174 THE ROTHAMSTED EXPERIMENTS. 



and nitrogenous manure in addition. It also shows — the gain 

 of carbon, that is the increased amount of it assimilated per 

 acre, and the gain of carbohydrates, that is the increased 

 production of them per acre, under the influence of the 

 nitrogenous manures ; and lastly, the estimated gain of 

 carbohydrates for 1 of nitrogen supplied in manure. The 

 figures show that, independently of the underground growth, 

 there was an increased assimilation of carbon per acre in 

 wheat — of 602 lb. by the application of 43 lb. nitrogen as 

 ammonium-salts ; of 1234 lb. by 86 lb. applied as ammonium- 

 salts ; and of 1512 lb. by 86 lb. applied as sodium-nitrate. 

 Or, reckoning the increased production of the non-nitrogenous 

 bodies — the carbohydrates, by the use of nitrogenous manures, 

 it was estimated that there was an increase of 1240 lb. of 

 carbohydrates per acre by the application of 43 lb. nitrogen 

 as ammonium-salts, of 2550 lb. by 86 lb. applied as ammonium- 

 salts, and of 3140 lb. by 86 lb. as sodium-nitrate. To put it 

 in another way — for 1 lb. of nitrogen applied as manure, there 

 was an increased production of carbohydrates in the grain 

 and straw of wheat — of 28.8 lb. when 43 lb. of nitrogen were 

 applied as ammonium-salts, of 29.7 lb. when 86 lb. were 

 applied as ammonium-salts, and of 36.5 lb. when 86 lb. were 

 applied as sodium-nitrate. 

 Nitrogen It is seen that in the case of the wheat, there was much 

 applied m more effect from a given amount of nitrogen supplied as 

 autumn, nitrate, which was always applied in the spring, than from 

 an equal quantity as ammonium-salts, which were applied in 

 the autumn, when the nitrogen would be subject to winter 

 drainage. Eeference to the table will also show that there 

 was more effect from a given amount of ammonium-salts 

 applied to barley than to wheat ; the application having been 

 made for the barley in the spring, and for the wheat in the 

 autumn. 

 Depend- It should be observed that there was such greatly increased 



enceon assimilation of carbon in the wheat and in the barley as the 



available n . . ... , » _,. . 



nitrogen, figures show, tor more than twenty years, without the addition 

 of any carbon to the soil. It is indeed certain that, in the 

 existing condition of our old arable soils, the increased growth 

 of our staple starch-yielding grains is greatly dependent on 

 an available supply of nitrogen within the soil. It is equally 

 certain that the increased production of sugar in the gram- 

 ineous sugar-cane in the tropics, is likewise greatly depen- 

 dent on the supply of nitrogen within the soil. 



In connection with the results showing the increased 

 assimilation of carbon, and increased production of carbo- 

 hydrates, under the influence of nitrogenous manures, it will 

 further be of interest to call attention to the connection 



