Precision Ag Reviews
Ep. 24: Breaking Down Variable Rate Seeding with Morgan Seger
Many growers have variability across their field that deems the field worthy of variable rate seeding. This isn’t a new technology, but one we see growers who invest in it get better with each year. Growers and agronomists all seem to have their own way of blending data to create a representative map of your field to serve as the base of the script. In episode 24 of Precision Points, I talk through information and strategies that have worked for growers in the field.
Before we get into building our script, we need to understand our field. This can come by way of one type of data or multiple types of data and almost always includes more than one growing season. Each layer has a unique value proposition with benefits and watch outs. I break down the different types of data that are most commonly used in variable rate seeding scripts today in a recent article about best practices for variable rate seeding. These layers include yield data, soil maps, satellite imagery, and elevation maps.
Once you have your zones identified, it's time to populate them. I often see people spend painstaking hours developing their zones and quickly throw populations into those areas. I think we need to slow down and really think about what caused the differentiation between areas and how hybrids and varieties will respond to that area. Understanding the minimum and maximum population the specific product can handle is a good place to start. Be sure to understand how to best populate your field
We recently shared a list of several insights you should have before populating your fields to point you in the right direction.
Before you hit the fields, let's get out your historical data and identify areas in your field that need to be pushed, and those that could benefit from more conservative pops. Use this technology as a way to get aggressive in areas of your field, while managing for risk in other areas. Setting up your field for success starts before you enter the field. Tune into the full episode here or comment below with any insights you have learned from variable rating your populations.
What services have you used for VR Seeding? Leave a review here.
Host: Morgan Seger
Morgan Seger (00:00):
Precision Ag Reviews is an independent website that shares real farmer feedback on all makes and models of precision technology. But before we dive into today's episode, we have a quick message from this episode sponsor.
Morgan Seger (00:13):
Spring planting is almost here, and so is the age-old debate during the planting season, speed or accuracy? Should we aim to get it done before the inevitable rainy days? Or should we pace ourselves to get the spacing right? Ag Leader says, why not both? Don't sacrifice precise seed placement for speed. Get Ag Leader's Sure Speed Planting System with sheer force hydraulic down force. Not feeling the need for speed? Ag Leader also has a range of planting technology that’s sure to meet the individual needs of your operation. Level up your planting this year, contact your local Ag Leader dealer, or visit agleader.com for more information. Ag Leader, technology that works for you.
Speaker 2 (00:58):
Welcome to Precision Points, an ag tech podcast, where we plant seeds of innovation to inspire informed decisions about precision technology and its impact for growers like you. We explore precision ag tools and technology, from the soil to the sky, with your host Morgan Seger.
Morgan Seger (01:19):
Welcome back to Precision Points, an ag tech podcast from precisionagreviews.com. I'm your host Morgan Seger, and in each episode, we strive to bring you unbiased ag tech information and ideas. Today on the show, I'm going to be breaking down for you, how to build a variable rate seeding prescription. So we're going to start by talking through what types of data you'll want to have on hand when you go to make your script, and then how those pieces of information can come together to really give you a good understanding of how your field is performing from a spacial look. So you can then put that information to work for you and build a variable rate seeding prescription.
Morgan Seger (02:01):
Now, I know that people have been doing variable rate seeding for a long time. This was a big part of my job over the last 10 or 11 years, was building prescriptions with growers. So a lot of this is going to be information you have already thought of, but hopefully I can bring you some information today that might get you thinking about the data in a different way.
Morgan Seger (02:20):
So we're going to talk about the value each level of data brings, and some of the real benefits and downsides to each data piece. Because in my mind, we are yet to find like a bulletproof one source of data. So we're going to talk about a lot of different types of data and then how we can use them all to build a really powerful recommendation. All right? So here we go.
Morgan Seger (02:40):
The first piece of information I'm going to talk about is yield data. So yield data is kind of table stakes When it comes to understanding the final performance of your field, you're high and your low areas. When I first started building prescriptions, there were a lot of people that had years and years of yield data. There were a few people that had a high level of confidence in that data. So that has always kind of been a challenge for me, and a question I always ask is how much do you trust your yield data? Like, are you calibrating your yield monitor? Are you making sure that you have the same operator? I've seen yield data maps look very different depending on who the operator is. So if you're switching, even sometimes just making notes of that, because if the data starts looking differently, you're definitely going to want to remember that it was a personnel thing, not actual performance in your field.
