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September 2010 Archive for Ask an Agronomist

RSS By: Farm Journal Agronomists, Farm Journal

Have your agronomic questions answered by a Farm Journal agronomist. E-mail us directly at TestPlots@FarmJournal.com, and we’ll respond on this blog to provide an interactive dialogue.

Factors That Impact Alfalfa Reseeding Success

Sep 28, 2010

Question: I have an alfalfa field that’s on a hillside that I want to reseed back into hay as this is the best way to manage this highly erodible ground.  My plan was to seed it with some wheat to get some quick plant establishment along with the alfalfa in the grass seeder on my drill.  A friend of mine told me I shouldn’t plant alfalfa back in--that I need to put the ground in straight wheat for a year because of some toxin alfalfa leaves in the ground, which will inhibit germination of the new seed. What do you think?

 
Answer: New alfalfa seedlings can die when seeded into an established alfalfa stand. This is known as autotoxicity. Autotoxicity can result in poor germination and reduced vigor of alfalfa seedlings replanted into destroyed (tilled or herbicide plus no-till) alfalfa fields without rotation (Volenec, Purdue). These negative effects come mainly come from the leaves and flowers. To reduce your risk, it is recommended that you wait at least one year before reseeding alfalfa into the field. If waiting one year before reseeding is not possible, there are a few things you can do to reduce autotoxicity. Tillage can help with this situation; however, your highly erodible fields may not allow that. If you are planning to no-till the new stand in, waiting four weeks after the old stand has been killed will help reduce autotoxicity. Rainfall and sandy soils tend to leach the toxin sooner which again reduces the autotoxicity. Purdue University has a great extension bulletin with more specifics, see the link below. 
 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.

You Can Address Marestail Control This Fall

Sep 24, 2010

Question: Could you please tell me what will kill marestail? The neighbor has it in his soybeans, and it is spreading over into our farm.

 
Answer: The majority of marestail emerges in the fall; however, some can also emerge in the spring or early summer. It is best to control marestail in the late fall or early spring. An application of 2,4-D ester in the fall will greatly reduce marestail populations the following spring. If you cannot apply in the fall, make a spring application when the marestail weeds are less than 2-inches tall. The combination of 2,4-D ester and glyphosate is a very effective and economical treatment. Keep in mind that many populations of marestail are ALS resistant and some are glyphosate resistant. Ohio State University has a great extension bulletin with more specifics. See the following link:
 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set-up, scouting, and other questions to: TestPlots@FarmJournal.com.

Consider Corn Moisture Levels

Sep 22, 2010

We answered a question earlier this week about the optimum corn moisture level at which to harvest. Del Voight, at Pennsylvania State University, provided some information via his blog that would be useful to farmers who are ready to start corn harvest but aren't sure about their corn moisture levels. You can read his blog at:

http://delvoightcrops.blogspot.com/2010/09/moisture-to-harvest-corn.html

 

What Is The Best Moisture Level For Harvesting Corn?

Sep 20, 2010

Question: What’s your recommendation on the best moisture level for harvesting corn? We’re actually getting a little dry here, but our corn isn’t at 25% yet. That’s what we harvested at the last couple of years when we were really wet.

Answer:  A lot of people had to harvest wet corn the past two years, but don’t let the past two years dictate what you do this season. Check-in with your seed dealer for specific recommendations on when to harvest your corn, because the “right” moisture level can vary by hybrid. Also, check corn moisture levels in a number of your fields, as the moisture level can vary quite a bit from field-to-field. Harvest the fields nearest to the optimum moisture levels first.
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.
 

How Much Potash Is Needed To Replenish An Alfalfa Stand?

Sep 17, 2010

Question: If 4 ton/acre of alfalfa is removed, how much potash is required to replenish the stand?

 Answer: Alfalfa is a big user of potassium. For every 1 ton of alfalfa, 60 lbs of K2O per acre are removed. This is equivalent to 100 lbs of potash (0-0-60). Your alfalfa yield of 4 ton/acre would need 400 lbs/acre of potash to meet crop removal rates. For alfalfa, it is recommended that the potash be applied at least two times per growing season. Ideally, apply the potash after the first and last cuttings of the season. The nutrient removal rates are book values to give us a general idea; you should also pull soil tests every two years to monitor your nutrient levels and pH. Also, keep in mind that alfalfa is highly responsive to boron as well. 
 
