Phyllis Bongard, Educational content development and communications specialist, Jeff Coulter, Extension corn agronomist, and Matt Pfarr, Extension educator-crops
With planting progressing across Minnesota, the kickoff session of Strategic Farming: Field Notes focused on strategies to optimize crop emergence. Guest speakers Dr. Jeff Coulter, Extension corn agronomist, and Matt Pfarr, Extension educator-crops, joined moderator Anthony Hanson, Extension educator-crops, for the May 7 webinar.
Rainfall has been variable in the state. Some areas in the Minnesota River Valley received 4 inches in mid-April resulting in rain delays.
Recommended overlap will depend on disc blade thickness (check OEM specifications):
The standard gauge wheel is about 4-1/2 inches in width. The inner lip and convex shape are designed for less drag as the wheel rolls on the soil surface.
Narrower wheels – 2-1/2 to 3 inches - reduce residue riding and achieve more consistent furrow depth in high residue situations. They also allow soybeans to be planted closer to last year’s corn rows (in no-till situations) and can be a space saver if row units are crowded.
Check that the wheels are a good fit to the seed disc opener. Make sure that there is no wear in any bushings or bearings, or gauge wheel arms and connection points so that wheels have true flush contact with the soil. Also inspect the gauge wheel arm for wear at the contact to the gauge wheel depth stop as this controls the furrow depth.
The pound of margin – or net applied force – for gauge wheels on soil will vary year-to-year and change with crop conditions. If the pressure is too light, the furrow will not close correctly resulting in uneven seed-to-soil and water contact. Conversely, if the pressure is too heavy, strong furrow walls or compaction can form which will hinder root development and stand establishment.
The trick is adjusting to changing crop conditions. Planting in early spring when soils are wet or at slower speeds requires less pounds of force on gauge wheels. Conversely, planting when soils are dry requires more pressure to bring water up to the seeds. Coarse-textured soils are more forgiving, since they are less prone to compaction. However, water holding capacity is more of a concern in these soils, so higher pressure on the gauge wheels is likely required. In addition, the increased friction of sandy soils can wear disc openers and gauge wheels faster, so check for damage.
Graphite is typically added in an 80/20 talc to graphite ratio mix. One-fourth cup is adequate for 80,000 corn seeds or 140,000 soybean seeds. If conditions are humid, a 70/30 mix or just added graphite can be used to keep seed dry and meters functioning.
Finally, remember to adjust the vacuum pressure to minimize seed skips. Corn research shows there is a greater net yield penalty from skipped seed drops as opposed to double seed drops.
Above normal temperatures are predicted for May and normal temperatures for the remainder of the growing season throughout the state.
Soil temperatures and the weather are favorable for finishing both corn and soybeans before the next rain event. With growing degree days (GDD) accumulating, it’s important to get the crop in the ground soon in good soil conditions, according to Dr. Coulter.
Anything that inhibits uniform and consistent moisture around the seed can hinder emergence and lead to uneven stands: inadequate seed-to-soil contact, cloddy soil, surface compaction, and/or crusting. For example, clods –formed when tillage is performed on wet soils – create large air pockets around the seed that inhibit even imbibition of water. Similarly, crusting can hinder emergence leading to uneven stands.
What are the effects of uneven emergence? Plants that are 1 leaf stage behind can lose 20% yield potential, while plants that are 2 leaf stages behind can lose up to 50% of normal yield. Neighboring plants can compensate for these losses to some degree, but can’t completely make up the difference, illustrating the importance of planting into good soil conditions.
On dry soils in western MN with little residue, seedlings may be cut off by soil particles that have been picked up and carried under windy conditions. Damaged corn seedlings should regrow, but uneven stands may result if this occurs.
Watch out for crusting if heavy rains occur on these soils and have your rotary hoe ready to break it up. Stands can typically be increased by 2,000 to 3,000 plants per acre by taking action. A few plants will be lost in the operation, but benefits outweigh losses.
Remember that planting date is important, too. Plant corn by May 10 to maintain full yield potential. Yields decline after that date, but the forecast is favorable for planting in a timely manner and delayed planting is currently not a concern.
