Iowa
Representative warm-season temperature is 21°C, inside the 18–28°C optimum. Annual rainfall is 771 mm, inside the 600–1,200 mm optimum rainfall band.
Compared on representative regional temperature and rainfall.
Commercial crop requirements
Growing Alfalfa: climate, soil and water requirements
Alfalfa has an optimum temperature range of 18–28°C within an absolute 5–40°C envelope.
Its profile calls for 730 mm of seasonal water and an optimum soil pH of 6.5–7.5.
How to read the figures
Profile figures come from the source cited at the foot of this page. Regional figures are representative reference values, not coordinate-level measurements.
Climate envelope
Use the optimum band for screening normal crop development and the absolute range as an outer tolerance boundary. Accumulated heat still depends on the local planting window and daily temperatures.
| Requirement | Profile value |
|---|---|
| Optimum temperature | 18–28°C |
| Absolute temperature range | 5–40°C |
| Heat to maturity | 1,000 growing degree days above a 5°C base |
| Photoperiod | Long-day response; no critical threshold is supplied |
| Vernalisation | Not required |
| Established-plant cold-hardiness limit | -30°C |
Soil and pH
| Requirement | Profile value |
|---|---|
| Optimum pH | 6.5–7.5 |
| Tolerated pH range | 6.5–7.8 |
| Waterlogging tolerance | Intolerant |
An intolerant rating means drainage is a screening constraint. Check infiltration, perched-water risk, field outlets and the duration of saturation before committing land.
Water
| Requirement | Profile value |
|---|---|
| Seasonal water requirement | 730 mm |
| Optimum rainfall band | 600–1,200 mm |
| Absolute rainfall range | 350–2,700 mm |
Irrigation becomes necessary when effective in-season rainfall is below the 730 mm seasonal requirement. Convert that gap into a field schedule only after accounting for soil water storage, application efficiency and local rainfall timing.
Nitrogen demand
The profile assigns Alfalfa nitrogen-demand category 1, which translates to low demand. It is a relative category, not a fertiliser rate.
Set the field program from soil and tissue evidence, expected removals, prior-crop effects and local nutrient rules.
Crop-level reference profile
| Requirement | Profile value |
|---|---|
| Average yield | 12 t/ha reference average |
| Growing period | Not derived: the heat requirement for this crop does not describe a single season |
Where it grows well
These examples pass a stated temperature or rainfall comparison using representative regional values. Regional screening, not parcel-level.
Kansas
Representative warm-season temperature is 23.9°C, inside the 18–28°C optimum. Annual rainfall is 642 mm, inside the 600–1,200 mm optimum rainfall band.
Compared on representative regional temperature and rainfall.
Texas
Representative warm-season temperature is 28°C, inside the 18–28°C optimum. Annual rainfall is 600 mm, inside the 600–1,200 mm optimum rainfall band.
Compared on representative regional temperature and rainfall.
Regional guides
Research basis
These papers support the qualitative interpretation of the crop profile. No paper-derived figure is used on this page; the named crop and region fields remain the only sources of displayed agronomic numbers.
- Interaction between Waterlogging Injury and Irradiance Level in Alfalfa
Flooding injury varies with plant stage and light conditions, reinforcing the need to screen drainage and saturation risk.
- Concerted changes in nitrogen and carbon primary metabolism in alfalfa under water restriction
Water restriction changes carbon and nitrogen metabolism, so nitrogen interpretation must account for fixation and water status.
Taking this to a field decision
This profile cannot set planting depth, row spacing, seeding rate, cultivar choice, fertiliser rate, harvest timing, irrigation schedule or drainage design. Those decisions depend on cultivar, local practice and field conditions.
Use a coordinate-level audit, local field evidence and commercial terms before a land or lending decision.
Crop profile source
FAO EcoCrop & agronomic literature (Medicago sativa).