Optimum Planting Conditions and Seed Placement for Corn-Alabama and Georgia
After a long winter and the arrival of spring, many growers want to get into the field. However, planting corn too early,
under poor conditions, can have a negative impact on yield. Planting date is one of the few factors a grower has control
over during the life of the crop and trying to get the best start possible is critical. It is important to plant according to soil
temperature and conditions as opposed to the calendar. When conditions are fit, proper seed depth and planting
density are critical to maximize yield potential.
Optimum Temperatures
The optimum soil temperature for corn germination is 55° F. Temperatures below the
optimum can cause seeds to remain dormant and become more vulnerable to diseases,
insects, and animal predators. Crops should be planted when soil temperatures are
optimal and within the target dates for the region. Keep in mind these dates are based
on the average year and the use of short or long relative maturity corn products will
affect these target dates. In addition, planting into cold and/or wet soils can lead to
numerous problems.
Saturated and Flooded Soils
Along with soil temperature, adequate soil moisture and high soil oxygen concentration
are favorable for germination and plant growth. In this region, planting is often driven by
soil moisture content. Saturated soils, which may include flooded or ponded soils, can
have a negative impact on emergence, even with high quality seed lots. The main side
effects include plant growth restriction and decreased oxygen availability to the plant.
For instance, saturated soils can inhibit root growth, leaf area expansion, and the
photosynthetic process. Young plants may develop yellow leaves due to slowing of
photosynthesis and plant growth. A prolonged period of saturated soil can reduce
germination and emergence due to lack of oxygen. In addition, portions of roots may
die as a result of no oxygen. However, there is still a chance for survival unless the
growing point is damaged.
Figure 1. Corn planting should begin only after soil
temperatures warm to 55OF for three days in a row.
Soil Crusting
The longer an area remains saturated, the higher the risk of plant death. Experts believe
that young corn can survive approximately 4 days of flooding if temperatures are
relatively cool (mid-60°'s F or cooler)3. If temperatures are warm (mid-70°'s F or warmer)
survival will be less than 4 days. Warmer weather may shorten these durations.
Soil crusting can occur when a crust layer forms on
the soil surface as wet soils dry. The crust layer can
delay or prevent seedling emergence. Crusting may
be more common in fields with fine textured soils,
low organic matter, and little surface residue,
especially where excessive tillage has taken place. A
rotary hoe can break up the crust and aid seedling
emergence. Timing is essential and breaking the
crust as soon as possible is most beneficial. If seeds
are not infected with disease, cooler soils will allow
seedlings to survive longer when trying to break
through the crust.
Soil Compaction
Corn Planting
Soil compaction takes place when soil particles are pressed together resulting in
decreased pore space and increased soil density. Compaction can result in yield
reductions due to decreases in seedling germination, root and plant growth, and nutrient
uptake. It is important to realize the majority of soil compaction can take place from
equipment passes over a field. Research indicates approximately 80% of soil
compaction happens on the first pass, while subsequent passes cause additional, but
progressively less, compaction. The best form of management is prevention. That
means staying out of the field until conditions for field work have improved. If mud sticks
to the tires and ruts are deeper than an inch, it is too wet to be in the field.
“The optimum time for planting corn is when the soil
temperature is 55O F or higher in the seed zone for 3
days in a row and the air temperature will allow that
same trend or warmer to continue,” says Dewey Lee,
extension agronomist, University of Georgia. “That’s
usually the first of March in South Georgia and Alabama, but it could occur earlier. History suggests
that optimum conditions generally occur about 2 to 3
weeks later for middle Georgia and two weeks after
that for north Georgia.”1
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Optimum Planting Conditions and Seed Placement for Corn-Alabama and Georgia
Decreases in corn yield due to uneven emergence arise when larger,
earlier emerging plants compete with the smaller, later emerging
plants. There are many different reasons why uneven emergence in
corn can occur. A few examples are: soil moisture variability in the
seed zone, soil temperature variability in the seed zone, soil crusting,
improper planting depth, and insect or disease damage. Poor seed-to
-soil contact can also cause uneven emergence due to cloddy soils
and worn or misadjusted coulters or disc openers. Many of the
factors that cause uneven emergence can be avoided by waiting to
plant until conditions are fit for planting.
Corn seed placement is critical to help maximize yield potential.
