Book II. CULTURE OF THE SOIL AMONG TREES. 647 



is also sufficiently known to all who have attended to the physiology of vegetables, and 

 is o-reatly confirmed by some experiments laid before the Royal Society {Pkil. Trans. 

 1803, 1804), that the solid texture of the wood greatly depends upon the quantity of sap 

 which must necessarily descend, and also on the slowness of its descent. Now, both 

 these requisites are materially increased by side branches, which retain a large quantity 

 of sap, and by their junction with the stem occasion a contraction, and twisted direction 

 of the vessels," which obstructs the progress of the (proper) juice. That this is true, in 

 fact, is well known to those accustomed to make wine from maple and birch trees ; for 

 in this business it is found, that those trees which have fewest side branches bleed more 

 freely than the others, but during a much shorter space of time. These lunts, therefore, 

 afford additional evidence against pruning, and particularly against pruning fir-trees ; 

 which, as Mr. Knight justly observes, have larger vessels than the others, and, therefore, 

 when in an improved soil and climate, side branches, for the purposes above mentioned, 

 are essentially necessary to them, if solid, resinous, and durable timber be the object in 

 view. (Sir Henri/ Steuart's Planters Guide, p. 444.) 



3973. Sir Henri/ Steuart, concurring in these facts and observations, deduces the fol- 

 low ing practical conclusions respecting the influence of culture : — 



397+ First ■ that all timber trees thrive best, and produce wood of the best quality, when growing in 

 soils and climates most natural to the species. It should, therefore, be the anxious study ot the planter, 

 to ascertain and become well acquainted with these, and to raise trees, as much as possible, in such soils 

 and climates. , , - . . 



3975. Secondly ; that trees mav be said to be in their natural state, when they have sprung up fortui- 

 tously, and propagated themselves without aid from man, whether it be in aboriginal forests, ancient 

 woodlands, commons, or the like. '1 hat in such trees, whatever tends to increase the wood, in a greater 

 degree than accords with the species when in its natural state, must injure the quality ot the timber. 



3976. Thirdly; that whatever tends to increase the growth of trees, tends to expand their vegetable 

 fibre. That when that takes place, or when the annual circles of the wood are soft, and longer than the 

 general annual increase of the tree should warrant, then the timber must be less hard and dense, and 

 more liable to suffer from the action of the elements. 



3977. Fourthly; that a certain slowness of growth is essentially necessary to the closeness of texture 

 and durability of all timber, but especially of the oak ; and that, whenever the growth of that wood is 

 unduly accelerated bv culture of the soil (such as by trenching and manuring , or by undue superiority 

 of climate, it will be injured in quality in the precise ratio in which those agents have been employed 



3978 Fifthly ■ that, as it is extremely important for the success of trees, to possess a certain degree of 

 vigour in the outset, or to be what is technically called, " well set off," the aid of culture is not in every 

 case to be precluded, by a consideration of the general rule. That if trees be in a soil and climate worse 

 than those that are natural to them, then culture will be of some advantage ; as the extra increase of 

 wood will be of a quality not inferior to what, in its natural state, it would obtain ; or, in other words^, it 

 will correspond with that degree of quality and quantity of timber, which the nature of the species admits 

 of being obtained : but culture in this case must be applied with cautious discrimination, and a sound 

 judgment. That, on the other hand, if trees be in a better soil and climate than are natural to them, 

 and, at the same time, that the annual increase of wood be promoted by culture as already said), it will 

 be a decided disadvantage, and deteriorate the wood, in the same way, if trees be in their natural state, 

 the annual increase of timber, obtained by culture, will injure its quality, in a degree corresponding with 

 the increased quantity. 



3979. Sixthly; that such appears to be a correct, though a condensed view of the operation of those 

 general laws respecting growth, which govern the whole vegetable kingdom, and especially of their 

 effects on woodv plants, and of the salutary restraints, which science dictates to be laid on artificial 

 culture, of which pruning, as well as manuring, forms a constituent part, as has been explained above, 

 at so much length. That it is bv a diligent study of the peculiar habits of trees, and the characters of 

 soils, illustrated and regulated by facts drawn from general experience, that rash or ignorant systems of 

 arboriculture are to be best corrected, and science brought most beneficially to bear on general practice." 

 (Planter's Guide, i'd edit. p. 478.) 



Subsect. 2. Culture of the Soil among Trees. 



3980. With respect to the culture of the soil, it is evident, that young plantations should 

 be kept clear of such weeds as have a tendency to smother the plants ; and though this 

 is not likely to take place on heaths and barren sites, yet even these should be looked 

 over once or twice during summer, and at least those weeds removed which are con- 

 spicuously injurious. In grounds which have been prepared previously to planting, 

 weeding, hoeing by hand or by the horse hoe, and digging or ploughing (the two latter 

 rarely)," become necessary according to circumstances. The hoeings are performed in 

 summer to destroy weeds, and render the soil pervious to the weather; the ploughing 

 and diggings in winter are for the same purpose, and sometimes to prepare the soil for 

 spring crops. These, both Pontey and Sang allow, may be occasionally introduced 

 among newly planted trees; though it must not be forgotten that, relatively to the trees, 

 the plants composing such crops are weeds, and some of them, as the potato, weeds of 

 the most exhausting kind. Sang uses a hoe of larger size than usual. (Jig. 590. d.) In 

 preparing lands for sowing woods, Sang ploughs in manure, sows in rows six feet apart, 

 by which lie is enabled to crop the ground" between with low-grow ing early potatoes, 

 turnips, and lettuce ; but not with young trees as a sort of nursery, as they prove more 

 scourging crops than esculent vegetables ; nor with grain, as not admitting of culture, 

 and being too exhausting for the soil. Marshal, and some other authors, however, 

 approve of sowing the tree seeds with a crop of grain, and hoeing up the stubble am! 

 weeds when the crop is removed. 



3981. Ponlei/ observes, " that wherever preparing ihe soil for planting is though 

 necessary, that' of cultivating it for some years afterwards will generally be thought the 



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