Tag Archives: relative maturity

New tool for Soybean Variety Trial Data

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David Holshouser, Virginia Tech Extension Soybean Agronomist & Virginia Sykes, University of Tennessee Extension Variety Testing & Agroecology

Which soybean variety is best suited to my region? State variety testing programs provide critical research to help answer that question by evaluating hundreds of soybean varieties every year across multiple locations within a state. But what if we think beyond the bounds of our state borders when it comes to variety evaluation?

While a single state alone provides valuable data, our growing regions often cross state lines. A location in southeastern Virginia may share more similarities to sites in eastern North Carolina than it does to the Northern Piedmont of Virginia. Furthermore, by combining variety testing data across multiple states, we can create a more robust dataset that allows us to better predict which varieties are best suited to specific regions and growing conditions.

Pulling and combining data from select locations within multiple state variety testing programs can be a daunting task. Over the past year, a team of variety testing coordinators from Tennessee, Arkansas, Kentucky, North Carolina, and Virginia have been working to make that process a lot easier. Through funding from the United Soybean Board and in collaboration with Centrec Consulting Group, LLC, we created a tool that will allow users of variety test data to combine and visualize soybean variety testing data across multiple states in the Mid-South. This new tool is available at https://marketviewdb.centrec.com/?bi=MidSouthVarietyTrials.

In addition to choosing locations, another key component of this database is the ability to filter the results to include only the relative maturities, brands, and herbicide tolerances that you want. It can also let you chose whether to include irrigated and/or non-irrigated, or full-season and/or double-crop sites.  You can also chose the soil textures that you are interested in.

I won’t go into the details of how to use the site in this blog.  But, try it out.  Contact me with questions or comments.

The database currently contains 2018 – 2020 data but will be updated as 2021 soybean variety trial data becomes available. We hope that you find this tool useful. We would value your feedback/suggestions as we continue to refine this product to better meet stakeholder needs. A brief survey can be found at https://utk.co1.qualtrics.com/jfe/form/SV_6u5lHEwEOXnXODA.

The database described in this article was developed with support from the United Soybean Board.

Full-Season Soybean Planting Dates, Maturity Groups, Seeding Rates, and Seed Depth

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Best Planting Dates & Maturity Groups (MG). If you’ve seen some of my presentations in the past, the best maturity groups will largely depend on location, but also on field productivity. Still, we cannot talk about maturity groups without a discussion on planting date, as they influence each other. Here are some general full-season guidelines:

Planting Date x Relative Maturity Experiment in Caroline County, VA, 2019

Planting Date. On average, there is little advantage, although no disadvantage, to planting in April if using adapted varieties. My data indicate that late-MG 4s and early 5’s are generally the best choice at both planting dates. But note my comments below regarding field productivity.

Location and Maturity Group. On average and most consistently, late-MG 4 and early- to mid-MG 5 varieties have yielded more than other relative maturities when planted in May in most of Virginia. Exceptions are the Northern Piedmont and Eastern Shore. In the Northern Piedmont, late-3s through late-4s yield more than 5s. On the Eastern Shore, early- and mid-4s appear to have the advantage.

Note that these comment are based on relative maturity and planting date studies over the last 3 years and from 10 years of variety test data. This does not mean that you will see similar results every year on every field. There are always exceptions, including the following.

Early planting dates and maturity groups work best on the most productive field. By planting early with an earlier-than-adapted relative maturity will place the most critical time of soybean growth and development, the pod and seed stages, earlier in the year. We generally experience more water and heat stress earlier in the summer; therefore, a more productive field/better soil type will better tolerate the stress (and better take advantage of the longer days).

Later planting dates and later maturity groups work best on less productive soils. By planting later (up to the first week of June) and with later maturity groups (mid- to late-5s), we can avoid the most stressful time of the year, placing the critical pod and seed development into a less stressful time of the year.

Full-Season Seeding Rates: In general, 100,000 to 140,000 seed/acre (assuming at least 75% emergence) is enough to maximize soybean yield when planted in April and May. I’ve even maximized yield with less seed when early-season growth is good. All we are trying to do is grow enough leaves to get 90 to 95% light interception by early pod fill (R3).

