2018 feels like the winter that just won’t quit, and Western Canada, Ontario, Quebec and the Maritimes are all in the same boat it seems.
But spring is just around the corner, and we will get corn and soybeans planted like we always do. We can’t change the weather but we can certainly manage how we plant.
You will hear many agronomists talk about planting when it’s fit. But what does ‘fit’ really mean?
We consider it to be the following:
- Soil moisture is such that you can’t ball the soil in your hand when you squeeze it, throughout much of the field
- Soil temperature is close to 10 degrees Celsius and is warming
Let’s start with soil temperature and the reason it is so vital in giving the seed the best start you can.
A corn seed needs to take up 50% of its weight in water to start germination, and the soil temperature needs to be 10 degrees C or greater to start germination.
If that water is colder than 10 degrees C, either from soil moisture or a rain, it can cause what’s called Imbibitional Chilling Injury (ICI).
In the above photo you can see what the cold injury does to the seedling, making the mesocotyl appear almost like a corkscrew.
ICI can also cause the seedling to leaf out underground as seen in this next photo. When this happens, the chance of having a reduced stand and delayed emergence is greatly increased.
In corn, every unharvestable ear in 1/1000th of an acre equates to 5-7bu/ac in yield loss. To put that in perspective, in a 30” row width, measure 17’ 5” and that is equal to 1/1000th of an acre.
An unharvestable ear is one that is much further delayed than the rest or maybe didn’t pollinate. In extreme cases, the plant may not even produce a single ear.
In silage, remember that the ear represents 50% of your yield, so that can mean some pretty big losses.
This is the number one reason we want the soil and weather to be in a warming trend when we plant corn.
We mentioned the soil should not being able to be balled in your hand as an indicator of ground fitness.
This is also very important as compaction is a killer to corn. The corn root needs to move left and right out of the seed trench as it grows, not just down the row creating what we would call ‘hatched’ roots.
The corn plant needs to anchor itself into the ground well enough that it doesn’t lodge so that it can get to the water and nutrients.
Many of us put a 2x2 fertilizer band down and also side dress our N in crop. If the roots can’t get out of the seed trench due to sidewall compaction, they can’t do any of the work they need to.
The opening disc and gauge wheels on the planter generally cause sidewall compaction under wet conditions. This can be seen in the photo below. Sidewall compaction can be slightly reduced under less than ideal conditions by decreasing the amount of down pressure on the gauge wheels of the planter.
The best thing to do though if the field isn’t fit is to just stay out as long as you can, even when the calendar tells you it’s time to go.
Anything we do wrong when we plant corn can haunt us all season long. Every year we only get one chance to plant our crops well, so if we are already delayed a week or two, waiting another day or two isn’t a bad idea.
Remember, corn is one of the most unforgiving crops when it can’t get a good start, so give it the best start you can.