The Lois Weedon Plan of Growing fllieat. 607 



land field, with which the surface-soil is intermixed, both give a 

 higher percentage than either the Rothamsted or the Lois Weedon 

 beavy-land subsoil — that of the light-land subsoil being 0782, 

 and that of the marl 0*0905 per cent. Lastly on this point, 

 whilst the subsoil of the Lois Weedon heavy-land unmanured 

 wheat-plot gives 0*0652 per cent., the subsoil of the plot devoted 

 to rye-grass, with, liquid manure, in the same field, gives 0*0790 

 per cent. 



To resume — the comparison of the percentage of nitrogen in 

 the Lois Weedon and the Rothamsted soils submitted to Mr. 

 Smith's methods of growing wheat, the one with so much success, 

 and the other with such signal failure, shows that the former 

 contain a higher percentage of nitrogen than the latter. Thus, 

 whilst the mean percentage in the trenched plot at Rothamsted is 

 0*1417, that in the light land at Lois Weedon is 0*1550 per 

 cent., and in the heavy land at Lois Weedon (taking the mean of 

 the eight determinations on both stubble and fallow plots) is 

 0*1827. Independently, then, of mere physical condition of 

 soil, of mineral richness, or of other circumstances affecting the 

 relations of the plant to the soil, we have here an intelligible 

 chemical difference, perfectly consistent with what all other expe- 

 rience regarding the requirements for the vigorous growth of the 

 wheat-crop would lead us to anticipate. 



The f^uestions still remain, however, whether the Lois Weedon 

 soils, in all probability, h^ve a greater power to acquire nitroge- 

 nous plant-food from atmospheric sources, or are likely more 

 lightly to retain, or more easily to give up to the plant in an 

 assimilable form, their previously existing or newly-accumu- 

 lated stores of nitrogen ? 



With a view of getting such indications on these points as 

 limited time would permit, the following experiments were made. 

 Rather more than one thousand grains, in a finely-powdered state, 

 of each of the soils enumerated in the Table (V.) given below 

 (whose nitrogen had previously been determined), were put into 

 a water-bath for about six hours, in order to secure an equal 

 state of dryness. Exactly one thousand grains of each were then 

 weighed, and respectively placed in small but equal-sized basins. 

 Each of these was then rnounted upon a small porcelain pot an 

 inch and a half in height, and so placed in a large glass basin 

 containing water to the dej)th of about an inch. The large b;isin 

 was then covered with another sucli, and the whole left for three 

 <lays at a temperature of 100^ or more; by which from H to 

 nearly 4 per cent, only of water was absorbed by the different 

 soils. The water in the large basin was then replaced by pretty 

 strong ammonia-water; and the whole, covered as before, was 

 left for four days in a warm room, the temperature being main- 



2 s2 



