Even as nitrogen-fixing plants, nitrogen deficiency in soybeans can be problematic for farmers. Soybeans can fix up to 50% of their own nitrogen while the other 50% is sourced from soil. Root development and soil health are key drivers of nitrogen deficiency.
A primary cause of nitrogen deficiency is poor inoculation. Rhizobia – the nitrogen-fixing bacterium responsible for prompting nodulation – cannot survive well in coarse, sandy or saturated soils. Cold and wet soils can also suppress rhizobia activity and reduce nodulation.
Soils with low pH can prevent root nodulation and reduce nitrogen absorption Flooding or highly saturated soils can also prevent nitrogen uptake, even if nodulation occurred successfully.
Scouting for Nitrogen Deficiency
Nitrogen is a mobile nutrient, moving throughout the entire plant. It moves to the newest leaves first, leaving the oldest leaves more susceptible to deficiency. In nitrogen-deficient soybeans, the lowest leaves will appear a pale shade of green or show signs of yellowing. Some leaves will also have dark green veins.
Be sure to check nitrogen levels in the soil before R1. As nodules can appear as soon as V1. Check the health of nodules by squeezing them open. If A pink color on the inside indicates that nodules are active and healthy.
Treatment and Implications
A single bushel of soybeans uses 4.2 pounds of nitrogen. Purdue University observed a 38% decrease in yield from nitrogen deficiency – a decline from 65 bu/acre to 40 bu/acre.Rhizobia population can carry over from season to season and continue to support soybean growth. We advise applying inoculantin fields where soybeans have not recently grown.The inoculantcan help to stimulate rhizobia activity and promote nodulation.
It is advised to apply 20 to 40 pounds of nitrogen per acre during the R3 growth stage. However, applying nitrogen at planting – especially too much nitrogen – does not increase yield and can actually reduce nodulation. It’s important to determine the best nitrogen application and treatment plan to fit your unique needs. Contact your Data Forard™ Advisor orLatham Representative to discuss your options.
Iron deficiency chlorosis (IDC) is a disorderthat appears in soybeans during the early stages of the growing season. IDC can reduce yield and lead to stunting if it goes unaddressed year to year. Every year, farmers lose over $100 million to IDC and yield loss estimates range from 20-30% in severe cases.
Credit: Soybean Research Information Network
What to Look For
Iron is an essential nutrient that supports key plant functions including nodulation, energy transfer and plant metabolism. Iron deficiency can reduce the absorption of other essential nutrients including nitrogen. Deficiency in iron prevents chlorophyll from forming which leads to the yellowing of leaves.
In soybeans with IDC, the youngest leaves will begin to turn yellow or white while the veins remain green. Unlike mobile nutrients such as nitrogen or potassium, iron is immobile within the plant. As a result, yellowing and signs of IDC will only be seen on newer growth. Beyond yellowing, severe cases of IDC can cause leaves to turn brown.
Causes and Implications
Upon testing, soils may have abundant levels of iron, but must be in a usable form.Wet soils, salty soils and soils with high pH (greater than 7.5) will cause IDC to occur as these factors prevent iron absorption. Calcareous or chalky soils are also favorable conditions for IDC.
IDC occurs most often in shallow areas that are wet where salts and carbonates have built-up overtime. Under these conditions, calcium particles bind to the soil, making the iron inaccessible to soybeans. Calcium carbonate neutralize acid in roots that is needed to make usable iron. For this reason, soils containing limestone with carbonate levels higher than 5% can make iron insoluble.
High nitrates can worsen IDC since absorbing nitrogen decreases the amount of usable iron. Fields with over 100 pounds of nitrogen per acre can be problematic for soybeans and lead to IDC.
Treatment
IDC cannot be managed in-season. We recommend selected a portfolio of defensive varieties to fight this in your fields. Check our line of Ironclad™ soybeans. Our Ironclad brand has been designed to fight this disorder.
Reducing stress levels for soybeans is critical for preventing IDC or worsening its impacts. Other factors including compaction, over-tillage and herbicide injuries can make soybeans more susceptible to chlorosis or lower their chances of overcoming the deficiency.
Soybean varieties that are resilient to IDC should be planted, especially if a field has produced soybeans with chlorosis in the past. In addition to selecting the right varieties, planting iron-coated seeds can be a way to combat the onset of IDC. In-furrow application of iron chelate fertilizer can also address IDC.
Rotational planting or companion cropping with oats are also solutions for preventing IDC. Intercropping soybeans with oats and wheat can reduce levels of soil nitrates that would otherwise lead to chlorosis. Contact your local Latham Representative to determine a treatment plan that meets your specific needs.
