Tag Archives: seeding rate

Planting Tips for Profitable Double-Crop Soybean

   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!

Seeding Rates for Late-Planted Soybean

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.

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

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.

Full-Season Soybean Seeding Rates: Maximize Your Yield and Reduce Your Risks

In general, high seed costs have resulted in a reduction in the number of soybean seed planted per acre.  For our full-season production system, most have reduced their seeding rate to 140,000 or less.  Some have even had success with rates as low as 80 to 100 thousand seed/acre.  My research over the years has shown that we only need, on average, about 70 to 80 thousand plants/acre to maximize our yield.  But is this too low? Yes, it could be – in some situations.

There is also interest in varying seeding rates.  I said many years ago that it appears that this is possible.  But our approach to variable-rate soybean seeding will be just the opposite of how we vary our rates with corn.  With corn, we increase seeding rate as our yield potential increases.  With soybean, we do just the opposite – we reduce our seeding rate as yield potential rises.  But, how much can we reduce seeding rate with rising yield potential?

To answer both questions – Is a final stand of 70 to 80 thousand plants too low? and How do I vary soybean seeding rates?, I analyzed over 10 years (over 25 experiments from 2003-2011) of on-farm and small-plot research to determine the optimal seeding rate for three different yield potentials.  The results along with my recommendations are shown below.

For low yields of 20-40 bushels/acre:

Plant 120 – 140 thousand seed /acre.

Why not less?  The data to the left indicates that the optimal seeding rate (area between the two vertical dotted lines) ranges between around 100 to 120 thousand seed/acre.  Why is this not my seeding rate.  There is too much variability in the data; therefore too much risk.  In some years, yields could have been reduced with this rate.  So, I’m hedging towards less risk at these yield potentials.

 

For medium yields of 40 to 55 bushels/acre:

Plant 100 – 120 thousand seed/acre.

You will notice that the optimal seeding rate has declined to around 90 to 110 thousand seed/acre.  Note that this is only about 10,000 seed less that the previous graph, but I lowered my recommendation by 20,000 seed.  Why?  There is little variability in these data; hence, I have more confidence.

 

 

For high yields of 55 to 70 bushels/acre:

Plant 90 to 110 thousand seed/acre.

Like low yield potentials, I’m starting to hedge a little here towards less risk although my data indicates that I can go lower.  There were cases where is took nearly 120,000 seed to get the maximum yields.

 

 

One comment that I get with these data is: “These data are old.  Does it still hold up with newer varieties?”  A good question!  So, I’ve conducted seeding rate experiments over the past 2 years and I’ll continue this coming year.  To summarize, the most recent data has not changed my recommendations – I think that these trends still hold true.  However, we did see some differences last year – a year of wet and cloudy conditions.  The data are below:

With our maturity group 4 trials, we saw yield continue to rise with seeding rate, and our yields were in the high range (about 50 to 60 bushels/acre).  But yields with the group 5 soybeans tended to level off at about 120 thousand seed/acre.   Why a different response and why did maturity group matter?

 

 

I think the answer is lack of sunlight.  Total photosynthetically-active radiation interception differences are one of the reasons that we get yield responses to seeding rate.  In most cases, this is a lack of leaf area; we are not intercepting all the light.  But, this was not the case in 2019.  We had what I normally consider enough leaf area, at least enough for a sunny year.  But we had less light in 2019.  The group 5 soybean did have more leaf area than the group 4 soybean; I’m assuming that these few extra leaves made up a little for the lack of light.  Cloudiness is one of the risks we take.  Still, I won’t change my recommendations based on last year since it was rather unusual.

In conclusion, if you want to chose the best full-season seeding rate in Virginia for your yield potential, my recommendations are:

Low yields: 120 to 140 thousand seed/acre

Medium yields: 100 to 120 thousand seed/acre

High yields: 90 to 110 thousand seed/acre

 

Wet Soils, Poor Stands – Do I Replant?

The decision of whether or not to replant arises every year; however, the wet soil conditions seem to have worsened the problem this year.  There of course will be areas that the decision is easy – flooded areas resulting in almost no stand.  But, what about fields that just are not living up to your expectations?  I’ve seen and heard many reports of stands being reduced 25 to 50% of what was expected (keep in mind that our expectations are sometimes too high).

First, I must mention that final average stands of 60,000 to 80,000 plants/acre rarely profit from replanting.  Only when you get below 50,000 can it be economically justified.  I refer you to the seeding rate data shown.  Note that yield does not fall off until seeding rates fall below 90 to 120 thousand seed/acre (76 to 107 seed/acre on productive soils).  Stands generally averaged 75%; so, this is equal to  65 to 90 thousand plants/acre.  Once you add in the cost and of and time required to replant, it’s not usually worth it – unless the stand less than this.

 

 

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

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!

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

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.

Soybean Seeding Rates – How Low Can We Go?

It seems that everything that you read about soybean seeding rates is that we are planting too many seed.  In general, I agree – at least for full-season soybean.  We still seem to have that mindset that it takes 1 bag of seed per acre.  But many of you have been listening and are taking the seeding rate down to 100,000 to 120,000 seed per acre, with no noticeable difference in yield.   But, can you go lower?  And how low can you go?

