Author Archives: David Holshouser

About David Holshouser

David serves as Associate Professor & Extension Agronomist at Virginia Tech’s Tidewater Agricultural Research and Extension Center. He provides leadership for agronomic extension and research programs that lead to profitable and environmentally-responsible agriculture.

Workhorses, Racehorses, and Quarter horses

Posted on by

Today is the first day in 2 weeks that we’ve been able to harvest due to weather and a combine breakdown.  So, we are not that much farther along in getting variety test data to you than we were last week.  However, I hope to get out some preliminary data by Thanksgiving.

Last week, I indicated that certain relative maturities do better in some parts of Virginia than others.  This week, I I’ll get a little more specific and discuss choosing the best variety for a given yield potential.

First and foremost, I will continue to emphasize that variety selection should be based on multi-year multi-site data.  Basing your selection on a single test (maybe closest to you) and single year is a recipe for failure.  However, I don’t necessarily recommend always choosing a variety based on average yields over site-years – although a very good place to start.  This may seem a little contradictory, but let me explain.

Certain varieties do better under high-yielding environments.  I like to call these “racehorse” varieties.  Choose such a variety if you want to win a yield contest.  Other varieties may yield more than others under stressful conditions.  I refer to these as “workhorses”.  And there are some that tend to do well, regardless of the yield potential – I’ll call these “quarter horses” (quarter horses can run very fast for short distances and you can still ride them long distances over quite rugged terrain).

Last year, we analyzed 5 years of variety test data and classified all varieties that we tested as one of the above.  Examples of our results are shown below. The graphs represent the yield of a single variety versus the yield of all varieties tested at that site and year.  Each symbol represents a different site-year.

To summarize, the vast majority of varieties are neither racehorses or workhorses; they perform equally in all yield environments.  So, averages will work just fine in most cases.  But, if you know you have a great- or poor yielding soil or if you are irrigating, then you may want to look into those varieties that fit that situation.

We have all of these data in an excel spreadsheet.  If interested, let me know; I’ll be happy to share upon request.

What’s the Best Soybean Maturity Group for your Farm

Posted on by

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.

Estimating Soybean Yield

Posted on by

This is the time of year when many are wondering what kind of yield potential is out there.  You can estimate your yield using the steps outlined below.  But I will warn you that such an estimate is not very accurate until soybean reach the late-R6 or R7 stage.  In my experience, when trying to estimate yields during the late-R5 or early-R6 stages, cut the estimate in half – believe it or not, that usually works!

My point is to use extreme caution.  Never make additional sales based on these “estimates”.  But, such an estimate is useful if you’re thinking about entering a yield contest or just to help ease some worries (or maybe cause more).

To estimate soybean yield:

  1. Calculate the number of pod-bearing plants per acre.  Use the 1/100th of an acre method: Count the number of plants per 70 foot of row (7.5-inch spacing), 35 foot per row (15-inch spacing), or 17.5 foot per row (30-inch spacing) – You can adjust this for other row spacings; then multiply by 1000.  Do this in 5 to 10 locations per field, depending on field size or area of interest.
  2. Estimate the number of pods per plant.  Some say to collect 10 random plants.  I don’t particularly like this method because we tend to select the best plants and overlook the weaker ones with few pods.  I suggest taking 10 plants in a row from the same locations you sampled for plant population.  Divide the number by 10 to get pods per plant.
  3. Estimate the number of seed per pod.  This gets a little more difficult.  You can choose a number from visually observations or you can just use 2, 2.5, or 3 seed per pod to get a range.  If the seed are mature, you can shell and count all pods from several plants at each  sampling location (just remember how many pods you shelled).
  4. Estimate the number of seed per pound.  3,000 seed per pound is about average, but it can range from 3,500 to 2,500 per pound.  Also, be careful with varieties that commonly contain 3 seed pods; the seed of these varieties will almost always be smaller.  Another way to do this is to weigh the seed that you shelled from step 3 – be careful, you need to account for seed moisture and if the seed are not yet mature, they may have not stopped filling.

