Topdress to fill the holes does not add up
Take a normal setup: half-inch hollow tines on a 2 by 6 inch spacing, three inches deep, one pass. That is 12 holes a square foot. Each core is pi times a quarter-inch radius squared times three inches, which is 0.589 cubic inches. Over 1,000 square feet that is 12,000 holes and 7,069 cubic inches of soil, which is 4.09 cubic feet, or 0.152 cubic yards.
Now the topdress. A quarter of an inch over the same 1,000 square feet is 20.83 cubic feet, or 0.772 cubic yards. That is 5.09 times the core volume. The topdressing is not backfilling the holes; the holes absorb a fifth of it and the rest becomes a layer on the surface.
To actually remove as much soil as a quarter-inch topdress adds, you would need about five passes at that tine setup. Nobody does five passes. So the honest description of the operation is that aeration relieves the surface and topdressing builds the profile, and they are done together because the timing suits both, not because one balances the other.
| Operation, per 1,000 sq ft | Cubic feet | Cubic yards |
|---|---|---|
| One pass, 1/2 in tines, 2 x 6, 3 in deep | 4.09 | 0.152 |
| 1/8 in topdress | 10.42 | 0.386 |
| 1/4 in topdress | 20.83 | 0.772 |
| 1/2 in topdress | 41.67 | 1.543 |
Holes a square foot, and what the surface actually sees
Hole density is 144 divided by the product of the two spacings in inches. A 2 by 6 spacing is 12 holes a square foot; a 2 by 2 spacing is 36. The fraction of the surface actually opened is that density times the area of one hole. For half-inch tines at 12 holes a square foot, one hole is 0.196 square inches, so the opened area is 2.36 square inches out of 144, which is 1.64 percent.
That number surprises people who have just watched a machine chew up a field. It looks like a lot of damage and it is a very small fraction of the surface. This is why compaction relief is a programme rather than an event, and why the answer to a hard field is more operations over more seasons rather than one aggressive day.
Whole-field numbers get large quickly
Scale the same setup to a 330 by 195 foot field, which is 64,350 square feet. One pass is 772,200 holes and 9.75 cubic yards of cores. A quarter-inch topdress on the same field is 49.65 cubic yards. Split 80 sand to 20 compost that is 39.72 cubic yards of sand and 9.93 of compost, and at 1.35 and 0.7 tons a yard that is 53.63 tons of sand and 6.95 tons of compost — nearly 61 tons of material for a layer a quarter of an inch thick.
At a 20 cubic foot hopper, 1,341 cubic feet of topdressing is 68 spreader loads. That is the number that decides whether the job happens in a day, and it is usually the constraint rather than the material cost.
Where the blend comes from
The sand and compost split is a field because it is a decision about your profile, not a universal ratio. Sand over a soil field creates a boundary that water sits above rather than crossing, and once several seasons of it are down it is not easily undone. Whether the sand you are buying matches what is already in the ground is a question for a particle size analysis and a turf agronomist, and it is worth the cost of the test before it is worth the cost of the sand.
Compost brings the opposite risk: it is light, it is variable, and its weight per cubic yard moves a lot with moisture, which is why the density is a field too rather than a constant.
What this page does not do
It does not recommend a depth, a frequency, a tine size or a blend. It does not cover fertility: what goes on a field, at what rate and how often is decided by a soil test and by your local extension service, and any product label overrides everything else. It does not touch pesticides, herbicides or fungicides at all.
Before anything goes into the ground
Irrigation mains, drainage, electrical runs to scoreboards and lighting, and old utility crossings all live under sports fields, frequently at shallow depths and frequently not where the as-built drawing says. Call 811 before you dig, trench, drive a stake, auger a post or set an anchor, and give the locate time to be marked. Private lines on the facility side of the meter are usually not covered by the public locate service, which is what catches out a crew that did everything else right.
Open fields are also the place people get hurt by heat and by machinery. A groundskeeper on a mower or an aerator in July is exposed on both counts at once, and neither risk announces itself.
Related pages: the sod and seed calculator covers the reseeding that usually follows aeration, the fertilizer calculator converts a rate from your soil test into pounds of product, the compost amendment calculator handles beds rather than fields, and the watering depth calculator deals with the irrigation side. For the skinned parts of a ball field, see the infield mix calculator.
Questions people ask
Does topdressing fill the aeration holes?
Mostly not. One pass with half-inch hollow tines at a 2 by 6 inch spacing and three inches deep removes about 4.09 cubic feet per 1,000 square feet. A quarter-inch topdress over the same area is 20.83 cubic feet, which is 5.09 times as much. The holes take a fraction of it and the rest becomes a surface layer. That is fine, and it is what the operation is for, but it is not a balanced exchange.
How many aeration holes per square foot?
144 divided by the product of the two spacings in inches. A 2 by 6 inch spacing gives 12 holes a square foot, a 2 by 2 gives 36, a 4 by 4 gives 9. Multiply by the number of passes. On a 330 by 195 foot field, 12 holes a square foot is 772,200 holes in a single pass.
How much of the surface does aeration actually open?
Less than it looks. Half-inch tines at 12 holes a square foot open 2.36 square inches of every 144, which is 1.64 percent. Even a double pass at a tight spacing rarely gets past a few percent. This is why compaction relief is treated as a season-long programme rather than something one operation fixes.
How much sand does a quarter inch topdress take?
Area times depth in feet, divided by 27. On 64,350 square feet a quarter inch is 1,341 cubic feet or 49.65 cubic yards. At an 80 percent sand blend that is 39.72 cubic yards of sand and 9.93 of compost, which at 1.35 and 0.7 tons a yard is 53.63 and 6.95 tons. A quarter of an inch is nearly 61 tons of material on one field.
What blend of sand and compost should I use?
That depends on what is already in your profile, and getting it wrong is expensive to reverse. Sand laid over a soil field creates a layer that water perches on rather than passing through, and several seasons of it become a permanent feature of the ground. The right answer comes from a particle size analysis of your existing soil and a conversation with a sports turf agronomist. The blend is a field on this page so you can price the option someone qualified has recommended.