“New Yorn AGRICULTURAL EXPERIMENT Svrarion.. 461 
the other none; one well colored fruits, the other poorly 
colored specimens. These are but illustrations of the freakish- 
ness of the sod-mulched trees. Branches and foliage showed 
similar tendencies to depart from the normal. 
One need not seek long for an explanation of such behavior 
of the trees. No matter how uniform the sod (Plate XX VII 
shows the sod in the Auchter orchard to be as uniform as sod 
often is in orchards) there will be areas well grassed and areas 
poorly grassed; areas in which there is an admixture of some 
plant not to be found in the same quantity elsewhere. Now 
this lack of uniformity of environment cannot but bring about 
ununiformity in the trees themselves. On the contrary, tillage 
is conducive to a uniform environment as it secures surface 
uniformity of the field, equalizes the depth of soil; and tends 
to evenness in the amount and availability of moisture and 
food. One of the reasons for cultivating any crop is to secure 
an equally vigorous growth over the entire area cropped. 
Effects of the two treatments on the tree.—In the long run, 
crop performance measures the vigor and health in a plant 
but in period of so few years as the one in which this experi- 
ment has been in progress it is possible for trees to have a 
high record in bearing fruit and yet lose in vigor. I¢ is neces- 
sary, then, to consider the effects of the two methods on the 
trees. It is not fair to measure the effects of a treatment by 
considering one or a few phases of tree growth. It may be 
that all tree characters do not respond in exactly the same de- 
eree. to treatment. If, however, the methods of gauging vigor 
are correct there should be fairly close agreement in the growth 
of different parts of trees as affected by the two treatments. 
Thus in all of the fruit characters indicating vigor, the ad- 
vantage has been strongly with tillage; so, it will be found, 
too, in all tree characters, tillage has SB cg greater vigor 
and health than the sod-mulch. 
Diameter of trees.—The vigor of trees is almost directly 
proportional to the increase in diameter of the trunk. We 
examine the rings in a cross-section of a tree and tell: of the 
good and poor seasons in its life by the thickness of the rings. 