Use the numbers above to calculate yield using the equation below:

Bushels per Acre  = [(plants/1,000th acre) x (pods/plant) x (seeds/pod)] ÷ (seeds/pound) ÷ (60 pounds/bushel)

The easiest mistake to make is in steps 3 and 4.  I suggest using a range of seed per pod and seeds/pound.  With experience, you’ll get pretty good with yield estimates.

2017 Virginia Soybean Yield Contest

Posted on by

The Virginia Soybean Association in cooperation with Virginia Cooperative Extension would like to announce the 2017 Virginia Soybean Yield Contest. The purpose of the Virginia Soybean Yield Contest is to emphasize and demonstrate the practices necessary to produce maximum economic yields, to recognize those producers who grow high-yielding soybeans, and to gather data on the practices utilized by these outstanding producers. With the help of various seed companies, we reward and promote the achievements of Virginia’s most productive soybean farmers.

There are four Soybean Yield Contest categories: 1) Full-Season, Non-irrigated; 2) Double-Crop, Non-irrigated; and 3) Irrigated (encompasses Full-Season and Double-Crop); and 4) Most Efficient Yield (MEY). First, second, and third place winners of the full-season, double-crop, and irrigated contest will be recognized with appropriate trophies or plaques. In addition, cash awards of $200, $100, and $50 will be presented to the first, second, and third place winners in each of these categories. The winner of the MEY contest will receive a plaque declaring him or her the most efficient soybean producer in Virginia for that year.

In addition, the United Soybean Board is supporting a Soybean Quality Contest for the 2017 season.  The Iowa State University Grain Quality Lab with evaluate these samples for protein, oil, and other quality measures.  You can obtain a sample bag from me.  If you do not have one at the time of harvest, just save a seed sample in a 1 gallon bag and send in to my office.

Printable entry forms and contest details can be obtained from your County Agent or on my website:  (https://www.arec.vaes.vt.edu/arec/tidewater/extension/soybean.html).  I look forward to seeing your entries.

What You’ll See in the Field at the Virginia Ag Expo

Posted on by

As another reminder, the Virginia Ag Expo is Thursday, Aug. 3 at Renwood Farms in Charles City.  The event opens at 7:30 am and will run through mid-afternoon.

There is something for all corn and soybean farmers in the field this year.  Go on the field tour and you will be able to chat with Extension Specialists, company reps, and others about the research being conducted or anything else on your mind.

As always, the Ag Expo is home of one of our numerous on-farm corn hybrid and soybean variety tests.  This year, you will view 31 corn hybrids from 11 companies and 47 soybean varieties from 14 companies.  Drs. Mike Flessner and Charlies Cahoon will demonstrate off-site herbicide injury with some of our newest seed/chemical technologies.  Dr. Wade Thomason is evaluating in-furrow and starter fertilizer in corn.  The soil fertility team, led by Dr. Mark Reiter, is investigating fertilizer recommendations to ensure optimum production for high yielding soybeans.  You will view one of Dr. David Holshouser’s seeding rate trials as he is in the process of establishing variable rate seeding recommendations.  You will also see an experiment that you may have viewed at last year’s Ag Expo investigating the interaction of planting date with relative maturities.  Companies are participating in our plots with in-furrow and foliar sprays that offer potential to enhance yield potential under high-yielding conditions.  Finally, you’ll go below ground to view Virginia’s state soil, a Pamunkey loam, and discuss this yield contest-winning properties with NRCS personnel.

This is a walking, go-at-your-own-pace tour designed to fit your interest and schedule.  Buses will be running continuously to take you to and from the plots.  Enjoy!

2017 Virginia Ag Expo Returns to Charles City County

Posted on by

Please note: the date for the Virginia Ag Expo is August 3, 2017.

“Focused on Productivity, Management and Stewardship” is the theme for the 2017 Virginia Ag Expo.  The Virginia Ag Expo, hosted by the Virginia Grain Producers Association and the Virginia Soybean Association in partnership with Virginia Cooperative Extension, is the largest agricultural field day held in the Commonwealth of Virginia.  As an educational, marketing and social event farmers and agribusiness look forward to the Virginia Ag Expo each year.

