Take a Stand
Now is the time to walk those corn fields to evaluate stands and proficiency of your planter for placing seed in the ground at the right depth, spacing and right firmness. Wide-ranging weather and varying soil conditions have also given us plenty of reasons to tweak planter settings to match conditions in each field -- and sometimes within fields.
To evaluate plant stands, count the number of plants in a length of row (17 feet 5 inches in 30-inch rows and 26 feet 2 inches in 20-inch rows) and multiply by 1,000. Repeat this math exercise at least a dozen times throughout the field. If you drop 33,000 seeds and plant in good conditions, use a good planter with a good window of weather, you should end up with 32,500 emerged plants.
A loss of 2,000 plants per acre was the norm a decade ago. Today, improvements in planters, genetics, seed treatments and planting skills are resulting in much higher stand counts.
Still, plants can be lost due to planter malfunctions, insect or disease damage, cold or wet soils, unfavorable weather conditions after planting and poor residue management at planting.
Planter problems usually show up as a repeatable pattern. Soil issues are often isolated and occur in spots in a field. Insect and disease damage can be more isolated and random throughout the field (depending on pest).
P[L1] D[0x0] M[300x250] OOP[F] ADUNIT[] T[]
Take time to evaluate stand and emergence uniformity across the field. An unevenly spaced stand will yield less than an even stand with the same number of plants. Emergence delays influence yield too. Later-emerging plants fall behind and consume resources -- they often produce a smaller ear or are barren. The rule of thumb is to have seeds emerge in a two-day window to get the desired stand uniformity.
Use a tape measure to count the number of plants and record the distance between individual plants in 20-foot lengths. Repeat six to 10 times across the field. Add readings together and divide by the number of plants observed to calculate the distance between plants. The goal is plus or minus 2.75 inches. Expect a 4- to 5-bushel-per-acre yield reduction for each inch of variation greater than 2.75 inches.
Uneven emergence can be caused by variations in soil moisture and temperature, seed-to-soil contact, hair-pinning residue around the seed, soil crusting, seed depth and seeding blight. Any loss in population or uneven emergence can also allow light to penetrate the canopy. Weeds in those areas can easily overrun a poor stand.
Do some digging if you see pockets of seedlings that are behind the average plant size. Look at planting depth. Was there any crusting or sidewall compaction? Was the seedling deformed or damaged? Did insects such as cutworms cut the plant above the soil surface?
Today's planters are equipped with the technology to produce as-planted maps that can help point you to problems. Still, there's no substitute for getting a firsthand look right now while the corn is small. If what looks like a picket fence from a distance turns out to be just that, then you can celebrate a job well done.
For more information on taking stand evaluations:
http://www.thefieldposition.com/…
Dan Davidson can be reached at AskDrDan@dtn.com
Follow Dan Davidson on Twitter @dandavidsondtn
(PS/AG/CZ)
Copyright 2015 DTN/The Progressive Farmer. All rights reserved.