Corn profitability: A function of planting rate and depth
Is your corn up and soaking in the sunshine, or is it struggling to emerge and has a stressed and ragged appearance? Even emergence means every plant has the same chance to succeed, but uneven emergence means first up and out will have a better chance at nutrients and never be shaded like the last up and out seedlings. Getting your crop off to a good start means a better chance at higher yield and higher profitability, if that is where you want to be.
Good efforts at corn production are obvious, once you think about it and understand the potential advantage. Ohio State University agronomist Peter Thomison reports in his weekly newsletter that tillage should only be used when necessary. When wet soil is worked, clods will hang around throughout the year, and fuel will be consumed unnecessarily to break them up. Shallow compaction also results, and spring is not the best time for deep tillage.
While the early spring has given many farmers the chance to complete their planting operations earlier than normal, Thomison says corn should be in the ground by early May. His asterisk on that rule of thumb is when soils are dry and showers are anticipated. His suggestion is to begin planting prior to the optimum date because you may only get one out of three days in which to plant. Thomison says avoid early planting on soils prone to ponding, because “mudding in” seed will delay emergence if the kernel is absorbing cold water instead of warm. He says, “Such injury in corn seed ruptures cell membranes and results in aborted radicles, proliferation of seminal roots, and delayed seedling growth. When temperatures remain at or below 50 degree F after planting, damage to germinating seed is particularly severe.” And he stresses that any replanting will be done without your first choice on a corn hybrid.
Thomison says planting depth should depend on soil conditions and temperature. The key is to find the proper depth to put the seed into the optimum temperature and moisture zone for its germination and emergence. But he says that will vary.
- 1.5 to 2 inches should provide frost protection and good root development.
- If the soil is moist and evaporative rate low, then the seed should be no deeper than 1.5 in.
- As the evaporative rate increases, planting depth should increase.
- If planting in late May or early June when soils dry rapidly, 2.5 in. depth may be required.
- If the planting depth is too shallow, secondary root development will suffer.
- Planting at a shallow depth will also allow the seedling to absorb herbicides.
- Corn planted less than 1 inch will result in a yield that is at least 14% less.
Thomison says the planting rate should be adjusted to reflect the potential soil productivity.
- Higher seeding rates should be reserved for soils with higher fertility and water holding capacity.
- A final stand of 33,000 may be required to maximize yields.
- Lower seeding rates are recommended for droughty soils or late planting, which are planted after June 1
- Seeding rates can also be reduced to lower production expense, but that alternative usually costs more than it benefits.
- Adjust the seeding rate 10% to 15% higher if emergence problems are anticipated due to an early planting date.
Yield potential is increased if emergence is uniform and a good seedbed can be created with reduced tillage. Planting depth should be determined by temperature and moisture friendliness to the seedling. Planting rate should be determined by the soil fertility and water holding capacity.
Source: FarmGate blog