228 



THE KOTHAMSTED EXPERIMENTS. 



Effect of 

 the con- 

 sumption 

 of roots on 

 land. 



Nitrogen 

 in grain 

 and straw 

 of barley. 



Effects of 

 manures. 



Comparing the amounts of nitrogen taken up by the rota- 

 tion with those by the continuously grown barley, it is seen, 

 as might be expected under the conditions described, that 

 both without manure and with superphosphate, the rotation 

 barley took up much more than the continuously grown. 

 Where, however, nitrogenous manure had been applied for 

 the roots, and they had been removed, the succeeding barley 

 took up less nitrogen than the continuous crops which an- 

 nually received nitrogenous manure ; but where the roots 

 had not been removed from the land, the nitrogen was nearly 

 the same in the rotation as in the continuously grown barley 

 — about 47 lb. per acre per annum. 



The influence of the manuring, and of the amount and 

 treatment of the previous root-crop, on the available supply of 

 nitrogen within the soil for the succeeding barley is, therefore, 

 throughout clearly traceable. 



■ Lastly, in regard to the nitrogen statistics of the barley 

 crops, it is to be observed that, under whatever conditions of 

 manuring or other treatment, and whether grown in rotation 

 or continuously, there was generally three-fourths or more of 

 the total nitrogen of the crop accumulated in the grain, that 

 is, in the portion which is as a rule sold off the farm ; only 

 about one-fourth, therefore, remaining in the straw which is 

 supposed to be retained on the farm. 



The Nitrogen in the Leguminous Crops. — The third division 

 of the Table (61) gives the results relating to this point. 



Eeferring first to the amounts of nitrogen in the total bean 

 crops (corn and straw together), it is seen that, under each of 

 the three conditions as to manuring, there was from twice to 

 twice and a half as much in the rotation as in the continu- 

 ously grown beans. The details further show that the ad- 

 vantage was proportionally greater in the corn than in the 

 straw. 



It is next to be observed that the amounts of nitrogen 

 taken up by the rotation beans were — without manure about 

 36 lb. per acre per annum, and with superphosphate between 

 40 and 50 lb. ; whilst with the mixed manure, containing 

 nitrogen, there were in one case 63.6 lb., and in the other 70.2 

 lb. In fact, both without manure and with superphosphate, 

 the amounts taken up in the beans were much greater than 

 in either the preceding roots or the preceding barley. "With 

 the mixed manure supplying nitrogen, they were also much 

 more than in the preceding barley, but less than in the 

 root-crops, to which the mixed manure had been directly 

 applied. 



The point of greatest interest in the results is, however, 

 that under each condition as to manuring, the clover took up- 



