374 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
may be said, however, as to the examination of effect of grass on the 
supply of water and food reaching the tree. 
That the growth of grass is accompanied by the evaporation of 
much water from the soil is well known, and, though this may gener- 
ally result in the soil below grass becoming drier than that where the 
surface is kept tilled, this is by no means always the case, for, though 
water is lost by the physiological action of the grass, the grass protects 
the soil from a loss of water due to physical causes — the action of sun 
and wind — and the balance of these opposing actions may sometimes 
be in one direction, sometimes in another. As a matter of fact, it was 
found that, in the case of the original grassed plots of apple trees at 
the farm, the soil under the grass was, during the two years when 
observations on this point were made, actually v/etter than that in 
the neighbouring tilled plots, so that lack of moisture could not be the 
explanation of the effect in this case. Numerous other direct experi- 
ments have been made on the subject, and all led to the same negative 
conclusion : where the trees were benefited by additional water, those 
in grassed ground were benefited to the same extent as those in tilled 
ground, but the additional water, even when supplied from below the 
roots of the trees, so that they should receive it before the grass, did 
not obviate the deleterious action of the grass. The most conclusive 
evidence on this point was obtained by growing trees in large earthen- 
ware pots, when, by weighing the pots every day or two, the water 
contents could be kept up to some definite standard, or altered to a 
known extent. 
The question of nutrition is intimately connected with that of the 
water-supply, for in a fertile soil, so long as the trees are not in 
want of water they cannot lack nutrition. That the growth of grass 
impoverishes the soil in our experiments cannot be maintained : the 
grass, when cut, is not removed, but is left to rot on the ground, and 
direct analysis of the soil has shown that, in accordance with what 
has been established elsewhere, grassed soil is actually richer than the 
tilled soil ; and this has been further established by finding that trees 
will flourish better in soil which has grown grass than in soil which 
has not done so. Thus, if the trees under grass are suffering from 
starvation, it is starvation in a land of plenty ; and this is just the 
characteristic of toxic action — the presence of some baleful agent which 
prevents the plant from assimilating such nourishment as is present. 
As in the case of the water-supply, pot experiments have been found 
most useful in examining the question of the food-supply, and special 
attention may be drawn to certain of these. Several series were made 
wherein the trees were grown without grass or with grass, and, in cases 
where grass was present, the grass roots were, in some instances, allowed 
to intermingle in the usual way with those of the tree, whereas in others 
they were prevented from so doing by a layer of very fine copper gauze 
placed four or five inches below the surface of the soil, all the water 
and nourishment supplied being added from below, so that the trees 
could take what they wanted before it reached the grass. Yet this 
almost complete separation of the grass from the trees failed to diminish 