The outlook for northwestern MN is somewhat cooler and a little behind southern MN, but very good yields can be achieved in this part of the state. However, this region does tend to be drier overall and can face late season drought. The season can also end abruptly with a hard freeze before corn reaches maturity. As a caution, don’t push hybrid relative maturity too much due to the potential for a shorter growing season and delayed planting due to cold, wet soils. Select hybrids that you know have a good likelihood of making it to maturity before harvest.
Thanks to the Soybean Research and Promotion Council and the Corn Research and Promotion Council for their generous support of this program.
Weather recap
Most will remember the record-setting rainfall in June, 2024 that was followed by very dry fall and winter seasons. Fall tillage under these dry soil conditions was unlikely to contribute to compaction, but did add a fine-textured layer of dust to the soil surface. When combined with April nighttime temperatures averaging 10 degrees F below normal, soil warmup has been slow this spring. Soil temperatures are just now getting into the upper 50s F at the 2-inch seed furrow zone.Rainfall has been variable in the state. Some areas in the Minnesota River Valley received 4 inches in mid-April resulting in rain delays.
Spring tillage
If field cultivating, Pfarr urges growers to avoid letting the shovels go too deep into the soil profile where they will pull up mud and create clods. Instead, cultivation should be used as a leveling pass. Use speed and shallow shovels to achieve the appropriate seed bed. In contrast, the coil (spring) tine harrows on the cultivators should be set as aggressively as possible. This means one setting higher than where the residue starts to bunch and drag. Spreading out the surface residue in this way will make it easier to clean the planter row and prevent residue inoculation in the furrow.Planter tips for even emergence
Row cleaners
Floating row cleaners on modern planters can be adjusted to clear residue and minor clods. However, they shouldn’t be so aggressive that they are doing tillage and reducing the fluffy seedbed. Leaving a muddy soil profile can lead to issues like sidewall compaction. Rather, the row cleaners should touch the surface just enough to allow for appropriate seeding depths in a good seedbed.Seed disc openers and gauge wheels
The most important part of crop seeding is even emergence – and consequently maintaining yield potential – which is controlled by seed disc openers and gauge wheels. The role of a seed disc opener is to create a furrow for proper seed placement while the gauge wheels firm the soil and maintain proper seeding depth.Seed disc openers
Check trueness from Original Equipment Manufacturer (OEM)
Seed disc openers should ride true to the direction of travel. To check trueness, follow these steps:- Put a 5/8-inch bolt or one that fits the center of the seed disc bearing into a bench vise and make sure it’s plumb.
- Slide the disc over the bolt.
- Position a 90-degree carpenter’s framing square perpendicular to the seed disc.
- Spin the disc slowly and watch for any change in distance to determine if the seed disc opener is riding true.
Setting disc openers
To create the critical ‘V’ opening for seed placement, disc openers require a certain amount of overlap. To easily measure contact, slide a business card between the discs until it catches. Take a second card and slide it from the other side until it too catches, then measure the distance between the two cards. Rotate the discs and measure these contact points in at least three other places.Recommended overlap will depend on disc blade thickness (check OEM specifications):
- 3 mm blade: 2 to 2-1/2 inches
- 3.5 mm blade: 1-1/2 to 2 inches
- 4 mm blade: 1 inch
Wear and tear
Seed disc openers should be adjusted and inspected every year. Once ½-inch is worn from the original disc diameter, it should be replaced. Similarly, if discs are worn, dull, or edges damaged from impacts, they should also be replaced. Replacing worn seed disc openers is one of the best returns on investment one can make.Gauge wheels
Gauge wheels are the 2nd most important part of the planter for achieving good seed placement. Not only do they hold soil down along the seed disc openers, but they also press water up to the seed and firm the furrow for good seed-to-soil contact.The standard gauge wheel is about 4-1/2 inches in width. The inner lip and convex shape are designed for less drag as the wheel rolls on the soil surface.
Narrower wheels – 2-1/2 to 3 inches - reduce residue riding and achieve more consistent furrow depth in high residue situations. They also allow soybeans to be planted closer to last year’s corn rows (in no-till situations) and can be a space saver if row units are crowded.
Check that the wheels are a good fit to the seed disc opener. Make sure that there is no wear in any bushings or bearings, or gauge wheel arms and connection points so that wheels have true flush contact with the soil. Also inspect the gauge wheel arm for wear at the contact to the gauge wheel depth stop as this controls the furrow depth.
