Planting Tips for Profitable Double-Crop Soybean

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   Before I get into tips for soybean, I must emphasize one must focus on the entire double-crop wheat-soybean system.  Both crops must contribute to profit; one crop cannot carry the other.  You will may save some input costs such as lime, fertilizer, and rent (making those seasonal cost spread over two crops) with the double-crop system, but certain costs such as soybean seeding rate will increase.  In the end, these inputs roughly equal out with the exception of land rent that can vary greatly over Virginia.

   With that said, the most important thing to insure a profitable double-crop system is yield, yield of both crops.  Without a minimum of 80+ bushel/acre wheat and 33-35+ bushel soybean, the system will not likely be as profitable as the full-season soybean system, especially with today’s low prices. 

Assuming that you will intensely manage both crops during the growing season (note that intensely managing does necessarily not equate to greater input costs, but instead greater attention), the most important thing that anyone can do right now for greater yields is to harvest the wheat crop as soon as possible, and then immediately plant the soybean.  Our 3-year, 5-state (PA, MD, DE, VA, NC) project conducted just a few years ago clearly confirmed that this is one of, if not the most important decision that a double-crop farmer can make.  In that project, we generally showed a rapid decrease in both wheat and soybean yield with delayed harvest and planting after mid-June.  Wheat yield declined anywhere from 0.5% to 2.5% per day, depending on location and year, versus wheat that was harvested at 18-20% moisture.  This was largely due to rapidly declining test weights afterwards.  And we also noted that quality decreased in many test locations. Note that if wheat is harvested this wet, then it will need to be dried almost immediately.  I don’t recommend this unless you have a continuous-flow drier or have a buyer willing to take the high-moisture wheat without severe price dockage. 

Although we found a benefit to the wheat crop, probably the bigger benefit however to harvesting wheat at high moisture is earlier planting of the soybean.  On average the soybean yield began to decrease about ½ bushel/acre per day by mid-June, but this increased to 1-2 bushels per day once we got into late-June (more northerly Mid-Atlantic states) and early-July (more southerly Mid-Atlantic states).   This resulted in a major income difference. 

Just to re-emphasize this most important point, harvesting the wheat and planting the soybean ASAP is the most important thing a farmer can do to make this system as or more profitable than a full-season soybean system.  The current weather is not helping with this (we could have harvested much of our wheat this week), but hopefully next week will bring drier weather.

Here are some other tips that are very important when planting double-crop soybean.

Variety Selection. Select the latest maturing varieties that will mature before the frost.  This will assist with growing as much leaf area and having as many reproductive nodes as possible.  Plant the earlier maturing varieties in this maturity range on your best soils and the later relative maturities on the poorer-yielding land.

Always Plant in Narrow Rows.  I prefer 15 to 20 inch rows seeded with a planter that singulates the seed.  Seed singulation insures uniform seed placement within the row and no big gaps between plants.  The other option is to plant with a drill, which achieves the narrow rows but results in what many refer to today as a “controlled spill”.  This results in many gaps, 2 or 3 seed planted in the same place, and generally lower yields (we proved this in some on-farm double-crop studies in the early 2000s).  Still, a drill is better than 30-inch (or wider) rows at such a late planting date.

Seeding Rate. Beginning next week in Virginia, plant 140,000 to 160,000 seed/acre and increase that rate by 20,000 seed/acre with each successive week.  This will of course put the seeding rate up to 200,000 to 220,00 plants by the first full week of July, sharply decreasing your profit with greater seed costs and lower yields.  Again, this is to insure maximum leaf area and node development.  Note that as one moves north and west, greater seeding rates may be needed due to the shorter growing season (e.g., northwest Virginia may require a greater seeding rate than southeast Virginia, or North Carolina). If using a drill, I suggest increasing these rates by 10%.

Insure Good Soil-to-Seed Contact. First, adequately spread the wheat residue.  No planter will uniformly plant through inches of matted residue. Then make sure the planter is properly set to 1) cut the residue, 2) penetrate the soil to the proper seeding depth, and 3) ensure good soil-to-seed contact.  These steps must take place in order. And they affect each other; a mistake in accomplishing one of the steps can result in mistakes in the other two.  I suggest waiting until late morning to begin planting to insure that the small grain residue to dry – unless the residue is dry, cutting through it will be a problem, resulting in hair-pinning of the residue and prohibiting proper soil-to-seed contact. 

Plant into soil moisture.  If there is plenty of moisture, you can plant as shallow as ¾ inch and get good and rapid emergence.  If a little dry on top, you can plant as deep as 1.5 inches.  With warm soil temperatures, soybean will generally emerge well from this depth and may even emerge from even deeper depths (but I don’t recommend).  Unless you farm in wet, poorly drained soils or are growing continuous soybean, I don’t usually recommend a fungicide seed treatment during June and July due to warm soils.  Double-crop soybean usually emerge quickly if planted into soil moisture and will “out-grow” any seedling disease.