Extension agronomist Dewey Lee recommends planting 1.5 to 2
inches deep. “Planting too shallow can result in poor nodal root
development. Shallow planting can also increase the risk of injury from
some soil-applied herbicides. Planting when the soil is too wet can
cause sidewall compaction and poor root development. Growers
without irrigation should wait for soil moisture before planting. I’d
rather wait 4 or 5 days for moisture than risk an uneven stand by
planting into dry soils,” he says.1
Generally, corn yield potential will become greater with increasing
populations6,7. However, the optimum plant population density can
vary depending on product genetics8,9,10. Factors such as plant
structure and ear placement can influence weather and insect-induced
lodging6. Consequently, many Southern producers plant corn at lower
than optimal plant populations, which may decrease yield potential
and profit. To help reach optimum yield potential, the recommended
planting populations for the latest DEKALB® brand corn products are
shown in Figure 1.
Summary
Planting when soil temperature and conditions are favorable is very
important to give the crop the best chance of emerging properly and
getting off to a good start. Waiting for good soil temperatures and
planting conditions may help avoid disease, lack of oxygen to the
seeds, and restricted plant growth which can all lead to poor
emergence. However in some instances, such as a late spring frost,
injury may be unavoidable. Rushing to plant in cold, wet conditions
can lead to problems that can reduce yield potential.
When conditions are fit for planting, proper seed depth and planting
density are critical to maximize yield potential. Lodging is one issue
associated with planting too shallow and at higher than optimum
planting densities. Emergence problems associated with planting
deeper than necessary and planting at lower than optimum
populations can also decrease yield potential.
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Average Yield by Population
Yield (bu/acre)
Corn smaller than the V6 (six leaf) growth stage can tolerate a light
frost if the temperature does not drop below 30° F4. A moderate frost
to corn at the V6 growth stage or smaller will injure the existing corn
leaves. However, new leaf growth can occur in four to five days, which
allows the plant to fully recover. As a corn plant’s growing point
reaches the soil surface, the chance for permanent injury increases, as
well as the chance for uneven emergence.
220
210
200
190
180
170
160
150
140
33000
36000
39000
Figure 2. Average yield of different DEKALB® Brand corn products at three
different plant populations. Source: 2012 Scott Learning Center Demo Trial5.
Sources: 1Personal interview with Dr. Dewey Lee, extension agronomist, University of Georgia. 2Boman, R. 2010. Soil Temperatures for planting cotton. USDAARS. Available on-line: http://www.plainscotton.org; 3Nielsen, R.L., 2008. Effects
of flooding or ponding on young corn. Corn News Network Articles. June 2008;
4
Kruse, K.S. et al. November 2011. Corn Hybrids for Grain 2012. Louisiana State
University Ag Center Research and Extension. Publication No. 2827; 5Evaluation
of DEKALB® Brand corn products to planting density. 2012 Scott Learning Center
Summary. 6Thomason, W. 2005. Corn plant populations and yield goals. Virginia Tech Cooperative Extension. Crop and Soil Environmental News, March
2005. Available online: www.ext.vt.edu/; 7Williams, W.A., Loomis, et al. 1968.
Canopy architecture at various population densities and the growth and grain
yield of corn. Crop Sci. 8:303-308; 8Collins, W.K., Russell, W.A., Ederhart, S.A.
1965. Performance of two-ear type of Corn Belt maize. Crop Sci. 5:113-116;
9
Cox, W.J. 1996. Whole-plant physiological and yield responses of maize to
plant density. Agron. J. 88:489-496; 10Widdicombe, W.D. and Thelen, K.D. 2002.
Row width and plant density effects on corn grain production in the northern Corn
Belt. Agron. J. 94:1020-1023; Additional references used in developing this publication: Al-Kaisi, M. and Pedersen, P. 2007. Wet conditions: challenges and
opportunities. Iowa State University Extension. Integrated Crop Management.
ICM > 2007 > IC-498 (9) -- May 7, 2007; Elmore, R. and Abendroth, L. 2008.
Flooded corn and saturated soils. Iowa State University Extension. May, 30,
2008; Iowa State University. 2006. Did the recent cold weather affect corn germination and seedling growth? Integrated Crop Management. May 1, 2006; Kennel, H. S. 2011. Seed germination. Washington State University Extension;
Nielsen, R.L. 2008. Crappy stands of corn. Dept. of Agronomy. Purdue Univ. May
25, 2006; Nielsen, R.L. 2008. More thoughts on late corn planting. Purdue University. Corny News Network Articles. May 23, 2008; Thomison. P.R. 1990.
Assessing effects of uneven emergence in corn fields. Ohio State University Extension. Agronomy Facts. Publication no. AGF-122-90.
For additional agronomic information, please contact your Asgrow®,
DEKALB® and Deltapine® Brands Seed Representative.
Individual results may vary, and performance may vary from location to location and from year
to year. This result may not be an indicator of results you may obtain as local growing, soil and
weather conditions may vary. Growers should evaluate data from multiple locations and years
whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Asgrow and the A Design®, Asgrow®, DEKALB Wingwear and Design® and DEKALB® are
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