224 THE SYSTEM OF FARM-YARD MANURING. 



namely in phosphoric acid and, perhaps, also in nitrogen. 

 Hence, with an equal supply of phosphates and ammonia 

 on the three fields, the topmost layer of the ground at 

 Cunnersdorf, being poorer in these constituents, would 

 retain a great deal more of them than that of the other 

 two fields. 



The increase in the potato crop and in the produce of 

 oat-grahi and straw, on the Cunnersdorf field, clearly 

 indicates that certain dung-constituents made their way 

 to that layer of the soil from which the roots of the oat 

 plant principally derive their food, which layer, being 

 richer in corn and straw constituents than the arable 

 surface soil, permitted a small proportion of nutritive 

 substances to pass through it and thus reach the clover. 



If we compare ^Yith. this the field at Kotitz, and look 

 at its extraordinarily scanty crop of oat-grain and straw, 

 we see at once that in the latter field the deeper layers of 

 the soil were much poorer in corn and straw constituents, 

 but that the topmost layer was much richer in corn 

 constituents than the land at Cunnersdorf. 



Although the Kotitz field received above 25 per cent, 

 more farm-yard manure than the CVmnersdorf field, yet 

 only a very insignificant portion of that manure found its 

 way down to the clover, as the layer above had retained 

 the substances nutritive to clover, and these had prin- 

 cipally served to benefit the oat-plant. The increase in 

 the produce of oat-grain at Kotitz was more than double 

 that obtained fi'om the Cunnersdorf field. At Mausegast 

 the relations were similar ; from the micommon abundance 

 of corn and straw constituents in the arable surface soil, 

 the absorptive or retentive power of the latter for the 

 dung-constituents in solution was comparatively less, 

 and a considerable proportion of these substances was 

 thus permitted to reach the deepest layers. The uniform 



