It’s time to be evaluating stands
By KRISS NELSON
A good stand assessment at the beginning of the growing season can help better understand any potential issues now rather than from the combine.
Mark Licht, assistant professor and extension crop systems specialist at Iowa State University said looking at crop performance in the spring can not only help determine if there would be a need to re-plant, but looking beyond that to learn about any potential mechanical or operator error and to use some of those problem fields for comparison.
When looking at crop performance in stand assessments, it can be viewed in two ways:
- “We can use the fields that have some challenges, I call them because of sidewall compaction or whatever else,” he said. “We can use those fields as a sentinel plots to give us an indicator if we have wet weather, dry weather – those fields are already stressed, so they are going to maybe show stresses that may be affecting other fields in the future, they show stresses first.”
- Licht said the other side is if you have done a good stand assessment early in the year, you have given yourself or your client nine to 12 months to work on planter performance or operator performance to improve for next year.
“That gives the ability to adjust, whether they need to be replacing parts on the planter, need it maintained differently, set up differently, reconsider what speed they are going through the field,” he said. There are a lot of reasons why we want to be doing these stand assessments because it can help to start to decipher what we are seeing later in the year and improve things for subsequent years.”
Taking stand assessments
Licht said when it comes to taking stand assessments, he really likes to apply the “who, what, when and why” to the process.
“I think it is important to understand, in my opinion, the things that may not always get done to the fullest extent that I could,” he said.
Who should be doing these stand counts?
Licht said farmers, agronomists and crop scouts, just to name a few.
“If I think from a retail perspective, is the ability to start to be able to decipher what the stand was as it came out of the ground. Were there seeding issues? Planter issues? Or did we have seedling diseases? Or hopefully we aren’t looking at herbicide injury at this point of the game,” he said.
When making stand assessments Licht said to be looking for plant density, plant population, stand count, emergence uniformity and seedling vigor.
“We want to be able to identify if we don’t have uniform emergence we want to dig into why we don’t have that and what are the anomalies we are seeing,” he said. “What was the seed depth? Root growth issues? Sidewall compaction? Things like that.”
Licht said he prefers to start doing stand assessments somewhere after emergence to the V3 stage.
“Emergence is probably a little bit on the early side. Keep note of what the soil conditions were at and following planting. Some of the insect and disease things that might be a little easier to see once you get to the V1, V2 or V3 stages,” he said.
Check every field
“I am big proponent of we should be doing it in every field because every field got planted into different conditions, maybe using a different seed, may have different management from field to the next,” he said.
Be sure to know the history of weather events in each field and check all areas of the field.
“My recommendation is to kind of look at this like zone sampling,” he said. “Break the field up into 10 acre sections. Do a stand establishment once or twice in a 10 acre section and then go across the field.”
Checking soybean stands
When doing stand counts, Licht said a lot of times he measures 17 feet-5inches, but you may not want to do that with soybeans.
“If you are doing 17 feet, 5 inches for a 30 inch row in soybeans, now you may be counting 100 to 140 or 150 to 200 plants in that row length and that could take a little bit more time,” he said.
Licht recommends when taking soybean counts, is measuring four feet of a row; counting the number of plants in that row length in order to help estimate beans per foot.
Emergence uniformity versus plant spacing in soybeans
Licht said he is not as concerned about emergence uniformity in soybeans as much as he is about plant to plant spacing.
“I think trying to get those even spacing’s are more critical than making sure you are having soybeans emerging at the same date,” he said. “At the same point, I am probably not as concerned as a number of 2, 3, 4, 5-inch gaps than I am more concerned with plant spacing gaps of 12- to 24-inches or something in that range. Those tend to have more of an impact on yield than having the shorter gaps.”
If you are noticing large gaps between plants, Licht said one of the things you can do is pop open the seed furrow and look to see if the there is a seed there or a plant that just has not emerged yet.
You can also dig up these areas where we have a growth stage difference if you are concerned.
“If you dig them up and the soybeans that are further along were at a half inch or 3/4-inch seed depth versus the ones that are just emerging are down at 11/2 to 2 inches, that could explain that difference there,” he said.
After measuring 17 feet, 5 inches when assessing stand counts in corn, Licht said you are looking for how many plants are there for an estimation of plant population.
“After I do those counts, I start to assess that emergence uniformity. Do we have good spacing or not,” he said.
Again like soybeans, Licht said you can pop open the seed furrow to see if there is a seed there, a plant that didn’t emerge or a seed that didn’t drop.
“That can come back to estimating was it a planter performance issue or a biotic issue that came into play there,” he said.
If the corn is in the V1 to V2 stage, but have one plant that is still in the emergent stage, Licht said the question is why did that plant emerge so much later?
“Was there a cold stretch following planting so we could have some cold injury on the seed that affected this seed with this being weaker than the other seeds and so it had delayed germination, delayed emergence on it,” he said.
If it is just one plant in that row length, Licht said it’s probably not a huge concern or a huge issue, but something to make note of.
“If it occurs more frequently, that is definitely something to make note of so we can make improvements on the next year and we can also make some assessments based on the frequency of that delayed emergence and degree of that delay then we can start to assess are their yield impacts that we should be accounting for? Should we be considering the replant situation here,” he said.
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