Renwood Farms, owned and operated by The Stanley Hula Family, will be hosting this year’s Ag Expo on August 3.  The Hula Family’s farm is a diversified operation growing over 6,000 acres of corn, soybeans and small grains; along with seed conditioning and sales.  A focus on management and productivity at Renwood Farms has produced the world record corn yield of 532 bushels per acre by David Hula.  In addition, the USG soybean seed that produced the world record yield of 172 bushels per acre was grown and conditioned at Renwood Farms.

Over 150 exhibitors and sponsors will have on display all of the most up to date equipment, goods and services for agricultural producers and property owners no matter how large or small.

The event opens at 7:30 am.  The field tour, starting at 8 am, is a walking, go-at-your-own-pace tour designed to fit your interest and schedule.  Buses will be running continuously to take you to and from the plots.

Breakfast and lunch will be provided by Virginia food vendors. Attendees will be able to eat any time from 6:30 AM to 2:00 PM.

Renwood Farms is located at 17303 Sandy Point Road, Charles City, VA 23030.

Soybean Planting Dates, Seeding Rates, Re-planting, Weeds, etc.

Posted on by

June is usually the time of the year when full season soybean is kicking into high gear and we begin planting double-crop soybean.  And like always, various issues are beginning to arise, whether its the weather or finding out mistakes made a few weeks earlier.

Unbelievably, double-crop soybean is wrapping up in many areas due to small grain maturing earlier than normal.  Out of necessity, we were forced to harvest wheat and plant soybean at the same time we were trying to make timely postemergence herbicide applications and generally trying to pay attention to the rapidly growing soybean that we planted in April and May.  But, issues such as these are not unusual.

This week, I thought I’d mention a few things that we are facing and continue to remind you of the need to plant as soon as possible and adjust seeding rates accordingly.

Planting Date.  We are now losing about 1/2 bushel per acre per day with each delay in soybean planting.  Plant as soon as possible, but don’t cause more serious problems by planting into too wet or dry soils.

Seeding Rate.  My data indicates that seeding rates now need to be at least 180,000 seed per acre, even on the best of soils.  I would bump those up about 20,000 seed for each week’s delay in planting.  See Soybean Seeding Rates for June and Later for more information.

Replanting.  Generally, replanting does not pay this time of the year (due to the planting date penalty) unless the stand is horrible.  For more information, see Soybean Replant Decisions or contact me.

Seed Treatments.  I’ve seen few benefits of fungicide or insecticide seed treatments this time of year.  Plants usually emerge and grow quickly.  The exception is wet soils – soybean will emerge very slow when soils are saturated.  With that in mind, you may consider a fungicide on the seed if you have poorly-drained soils, your soils are already wet, and rain is predicted.

Seeding Depth.  Those of you know that I usually don’t like to plant soybean greater than 1 inch.  But, I’ve found that planting soybean at 1.5 inch (and occasionally 2 inches) works just fine when soils are warm.  Sometimes, it’s better to plant deeper to hit moisture than to plant into dry soils.

Weeds.  First, Drs. Charlie Cahoon and Mike Flessner is who you need to consult regarding weeds, but here are a few of my observations.  We may have let a few weeds get too big for adequate control – this is especially a problem with glyphosate-resistant weeds.  Marestail continues to be a problem.  When this weed is glyphosate resistant and you’re not growing Liberty-Link soybean, about the only somewhat effective herbicide that we have left in our arsenal for Roundup Ready soybean is FirstRate, although a few other herbicides may burn the weed – just don’t expect very much from anything.  I’ll let you mull over your other options if you have planted Xtend soybean.  Finally, don’t depend on glyphosate alone – even if you weeds are not yet resistant, its a good practice to diversify to insure that they do not become so.

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

Posted on by

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.

Soybean Seeding rates for June and Later

Posted on by

Due to the rainy weather over the past two weeks, we are still planting full-season soybean in some areas.  In addition, it appears that wheat harvest is not far off (some wheat at the Tidewater AREC was at 23% moisture today!).  So, should we be increasing our seeding rates?