 
  Alfalfa Nutrient Removal Rates
Crop
Unit
P2O5
K2O
Mg
Ca
S
Alfalfa
Ton
15.0
60.0
5.0
28.0
5.0
 
 
lbs of nutrient removed per ton
 
Alfalfa Fertilizer Removal Rates
 
Yield Goal
P2O5
MAP
DAP
 
 
Alfalfa
4
60
115
130
 
 
 
 
 
 
 
 
 
 
 
K2O
Potash
 
 
 
 
 
240
400
lbs per acre for 4 ton
 
 
 
 
 
 
 

 

This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.
 

 

 

 

 

 

Farmers See Abnormal Corn Ear Development This Year

Sep 14, 2010

Farmers See Abnormal Ear Development This Season 

If you saw abnormal corn ear development in your fields this year, you weren’t alone. We’ve received a number of reports and questions from farmers across the Midwest who saw various corn ear abnormalities – including curved, bent and twisted ears.
 
Bent ears develop when variations in kernel set occur on one side of the corn ear versus the other. Various nutrient deficiencies and drought typically contribute to the problem.
 
Under nitrogen stress or drought we can see kernel abortion down one side of the ear and not the other side, causing the ear to bend when the kernels on the good side continue to grow and develop. The thing I look for is kernel abortion on the tip or coming down one side of the ear.
 
If the tip of the corn ear is curved and only partially filled up, the issue may be a boron deficiency. Twisted corn ears or irregular kernel rows can indicate insufficient phosphorus. Pull an ear leaf tissue test and a soil sample to rule out a boron or phosphorus deficiency. 
 
For more information on abnormal corn ear development and the factors that contribute to it, check out the excellent information and poster of examples provided by the Ohio State University at the following link.
 
 
 

This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.

Know How Your Corn Hybrid Utilizes Nitrogen

Sep 10, 2010

Question: I know you say understanding how your corn hybrids use nitrogen is important, but I’m not sure why. I’m picking hybrids for next year and would like to know about that.

Answer: Knowing how a corn hybrid responds to nitrogen can help you determine where to place that particular hybrid in your fields and how to manage the nitrogen that it needs. Part of that process includes knowing that the amount of carbon present in a field impacts nitrogen availability. I call this the carbon penalty, and I believe it’s good that growers know that large volumes of crop residue will lead to the immobilization of nitrogen in their fields. In corn-on-corn or fields with a high carbon penalty, plan on using extra caution in managing nitrogen with those hybrids that prefer it early. If you plant hybrids that like nitrogen late on soils with high susceptibility to leaching and denitrification, a late-season nitrogen application may be beneficial.
 
Check out these tools for more information about nitrogen use in corn.
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.
 

How Do I Select A Tire That Won't Contribute To Compaction?

Sep 07, 2010

Question: We are looking into how to manage compaction better. In a 30-inch row set up what is better--a wider tire (520/85r46 @ 8.5 psi of ground pressure) which is closer to the row or a narrower tire (480/80R50 @ 10.5 psi of ground pressure) that is further away from row? Is it better to have less ground pressure closer to the row or a little more ground pressure further away from the row?

Answer: Tire inflation pressure is the primary factor affecting surface soil compaction. By selecting large, low-pressure tires we can reduce compaction. Also, adding duals can help with this as well. Even though we would be closer to the row with the wider tire, the impact of down force would be less since the tire is wider and runs with lower pressure. So, in the 30-inch row setup, I would choose the wider tire with the lower pressure. 
 
 
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.

Curved Ears Indicate Insufficient Nitrogen

Sep 02, 2010

Question: Why am I seeing curved corn ears in my field this summer?

Answer: Curved ears, also called banana ears, are an indication of poor pollination due to a nitrogen deficiency. If the problem resulted from insufficient nitrogen, you usually find that curved ears also have a barren area or strip on one of their sides where no kernels are present. This problem is fairly common this season throughout the Midwest because of heavy rains early on which resulted in nitrogen leaching from the soil profile.
This blog is provided as an interactive way for you to have your questions answered by our Farm Journal Agronomists. E-mail your nitrogen, soil fertility, soil density, planter set up, scouting, and other questions to TestPlots@FarmJournal.com.
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