1'.-. 



l>rrhaps that each of these sources had contributed 

 more or less to the result. 



Owing to the uneven character of the subsoils which 

 has been referred to, it is impossible to determine by 

 the direct or statistical method, whether, or to what 

 extent, the subsoil has lost nitrogen. It is, as has been 

 intimated, in regard to these Leguminous plant- plots, 

 and to the comparison of the condition of the nitrogen in 

 their subsoils with that in Gramineous crop subsoils, and 

 especially in the subsoils of the immediately adjoining 

 urimanured wheat-fallow plots, that the investigation, 

 and settlement, of an indirect method, as suggested at 

 pp. 14-16, would be of very great interest and importance. 

 The samples of subsoil already collected from the 

 Leguminous plant, and wheat-fallow plots, would, if any 

 such indirect method were established, probably yield 

 very fruitful results ; but, as time goes on, the character 

 of the subsoils in the two cases will, on the supposition 

 in question, become more and more distinct. 



It need only be added in regard to these Leguminous 

 plant experiments in Hoosfield, that so far as the sur- 

 face soils are concerned, the determinations of nitrogen 

 by soda lime, and so far as both the surface and the 

 subsoils are concerned, the determinations of nitrogen 

 as nitric acid, have already been published and discussed 

 in our paper in the " Philosophical Transactions," 

 numbered 77 in the list ; and later results are given in 

 No. 81. 



It is a question for consideration when, and from 

 which plots, samples of these leguminous plant soils 

 should be again taken and investigated. 



THE CONTINUOUS GKOWTH OF LEGUMINOUS CROPS. 

 2. In Gfeescruft Field. 



This field was devoted to the growth of the Legumin- 

 ous crop beans for a period of 32 years ; but owing 

 to frequent failures of the crop, wheat was once taken, 



