124 



ERRORS OF THE EXPERIMENTS, 



other pieces, eight bushels should be deducted from all the dif- 

 ferent applications, and the estimate will stand thus : 



Even the piece covered with both marl and stable manure (w t) 

 shows according to this estimate a diminished effect equal to 10 J 

 bushels ; which was owing to the marl not being able to combine 

 with, and fix, so great a quantity of manure, in addition to the 

 vegetable matter left by its natural growth of wood. The piece 

 w p, marled at 450 bushels alone, has shown a steady increase of 

 product at each return of tillage, and thereby has given evidence 

 of its being the only improvement made in such manner as both 

 judgment and economy would have directed. 



[After the crop and measurement of 1832, it was inferred that 

 the separate products of such small spaces could no longer be relied 

 on, owing to the mixture of the surfaces of adjacent parts, necessa- 

 rily caused by tillage. -Therefore the previously omitted parts were 

 marled before the next course of crops came round. 1842.] 



CHAPTER XII. 



EFFECTS OF CALCAREOUS MANURE ON ACID CLAY (OR STIFF) SOILS, 

 RECENTLY CLEARED. 



PROPOSITION 5 continued. 



THE two next experiments were made on another field of thirty 

 acres of very uniform quality, marled and cleared in 1826 and the 

 succeeding years. The soil is very stiff, close, and intractable un- 

 der cultivation seems to contain scarcely any sand but, in fact, 

 about one half of it is composed of silicious sand, which is so fine, 

 when separated, as to feel like the finest flour. Only a small pro- 

 portion of the sand is coarser than this state of impalpable powder. 

 Clayey earth of a dirty pale yellow colour forms nearly all of 

 its remaining ingredients. Before being cleared of the forest 

 growth, and ploughed; the soil is not an inch deep ; and all below, 



; 



