The load count is settled before you leave the yard
Loads are the volume divided by what actually goes in the box, rounded up. Eighty-nine cubic yards into a six yard spreader filled to 85 percent — 5.1 yards a load — is 18 loads, with the last one carrying 2.3 yards. That is the number, and it does not care how wide the machine throws, how fast you drive, how far the field is or what rate you are applying at.
Acres are the same kind of number from the other end: 89 cubic yards at 12 to the acre is 7.42 acres, whatever the machine does. Width and speed change how long the job takes and how many times you cross the field. They do not change the loads and they do not change the acres. It is worth being explicit about that because spread width is the specification people shop on, and it is the one that has no effect on either of the two figures the job is actually measured in.
Spreading is the short part
At the defaults the field work comes to 14,957 feet of driving — 2.83 miles, 831 feet a load. At 5 mph that is 1.9 minutes per load of actual spreading. The same load takes 6 minutes to fill, 6 minutes to haul out and back over a 0.6 mile run at 12 mph, and 3 minutes of turning. The cycle is 16.9 minutes and spreading is 11.2 percent of it.
The whole job runs 5.07 hours of machine time for 18 loads, at 1.46 acres an hour. Close to nine tenths of that is loading, driving and turning around.
Which lever moves it
The page works the four out rather than asserting a ranking, because the ranking moves with the haul distance. On the defaults, taking a quarter off the haul saves 27 minutes, spreading a quarter wider saves 6.8, loading a quarter faster saves 27, and putting a quarter more in the box saves 60 and drops the job from 18 loads to 14. The bigger box wins there by more than two to one, and cutting the haul and loading faster tie for second.
Take the haul out to two miles and the picture changes completely — the haul term is proportional to distance and everything else stays where it is. That is why the block is computed for the numbers in the form rather than printed as a rule of thumb. The general shape holds though: on almost any small place, the thing worth attacking is the number of round trips, and there are only two ways to reduce it — carry more per trip, or make the trip shorter.
Overlap costs more than it looks
A 24 foot machine at 10 percent overlap covers 21.6 feet of new ground per pass, so an acre takes 2,017 feet of driving instead of 1,815. That is 11 percent more distance for the same acre, which is exactly the overlap back again — overlap is a distance penalty, one for one. It is small against the haul on the defaults and it stops being small on a place where the pile sits at the field gate.
What the hours do not include
This is wheels-turning time. There is no gate in it, no waiting for the loader, no blocked spreader, no fuel, no breakdown and no ground too wet to travel. A day that the arithmetic says is five hours is not a five hour day, and anyone who has spread manure knows by how much. Use it to compare options against each other rather than as a forecast of when you will be finished.
Questions people ask
How many spreader loads is a pile of manure?
The volume divided by what actually goes in the box, rounded up. At the defaults — 89 cubic yards into a 6 cubic yard spreader loaded to 85 percent, so 5.1 yards a load — that is 18 loads with 2.3 yards in the last one. Spread width, speed and field size do not enter it at all.
How many acres will one spreader load cover?
The load size divided by your application rate. At 5.1 cubic yards a load and 12 cubic yards to the acre that is 0.43 acres. The rate is a field on this form and it comes from your own nutrient management plan or your agronomist — this page has no rate in it and offers no recommendation about one.
Does a wider spreader make the job faster?
A little, and less than people expect. At the defaults, spreading a quarter wider takes 6.8 minutes off a job that runs 5 hours and 4 minutes. Width only affects the time actually spent crossing the field, which is 11.2 percent of the cycle. Loading and hauling are the other 89 percent, and a quarter more capacity in the box saves an hour because it removes four whole round trips.
How long does it take to spread manure?
At the defaults, 18 loads at a 16.9 minute cycle is 5 hours and 4 minutes of machine time for 7.42 acres — about 1.46 acres an hour. That is wheels turning with no gates, no breakdowns, no waiting for the loader and no wet ground, so treat it as a floor rather than a forecast.
What application rate should I use?
Not a question this page answers. The rate is a field you fill in from your own nutrient management plan or your agronomist, and what may be applied, where, when and how close to water or a boundary is regulated locally and can carry real penalties. The page multiplies your rate by your volume to get acres, and does nothing else with it.