Planting season is or soon will be underway. This presents an opportunity to talk about a few things; 1) ideal conditions for planting, 2) seeding depth, and 3) imbibitional chilling.
Ideal planting conditions are when the soil temperature reaches 50oF and is expected to rise. This temperature is key to getting germination and emergence within 7 to 10 days (90-120 GDU). While soil temperature is definitely important, it’s not the only indicator to go by when deciding to get the planter rolling; make sure conditions are not too wet. Planting when the soil is wet is more risky than planting into dry soil and will often result in sidewall compaction and increased risk of seed and seedling diseases.
Seeding depth is important, not only absolute planting depth but uniformity of planting depth. Absolute seeding depth (ie. what you set the planter at) is important because it can minimize the diurnal temperature fluctuations. Corn should be planted no less than 2 inches. Uneven planting depth results in uneven emergence which result in dominant and dominated plants. Dominant plants have a higher yield potential then dominated plants. Uneven planting depth can often be corrected by ensuring that there is adequate down pressure on the pressure wheels.
Imbibitional chilling is a favorite of mine. Often times this occurs because there is the assumption that the seed won’t take up moisture or germination hasn’t occurred yet. Reality is that as soon as the seed is planted water begins to be imbibed and metabolic processes begin soon after. It is for this reason that planting is not recommended 12 to 36 hours ahead of cold, wet conditions. And in some circumstances, if corn has emerged prior to frost conditions there could be a detrimental impact on stands.
Good luck with spring planting!