The pound of margin – or net applied force – for gauge wheels on soil will vary year-to-year and change with crop conditions. If the pressure is too light, the furrow will not close correctly resulting in uneven seed-to-soil and water contact. Conversely, if the pressure is too heavy, strong furrow walls or compaction can form which will hinder root development and stand establishment.
The trick is adjusting to changing crop conditions. Planting in early spring when soils are wet or at slower speeds requires less pounds of force on gauge wheels. Conversely, planting when soils are dry requires more pressure to bring water up to the seeds. Coarse-textured soils are more forgiving, since they are less prone to compaction. However, water holding capacity is more of a concern in these soils, so higher pressure on the gauge wheels is likely required. In addition, the increased friction of sandy soils can wear disc openers and gauge wheels faster, so check for damage.
Seed meter units
Graphite is used in modern seed meter units with pneumatic systems to increase seed flowability by reducing both static electricity and friction. Reducing friction also helps maintain seed treatments.Graphite is typically added in an 80/20 talc to graphite ratio mix. One-fourth cup is adequate for 80,000 corn seeds or 140,000 soybean seeds. If conditions are humid, a 70/30 mix or just added graphite can be used to keep seed dry and meters functioning.
Finally, remember to adjust the vacuum pressure to minimize seed skips. Corn research shows there is a greater net yield penalty from skipped seed drops as opposed to double seed drops.
Bottom line
“Take care of the hardware so there’s more time for the electronic gremlins,” states Pfarr. “And of course, get out of the cab and dig around before and after the closing systems to check the furrow formation and seed depth.”Even corn emergence protects yield potential
Forecast outlook
After a relatively dry spring, the NOAA forecast predicts below normal precipitation for May across the state, but normal levels for the rest of growing season, except for western MN which is predicted to be drier than normal. Timely rains will be needed to avoid temporary drought stress in early July and beyond in western MN.Above normal temperatures are predicted for May and normal temperatures for the remainder of the growing season throughout the state.
Planting progress
According to the most recent NASS report, forty-four percent of the corn in Minnesota has been planted. This varies by region with currently much of the planting complete in western Minnesota and about 60% complete in regions that received more rain.Soil temperatures and the weather are favorable for finishing both corn and soybeans before the next rain event. With growing degree days (GDD) accumulating, it’s important to get the crop in the ground soon in good soil conditions, according to Dr. Coulter.
Minimizing risks for uneven emergence
Corn seeds must imbibe 50% of their weight in water to break dormancy and germinate. If plants emerge within a 3-4 day window, then yield potential should be maximized under most conditions.Anything that inhibits uniform and consistent moisture around the seed can hinder emergence and lead to uneven stands: inadequate seed-to-soil contact, cloddy soil, surface compaction, and/or crusting. For example, clods –formed when tillage is performed on wet soils – create large air pockets around the seed that inhibit even imbibition of water. Similarly, crusting can hinder emergence leading to uneven stands.
What are the effects of uneven emergence? Plants that are 1 leaf stage behind can lose 20% yield potential, while plants that are 2 leaf stages behind can lose up to 50% of normal yield. Neighboring plants can compensate for these losses to some degree, but can’t completely make up the difference, illustrating the importance of planting into good soil conditions.
On dry soils in western MN with little residue, seedlings may be cut off by soil particles that have been picked up and carried under windy conditions. Damaged corn seedlings should regrow, but uneven stands may result if this occurs.
Watch out for crusting if heavy rains occur on these soils and have your rotary hoe ready to break it up. Stands can typically be increased by 2,000 to 3,000 plants per acre by taking action. A few plants will be lost in the operation, but benefits outweigh losses.
Remember that planting date is important, too. Plant corn by May 10 to maintain full yield potential. Yields decline after that date, but the forecast is favorable for planting in a timely manner and delayed planting is currently not a concern.
The outlook for northwestern MN is somewhat cooler and a little behind southern MN, but very good yields can be achieved in this part of the state. However, this region does tend to be drier overall and can face late season drought. The season can also end abruptly with a hard freeze before corn reaches maturity. As a caution, don’t push hybrid relative maturity too much due to the potential for a shorter growing season and delayed planting due to cold, wet soils. Select hybrids that you know have a good likelihood of making it to maturity before harvest.
Thanks to the Soybean Research and Promotion Council and the Corn Research and Promotion Council for their generous support of this program.
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