Results of Similar Experiments compared. Ill 



nitrate of soda; but so far as could be judged from direct 

 experiments on the point, it would appear to be, at the 

 same time, less subject to loss by drainage. Certain impor- 

 tant mineral or ash constituents of manures potash and 

 phosphoric acid, for example are, at any rate, in the case 

 of the heavier soils, almost wholly retained by them within 

 the range of the roots ; and they are found to be very 

 lasting in their effects upon succeeding crops, provided 

 there be a sufficient available supply of nitrogen within the 

 soil. 



THE EXPEEIMENTS ON THE CONTINUOUS 

 GROWTH OF BAELEY COMPAEED WITH OTHEE 

 SIMILAE EXPEEIMENTS. 



As in the case of the wheat experiments, so with those on 

 barley, it may reasonably be objected that results obtained 

 on one field alone are scarcely susceptible of general applica- 

 tion until they have received some degree of confirmation 

 based on similar experiments on other land. The investi- 

 gators have provided against this objection by means of two 

 sets of experiments, in one of which barley was grown for 

 three years in succession on a series of plots which had pre- 

 viously been differently manured, and had grown ten crops 

 of turnips in succession ; whilst, in the other, barley has been 

 grown in four-course rotation, without manure, and with 

 different descriptions of manure. 



In the Barn Field, barley was grown for three years, after 

 ten years (1843-52) of turnips. The average produce of 

 turnips over the last eight years (1845-52) was : 



