221 



be favourable, many of tlie plants are lost during the winter ; should circumstances prove other- 

 ^yise, the autumn sowing will he found the most advantageous, as it afFords nearly a full crop in 



,)je ensumg season* 



It was before observed, that dry thin sandy pastures are the least capable of improvement, 

 from the defect in ihe constitution of the .-soil, which arises from the want of clay and marl. 

 The process of paring and burning, which is so efficacious in converting bogs and rouoli tena- 

 cious clays, is found to injure thin sands; yet, without this process of burning the surface, the 

 crops that follow the ordinary mode of breaking up such soils by the plough only, arc devoured 

 by insects at the roots, and seldom i^epay the expence of labour. 



The comparative disadvantages which attend the ordinary mode of converting thin sandy 

 pastures into tillage by ploughing only, are found by experience, to he far greater than those 

 ■\vliicli result to the soil by the process of burning. Sir Humphry Davy says, that " the process 

 of burning renders the soil less compact, less tenacious, and retentive of moisture ;" burning, 

 therefore, increases the natural defects of sandy soils, and lessens the quantity of soluble vege- 

 table matter they contain. It seems probable, however, that the process of burning may be con- 

 ducted in such a manner as to prevent any diminution of the original quantity of soluble vege- 

 table matters contained in the soil. For when the parings or turfs are submitted to the fire, 

 tliey should only be burnt till the ashes are black, and will then contain carbonaceous matter, 

 which will be found to aflFord more soluble vegetable matter than the soil originally contained. 

 But when the parings are burnt till the ashes are red or white, the carbonaceous matter is de- 

 stroyed, and the ashes that remain will be found to consist of oxides, and saline matters of little 



\ 



With 



cannot he too much burnt, by the ordinary process of burning, as the object here is not so much 

 to destroy insects and the seeds of noxious plants, as to correct the texture of the soil, by render- 



r 



ing it more friable, and less tenacious or retentive of moisture. 



It is evident that the application of clay or marl, and vegetable manure, even in small quan- 

 tilies, will compensate the soil for the greater division of its parts and loss of decomposmg ve- 

 getable matter, let the process of burning be conducted in what manner it may; but there 

 are no remedies at present known, for the prevention or even palliation of the ravages ol the 

 wire-worm, grubs, and other voracious insects with which these soils generally abound, except 

 tliat of burning, which, when properly effected, experience has proved to be effectual to thcu' 



destruction. 



In Scotland and in England I have witnessed the practice of converting rough pastures, con- 



come 



on its natural soil ; till by good management, under tillage begun with paring and burning the surface, and by adding clay 



" marl, a permanent change is effected in the nature of the soil. 



20. Polygonum aviculare. E. Bot. 1252. Knot-grass, Snake-weed, Red-weed. ?-This is a biennial plant, flo^vcring^f^om 



April to October. It is one of the most noxious weeds that infest dry sandy soils, and even on rich soils, under ju .cious crop 



1 1- u J ;„ y^.A^i <in\U The seeds appear to 

 ^'% it is often met with ; so difficuU it is to destroy it, when once the roots get established in light soi . ^^^^^^^ ^^^^^^i^ ^^ ^^^^ 



^•^ as grateful to birds as those of buck-wheat. (Polygonum fa go vyr urn). There appears to ^"^ """^^'J^J^'^^^^^^^^^^ 

 S^o^vlh and propagation of this weed, so much as severe cropping with successive white grain crops, an & 



^'^'ill mode of cultivation. 



" The knot-grass fetters there the bands. 

 That once could have burst iron bant^s." Scott, 



* Young's Annals, viii. p. 73 ; ii. p. 360. 



3 I- 