A more detailed analysis of my data however revealed that under relatively low-yielding conditions (less than 35 bushels/acre), we need the greater seeding rates. And the lower rates sufficed under higher yielding conditions. Others have found the same thing in the Midwest and South America. What does this mean as far as adjusting your seeding rates?

First, on historically poor-yielding land, use 130,000 to 140,000 seed/acre. On historically better-yielding land, you can reduce that rate down to 100,000 to 110,000.

Note that the later you plant, as you approach June, greater seeding rates will more likely insure maximum yields.

Also note that plant emergence may be less when planted on cold, wet soils; therefore, increase the seeding rate by 10% or so.

Seed Depth. My philosophy on seed depth is plant into moisture at a depth that will give you the best and fastest emergence. Note that the longer the soybean is in the ground, the more likely it will be affected by a seedling disease. I usually recommend 1 inch deep to the bottom of the seed. Under cool and moist soils, plant as shallow as 1/2 to 3/4 inch deep. This will hasten emergence.

Once the soil warms up, you can plant deeper since germination and emergence will take place faster. But, try not to plant over 1.5 inches deep, especially in April or May. Only do so if the soil is very warm and there is little moisture in the top 1 to 1.5 inches.

Would Soybean Yields Rise If We Started Planting in April?

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April planting is thought to have an advantage over May planting because we can shift the development of soybean to an earlier time of the year  where there is more sunlight.   More total sunlight per day should result in greater yields.  But, does this hold up in Virginia?  Likewise, an earlier variety will also shift maturity, and the critical stages of development, to a time of the year when the days are longer.  So in theory, planting early-maturing varieties early should result in the greatest yields.

My concern is that when you shift your development to earlier times of the year, you are also placing the most critical pod and seed development stages in a hotter and drier time of the year.  While you could possibly alleviate the dry part with irrigation, I know of no way to keep the temperature from rising.

To test these hypotheses, we planted 10 to 12 varieties ranging in maturity from late-3’s to early-6’s in April, May, and June at three Virginia locations in 2017 and 2018.  I’m not going to show the data because we found relative maturity responded differently depending on location, and it would just take up too much room to show all the graphs.  However, we have seen no benefit to planting soybean in April versus May, although April plantings did not usually yield less than May plantings.  Maturity group response depended more on location and when the rain fell.

So, I suggest that you base your planting date and or relative maturity decisions on your need to spread out planting or harvesting.  April planting date is OK, but not necessary for greater yields.  Keep in mind that soils are usually cooler in April, so it will normally take soybean longer to emerge than when planted in May.  Fungicides will be needed for April and early-May plantings.

Planting a slightly earlier maturing soybean is usually OK also.  For more information on maturity selection, see my previous blog, “Improving Your Soybean Variety Selection Decisions – What maturity is best?”

If you do plant in April and/or want to use early-maturing varieties, then do this on your best soils.  If you move the critical stages of development to a hotter and drier time of the year, you’ll need the greater water-holding capacity of those soils.

Improving Your Soybean Variety Selection Decisions – What maturity is best?

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Variety selection continues to be one of the most important decisions that we can make.  It is also one of the first steps to take that insure success.  It’s a hard choice because there are so many varieties available.  Still, this choice is one that will affect your profitability throughout the year.

Soybean yields in our variety tests have increased by an average of 0.4 bushels per year over the last 30 years.  Some of this increase is due to better varieties, some is due to better management.  In those tests, the highest and lowest yielding varieties varied by 20% or more (8-10 bushels).  It is therefore clear that making the wrong choice will seriously impact next year’s soybean crop.  Unfortunately, environment (rainfall, temperature, soil type, field, etc.) affects yield variation more than variety – there is always lots of year-to-year and site-to-site variation.  Still, each variety has specific strengths and weaknesses that make it more or less suited for any given situation.

