With a stretch of cold weather coming up and many vegetable crops already planted, here are some resources on protecting your crop.
Rebecca Shortt – OMAFRA
Q. I don’t have complete sprinkler coverage and can’t frost protect (e.g. drip, traveling gun). Should I irrigate before the frost event?
A. If the soil is dry then, YES, an irrigation today, BEFORE the soil cools, will help (can protect 1 degree C or so). Do this before evening – you want the plants to be dry tonight.
Links:
Should I Irrigate Ahead of the Coming Freeze? – MSU
Irrigation For Frost Protection – OMAFRA
Frost Protection Tools – OMAFRA
Moist, non-cultivated soil retains more heat – MSU
Frost/Freeze protection using irrigation – Irrigation-Mart
Freezing crops and soil – Iowa State Extension
Anne Verhallen – OMAFRA
Comments on irrigation water temperature
- Where is the irrigation water coming from – in regards to temperature – is it cooler than the soil currently (years ago researchers at Harrow looked at watering from the well on site – it actively cooled the soil which was a problem early on with tomatoes – and yes I realize they are more cold sensitive)
- What is the forecast in terms of sun – moist soil will hold heat but it needs sun to build heat (again years ago working with windstrips again in tomatoes, I never worried if we were sunny before a cold night – the worrisome ones were the cool cloudy days followed by the clouds disappearing and a cold clear night)
Effect of Different Soil Surfaces on Temperatures at 4 ft – Original Source
| Soil | Relative Temperature |
|---|---|
| Bare, firm, moist soil | Warmest |
| Moist soil, shredded cover crop | 0.5 F colder |
| Moist soil, low cover crop | 1 to 3 F colder |
| Dry firm soil | 2 F colder |
| Freshly disced soil | 2 F colder |
| High cover crop | 2-4 F colder |