The number one factor hurting the performance of this years corn crop is uneven emergence.Soils were
slow to dry in the spring of 2009.The cool moist weather of late April and early May lead many fields to remain pasty at the 2 inch depth.This made it extremely difficult to avoid planters from creating sidewall compaction in the slower drying areas of fields.As the planters double disc openers moved through the soil they often created a pressure point against less than totally fit soil leaving the sidewalls of the seedtrench to compress.As these areas of the field eventually dried it created a tighter more condensed rootbed environment for the young seedlings roots to penetrate.This in turn created a delay in plant growth in these areas leading to smaller rooted, smaller stalked plants to develop.The end result is what you see in the photo above and below.Smaller ears that in some instances are not nearly as well pollinated as we'd like them to be.
Note the smaller stalks of these plants.Smaller stalks are a prime indicator of delayed emergence due to either cooler seedbeds slowing plant growth,sidewall compaction in the seed trench causing restricted plant development ,crusted soils or leafing out underground.When a plants development is significantly delayed it can lead to poorer pollination like what you see here due to insufficient pollen being present to fertilze silks when they eventually emerge.
An illustration of small stalk diameter.Consistent uniform stalk diameter is the key to uniform emergence.
Consistent ear sizing with good ear tip fill like that shown here is the end resolve of strong uniform emergence.This can only occur with uniform planting depth, excellent seed to soil contact and dry friable seedbeds with no sidewall smearing and good soil warmth transmission.
Consistent ear sizing like that shown in the above photo was characteristic of nearly every growers corn fields in 2008.Why you ask ? Because last year soils came through the winter in great shape.There were no pounding rains in late April and early May to compress soils and make them hard to dry.And soils were warmer in the spring of 2008 because of it.Also in 2008 no rainfall event of any significance occurred between April 23 and June 9th.This lead to the most consistent uniform stands of corn that I've seen in a long time.Followed up with sufficient timely rainfall and voila we experienced the biggest highest yielding corn crop in the history of Ontario farming.
Ear sizing will be propionate to stalk diameter development.Take a good look at the stalks of these eared plants in the photo below.
Produce consistent large diameter stalked plants like those shown here and you're on your way to BIG YIELDS !!!If you are finding too much variation in stalk diameter in your fields then you need to start asking yourself these questions?
Did you push your planting date ?(in that was the field really fit for planting - there was more evidence of sidewall smearing in more corn fields in the spring of 2009 than I've personally seen in a decade)
Did you plant deep enough ?( ideal planting depth is between 1 3/4 and 2 1/4 inches
Are you getting too much planter bounce ?( ideal planting speeds are between 5 and 6 mph depending on planter type
Are you leaving your fields level enough ?
Are you clearing sufficient residues ?( with trash whippers) to avoid seed furrow pinching and improve seedbed temperatures
Are your units properly calibrated ?
Are your double disc openers worn too much ? ( they should have at least 2 and 3/4 inches of contact at their front cutting point and they should be at least 14 7/8 inches in diameter
Are your depth gauge wheels properly shimmed in ?
Have you installed Seed Firmers ?
Did you check both your closing wheel alignment and down pressures ?
NOTHING BEATS UNIFORM EMERGENCE FOR HIGH YIELD CORN PRODUCTION !