TEEE CULTUEE IN SOUTH AUSTRALIA. 5 



of trees on the groiind whicli they occupy, must enrich it to a very con- 

 siderable extent. This vegetable matter becomes decomposed and 

 amalgamated with the soil, and thus the surface soil becoming of a 

 porous and absorbent nature, the rain is retained and stored up for the 

 use in dry weather of the plants growing upon it. Moreover, on soils 

 of a stiEE and clayey character, the roots of trees planted upon them 

 would penetrate and ramify in all directions through them, and thus not 

 only act as a subsoUer in breaking up the hard pan below for the easier 

 entrance of the small fibrous roots of cereals and other agricultural crops, 

 but at the same time would open up a way for the percolation and 

 retention of the water which would otherwise flow along the surface and 

 find its level elsewhere, without being retained for the after and gradual 

 use of the plants growing upon them. 



Less Evaporation would take place.— ~lt is, perhaps, almost superfluous 

 to remark, that very great evaporation takes place all over the colony at 

 all seasons of the year, from the thoroughly exposed character of the 

 country generally to the full power of the sun's rays. In consequence 

 of this, what rain falls upon the ground is, almost as soon as it reaches 

 the ground, again taken up into the air by evaporation, without being 

 retained in the soil for the use of the crops growing upon it. Even on 

 those parts of the country which are under indigenous forests, from the 

 scattered and generally sparse crop of trees constituting these, together 

 with the peculiarly characteristic feature of the Australian trees, affording 

 but little shade to the ground — owing to upright habit of the foliage — 

 evaporation goes on in a very rapid manner. It is chiefly to these causes 

 alone that I attribute the fact of there being so few never-failing creeks 

 and rivers in this colony. Now, were there judiciously laid-out planta- 

 tions all over the country, and the trees constituting them being at such 

 distances apart and of such kinds as would effectuaEy shade the ground 

 from the sun, and prevent evaporation to a large extent from these parts — 

 or at least in a much slower manner than is done at present— the rain 

 would have time and opportunity to be absorbed into the ground, and by 

 percolating to considerable depths, come out again at a lower level, and 

 thus cause streams of water where none exist at present, and so on from 

 place to place, keeping up a general degree of humidity to refresh and 

 encourage the growth of vegetation. 



On the other hand where forests have been felled, and the surface left 

 exposed, great evaporation takes place ; and the rainfall which formerly 

 went to feed streams has been carried away, and these h ive in conse- 

 quence dried up. 



Destructive Floods would be avoided. — Sudden, and therefore damag- 

 ing, floods, are characteristic features of the climate of this colony. 

 This is to be expected, and can be easily accounted for. The surface of 

 the country being very much exposed to the sun's rays, becomes baked 

 and parched : and, in consequence, when heavy rains come on, the soil 

 not being open and porous, these flow along the surface of the ground 

 and accumulating in the hollows, rush downwards, causing inundation 

 and ruin in their course. 



