Corn and Soybean
Replanting Considerations
The ideal planting time for
corn and soybeans lasts only a few days, and in most years, planting
outside of this window of opportunity will reduce yields. In these situations,
it is expected that final stands will be reduced 5 to 10% from the original
seeding rates. However, farmers are periodically confronted by additional
stand loss due to unexpected factors such as a late frost, hailstorms,
insect attack, herbicide/fertilizer injury, flooded field or unfavorable
seedbeds. When stands are less than desired, you may need to consider
replanting the field.
The decision to replant has
no formula answer but depends upon the facts surrounding each situation.
Some of the information that needs to be collected and considered includes:
-
Original target plant
population (approximately 90-95 percent of seeding rate).
-
Cause of the decreased
plant stand.
-
Plant stand after damage.
-
Uniformity of plant
stands after damage.
-
Original planting date.
-
Possible replanting
date.
-
Likely replanting pest
control and seed costs.
Corn Considerations
Do not make an assessment
of a poor corn stand too quickly! A corn plant’s growing point
remains protected below the soil surface until six or seven leaves have
emerged. Therefore, early damage to the above ground plant does not
necessarily kill the plant.
When determining stand counts,
also note the distribution within a row. Yield losses are caused not
only by the loss of plants but also by an uneven distribution of the
remaining plants. Research studies have confirmed that the more numerous
and longer the gaps between plants within a row, the greater the yield
reduction.
When stands are less than
desired, you may consider replanting the field. Base this decision on
the anticipated cost of replanting compared to the potential yield gain.
In many cases, it is advisable to leave a reduced stand and forego replanting,
since the yield potential of the replanted corn may not be high enough
to justify the cost. Many universities have published charts that show
estimated grain yields for various planting dates and population rates.
Use data from your state as a guide for estimating the yield of replanted
corn.
Soybean Considerations
Unlike corn, a soybean’s
growing point is not protected below the soil surface. As a soybean
plant emerges in the spring, the growing point is positioned above the
soil surface and vulnerable to damage.
Farmers often underestimate
the yield potential of a decreased stand! Soybeans have a tremendous
ability to compensate for low populations or gaps in rows with little
or no loss of yield. Replanting soybeans will, in most situations, not
result in yields higher than those produced by a deficient stand due
to the yield penalty for delayed replanting.
In most situations, farmers
should not consider replanting uniform, thin stands unless the plant
population is less than 50,000 plants per acre, provided the weed control
and soil moisture are adequate. Replanted soybeans will rarely have
higher yields than a timely planted, thin, uniform stand.
