168 LETTER-FILES OF S. W. JOHNSON 



societies, and of the Rothamsted Laboratory, which 

 was then the private philanthropy of Mr. (afterward 

 Sir) John Bennett Lawes, the earliest English manu- 

 facturer of artificial fertilizers, senior member of 

 the celebrated scientific partnership of "Lawes and 

 Gilbert." 



Mr. Lawes at an early age instituted on his Rotham- 

 sted estate a series of field experiments upon soil 

 exhaustion and rotation in crops. In the following 

 letter, after commenting upon the points which particu- 

 larly interested him in Professor Johnson's lectures 

 upon the same subjects before the Board of Agricul- 

 ture in 1872, he expresses his recently proclaimed 

 intention to provide for the permanent maintenance of 

 his Rothamsted institution. 



(J. B. L. TO S. W. J.) 



Rothamsted, St. Albans, Nov. 7, '72. 



Dear Sir, — I have read with much interest and pleasure 

 your paper on soil exhaustion and rotation of crops, and I 

 beg your acceptance of a summary of our clover experiments, 

 by which you will see that we have altogether failed to grow 

 clover by means of manures placed at different depths through 

 the soil. I think we have almost exhausted all ordinary 

 modes of field experiments, and I am disposed to think that 

 the solution of this problem will not be effected until more 

 refined investigations are commenced. We are obtaining 

 some very interesting results on a piece of permanent pasture, 

 which at the commencement of the experiments consisted of 

 a fair proportion of graminaceous and leguminous herbage. 

 For 16 years a portion has been manured with mineral manure 

 alone without organic or nitrogenous substances. Another 

 portion has the same minerals with 100 lb. pr. acre of nitrogen 

 either as nitrate of soda or salts of ammonia. Where the 