In general, yes.  But, big increases probably will not be needed until late-June.  Below are some seeding rate data that we collected from soybean planted in early-June after barley.  First, we don’t have a lot of data of soybean grown after barley, so I don’t have as much confidence in the exact seeding rate needed.  Note that there is a wide range in the optimal seeding rates, illustrated by the area between the dotted lines in the graph.  Although, these data may not directly apply to full-season soybean (no small grain), it should be close.

I think that we should now be using 120,000 to 160,000 seed/acre.  The range will depend on the planting date.  In general, I’d suggest bumping up your seeding by 20-30,000 seed/acre per week through June.

If you remember the seeding rate data that I shared in this blog last month for May-planted soybean (see Soybean Seeding Rates – How Low Can We Go?), I stated that maximum yields could be obtained with only 95,000 to 110,000 seed/acre when the yield potential is greater than 40 bushels/acre.  That’s pretty low, but was adequate for maximum yield under good growth conditions.  For less than 40 bushel potential, seeding rates needed to be a little higher.   In the above graph, it appears that more seed is needed to obtain 55 to 70 bushels/acre after barley, I cannot fully explain why; therefore, I would assume that this response is primarily due to the location that we obtained the data (again, we don’t have a lot of data).

Once we get into mid- to late-June, I’d rather see a seeding rate of 180,000 to 220,000 seed/acre, depending on planting date.  This is based on the data to the right.    You’ll notice that, like full-season soybean, the optimal seeding rate falls with greater yields.  This is most likely due to greater leaf area with those high-yielding locations.  As I’ve stated often, the seeding rate response can usually be traced back to whether or not the crop developed enough leaf area to capture 90-95% of the light by early pod development.  Unfortunately, I don’t have any double-crop data planted following wheat with yields greater than 55 bushels/acre.  I hope to solve that problem this year with new experiments.

Should you inoculate your soybean?

Posted on by

Soybean, being a high protein crop, require more nitrogen than any other nutrient. Fortunately, through a symbiotic relationship with soil bacteria, soybean is able to fix its own nitrogen.  You can easily see this relationship with bacteria by examining the roots for nodules.  If there are plenty of nodules and they are pink inside, the nitrogen-fixing process is working and no nitrogen needs to be applied to soybean.  However, if nodules do not form, you could end up with a field similar to the one shown on the right.  Below are what the roots looked like.

To insure that you have enough nitrogen for your soybean, you can use an inoculant containing the soil bacteria Bradyrhizobium japonicum.  Do soybean inoculants work?  Yes.  As long as the bacteria is still alive when you put it in the soil.

Do you need to inoculate your soybean seed?  Maybe.  If you’ve never grown soybean in the field that you plan to plant them, definitely add the inoculant to your seed.  Or better, inject a liquid inoculant into the furrow (you’ll get 3 to 4 times the amount of bacteria).  Also, if you don’t have a long history of soybean in the field, inoculate; it will likely pay off.

But what if you are rotating the land to soybean on a regular basis?  You are not likely to get a yield response.  In a 2-year study on soils that were rotated regularly with soybean, I only found 1 of 18 sites that responded to an inoculant.  And the site that responded was land that had only been in production for less than 5 years (formerly pine trees).  In all fairness, one inoculant product at one other location (SUF DC, 2012) did yield more than the untreated check.

Inoculant Expts 2012-13There are some caveats that I should mention.  Sometimes, a yield response if more probable.  If you haven’t grown soybean in the last 4 to 5 years, then it may be good insurance.  If the field was flooded or if it experienced extreme drought conditions in the previous year, bacteria might have died off; therefore, there is a greater likelihood of a yield response to the inoculant.

In summary, inoculants do work and they are good insurance treatments.  But, they will rarely result in a yield benefit if the field has been regularly rotated to soybean.

If you do decide to use an inoculant, follow the label closely.  I prefer to apply the inoculant as close to planting as possible.  Note that certain chemical seed treatments (including molybdenum or “Moly”) can injure or kill the bacteria.  The less time that these chemicals are in contact with the bacteria, the better.