Putting the Right Variety in the Right Field

With all this variation, it is very important that you place the right variety in the right field.  This will be influenced by 1) planting full-season or double-crop; 2) maturity; 3)herbicide tolerance; 4) disease and/or nematode tolerance; and finally 5) yield potential.  There are also a number of other factors that differentiate varieties such  as shattering and lodging susceptibility, height, branching ability (thin vs. bushy), seed size, seeds/pod, protein and oil content, other specific traits, etc.), but these will rarely affect your bottom line.   Although all of the top five things I listed are important, yield potential is clearly what is of most interest.  However, if you do not pay attention to numbers 1 through 4 first, your yield potential can be low.

To cover all of the things that make variety selection important would take more words than this blog will allow, so we will first focus on the choosing the right maturity.

Relative Maturity Choice: Spreading Out Environmental Risk

First, I should say something about early planting of an early-maturing variety.  I define this as planting in April or early May a variety that is about one full maturity group earlier than the maturity that is most adapted, based on historical data, for your area.  First, early-planted early-maturing varieties will always have a greater risk of poor quality seed.  The seed of these varieties are maturing during September and early October, when the weather is relatively warmer.  Warm and wet weather are perfect conditions for seed decay.  2018 has been one of the worse years for this, primarily due to excessive rainfall and much warmer September temperatures.  To the right is an example of a maturity group (MG) 3 soybean planted in April in Madison County (MG 4 is the most adapted maturity for this area).  Clearly, you don’t want to end up with this.  While early maturing varieties have their advantages, their associated risks should keep the percentage of acres planted to a minimum.

On the other hand, do not keeping all varieties in a tight maturity range.  The performance of varieties within a certain maturity range will almost always depend the environment that they experience during pod and seed fill.  If conditions are good (adequate rainfall, moderate temperatures, good soils) during that time, yields will be high.  Unfortunately, the weather cannot be predicted in our humid southeastern U.S. environment.  While late-July and early-August are generally our hottest and driest times of the year, we have just as good of a chance of going through a hot and dry period in June as well as July as well as August, and sometimes in September.          Still, on average, certain relative maturity ranges yield more than others in the south central part of Virginia.  Below are the average yield balance (no. of bushels/acre greater or less than average) of a range of soybean maturities tested in our full-season variety tests over the last 10 years, separated by location.

I’ll use our Southern Piedmont location (Blackstone) as an example of a location that shows the greatest yield gap between the earliest and latest varieties (nearly 15 bushels!).  This is likely due that area typically experiencing the more stress (hot and dry) from late July through August than other regions.

Similar but on the opposite end of the spectrum, MG 3 and 4 varieties work best at the Northern Piedmont (Orange) location.  Maturity group 5 varieties generally not as adapted in that northerly environment.

The northern and southern Coastal Plain sites (Warsaw and Suffolk) behave similarly to Blackstone – MG 5 outperform MG 4 varieties; but the yield gap between relative maturities is not as wide.

Our Eastern Shore location does not follow the same trend of MG 5’s being the highest average yielding varieties as one moves south and east.

Note that maturity group (MG) 5 varieties relatively better in the more eastern and southern locations of Virginia’s mainland, while MG 4 varieties tend to do better in our most northwestern location (Orange) and on the Eastern Shore (Painter).  While MG 3’s don’t yield as well, the group 4’s are the highest yielding.  Why?  I attribute it to two things: yield potential and temperature.  In general, this site has over time been one of our highest yielding sites.  Although rainfall patterns are similar to other locations in Virginia, it is our coolest location (and there is usually a breeze) – both likely a water effect.  Therefore, the site experiences less stress.  So, pushing the critical pod- and seed-filling stages slightly earlier in the year are not as problematic.

So, should you stick only with maturities that perform best on average?  Not necessarily.  Using Blackstone as an example, note that although the late-group 4 varieties yield less than MG 5’s on average, they yield much better than earlier 4’s.  And late-4’s yield just as well as 5’s in Orange and Suffolk.  I stress that these are averages – 10-year averages of all varieties within those relative maturity ranges.  Is it possible for the MG 4 varieties to yield more than the 5’s in Blackstone or Warsaw?  Is it possible for MG 5’s to yield more in Painter?  Yes!  It just does not happen as often.

