On Tuesday April 28, WAC and CCE staff checked soil temperature in several fields in Delaware County, both corn stubble and grass sods. Temperature were taken at the 2-3” depth. The results are in the table below.
The results were surprising, despite the snow fall only two days prior; most corn fields, both those with and without rye cover crops and across a range of elevations were in the 55-60° F range, and some even warmer!
The guideline for minimum soil temperature to commence planting field corn is 50° F. Clearly many fields, especially those that are well drained are ready to plant with the rain stops.
One caveat to planting when temps are at 50° F especially on less well drained ground, is if a cold rain is in the forecast followed by a forecast of cool temperature; In this case the seed can imbibe cold water but not experience warm enough temperatures for long enough to initiate or sustain root growth. In this scenario, seed rot and inconsistent stands are more likely. This is far less likely on well drained soils, as the soils will dry out and warm up faster at this point. The risk would be soils that get wet and chilled and remain so for an extended period of time. See our note below about spring killed sod fields.
Most sod fields were still in the mid to upper 40° F range, due to the ground cover. These fields still need a little time to warm up.
Our guidelines on planting corn at this point follow are as follow:
- Well drained fields: As soon as fields are trafficable and the seed slot can be opened and closed properly after the pending rains, planting may commence. Take advantage of an early start to get ahead before haying!
- Moderately drained fields: Stay tuned to our soil temp reports, or check your own. Once temperature are consistently above 50° F and no cold rains are in the forecast, planting may begin.
- First year corn on spring killed sods: Stay tuned to our soil temp reports, or check them yourself. Once soil temps are consistently above 50° F and no cold rains are in the forecast, planting may begin. Be careful on spring killed sod fields that are on less well drained soils! The sod residue and the moisture will keep the soil cooler longer; monitor soil temps and make sure seed slot gets closed properly.
The best way to know when it’s safe to begin planting is to check soil temps. Check them to a depth of 2-3”, a typical planting depth. If you want fields checked, let us know.