Armyworms and cutworms are known to reduce soybean stand and yield by feeding and cutting. Armyworms damage leaf tissue while cutworms clip young plants just above the soil. These worms are differentiated by their appearance.
Black Cutworm (Credit: Iowa State University)
Cutworm
Soybean cutworm species include dingy cutworm, variegated cutworm and black cutworm. Cutworms begin feeding on winter weeds before moving to soybean plants. Cutworms will burrow in the soil surrounding injured plants. Smaller larvae willfeed on leaves and larger larvae will cut the plants.
Scouting and Treatment
Dingy Cutworm (Credit: Purdue University)
Begin scouting for cutwormsat emergence. The most common signs of cutworm infestation are cut plants, discoloration or wilting leaves.Reduced tillage, no-till and corn on corn rotations can make cutworm infestation more likely. Legume cover crops can alsoattractcutworms. This protective vegetation should be removed from the soil at least two weeks before planting.
Mature soybeans are the most resilient to yield loss from cutworms. As advised by researchers from Iowa State University, insecticide treatment should also be applied if more than 20% of feeding damage is observed and larvae are smaller than ¾ inch in length.
Yellowstriped Armyworm (Oklahoma State)Fall Armyworm (University of Tennessee)
Armyworm
The yellow-striped armyworm and fall armyworm are two populararmyworm species. Armyworms grow to be two inches long and feed on both soybean leaves and pods.
Scouting and Treatment
Typically, only one generation of armyworms can be produced in the Midwest due to their inability to overwinter in the cold. Armyworms like to seek shelter in winter annual weeds and grasses. Poorly drained fields can also bean attractive environment for armyworms to dwell.
Applying insecticide is recommended when armyworms are less than one inch. Once armyworms mature and exceed 1 ¼ inches in size, they willstop feeding so it is unnecessaryto apply insecticide. Contact your local Latham Representative to assess the best options for treating armyworm and cutworm infestation in your soybeans.
Frost damage occurs in corn and soybeans when plants are exposed to freezing or below-freezing temperatures. Damage can occur to the plants above and below the soil when temperatures range from 28 to 32°F and colder. Corn and soybean plants exposed to air temperatures below 28°F are often lethal and prevent plants from undergoing full recovery from injuries.The key in assessing frost damage is waiting five days to allow for any potential growth recovery or rehabilitation to occur.
Credit: Michigan State University
Fall Frost in Soybeans
Once soybeans begin maturity and already have developed pods, they are most often immune from frost injury. Soybeans placed in narrow rows can have more protection from freezing air temperatures in being covered by leaf canopies. Pods growing on the lower portion of the plant are less vulnerable to frost damage than those on the top part of the canopy. Injured soybeans exhibit elongated pods that shrink to smaller than normal sizes upon drying. Most yield loss occurs during the full seed maturity stage.
Soybeans damaged by frost should be dried at a temperature no higher than 130°F and may have lower oil content. Both frost damaged corn and soybeans may also have delayed dry down.
Credit: University of Minnesota
Fall Frost in Corn
Frost-damaged corn can exhibit softened kernels prone to breakage and should be dried at temperatures below 160°F and be stored at a moisture level no higher than 14%. The storage life for frost-damaged corn will be cut in half and damaged corn should be handled separately from uninjured corn.
Imbibitional chilling occurs during the process by which crops absorb water prior to germinating, a phase known as imbibition. Under optimal conditions, seeds should be planted when soil temperatures are above 55°F. When seeds are planted in soils below optimal temperature, the uptake of cold water can damage cells and cause seeds to rupture. This can lead seeds to become shriveled and cause seedlings to emerge late, in a corkscrew shape, or not at all.
If an injured seed eventually develops into an emerged seedling, it can become more vulnerable to disease or damage from herbicides. The risk of imbibitional chilling especially increases when soil temperatures fall below 50°F. Imbibitional chilling or cold injury can occur within 24 to 36 hours of planting, making the relationship between planting timing and soil temperature critical.
Preventing Chilling Injury
As the injury to seedlings occurs after planting, there is little preventive action that can be taken aside from planting when soil temperature is optimal. In the best case, if enough time is afforded between planting and the drop in soil temperature, a seed is less likely to undergo chilling if it is able to absorb warm water. There are ways to determine if imbibitional chilling has occurred after planting. When scouting, look for signs of inconsistent emergence. If a plant looks to be missing, dig into the soil around the area to see if a seedling can be found. If it has a corkscrew shape, underwent leaf emergence below ground, or is missing parts, these are also signs of imbibitional chilling. Delayed emergence of a seed can be the result of reduced seed vigor that can result from imbibitional chilling.