We took that same data and calculated the probabilities, not absolute yields, of obtaining similar or greater yields of all relative maturity groupings tested.  The results are below.

Once again, to use the Blackstone data as an example, we can see that growing a late-MG 5 variety will yield at least as much as all of the other relative maturities 90% of the time (bar height).  In addition, there is a 50 to 60% chance (height of the hatched portion of the bar) that the 5’s will yield significantly more than the 4’s.  So, it seems that you will never go wrong with those varieties, correct?  You’ll probably (~80% chance) not go wrong by growing a large percentage of those varieties, but should you should you only plant MG 5’s?  I suggest that you do not grow only MG 5 varieties.  There is still a 10 to 20% chance that the 5’s will yield less than the other maturities.  Plus, there is a 60% chance that late MG 4 varieties will yield just as much as MG 5 varieties (and a 30% chance that they will yield more).

Painter is another good example.  Although there is a yield gap between the 4’s and 5’s, there is a 50 to 70% chance that MG 5 will yield as well as MG 4 varieties.  And there is a 30% chance that they will yield more!  You can use the same thought process for the other locations.

Below are the same graphs for double-crop tests.The Right Mix of Maturity Groups in Virginia.  So, what is the right mix of maturity groups?  I suggest the following:

Southern Piedmont

  • Plant 60 to 80% of your land to MG 5 varieties. We have also found that later maturities generally do better on our more droughty soils, so take that into consideration if possible.
  • Plant 20 to 30 % to late-MG 4 varieties (4.7-4.9). If possible, plant these on your higher-yielding soils.  We have found that this range of maturities have our greatest yield potential throughout Virginia if the weather cooperates.
  • Plant 0 to 20 % to mid-MG 4 varieties. These are risky, especially on droughty soils or in double-crop settings.  It is highly likely that these varieties will experience some (or a lot) of stress during the seed and pod fill stages.  Plus, seed quality will almost always be poorer than other maturities.  If you do grow these, harvest as soon as possible as seed quality will continue to degrade with time.  Don’t plant these in April or early May. This places the most critical times of development (pod and seed fill) during late-July and August.  And seed quality will be even worse since they will likely mature during the warmer part of the year.  Still, yield potential can occasionally be quite high.

Southern Coastal Plain (same comments apply regarding droughty soils and seed quality)

  • Plant 30 to 60% of your land to MG 5 varieties.
  • Plant 30 to 50 % to late-MG 4 varieties (4.7-4.9).
  • Plant 10 to 20 % to early- and mid-MG 4 varieties.

Northern Coastal Plain (same comments apply regarding droughty soils and seed quality)

  • Plant 30 to 60% of your land to MG 5 varieties. In double-crop systems, reduce that percentage to 30 to 50%.
  • Plant 30 to 50 % to MG 4 varieties (4.7-4.9). In double-crop systems, increase that to 50 to 70% late-4’s and plant 10-20% early-or mid-4’s.
  • Plant 0 to 20 % to late-MG 3 varieties.

Eastern Shore (same comments apply regarding droughty soils and seed quality)

  • Plant 20 to 40% of your land to MG 5 varieties.
  • Plant 50 to 70 % to late-MG 4 varieties (4.7-4.9).
  • Plant 10 to 20 % to early- and mid-MG 4 varieties. Plant 0-10% in double-crop.
  • Plant 10 to 20% to late-MG 3 varieties.

Northern Piedmont (same comments apply regarding droughty soils and seed quality)

  • Plant 0 to 20% of your land to MG 5 varieties. Don’t plant MG 5’s double-crop.
  • Plant 60 to 80 % to MG 4 varieties (4.7-4.9).
  • Plant 10 to 20 % to mid- or late-MG 3 varieties.

The proportion of MG 4 and 5 will ultimately depend on your risk tolerance.  Note that as you move west and north, the risk of an early frost is greater; therefore, growing lots of late-maturing varieties may not be a great idea, especially double-crop, and the probability of slightly earlier maturities doing better is greater.

Hopefully, this will give you some guidance in choosing your maturities within the next few weeks.

