63 . 
THE EFFECT OF GRASS ON TREES. 
. !*“ f 
The effecjt of grass' on trees is probably inti mately connected with 
that fundamental question in agriculture to which no comprehensive 
answer has yet been obtained, namely, the fertility of the soil. The 
casual observer may dismiss the subject by stating that it is simply 
due to the grass robbing the tree of its nourishment or its moisture, 
but such a statement can only be based on ignorance of the facts, and 
of all the work which has been done in the matter. The subject has 
been under investigation at the Woburn Experimental Fruit Farm 
for the last 15 years : one report (the third) dealing with it was 
published in 1903, and it is hoped that another will be issued before 
very long. 
Although no final solution of the problem has yet been obtained, 
considerable progress has been made in the matter, and various 
possible explanations have been definitely negatived. Foremost 
amongst these is the theory that the action is due to the grass 
absorbing all the food and water from the soil. The original experi- 
ments are, perhaps, the most striking, though not the most precise, 
on this point. A large number of Apple trees were planted in rows, 
II feet apart, in 1904 : the ground in one row was kept tilled, and that 
in the other row laid down to grass ; the grass, when cut, is left to rot 
on the ground, and the same amount of manure is given to both rows 
of trees. Those in the tilled soil are now such large trees that half of 
them have had to be removed, their spread being some 15 to 16 feet ; 
those in grass did not grow at all for several years, and only began 
to make growth when their roots extended beyond the grassed area ; 
they are still miserable specimens of trees, about one-sixth the size 
of the others, and the crops borne by them have only been about one- 
tenth of that of their neighbours. Yet the grassed soil is actually 
richer than the tilled soil. In the 15 years it has had removed from 
it only one crop of grass (that actually growing at any given moment) 
and the small amount of material required for the stunted growth of 
the trees ; whereas from the tilled soil there has been removed mate- 
rial for an annual crop of fruit, and also for the vigorous growth of 
the trees. Analysis also shows that the grassed soil is the richer of 
the two, and it also shows that, in this particular case, there is prac- 
tically no difference between the water contents of the grassed 
and open plots. 
Of the many other experiments on these points, the most 
conclusive are, perhaps, those made with Apple trees grown in pots. 
In some of these the grass roots were separated from the tree roots 
by very fine wire gauze, through which the 1, former could not pene- 
trate ; the pots were weighed and watered every two days, so as to 
keep the water contents the same, and such water and food as 
was added, was introduced from below, so that the tree should have 
the first pull at it. Yet the trees still suffered badly from the grass, 
although th e soil was actually moister and richer than in the case of 
