rEE^[EABILITY OF SOILS TO MANURES. 2-23 



effected by caiTyiiig on the Imsbandiy of an estate by 

 the system of farm-yard manming. It will hereafter be 

 shown that by the continuous and exclusive use of farm- 

 yard manure, the composition of the soil is found changed 

 after eacli rotation. 



The last point wliich claims our attention, in reference 

 to the Saxon experiments, is the difference in the per- 

 meabihty of the soil to tlie dung-constituents in the 

 different locahties. The depth to which the alkalies, the 

 ammonia, and the soluble phosphates penetrate, depends 

 of course upon the absorptive power of the soil ; now, 

 assuming, for the sake of illustration, the soil of a field to 

 be divided from the top downwards into distinct layers, 

 wliich are not of course sharply separated from one 

 another, we find that in some locahties the dung-con- 

 stituents stop in the upper layers, whilst in others they 

 penetrate to the deeper layers of the ground. Thus, 

 for instance, in the Cunnersdorf field the clover crop had 

 derived no benefit from the farm-yard manure, being about 

 only 4 per cent, larger than the produce given by the 

 unmanured plot; whereas at Mausegast the manuring 

 caused an increase of 30 per cent., and at Oberbobritzsch 

 of 200 per cent. This result shows that certain mineral 

 constituents, indispensable for clover, penetrated much 

 deeper into the ground at Mausegast and Oberbobritzsch 

 that at Cunnersdorf and Kotitz ; or, what comes to the 

 same, that, in the two latter places, they were, on their 

 way downwards, retained by the upper layer of the soil. 

 On comparing the crops given by the unmanured plot at 

 Cunnersdorf with those obtained from the unmanured 

 plots in tlie other locahties, we see that the Cunnersdorf 

 field contained nearly as large a store of straw constituents 

 as the fields at Kotitz and Oberbobritzsch, while it was 

 decidedly poorer in the principal grain constituents. 



