How to use this calculator
- Enter or choose total farm area.
- Enter or choose area in.
- Enter or choose land not cropped (tracks, margins, buildings).
- Enter or choose crops (courses) in the rotation.
- The area per crop each year updates as you type. Use Copy result or Share to keep it.
Method
Net area = Total × (1 − Non-cropped%); Area per crop = Net area ÷ Courses; Field f grows crop ((f + y − 2) mod n) + 1 in year y
- Courses (n)
- number of crops or phases in the rotation, including leys or fallow
- f, y
- field number and year
Worked example
- Net area = 120 × (1 − 0.05) = 114 ha.
- Area per crop = 114 ÷ 4 = 28.5 ha.
- Each of the four fields moves one crop along each year, so a crop returns every 4 years.
A 120 ha farm with 5% uncropped land and a four-course rotation grows 28.5 ha of each crop every year.
What the result means
Equal blocks keep the area of each crop steady from year to year, which steadies workload, storage and income. If your fields differ in size, group them into blocks as close to the per-crop area as you can.
Assumptions and limits
- The rotation is balanced: every course gets an equal share of the land.
- Choosing which crops follow which (disease breaks, nitrogen, soil structure) is agronomic advice outside this calculator.
Questions
Do grass leys and fallow count as courses?
Yes. Count every year of the cycle, including temporary grass, cover crops occupying a whole season, or fallow.
What if one crop needs two years in the rotation?
Count it as two courses, for example a two-year ley in a five-course rotation takes two fifths of the land.