Insure Nitrogen Fixation. If soybean have not been grown in a field for the past 3 years, then be sure to apply inoculate to the seed with the proper bacteria.  This will insure adequate nitrogen fixation by the soybean plant. There is no need to apply nitrogen; definitely don’t apply more than 25-30 pounds/acre or you will inhibit this vital biological process. As a side note, we did find a fairly consistent 1 bushel yield increase with starter N at 25 lbs/acre due to slightly better early-season growth; but this did not pay for the cost of the N – so I don’t recommend.

Fertility (P, K, S, etc.).  Keep in mind that the straw contains quite a bit of nutrients.  If the straw is harvested, make sure that you are replacing those nutrients that are leaving the field.  For more information, see our VCE publication,  The Nutrient Value of Straw.  And make sure that you are being paid more for the straw than these nutrients and organic matter is worth!

Enlist Soybean Varieties for Double-Crop Production Systems

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Although it appears that we can use existing stock of labeled dicamba products (XtendiMax with Vaporgrip Technology, FeXapan, and Engenia) for Xtend soybean varieties, some may want to switch to or use Enlist varieties to control resistant or hard-to-kill weeds in their double-crop system.

Therefore, I’m listing this past year’s results of the performance of Enlist varieties from our variety tests. Note that most of maturity group (MG) 4 varieties. I tested no late-5 or 6 varieties.

Again, the varieties that you have already selected are likely the best-performing ones for your fields; therefore, I do not recommend changing unless you need the Enlist system to control weeds in certain fields.

Note that relative yield is the yield relative to all varieties tested within a relative maturity group (e.g., early-4, late-4, early-5, etc.). Relative yield of 105 means that the variety yielded 5% greater than the average of the entire test.

Virginia Wheat & Barley Yield Contest

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The Virginia Grain Producers Association has announced the rules and entry forms for the small grains yield contests.  This is a great way to promote good small grain management and for top producers to be recognized. 

Click Here for Virginia Barley Yield Contest Rules

Click Here for Virginia Hard Wheat Yield Contest Rules 

Click Here for Virginia Wheat Yield Contest Rules

Frost/Freeze Injury to Wheat and Barley New Symptoms

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I am receiving numerous reports of wheat and barley fields that were severely injured by cold temperatures. The symptoms are completely or mostly blank/absent kernels on entire heads. What I had seen prior to this week manifested as a few missing kernels on the head, or scattered white heads that were obvious freeze injury. These newly symptomatic fields either seem normal or just slightly ‘off’ from the road but on investigation many heads have no grain. In some cases, the stems are beginning to turn brown and die. At this point I think this is in a few local areas and not widespread. It was obviously a combination of low temps and particular fields that were at a very susceptible stage.
I encourage you to assess small grain fields. Any damage is much less severe near edges, roads or lanes, so scout well out into fields. Those with severe damage should contact their crop insurance adjuster or VCE agent ASAP to assess the yield potential in the field.

Xtendimax, Engenia, and FeXapan Registrations Vacated. What now?

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The dicamba products Xtendimax, Engenia, and FeXapan had their registrations vacated June 3, 2020 by the U.S. Court of Appeals for the Ninth Circuit. The EPA announced June 8, 2020 a final cancellation order for these products.

Existing stocks, in possession on June 3, 2020 (the date of the court’s decision), can be used by farmers and commercial applicators by July 31. Use of these products must be consistent with the previously approved label.

The EPA’s full statement is here:  https://www.epa.gov/sites/production/files/2020-06/documents/final_cancellation_order_for_three_dicamba_products.pdf. Details on use of existing stocks are on page 11.

More background information can be found here

Tavium (dicamba + S-metolachlor) is also still legal to use. Tavium was not mentioned in the lawsuit making Tavium the only way to legally apply dicamba to Roundup Ready 2 Xtend soybeans or Xtendflex cotton. This product is already in short supply and may be difficult to acquire. Tavium cannot be used on double crop soybean.

There are effective alternatives to dicamba. In RR2 Xtend soybean, I recommend Flexstar GT in place of dicamba. This product is not currently in short supply, but there is potential for that to occur. So I encourage farmers that plan to use Flexstar GT to go ahead and acquire it. Other alternative products can be found in Table 5.54 on page 5-182 of the Pest Management Guide. Additionally, information on controlling Palmer amaranth in soybean is here: https://www.pubs.ext.vt.edu/2808/2808-1006/2808-1006.html and common ragweed is here: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/spes/spes-143/SPES-143.pdf. In cotton, most varieties have the option of using Liberty, which is my recommendation in place of dicamba. But other alternative products can be found in Tables 5.112 and 5.113, starting on page 5-344.