IMPORTANT:  Keep in mind that the yields and yield balances shown are an average of all varieties in those relative maturity groupings.  This does not mean that every variety in those grouping perform in this manner on every field.  Make sure that you first the variety that meets your match your field’s pest management needs; then, select a high-yielding variety within that relative maturity range.

 

Finishing Out the Soybean Crop – What do we need for Good Yields?

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In general, we’ve had a good, but not great year for soybean in Virginia.  Although many areas were hit with a 3 to 4 week dry spell during July, August rains kept us in the game.  However, we did not see the ample  rains or cool temperatures that we experienced in August of 2017, which resulting in record yields.  Below is a summary of August rainfall and temperature anomalies for the U.S.

 

 

 

 

 

 

 

 

As you’ll notice,  we had about average or slightly below average precipitation and average to slightly above average temperatures for most of Virginia’s soybean growing areas.

So, I do not suspect that our yields will be as good as last year.  Still, our earlier-maturing varieties planted in April or May should yield quite respectably considering that most have made over 50% of their yield – they have reached the R6 stage (see photo below).  Yield of our later-maturing varieties, planted in May and early June, and our double-crop plantings are not quite there yet – much of our yield is yet to be determined – R5 soybean have only made roughly 25% of their yield at that time.

So, what do we need for good yields?  Rain is obvious.  Full-canopied plants with adequate soil moisture will draw about 0.25 inches of water/day from the soil.  But, we also need cool temperatures – soybean do not generally like 90+ degree days, especially when forming seed.

Below is the 10 day rainfall and temperature forecast for the U.S., and it does not necessarily look good for us.  Note that the rainfall is predicted accumulation and the temperature map shows anomaly.  Although we should get some rain this weekend only (more in northern parts), temperatures are supposed to be above average.  But, forecasts are only forecasts.  The weather does change.  I hope we will get the needed rainfall that they are predicting this weekend.  But a big ridge appears to be setting up over the Mid-Atlantic states for next week.  This usually means warm weather and only at the edges of ridges do we normally see rainfall – note the heavy rainfall predicted from Nebraska through Michigan.

 

 

 

 

 

 

I don’t mean to discourage, just to inform.  We still have decent soil moisture, at least in the subsoil.  With rain this weekend, we should get through next week without too much harm to the crop.

Our double-crop soybean (assuming late maturity group 4’s and group 5’s planted in late June to July) are just now in the R5 stage – it usually takes 80 to 100 days from planting to reach R6, depending on maturity and planting date.  So some timely September rains will usually result in good double-crop soybean.

When will our yield be “made”?  Below is table showing the number of days to soybean physiological maturity (R7; 95% of yield has made).  When can we expect to be harvesting our soybean?  Full maturity is reached about 2 weeks after R7 and harvest can proceed after the soybean have dried down to a harvestable moisture, usually within a week after R8.

What’s the Best Soybean Maturity Group for your Farm

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Yields are coming in from our variety tests – yields are good, not great, but good, ranging from the upper 40’s to low 70’s.  I hope to get a summary of the maturity group (MG) 3 and 4 tests out soon.  Be looking for them.

In the meantime, a questions that continues to arise if “What is the best maturity group for my farm?”  Or “What’s the best maturity group for my field?”  This is a very valid question.  Some years MG 4’s will shine and other years the MG 5’s are best.  Occasionally, MG 3 or 6 look good (the 6’s have been performing very well lately – as long as the frost holds off until mid-Nov!

An attempt was recently made (and published) to redrawn the MG lines in the U.S (Mourtzinis and Conley, 2017) – see the map to the upper right.  The researchers used variety test data from nearly all states to come up with the map shown.  While this map is more-or-less accurate when looking at the U.S. as a whole, it is not when you look closer (i.e., at individual states).

To better answer your questions regarding MG’s in Virginia, we took 10 years of our variety test data (around 15,000 plots) and began evaluating the probability of:

  1. a relative maturity (RM) yielding at least as high as the other RM’s tested at that location
  2. a RM yielding significantly higher than the other RM’s tested at that location.

