Tree Root Ball Diameter and Weight (ANSI Z60.1)

at roughly ten to twelve inches of ball diameter per inch of caliper for a shade tree, with the depth a fraction of the diameter rather than a sphere -- a ball is dug flat-bottomed and wide, because that is where the roots are. THE WEIGHT IS THE NUMBER PEOPLE GET WRONG, AND BY A WIDE MARGIN. A six inch caliper tree carries a five foot ball better than three feet deep, and at the density of moist loam that is well over three tons of soil before the tree above it. It is a crane or a large tree spade rather than a crew and a cart, and it is a number worth having before the delivery arrives rather than when it is sitting on the truck. WEIGHT GOES AS THE CUBE OF CALIPER at a fixed ratio, because the diameter, the depth and the width all scale with it -- so doubling the caliper is eight times the weight, and the handling method changes long before the tree looks twice as big. The caliper a given handling limit will carry is reported for that reason: it is the specification question, asked in the direction the site can answer. The trade the ratio represents is survival against handling. A larger ball retains more of the root system and transplants better, and every inch of it costs weight, equipment and money -- which is why the standard gives a range rather than a number, and why a specification that cuts the ball to what the equipment can lift has traded survival for a delivery. Soil density is the other lever and it is not a choice: a ball dug wet is far heavier than the same ball dug in normal moisture, and irrigation before digging is a real and often overlooked contributor to a lift that will not go. A volume and a weight from the standard's proportions. It does not select the ball size, which the specification and the standard do by species and by whether the tree is balled-and-burlapped, in a container, or spaded; the proportions differ for conifers, for multi-stem plants and for large-caliper stock. It does not address the rigging, the lifting points, or the fact that a root ball must be lifted by the BALL and never by the trunk, which breaks the root-soil bond and kills trees that arrive looking fine. It does not evaluate planting depth -- the root flare goes at grade and a ball set too deep is a slow failure -- backfill, staking, or aftercare irrigation, which decides survival more than any of this. ANSI Z60.1, the project specification, and a qualified arborist or nursery professional govern.

ball diameter = trunk caliper x the entered inches of ball per inch of caliper; ball depth = that diameter x the depth ratio; volume as a flat-bottomed cylinder pi/4 d^2 h; weight = volume x soil density; and the caliper a handling limit carries is the cube root of that relation.

The ANSI Z60.1 root ball proportions by name -- roughly 10 to 12 in of ball diameter per inch of caliper for shade trees, with the depth commonly 0.60 to 0.75 of the diameter -- and moist loam at roughly 100 to 110 pcf. The proportions differ for conifers, multi-stem plants and large-caliper stock and are entered. It does not address rigging, lifting by the ball rather than the trunk, planting depth, backfill, or aftercare. ANSI Z60.1, the project specification, and a qualified arborist or nursery professional govern.

One cylinder volume and one density; no ANSI table is reproduced.

Estimate. AHJ and licensed professional govern.

Field names used by the API: caliper_in, ball_per_caliper_in, depth_ratio, soil_density_pcf, handling_limit_lb, ball_diameter_in, ball_diameter_ft, ball_depth_ft, ball_volume_ft3, ball_weight_lb, ball_weight_tons, caliper_for_limit_in

• Proportions are entered per stock type conifers, multi-stem and large-caliper stock differANSI Z60.1
• No rigging or lifting method a ball must be lifted by the BALL, never by the trunka qualified arborist
• No planting depth or aftercare the root flare goes at grade, and irrigation decides survivalthe project specification