To help answer this question, we have re-analyzed about 10 years of data that we collected from dozens of experiments conducted from 2003 through 2011.  But instead of just looking at average yield response, we separated these responses into soybean yield potentials.

Why did we do this?  I’ve always thought that more seed is needed to maximize yield on low-yielding fields (or portions of fields) and less seed are needed or high-yielding fields or portions of fields.  Yes, this means that I’m asking you to spend more money on the least profitable fields and less money on the most profitable fields.  Still, this strategy will likely be more profitable over all acres.

There are a few things worth noting about the graphs to the left.  First, I’ve separated the data into low (20-40 Bu/A), medium (40-55 Bu/A), and high (55-70 Bu/A) groupings.  We decided on these levels by analyzing the data over and over at many different yield levels.  The resulting three levels were most stable and predictive.

Second, we used two statistical methods to fit a curve to the data to intentionally give us a range of seeding rates needed to maximize yield.  This allow us to recognize the variability in the data and reflects our confidence in the response.  Pay particular attention to the wide range of seeding rates necessary to maximize yield at the 20 to 35 bushel yield potential.  This reflects the yield variability and the variability in the response of yield to seeding rates that are common in low-yielding years or fields.  We just are not as confident in this set of data.  Some years or locations, we could get by with 100,000 seed/acre; in others, it took more than 140,000.  With the other yield potentials, the range is pretty tight.  In other words, I have more confidence in recommending 110,000 or even less than 100,000 seed/acre in these instances.

Finally, we see that it takes, in general, less seed at high yields – which verifies my earlier statement that less seed are needed for higher yield potentials.

So what have I settled on?  Below are my suggestions.

But, you may ask, “What about yields greater than 70 bushels per acre?  That’s a good question.  But, I cannot answer it confidently since we have little data in that range.  We are however conducting new experiments this summer to update our data.

But until that data is available, here are my thoughts.  I think that lower seeding rates will work until you get to the 100+ bushel yield range.  After that, I suspect that we are running low on reproductive nodes (node on the plant where pods can form).  For instance, if we only have 80,000 plants/acre, we would need 15 reproductive nodes containing 4 pods on every one of these nodes!  While this is possible, I’m assuming in this calculation that we will grow 2,500 seed/pound and 3.0 seed/pod. Taking that down to a more normal 2800 seed/pound and 2.5 seed/pod, that means we need 6 pods per node!  I think that we are starting the expect a little much from single plant in this case.

So, for 100+ bushel yield environments, I’d suggest to gradually increase your seeding rate from the ones suggested above.  I do understand that we have very few 100+ bushels fields, but I have seen parts of the field exceeding this when I’m watching a yield monitor.   An we commonly have plots within our small-plot tests exceeding 90 and 100 bushels.

Finally, am I suggesting that we may be able to vary our soybean seeding rate as we do corn?  Yes, I’m suggesting that.  We will be validating some variable-rate-seeding (VRS) on two farmer’s fields this year.  If you know of anyone who has VRS planters and who would like to participate in an on-farm test, let me know.

Do we need to bump up our soybean seeding rates?

It’s hard to believe, but June is here and we need to start thinking about increasing our soybean seeding rates.  I’ve been recommending only 100 to 115 thousand seeds per acre for full-season production, enough to give you 70 to 80 thousand plants – yes, that’s all you need to maximize yield.

But as the season gets shorter, yields will start falling with delays in planting date.  On average, we lose about 1/2 bushel/acre per every day we delay planting after the middle of June.  The graph below shows the results of last year’s 4-state early wheat harvest/soybean planting double-crop study.  Note that yield does not decline very much during the first week or two of June, but rapidly drops off afterwards.

2015 DC Soy Yield across Plant DateThe main reason for this yield decline is that the crop struggles to develop enough leaf area to capture 90-95% of the sunlight by early pod development, due to the shorter growing season.  We can alleviate some of this by narrowing rows and increasing seeding rate.

I usually suggest that farmers plant enough seed to result in a final plant population of 180,000 plants/acre for double-crop soybean.  That means planting 200,000 to 220,000 seed/acre.  Yes that is a lot of seed, but my research shows that yields (and profit) continue to increase up to this seeding rate, especially when planting is delayed until late-June and early-July.

There are stipulations.  More productive soils and irrigated soybean usually require less seed.  Good years that allow lots of quick growth require less seed (but who can predict a good year?).  Later maturity groups may require slightly less seed.  Less seed are needed as you move south (growing season is longer and you can plant a later relative maturity).  I think that a soil profile that is full of water at soybean planting (this year) might allow less seed to be planted – but I have not documented that – It just makes sense to me that plants will grow better when the small grain has not depleted most of the subsoil moisture.

What about now?  How many seed/acre do we need to plant in the first week of June?  Here are my suggestions.  Keep in mind that these are general guidelines; you need a gradual increase in seed/acre.  I’m assuming 80 to 85% emergence for June/July plantings.  To easily determine how many seed you need per row foot, see VCE pub 3006-1447, Suggested Soybean Seeding Rates for Virginia

May: 100 to 115K

June 1-7:  120-140K

June 8-14: 140-180K

June 15-21: 180-200K

June 22-30: 200-220K

July: 220-250K