Soil temperatures should be monitored and averaged for the week preceding the projected planting date. To determine the soil temperature on the chosen planting day, take the temperature of the soil just after sunrise – the coldest part of the subsequent 24-hour period. Soil temperature changes more slowly than air temperature, but air temperature can still be a strong indicator for what to expect with soil temperature. If it is projected that soil temperature will remain above 50°F for 24 to 48 hours after planting, imbibitional chilling can be avoided.
Many of our minds are already on the upcoming planting season. This week someone posed the following question, “How hard of a frost can soybeans withstand?”
It’s a great question, so I wanted to address the topic of early planting a bit, well, “earlier” than usual!
The first thing to keep in mind is that cold temperatures at or before planting can negatively affect the growing point of the plant. For corn, that growing point stays under the soil surface until the V5-V6 stage, helping protect the plant to a certain degree from colder weather spells for several weeks. For soybeans, however, the growing point comes out of the ground at emergence. Therefore, a soybean seedling is immediately vulnerable to cold weather.
Using a fungicide seed treatment will help protect young soybeans from seedling diseases at this early stage, but they are not designed to protect against cold temperatures. Soybeans typically require over 100 growing degree units (GDU’s) to accumulate before emergence, which is similar to corn that requires about 125 GDU’s. Abiding by the minimum soil temperature of 50 degrees Fahrenheit will keep you away from poor emergence and the seedling disease risk associated with soil temps below 50 degrees. That’s why I suggest watching the weather forecasts before you plant soybean seed, and do your best to ensure hard frosts (which take place at 28 degrees Fahrenheit) are no longer possible.
Remember, when soybeans emerge, they have a growing point at the base of each cotyledon and at the main shoot. The main shoot is the small leaves in-between the cotyledons. If you notice brown on the stem below the cotyledons, the plant will not recover. Early planting is proven to provide higher yields, but it is is fine balance between the two, so watch weather forecasts and soil temperatures so you can find the balance on your own farm.
Additional tips to keep in mind before planting:
Grab a clump of soil and watch how easily it crumbles. If it stays in a ball, conditions are NOT right for planting. If it crumbles easily, the soil is fit for planting.
Make sure your planting date is covered in your farm insurance policy – this includes your “do not plant before” dates. If you plant outside those dates, your insurance could be jeopardized.
Eastern Iowa farmers have been running long hours on soybeans for the past eight days. Soybean harvest is nearly complete, and many farmers are finishing corn. Fall tillage is right around the corner.
CENTRAL IOWA
Bryan Rohe
Harvest will wrap up in a week for many Central Iowa farms. Results have been variable, depending on soil types, drainage and weather events that occurredthroughout the growing season.
Now is a great time to evaluate decisions you made in 2018 and the changes you want to make for 2019. Jot down details about this year’s crop while they’re fresh in your mind. No detail is too small when you’re planning future crops.
One tool to make crop notes is Climate FieldView. You can overlay maps that show soil type, fertility and drainage – all of which contribute to your overall yield. You also can place pins in the exact location where you saw poor yields, tile issues or even a rock that you want to go back and pick up.
Did you know you can try Climate FieldView before you buy it? Ask me how! Call 877-GO-LATHAM (877.465.2842).
NORTHEAST IOWA & SOUTHEAST MINNESOTA
Craig Haaland
A Latham® dealer in Black Hawk County harvested this corn plot on October 25 under sunny skies with temperatures in the 50s. Not only was it a beautiful fall day, but Latham corn products were standing well after an especially challenging fall season. They were yielding well, too. Latham’s LH 5725 VT2 PRO RIB won the plot at 266.1 bushels per acre (bu/A). Second place went to LH 5635 VT2 PRO RIB at 248.6 bu/A. The earliest maturity planted in this plot was LH 5245 VT2 PRO RIB, which placed third at 235.6 bu/A.
WEST NORTH CENTRAL IOWA
Bart Peterson
On October 30, we harvested the Latham® SuperStrip plot today with FFA students in Belmond. Latham® dealer Eric Sturgeon was running the combine and his dad, Ron Sturgeon, was driving semi.
NORTH CENTRAL IOWA & SOUTH CENTRAL MINNESOTA
Cory Greiman
This week we harvested a Latham® corn plot south of Hampton. This plot was planted May 25 and harvested October 30. A bald eagle was flying overhead, most likely waiting for a “snack” to run out of the standing corn. Latham’s LH 5245 VT PRO RIB is having a great year! It topped this plot at 236 bushels per acre (bu/A) at 16.4% moisture. Yesterday I got a call that a whole field of 5245 yielded 252 bu/A at 16.5% moisture in the Cylinder area.
NORTHWEST IOWA
Darin Chapman
Farmers in Northwest Iowa are finishing up with soybean harvest and switching to corn. As expected, yields are extremely variable this year due to the challenging weather we received. Farms with tile are showing a major return on the investment.