Results are shown in the following graphs. Note that we split the results into full-season and double-crop soybean.  We have also divided each MG into early-, mid-, and late-RM’s.  The total bar height answers question 1 – the probability that the RM does at least as well at the others.  For instance, as expected, there is an 80 to 100% probability that MG 5’s will yield at least as much as other relative maturities in Blackstone (Southern Piedmont, droughty clay soils).

The hatched part of the bars answer question 2 – the probability that the RM yields significantly more that the other RM’s.  Using the Blackstone example, the 5’s yield significantly more than other MG’s 30 to 60% of the time.

Of course the “devil is in the details”.  There are soil properties and environmental conditions that control which RM is best in a given year.  If interested, contact me; I’ll give you my preliminary thoughts on that.  Rainfall is definitely the biggest influence – not how much we receive but when it falls; but that is random in Virginia.  There are other issues.

 

To summarize:

  • MG 3’s and 4’s are best suited for the most northern and western location (Orange).
  • MG 5’s perform best in our most southerly locations (Blackstone and Suffolk).  But, the late 4’s can make a strong showing in some years, especially at Suffolk (I think I know why; its not just when the rain fell. Contact me.)
  • Both MG 4’s and 5’s perform well at Warsaw (we can’t explain the full-season late-4 results, yet).  Note that yield potential of the later 5’s decline with double-crop plantings at this northerly, but Coastal Plain site (probably frost damage).
  • All MG 4’s (early, mid, and late) perform best when planted in May at our Eastern Shore location (Painter).  There are curious things happening here (while not that far south, its our most easterly and probably the most consistently favorable environment for growing soybean).  Note that early- and mid-4’s are no better than 5’s when planted double-crop.

1st Attempt at a Relative Maturity Map in Virginia

I’ve made an attempt at drawing a Virginia map.  But do not read too much into this!  This is based only on 5 locations (although 10 site-years and thousands of plots at each location) and the “devils in the detail”.  An I did not use GIS to draw this map (the lines are not 100% accurately located).

Do not assume that I want you to plant only these RM in these areas, only that these tend to do best in most years.

How do you use these data?  Make most of your chosen varieties fit these results.  However, allocate a smaller acreage to those RM’s that can occasionally break records.

On a closing note, these data also indicate that early RM’s do better on our best, most productive land.  But, that’s a topic for next week.

Greater Yields are Possible for Double-Crop Soybean in 2017!

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It appears that wheat harvest will be 1 to 2 weeks ahead of schedule this year.  We actually harvested some high-moisture wheat and planted soybean plots behind it today (May 31) in northeast N.C.  This is good news for soybean.  Earlier planting means greater yields!  This is clearly shown by the recent data obtained from our multi-state, multi-year double-crop project.

With earlier planting, have my recommendations for double-crop soybean changed?  In general no.  But below are a few things to consider.

Seeding Rate:  In general, you can probably back off on your seeding rates from what you were planning if you get your double-crop soybean in by mid-June.  I’d suggest that you start out with 120-160,000 seed/acre (depending on when you start planting) and gradually ramp that up by 20-30,000 for each week delay in planting.  For more information, see my recent blog, Soybean Seeding Rates for June and Later.

Relative Maturity:  Actually, my standard recommendation still stands, more or less.  Plant as late of a relative maturity (RM) as possible that will mature before the frost.  However, there are now some caveats.   By planting a week earlier, you’ll gain about 3 days in maturity.  Although a slightly later RM may work, I wouldn’t count on it – frost date will affect this more than planting date.  So, don’t plant a later RM.

But, can you plant an earlier RM, say go from an early-5 to a late-4?  Possibly.  Why do I say this?  Two things.  First, by planting a week or two earlier you have greater yield potential (see the above graph), which is due to the ability to grow more leaves.  So your yields are not necessarily so dependent on leaf area as they are with a late-June to early-July planting.  A slightly earlier RM planting in early- to mid-June will only have slightly less leaf area than a later RM.  And, we have generally found that under greater yield potentials, early RM will yield more than later ones.  Still, these are not great reasons to change your RM.  Generally, stick with what you planned.