb. per acre, and by 86 lb. as sodium-nitrate 731 lb. — 

 that is, there was considerably less increased production of 

 starch in potatoes than of sugar in either sugar-beet or mangel- 

 wurzel by the same applications of nitrogenous manure. 



Lastly, in the leguminous crop — beans, with its high yield 

 of nitrogen per acre, and the high percentage of nitrogen in its 

 dry substance — the increased assimilation of carbon under the 

 influence of nitrogenous manure was comparatively quite in- 

 significant. Thus there was, by the application of 86 lb. of 

 nitrogen as sodium-nitrate, an increased assimilation of carbon 

 of only 266 lb. per acre, or little more than one-sixth as much 

 as in wheat, and little more than one-eighth as much as in 

 sugar-beet, by the same application. 



Turning to the figures in the third column, it is seen that 

 there was a very greatly increased production of the non- 

 nitrogenous bodies, the carbohydrates, by the use of nitrogen- 

 ous manures. 



