ON MANURES. 187 



CHAPTER XVII. 



MISCELLANEOUS MANURES CONTINUED. CLAY SAND — POND, 



RIVER, AND SEA MUD. 



Clay. — Such frequent allusion has been already made to 

 the expediency of mixing together diflerent soils of a marked 

 character, as a means of ameliorating their distinct qualities, 

 that it is unnecessary to repeat that recommendation, when- 

 ever it can be carried into eliect with moderate expense. 

 This advantage is in no case more fully evinced than by lay- 

 ing clay upon sand lands, whether they be of the red, rich, or 

 more valuable descriptions, or those of an inferior quality 

 which usually contain a portion of moor and white sand. On 

 the former, about 50 tons per acre will effect a vast improve- 

 ment ; but the latter are seldom brought into a fertile state 

 with less than treble that quantity. The most eligible period 

 to apply it is in the autumn or early part of the winter, when 

 the land is in grass, and intended to be broken up for a crop 

 of corn; or otherwise at the same period when intended for 

 fallow. The frost, rain, and drying winds will then cause the 

 lumps of clay, however large, to open, and by repeated slight 

 harrowing, to divide and intimately cover the surface before 

 the land is ploughed, — a circumstance of little trouble if 

 attended to at the proper season, though, if not so reduced 

 before the land is ploughed, large pieces of clay will be 

 found to have been preserved from the atmospheric influence, 

 and consequently unbroken and unprofitable many years after- 

 wards. It is more profitable to repeat the operation afler aa 

 interval of a few years, rather than to lay on an immense 

 quantity at once, as by this means the clay gets more tho- 

 roughly incorporated with the sand; and it will be obvious 

 that the first ploughing ought not to be to the full deptb, lest 

 the clay be lost. It is, however, scarcely practicable to lay 

 clay, in its natural state, upon sand, both because of the 

 great labour of digging, and afterwards preparing it with the 

 requisite degree of care for mixture. If not rendered so fine 

 as to be perfectly incorporated with the sand, its tendency to 

 sink through light land gradually brings it to the bottom, and 

 renders it afterwards useless, if not injurious, by forming a 

 retentive subsoil. 



Sand is, however, not exposed to the same objections, for 



