On a 2,000-acre corn and soybean farm in northwest Missouri (an example), 900 acres of corn and 1,100 acres of soybeans are still unplanted on May 20, and one planter serves both. With the loss rates of an Illinois model, planting soybeans first costs this farm about $2,325 for each day of the wrong order. Give the day to the job that loses more per day that week. Before the season, write each job’s window, cut-off date and loss per day on one sheet, on paper or in a spreadsheet, one row per job.
The window is the span of dates in which a job gives its best result. The cut-off date is the last day that still fits the original plan. If a job will run past it, you change the plan: do that job first, hire a contractor or switch crops.
On many farms the choice is made that same morning, by habit (corn before soybeans) or by whichever machine is closest. Yield is then lost on every acre that waits, and at the end of the season nobody can say what the wait cost.
Which job gets the day when only one can run?
The one whose waiting costs more dollars that day. Multiply each job’s loss per day, in dollars an acre, by the acres still waiting for it. The larger product gets the day.
The loss per acre is borrowed, so it is a starting point. Replace it with a figure from a trial in your own region as soon as you find one.
Why does one late day cost more on a bigger farm?
Because the loss lands on every acre still waiting. Gary Schnitkey, an agricultural economist at the University of Illinois, priced the timeliness cost of one 12-row planter, the value of yield lost because the planter finishes late. He found $0.86 an acre on 400 acres and $32.81 an acre on 3,600 acres, at 2004 prices.
The area grew 9 times and the cost per acre about 38 times. With more acres, the same planter needs more days to finish, and each extra day falls on more acres still unplanted. Count the acres waiting for each job before you compare jobs.
Do all jobs lose the same per day?
No, and that gap is what you go by when you pick which job gets the day. Schuler and Frank, in a University of Wisconsin-Extension guide to machinery costs, reproduce a table from the American Society of Agricultural Engineers. In it, the share of the crop lost per day of delay is 0.005 for a planter, 0.003 for a combine, 0.011 for a boom sprayer and 0.028 for a baler.
A share of 0.005 is half a percent of the crop a day. At an expected corn yield of 180 bushels an acre (an example), that is 0.9 bushel an acre a day. To compare jobs on different crops, turn each loss into dollars an acre: price times quantity. These are general United States figures, not your farm’s.
The ranking also depends on the place. Iowa State University reports that in Iowa yield losses from late harvesting are generally not as severe as from late planting. That holds for one state’s corn and soybeans, not for every pair of jobs.
Does the loss per day stay the same through the window?
No: it starts low and climbs as the window closes. In the Illinois model, soybeans lose nothing until May 15, then 0.33 bushel an acre a day until May 31, and 1 bushel an acre a day after that. On the example farm’s 1,100 soybean acres at $11 a bushel, the cost of one more day of waiting goes from $0 to $3,993 to $12,100.
Trials agree on the shape. Scott Irwin summarized University of Illinois planting-date trials. Planting as late as May 10 cost only 4% of yield in corn and 6% in soybeans, and by May 30 the penalty was two to three times larger.
The same trials found the best planting window for corn and soybeans to be about the same, which upends the old rule of thumb that Illinois farmers should plant corn first and soybeans second. Habit follows a fixed order, and each loss climbs at its own pace. So you write a choice on the sheet for each week of the overlap, not a fixed place in a queue.
What do you write first, and how long does it take?
Start with one row per operation: the window, the cut-off date and the name of the person who makes the call. Add a loss per day taken from a published trial for your region, with its source beside it. Your extension service or your agronomist can point you to a trial. Then, for each pair of jobs that need the same machine or crew in the same weeks, write which one takes the day in each week of the overlap.
The dates themselves, and the choice of crop and variety, are a call for you and your agronomist. On the sheet you write them down where the crew can see them. Whether to buy a bigger machine is a separate decision for a written investment plan; which job gets the day is one you can make this season with the machines you already have.
After harvest, add four columns to the same sheet: the date each job was actually done, in or out of its window, the days late, and the reason in a few words. Copy the dates from the field log, not from memory. The plan and the log are usually written at different times by different people, so a job done ten days late goes into the log as done, with no mark that it missed its window.
With that estimate you can compare two late jobs on one scale. The reason column is the one to read when you set next season’s windows. A delay that looked like bad luck may have a cause that repeats, such as a planter that broke in the same week, and you can fix it before that window opens. Deciding before the rush and checking afterwards is part of everyday farm management and of planning the season.
It takes two hours before the season and an afternoon after harvest, with last season’s dates, the field log and a published loss per day for your main crops on the table.
In the first season, the loss-per-day column holds figures borrowed from trials far from your fields. After two or three seasons, your own days-late and reason columns sit beside it, and you can see which job keeps running past its cut-off date, and why.