Ultra High Yield Soybeans

I've written a lot about precision management of corn lately, so I figured I'd give soybeans a nod of the hand.  Here are the building blocks to insanely high soybean yields.

1.  Start with good soil.  If you haven't got any then improve it.
2.  Rotate with other crops.  Multiple years of corn, then cereal rye cover crop.
3.  Plant early.  Yield potential is established AFTER you plant and you need flowering sites.
4.  Time fertility for ~20# soil nitrates prior to V3.  This can be from variety of sources... no more, no less.
4.  Plant very long season variety.  Again, more flowering sites increase max potential.
5.  Adjust population to expected lodging and shade.  Tall beans never yield.
     A) Lower populations where soil nitrogen is expected to be higher than desired early.
     B) Lower populations in wider rows for less plant to plant competition.
     C) Lower populations with longer maturity (they'll make it up)
6.  No weeds allowed.  Spray early and often.
6.  Track soil moisture and only augment late if possible.  No irrigation? Pray for rain.
7.  If you have soil moisture late, top dress with N at beginning of seed fill to meet yield goals.
8.  Treat pests and disease according to scouting.
9.  Consider desiccant for harvest aid.
10.  Harvest timely and with proper settings.
11.  Sow cover crop to soak extra high N load from vibrant plants.

This is over simplified and highly opinionated.  It's also proven with experience on about a zillion field observations and various trials.  I left out some things that should be obvious, and also some details about things that will make this all automatic.  We're working on software that will help.  In the mean time, this should guide you.

The key to high yielding soybeans is having an environment that is rich for the plant's needs at each time of its life cycle.  There are two primary stages.  Vegetative and Reproductive.  They overlap from flowering until the end of new leaf development.  You want to maximize the nodes and thus flowering sites per acre based on your environment.  This changes across the field and throughout your planting window.  You need to adjust according to these things!  Furthermore, you should augment your available nitrates to stimulate bacteria to get to work early (a little N boosts leaf surface and juices the roots for faster and greater nodulation.) But, you don't want too much N early as the bacteria get lazy.  This might mean reducing your tillage and growing a high C:N cover to soak and tie up N early.  Sounds funny to suggest augmenting N levels to DECREASE nitrogen levels but it's truly important.  In fact, studies show too much N early can delay N fixing and ultimately crush yields.  Be careful.

Once healthy, evenly spaced plants have taken off in a nitrogen balanced environment, your job is to protect them so they can develop an insanely high number of flowering sites.  This means protecting their water source (soil), root development (compaction), and leaf surface (insect and disease.)  With crop rotation most of that is taken care of free of charge.  The planter becomes increasingly valuable as your populations become lower.  You cannot skimp here.  Try treating them with same affection as corn... seriously, try it.  Some people are known to time their row units so they drop equally spaced soybean seeds... and raise 160+ bpa records.

Ultra long season varieties have longer vegetative periods.  In fact, we have proven that the day length sensitive talk is bogus.  That's right... it's garbage.  Instead, focus on GDD heat units prior to flowering.  After flowering the soybean marches to maturity based on the fact that there is a night and not necessarily the length of the night (can anyone say, street lamp green beans?)  So, the plant sees the light switch, takes a nap and then wakes up to grab sunlight again.  You should focus on selecting a variety that will march to maturity close to or even after anticipated frost given your planting date and temperature outlook.  (obviously, you don't want to harvest every field after frost, but this post is talking about ultra high yield, okay!)

Soybeans grow like a cube.  Their geometry is much different than corn (a cylinder).  They will canopy at about the same height as their row width.  This isn't exact but it's a decent rule of thumb.  Given their ability to add flowering sites at an exponential rate, your exact population is highly influenced by your row width, planting date and maturity.  What is the best row width?  Tell me your planting date, seed variety and soil properties and I'll have an opinion.

As your tree-like soybeans sprawl out with tons of flowers and massive nodules on their roots, you'll want to know what your soil moisture profile looks like late in the season.  You should have well over 100 bushel potential based on node count per plant.  As such, you'll need to feed the seeds developing in all these pods!  History shows that good bean years favor dry early and wet late with good soil N mineralization happening late.  Soybeans require around 5# per bushel of N and can produce 60-70% from atmosphere.  This means that if your soil contributes 80# (3.5% OM soil) your cover crop releases some late and you want more than 100 bpa, you're going to need an additional 50-80# N top dressed.  How do you apply it and what source?  That's up to you but do as little crop damage as possible and get it into the root profile.  Foliars are not going to be enough.

For most of my midwest farmer buddies, the idea of spraying soybeans in October with a descecant sounds crazy.  I might get made fun of... but this won't be the last.  The truth is, a crazy lush, full season soybean plant is going to want to hang on and keep pumping late into the fall.  It really doesn't care that you have empty grain bins.  It wants more and more seed and will push the plant right up until you or mother nature say stop.  That's totally okay given your yield goals and investment here.  I can't advise trying this on every acre but with some experience you could probably uncover a means to justify harvesting 90+ bpa soybeans in October after a sprayer trip.

Oh, and I should run a budget on this... I'm pretty sure that seed rate adjustments could cover late N application costs (besides deferring rate decision until knowing exactly what soil moisture looked like.)

So that's it.  My nod to our poor secondary crop.  I love chatting about plant growth so drop a comment below.  There's so much I left out that others have tried with good success.  This is just my preferred crop plan for high yields.  What is yours?