Farmers should consider changing soybean herbicide traits for double crop acres or any soybean ground that has not yet been planted. LibertyLink, LLGT27, and Enlist are all good options in place of RR2 Xtend. Farmers may also consider a Roundup Ready variety as well, to potentially save tech fees compared to RR2 Xtend, but there are very few of these even before this announcement. I realize changing this late in the year may not be feasible and the best performing varieties may not be available. If farmers choose to change varieties, make sure that the variety has both strong yield potential and the herbicide trait of choice.

This ruling does not apply to dicamba products such as Clarity and Banvel, that are not labeled for use in Xtend traited crops, so these can continue to be used in pastures, corn, and other labeled uses. Dicamba products that are not labeled for use in dicamba-tolerant crops have been and continue to be illegal to use over-the-top of RR2 Xtend soybean and Xtendflex cotton.

This ruling comes at the absolute worst time during the season. There may be temptation to use dicamba illegally, but I strongly encourage us all to think about the implications of such actions on agriculture. These products have been and will continue to be under scrutiny from the non-ag public.

Should Court Ruling on Dicamba Affect My Seed Choice for Double-Crop Soybean?

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The court ruling yesterday has given a devastating blow to farmers that are depending on the Roundup Ready 2 Xtend herbicide program for their soybean. There seems to be much discussion regarding clarification of this ruling, including when the ruling can take effect and a possible “existing stocks” provision.

Until the ambiguity around the decision is clarified, it’s worth thinking about seed choice. Assuming there is little that can be done about soybean already planted and growing other than alter your postemergence tank-mixes, you may have an opportunity to switch varieties for the upcoming double-crop soybean planting.

First and most important, do not change your variety selection if you have weeds that can be controlled without the addition of labeled dicamba products (Enginia, FeXapan, Xtendimax) to your herbicide program. The varieties that your have already selected are most likely to be best for your farm and will maximize your yield.

However, if you must add dicamba to your glyphosate to kill glyphosate-resistant marestail (hopefully you’ll take care of this weed before you plant), Palmer amaranth, or common ragweed, then you have some options with Liberty-Link, Enlist, Liberty-Link GT27, or a few other varieties that have stacked the GT and LL traits.

Like all herbicide-resistant traits, there are good varieties and there are some that don’t yield so well. I suggest that you refer to our Virginia Soybean Performance Tests 2019 or other good private and public resources to see how these have performed.

Seeding Rates for Late-Planted Soybean

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The cool and wetter weather earlier in the month has delayed some soybean planting into June. In addition, some cotton growers have switched to soybean due to the same reason. The question that came to me often this week was “Should I increase my seeding rate?”

In general, our research has not found a dramatic yield response to more seed per acre until mid-June. This largely reflects the lack of decrease in yield due to late planting dates until about the same time. If planted by the first week of June, the soybean usually has time to build a canopy great enough to capture most of the light by flowering, and does not need the extra plants.

However, I usually recommend that you begin increasing seeding rates by about 20,000 seed per week beginning the first of June.

Therefore, I would suggest the following:

This week (June 1-6): 120,000 – 140,000 seed/acre

June 7-13: 140,000-160,000 seed/acre

June 14-20: 160,000-180,000 seed/acre

June 21-27: 180,000-220,000 seed/acre

On your better soils or with later maturing varieties, use the lower seeding rate. On your less-productive soils or with earlier varieties, use the higher rate. This will insure that you you have enough leaf area to maximize the yield for those planting date.

Will the cold weather harm my soybean this weekend?

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The weather reports of near-freezing temperatures in some parts of Virginia has many concerned about their wheat, corn, emerged and non-emerged soybean. I’m one of them, but we must try to be optimistic about this threat.

My weather apps seem to indicate lows in the lower 30’s in some of most northern and western growing areas on Friday and Saturday nights. This is never good, especially in May. A frost may burn off some leaves if the air remains calm, but a slight breeze during the night can keep the air temperature surrounding the plants above freezing, and in-turn the soybean plant above freezing. And as long as the temperatures don’t drop below freezing for an extended period of time, I think that our soybean will be O.K.

Why do I say this? Usually, it will take air temperatures of 28 F or less to cause permanent damage. Why is this? First, the soil temperatures are warm, in the 50’s and 60’s and the soil will not warm as fast as the air. The air nearest to the soil won’t be as cold due to this; there will be a buffer area. Even if temperatures do get down to 31-32 F, plant cells will not freeze because they contain solutes, which lowers the freezing point of the tissues. For a more thorough explanation of freeze damage to soybean, I recommend this article on the University of Wisconsin’s Cool Bean website.

Just in case, we do have some soybean damage, Purdue University has an excellent article on the subject for corn and soybean, Symptoms of Low Temperature Injury to Corn and Soybean, which include some good photos of injury. The photos show likely seedling soybean survival and death examples. If our soybean have several leaves (V1-V2) and there are some out there, it’ll take very cold temperature to freeze the entire plant. Even if frost burns the leaves off, the growing points in the nodes of these leaves will likely survive and regenerate a new stem, leading to a bushier but healthy plant. But, we can worry about that next week.

