Burning Land for Manure. 



49 



on which the agency of heat will reduce the same to an active or 

 available form. At the head of these soils will be found stiff chu s 

 and maris ; next stiff loams, and loams throughout their great 

 variety of gravelly, sandy, &c., down to silicious or sandy soils, on 

 which burning is utterly ruinous, except as will be mentioned 

 hereafter. As a general rule, it may with safely be stated, that 

 in proportion to the stiffness of a soil will the benefit to be derived 

 from burning be found advantageous. As a theory this rule may 

 be safely relied upon ; there are, however, many circumstances 

 which act as drawbacks to its general application, arising from 

 the fact that soils variously situated may be found of equal 

 tenacity, but at the same time of exceedingly varied adaptation, 

 and requiring varied methods of burning in order to produce 

 beneficial results. The varied circumstances here alluded to 

 arise from the fact that soils taken from distant places may pre- 

 sent to outward appearance the same mechanical tenuitv, whilst 

 their mineral constituents maybe in a different state of mechanical 

 division, in varied proportions, or of a somewhat altered chemical 

 character ; so infinite are these varieties, that it would be impos- 

 sible, even if the limits of this paper would permit the same, to 

 describe all the qualities and the various modes to be followed 

 accordingly. 



Two o^reat difficulties attend the burnins; of stiff soils — the one 

 arisino^ from the heat ensfendered beina: so g-reat as to bake instead 

 of to disintegrate the materials composing them ; the other, that 

 the heat may not be raised sufficiently high to alter the inorganic 

 constituents of plants contained therein from a passive to an active 

 or available form. The first difficulty arises from permitting a 

 too great draught of air, and consequently causing a rapid and, 

 often through draughts, a partial but excessive combustion : the 

 second difficulty arises from either the heaps or kiln being made 

 up too closely or too open ; in the former case, the too free access 

 of air occasions the fires to burn languidly, and consequently de- 

 ficient heat through the absence of sufficient draught ; whilst, if 

 the clay or sod is packed too closely, the absence of air retards 

 combustion, and thus necessarily the amount of heat required for 

 the due perfection of the process, and combustion will not unfre- 

 quently be put a stop to altogether by the interstices becoming 

 filled with ashes, and by that means almost wholly excluding the 

 atmosphere. As soils vary so much with respect to their capacity 

 for burnino: for manure, it cannot be imao-ined that rules can here 

 be laid down for every case ; in fact, unless a farmer knows from 

 experience the proper formation of heaps for burning, adapted to 

 the soil of his farm, it will be much better for him to make a few 

 experiments on a small scale rather than depend upon any written 

 or oral description. If in the course of these experiments he can 



VOL. VIII. E 



