It is wrong to imagine, however, that the establishment of such leguminous cover-plants obviates weeding. So far is this from being the case, that in practice it is found that the weeding “rounds” must be conducted at first with the same regularity as in ordinary working, but that naturally there is much less work to be done.
As the plants develop, they can be pruned or dug into the soil, as the case may be. The addition of the green material to the soil, either by digging or by burying in open trenches, is calculated to cause improvement in the condition of the soil. There may thus be a close connection between weeding, soil conservation, and soil improvement.
CHAPTER III
THINNING OF AREAS
On this subject there is unanimity regarding the necessity for the operation. Divergence of opinion exists only as to a matter of degree.
On the one hand there is the school of planters who would advocate the advisability of planting up to, say, 200 trees per acre, with subsequent thinning out by selection. At the other extreme there is the opinion that we should plant only a few more trees per acre than it is intended eventually to maintain, the argument being that by this method the growth and development of individual trees will be so much greater than in close planting that the necessity for drastic thinning out will not arise.
Unfortunately for the latter school, a very important point is overlooked—viz., that size and general development are not criteria of yielding capacity. It might thus follow that a stand of ninety well-grown trees per acre might give very disappointing yields per acre. In a few instances this has been noted with 30 by 30 feet planting, but it is doubtful whether the factor influencing such results has been appreciated.
The apostles of close-planting have this in their favour: that if the trees to be removed are selected on proper lines, it is possible to have all remaining trees of comparatively high-yielding strain. This is a very sound argument, but its practicability is limited very largely by the question of early growth and development. It would seem the sane course in any event not to plant more trees per acre than may grow normally, and without branch or root interference up to the fifth year (the normal first year of tapping).