Latham’s Seed-2-Soil® program is a great way to make decisions on where to place tile on your farm. This is just one of the many reasons it’s important to manage your farm operation with a Precision Ag platform. Contact me to learn more about Latham’s Data Forward and FieldxField services, which are designed to reduce your risk and maximize yield.
The attached photo shows where tile would be beneficial.
WESTERN IOWA & EASTERN NEBRASKA
Larry Krapfl
This is a common sight across western Iowa and eastern Nebraska. Soybean harvest is moving slower than expected fields are fields are wet. I’d say 20 to 30 percent of the soybeans are still standing in the Missouri River bottom. The river is running high and no one wants to get his combine stuck in the mud.
SOUTHERN WISCONSIN
Greg Mair
Soybean harvest is wrapping up in southern Wisconsin. Many farmers are experiencing a new challenge in soybeans and that’s how to effectively control waterhemp. The good news is, whatever route you take for waterhemp control, Latham Hi‑Tech Seeds offers a soybean that will work for you!
Technology advancements usually bring new genetics, and that appears to be the case this year with Xtend® soybean products. Xtend soybeans outperformed Roundup Ready 2 (RR2Y) soybeans by almost 5 bushels per acre in Latham’s Watertown plot. Latham brand L 1845 R2X and L 2295 R2X have performed well in back-to-back stressful growing seasons in southern Wisconsin. These two products would make a great soybean package for your acres whether you’re looking to control waterhemp with Xtend herbicide technology or just looking for high-yielding genetics with an outstanding disease package.
NORTHERN WISCONSIN
Joe Salter
Harvest has been steady over the last week. Soybeans are close to 60 percent complete, and many farmers are rolling into corn. I took off my first Latham soybean plot on October 30, and Latham brand L 1438 R2 did really well. The following soybeans also performed really well: L 0982 R2, L 1092 R2X and L 1184 R2X. In addition, we compared L 1438 R2 treated and untreated. The treated version out-yield the untreated seed by 4 bushels. For more info on our treatment options, please visit our website or contact me at 1.877.GO.LATHAM (1.877.465.2842).
NORTHERN MINNESOTA
Ken Highness
This 160-acre field of Latham’s LH 3877 VT2 PRO RIB was harvested October 30, averaging 202 bushels per acre dry and a weight of 56.2.
SOUTHEAST SOUTH DAKOTA
Ramie Coughlin
Harvest continues in Southeast South Dakota (SESD). Last week many farmers finished harvesting soybeans and switched to corn. This week a few farmers even finished their 2018 harvest. Yields are impressive! Latham’s 4452 RR out-yielded DeKalb’s 91-day VT2P by 17 bushel in Hamlin County. See how Latham has been performing against the competition by checking out the F.I.R.S.T. Trial Results. Latham® brand soybeans are once again having a great year, and we’re waiting to receive corn results as not many corn plots have yet been harvested. I’m excited to take out our SuperStrip plots in the coming week. After a slow start this spring, things really turned around and it has been a fun harvest for most.
NORTHEAST SOUTH DAKOTA
James Keltgen
Soybean harvest is pretty much done in Northeast South Dakota. Some farmers have also finished corn while others are just getting a good start. We’re hearing reports of record corn and soybean yields across the region this year. LH 3937 VT2 PRO RIB has excellent standability and great yield for an early hybrid in our region! The monitor below shows LH 4657 VT2 PRO RIB dominating this year!
EASTERN NORTH DAKOTA
Brian McNamee
So much harvest progress has been made this past week! Some farmers who have finished harvesting their own crops and now helping their neighbors down the stretch. It’s not uncommon to see four or five large class combines in the same field. Harvest storage issues, for the most part, have been minor compared to our expectations a month ago. There is an uncommonly large amount of soybeans being stored on the farm this year, but elevators and grain buyers have done all they can to help the farmers through these challenges.
After heavy, wet snow fell 15 days ago, many farmers are using a simple lift rod to help reduce harvest loss from downed soybeans. I’ve been surprised by the success of a rather simple application. Harvest loss from lodging was reduced from 2 to 5% due to this lift rod, plus harvest speeds could be increased to add efficiency.
We’re seeing big equipment and big yields across South Central North Dakota. I’m always amazed at the amount of work that gets done in a 10- to 12-hour shift.
SOUTHEAST NORTH DAKOTA
Gary Geske
In between rain and snow events, farmers are trying to get the crop harvested as quickly as possible. This Latham® SuperStrip plot was harvested after dark to maximize daylight hours for the crop. Kyle Geske harvested his plot with yields far exceeding spring planting expectations. It was exciting to see yields near 200 bushels per acre on variable soil types. For more yield information, make plans to attend one of Latham’s post-harvest meetings.
