In short
The best preceding crops for winter wheat are those that leave water and nitrogen in the soil and no shared disease: oilseed rape, grain legumes and, in dry regions, a managed fallow.
Wheat after wheat does worst in the trials below, and sunflower can cost the next crop soil water in dry climates. Trials differ by climate, so treat the ranking as a starting point. Planva keeps crop rotation by season, so the preceding crop of every field is on record.
What a preceding crop changes
The crop before wheat leaves three things behind. The first is soil water at sowing, which depends on how much the last crop took out. The second is nitrogen, which legumes tend to leave and cereals tend to use. The third is disease: a crop that shares a pathogen with wheat keeps it in the field for the next season.
What long-term trials report
The most detailed numbers come from Rothamsted in the United Kingdom, where winter wheat was grown after a range of preceding crops with and without nitrogen. The table gives the nitrogen needed for an optimal wheat crop, taken from the figure of 230 kg N per hectare after winter wheat.
| Preceding crop | Nitrogen need compared with wheat after wheat | Other findings |
|---|---|---|
| Winter wheat | 230 kg N/ha, the reference | Yield about 7.2 t/ha with optimal nitrogen, roughly 1.5 t/ha less than after most break crops |
| Spring peas | 40 kg N/ha lower | Take-all reduced to none or very slight |
| Winter oilseed rape | 30 kg N/ha lower | Take-all reduced to none or very slight |
| Winter peas, spring beans | 30 kg N/ha lower | Take-all reduced to none or very slight |
| Cultivated fallow | 30 kg N/ha lower | Highest autumn soil nitrate among the options |
| Winter oats | 10 kg N/ha higher | Yield limited by volunteer plants |
A longer trial from 1988 to 2001 compared 15 rotations of oilseed rape, wheat, barley, peas and oats. Unfavourable preceding crops cut the yield of the following crop by about a tenth on average, with large differences between years, and the effect of a break crop carried into the second year.
Roots and disease
A three-year trial published in 2023 found denser roots, measured as root length density, in wheat after oilseed rape than in wheat after wheat. Yield loss followed take-all severity in a wet year. In a dry year yields also differed between rotation positions with no visible infection, so disease is not the only reason a preceding crop matters.
Sunflower, fallow and soil water
In dry regions water decides. In the central Great Plains of the United States, where annual rain is about 420 mm, sunflower dries the soil to about 1.8 m, deeper than wheat does. USDA researchers there report that wheat yields may be lower after sunflower, yet a farm may still earn more overall from the rotation. Leaving tall sunflower stalks standing after harvest traps snow, and rotating sunflower every fourth year gave better yields than every third.
A fallow year is the opposite trade. It gives the next wheat crop stored water and costs a year of production. The pros and cons are set out in the guide to summer fallow.
How to choose for a field
- Read the field history. Note what grew in the last two or three seasons and any disease that followed.
- Judge the water. In dry climates compare what each crop leaves in the soil at sowing with what the wheat will need.
- Count the cost of the preceding crop itself. A weaker wheat yield after a profitable crop can still be a good rotation.
- Check your own recommendations. Regional research stations publish trials for local soils and climates.
How this works in Planva
- Crop rotation. Seasons with crop, variety, sowing and harvest dates, yield and harvest in tonnes.
- Rotation map. A crop filter on the map prints to PDF or JPEG with an area summary.
- What Planva does not do. It records what was grown. It does not rank preceding crops or recommend a rotation.
For a method to build a rotation, read the crop rotation plan, and for the history behind each field, field history records.
Sources
- McEwen and others, 1990, Journal of Agricultural Science, nitrogen residues and growth of a following wheat crop
- Sieling and Christen, 2015, crop rotation effects on oilseed rape, wheat and barley
- Arnhold and others, 2023, Frontiers in Plant Science, crop rotational position and root development of winter wheat
- USDA Agricultural Research, 1999, sunflowers in the Great Plains
Common questions
In the trials cited here, break crops such as oilseed rape, peas and beans gave the best results, and in dry regions a managed fallow stores water for the wheat. The best choice still depends on your soil, rainfall and disease history.
The real Planva interface, shown with test data.