The seed that are in the ground will survive. Again, the soil temperature will not drop dramatically with the cold weather. Still, soil temperatures in the 50’s is not warm. You’ll need a fungicide seed treatment protecting them. No seed treatment? We will have to wait and see. For more details, see my last article, Soybean Planting Tips for Cool Weather

Should you stop planting? We are not. I have a planter in the field today. But my seed are treated with a fungicide. But neither do you need to be in such a hurry. We generally don’t see a drastic yield decrease until planting is delayed after June.

Potential for cold damage to small grain and corn

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I’m sure this weekend’s forecast is generating some questions about the potential for frost/freeze injury.

First, let’s deal with corn. I don’t think any parts of our state are forecast to be cold enough to kill any young corn plants. Air temps would have to fall below 28 degrees or so for several hours for there to be a danger of plant death. What’s a lot more likely is that we get 32-35 with no wind and get a significant frost. For corn that is emerged, this may well result in death of those frosted leaves. While this will set the crop back, it should not harm the stand and plants should recover. After about three days, the growing points of plants can be examined for injury. Green, healthy tissue is a sign that plants will recover.
Purdue University  has a good, brief summary with photos.
https://www.agry.purdue.edu/ext/corn/news/timeless/FrostedCorn.html
Based on the cool weather and rainfall, I have been expecting to see lots of nitrogen, sulfur and zinc deficiency early in this year’s crop anyway. Cold injury may exacerbate this and bring those symptoms on even earlier. If deficiency symptoms do appear, an earlier than normal sidedress application may be needed this year.

Wheat is also a concern. The best resource that I know of on the subject comes from Kansas State. https://www.sunflower.k-state.edu/agronomy/docs/c646_Whole_Wheat_Freeze_Publication.pdf
Table 1 from that publication and shows that temperatures around 30 degrees can definitely cause damage to our crop based on the growth stage of many fields. But note that these expectations for injury are from two hours of exposure to that temperature, not just a few minutes.
Like with corn, it will take 3-5 days after the event to assess the damage so I would encourage you and your growers to scout for injury next week.

Soybean Planting Tips for Cool Weather

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It looks as if we have come out of the unusually warm pattern we experienced during late-March thru early-April and fallen back into a cooler one. I’ve watched unusually warm soil temperatures fall rapidly during that period. Although long-term weather forecasts are speculative, it appears that the next week or so will be cooler-than-average. Below are the GFS (U.S.) and European model predictions thru next Thursday. Although today (Thursday) is very warm (& wet), notice that both models are showing below-average temperatures.

Temperature anomaly predictions from 4/29 – 5/9, 2020. Screen captured 4/29.

These low temperatures are also predicted to persist thru mid-May, as shown below.

Temperature anomaly predictions from 4/29 – 5/14, 2020. Screen captured 4/29

Keep in mind that the predictability of these models are quite low past 1 week, so this could change substantially. Still, we are dealing with some relatively cool soils and that need to affect our planting decisions once things dry up.

When soils are cool, we must get the plants up and out of the ground as soon as possible. The longer a sprouted seed is in the ground, the more likely it will be infected with numerous seedling diseases. We must always strive for rapid emergence.

Before we get into too big of a hurry to plant, we must recognize that yields will not decrease drastically for over a month. Although the date when such a decline takes place will vary with the year, my data and experience indicates that this date will not occur to the first week of June. Depending on the number of acres you need to plant, you may not need to get in that big of a hurry. If the same 2-week pattern of cold then warm periods continue, I expect to see a warm-up and warmer soils by the second week of May.

If you must plant into cool soils, I suggest that you use fungicide-treated soybean seed. This will provide some protection if the seed does remain in the soil for an extended period. Below is a table that Dr. Hillary Mehl used this winter listing the effectiveness of several active ingredients with diseases that commonly occur in Virginia. Rhizoctonia and Fusarium have traditionally been our most troublesome. Pythium can also raise it’s head occasionally. Note that only one of these treatments listed are good on sudden death syndrome (SDS), but there is now at least one other product available . I caution that nematodes are often involved with SDS, so additional measures will likely be needed to fully manage that disease.

E=excellent; VG=very good; G=good; F=fair; P=poor; NR=not rated
1 Products may vary in efficacy against different Fusarium and Pythium species.
2 Areas with mefenoxam or metalaxyl insensitive populations may see less efficacy with these products.
3 Listed seed treatments do not have efficacy against Fusarium virguliforme, causal agent of sudden death syndrome

Finally, don’t plant the seed too deep. 3/4 to 1 inch deep is enough. Planting deeper will delay emergence.