610 The Lois JVeedon Plan of Groiciiig Wheat. 



that the Lois Weedon heavy land, which has yielded Mr. Smitb 

 his best resvilts, both contained more nitrogen in its original 

 State, and absorbed and retained, under equal circumstances, both 

 more water and more ammonia than the Kothamsted soil. Th& 

 Lois Weedon light land, however, although containing slightly 

 more nitrogen in its natural state than the soil at Kothamsted, 

 absorbed and retained, in the experiment above described, rather 

 less both of water and of ammonia than the Rothamsted soil. 

 In drawing any conclusion from the results of an experiment of 

 this kind, in regard to the probable comparative qualities of the 

 soils in their natural state and position, we must first carefully 

 consider what are the circumstances, in a necessarily artificial 

 experiment, which might vitiate a strict comparison of the 

 figures. It is to be borne in mind then, that the soils, when sub- 

 mitted to the absorption experiments, were in an equally finely 

 divided state, and they would, therefore, expose nearly equal 

 surfaces to the watery and ammoniacal vapours. Tlie results 

 should, therefore, show the comparative absorptive powers of 

 equal surfaces of the respective soils. And this being so, of the 

 three surface soils the Lois Weedon heavy land has the highest, 

 the Rothamsted soil the next, and the Lois Weedon light land 

 the least absorbent power in relation to a given surface exposed. 

 But in its natural state and position the Lois Weedon light land 

 would undoubtedly expose a much greater surface of atmos- 

 pheric influences than the Rothamsted soil. Hence probably 

 the reason that the Lois Weedon light land, though it did not 

 absorb more ammonia in the experiment cited, yet in its natural 

 state contained a higher percentage of nitrogen than the Rot- 

 hamsted soil. Hence probably also, this Lois Weedon light land 

 •would both absorb or otherwise accumulate more nitrogen in an 

 available form, under equal climatic circumstances, and yield it 

 tip more readily to the plant, than the soil at Rothamsted. 



Since the above was in type, the additional experiments referred 

 to have been concluded, and we give here a short statement of the 

 results. In this second series of absorption experiments, the object 

 ■was to include the surface and subsoil of the land devoted to the 

 Lois Weedon experiments at Rothamsted ; and also to submit the 

 soils in a rather moister state to the ammoniacal vapours. 800 

 grains, in an equal state of dryness, of each of the soils enu- 

 merated in the Table below, had 25 septems, or about 23 per- 

 cent., of water added to them. In this state they were submitted, 

 in the same manner as in the previous experiment, to moist am- 

 moniacal vapours at a temperature of about 70° ; though in this 

 case for only 3 dajs instead of 12 as formerly. At the con- 

 clusion of the absorption period each little basin of soil was. 



