To check whether each operation was done inside its window, take a sheet of paper and give each operation one row. The window is the span you planned for the operation before the season, from the earliest to the latest date it should be done. A window is shorter than it looks: in Iowa, where about four spring days in ten are too wet for field work, the 20 to 25 field days of tillage and planting take five to six weeks on the calendar.
Each row holds five things: that window, the date the operation was actually done, a mark for in or out of the window, the days late when it was out, and the reason in a few words. That is the window check sheet.
Many farms keep both halves, the plan and the record of the work, but few set one beside the other. On many farms the windows are written in the season plan, or kept in someone’s head, while the work goes into the field log, the notebook where each operation is written down the day it is done. The two rarely get compared. An operation done ten days late goes into the log as done, with no mark that it missed its window, and the run of delays comes to light at the end of the season, when it is too late to change anything.
Why is a late operation worth writing down?
Because a window holds fewer working days than the calendar suggests, so each lost day weighs. Iowa State University, in the United States, publishes a guide for farmers choosing machinery. According to the guide, the weather there is suitable for field work about 60 percent of the time in the spring, so about four days in ten are lost. With the machinery that came out cheapest in the guide’s comparisons, tillage and planting usually took about 20 to 25 field days, a field day being one dry enough to work. At six workable days in ten, that is about five to six weeks on the calendar.
Rurivia calculation from Iowa State University, Farm Machinery Selection (A3-28): 20 to 25 field days divided by 0.6 gives about 33 to 42 calendar days.
Missing the best date can also cost yield. According to the same guide, in Iowa corn yields start to decline once planting runs past about May 10 to 14. Those dates and percentages belong to Iowa and will be different on your farm. What carries over is the reasoning: a window has fewer working days than it seems, and an operation done late can cost something. That is why the days late go on the sheet.
Why don’t the plan and the record get compared?
Because they are written at different times, and often by different people. The windows are written before the season, by whoever plans it. The field log is written day by day, by whoever does or supervises the work. If you have never written windows down, you can learn how in the article on writing a window for each operation: the earliest and latest date for each operation, set before the season starts. For the actual dates, keep a field log of what got done, one line per operation with the date, the field and who did it. The planned column of the sheet comes from the windows, and the actual column from the log.
Kept apart, the log has the late operation as done, the plan has only the date it should have been done, and nobody works out the days between the two. The reason for the delay never reaches next season’s plan.
What do you see with the plan and the log side by side?
The pattern of the delays. One late entry in the field log looks like one bad week. On the sheet, with the operations in date order, you see every operation that missed its window and the week when the delays began: planting on time, say, and spraying late from the third week onward. Many farmers know that planting late can cost yield, yet many farms never count how many days late they actually were. With the days counted, you can see which operation to fix first.
Why write the days late and not the yield lost?
Because you can work out the days late from two dates you already have. The yield lost you cannot: it depends on the crop, the weather that season and the region, and two dates are not enough to estimate it. From the Iowa date you know when losses start there, not how many tonnes your farm lost.
So on the sheet you write the days late and leave the lost tonnes off.
Who writes the reason, and what is it for?
Name one person to fill in the sheet: the farmer, the manager or whoever already keeps the field log. That way it is clear who does it.
Of the five columns, the reason is the one worth the most time. Marking an operation out of its window changes nothing by itself. The reason is what you can act on: rain that would not stop, a machine down, the crew on another field, an input that came late. When you set next season’s windows, you read each reason again and decide what to do about it. If a broken planter held up planting, you can have it serviced before the window opens.
Where to start
Set aside an afternoon, with this season’s windows and the field log side by side on the table. If the windows were never written down, write the ones you had in mind for this season before you open the log, and next season write them before the work starts. Use one sheet, with one row per operation, in date order.
The sheet is worth most at the end of the season, when you read the reason column while setting next season’s windows and find that a delay that looked like bad luck has a cause that repeats. Seen alone, one late operation leads to asking whose fault it was. Seen in date order with the rest of the season, it leads to a more useful question: what to fix first next time.
On the farm management page you will find where this end-of-season check fits in the rest of running a farm. The other planning articles cover setting the windows, keeping the field log and keeping one operation number someone else can check, such as planter hours per day, through the season.