Morgan Seger (03:37):
But this data is very, very powerful because it's your data. You know if you can trust it and it helps you start breaking your field down into zones. I know when we talk about management zones, some people really like that terminology, some people don't. But for me, I'm just generally talking about an area in your field that you are going to be managing a little bit differently based off of its performance and history.
Morgan Seger (04:01):
So yield data is a great place to start. If you have a couple of years of yield data, I definitely recommend using that. Because as you know, we're working with Mother Nature. Every year is a little bit different, and so the performance of the field can vary off of the environmental conditions that you're growing in. So having what it looks like in a wet year, in a dry year, in average years, all of that is very valuable when it comes down to understanding what's going on in your field and to create the most predictable map for the next year.
Morgan Seger (04:33):
One of the other upsides of using your own yield data, is it's showing you actual production off of that field. So in some of the other data pieces we're going to be talking about, you don't get real yield numbers where obviously in yield data, you do. And so this is very valuable, especially if you're working with someone else to help you build the prescription, to help them understand what the true productivity is in that field.
Morgan Seger (04:57):
A couple of watch outs. Obviously you want to make sure you have clean yield data, but there's a lot of things that impact your yield data and can sway your opinion on if you should be using it or not. So for instance, if you have a field that's very poorly drained, and you have five years of yield data, and then you systematically tiled the field, I would expect that performance to be drastically different the next year. So it's going to take you understanding how big of a change that is, and if you want to use your five years of historical yield data, or if you just want to start using your data that you have from post drainage. Because that may more accurately predict what that field is going to do the next year.
Morgan Seger (05:39):
The other thing is, like I said in the beginning of this yield data chat, it's very good at helping us understand how that field actually performed at the end of the year. But sometimes we have things happen towards the end of our growing season that makes yield data show how it yielded, but not actually representative of its potential. So I'm talking late season hurricane winds and things like that, that could have come through. You know you hate to see it, but we've had years where the corn has been flattened and we've lost a ton of yield really late in the season. And you have to think about that when you're using this level of data in your analysis, because yes, that's how it yielded, and that is true data. But it's not really reflecting the potential that crop had. So that's another thing to just keep in mind. When you do have very extreme weather patterns, you always have to be a little extra critical of your data to make sure it's going to serve your needs moving forward.
Morgan Seger (06:38):
The next piece of data I'm going to talk about are soil maps. So the USDA has provided SSURGO maps for almost every area of interest across the United States. So SSURGO stands for a Soil Survey Geographic Database, and essentially they have taken surveys of almost every acre. You can get this information for free through web soil service if you don't already have this provided for you. It's very valuable for understanding the soil variability across your field. It's a really great starting point for growers who maybe don't have access to other types of data that they can trust. Or you pick up a new field, this is a really good place to start because it gives you the soil name, some characteristics about it. So lots of times it will tell you if it's coarse, fine, silty, things like that. And then it will also tell you the slope and other variables that you're going to run into across that field.
Morgan Seger (07:32):
So the benefit to this piece of information is it's very simple and straightforward and helps you understand the variability across your field. Regardless of how long you have farmed it, you can access this information. The downside is, is I have run into lots of situations where this data can be a little inconsistent with what you actually see when you have boots on the ground in the field. So the transitions may be a little bit off, or it might not be picking up on some of the changes you can see when you're actually walking the field. So if you are using the SSURGO data for a main building block in your variable rate seeding prescription, I would definitely recommend you get out into the field GroundTruth the map and make sure it's as accurate as possible before using this as a main layer.
Morgan Seger (08:20):
All right. So next, we're going to talk about satellite imagery. Now, satellite imagery is where I personally have the most experience. I've worked with satellite imagery for most of my career, and I will say it has really come a long way. I remember when I would go on farm calls in the beginning of my career, so back in 2009, 2010. We would pull up Google maps and just show the growers we were working with aerial images of their field. There's a little time slider up at the top where you can go back year after year, and we would spend so much time looking at how their fields have changed. But then also looking at what truck was in the driveway and other things that Google could provide us. So it was pretty rudimentary when we were just getting started. But over the last 10 years, this information has really changed, and in my opinion, transformed the way we can make management decisions on our farm.
Morgan Seger (09:18):
So here's a couple of reasons why I like it so much. First is satellite imagery is available for pretty much every acre everywhere. So depending on who you are working through to access your satellite information, they can generally call up a field. So if it's your first year farming it, you can get historical information for that field usually with a couple of clicks of a button. The second reason why I really like satellite imagery is because it can show you the yield potential rather than showing you end of season yield. So like I said when we were talking about yield data, there are lots of variables that go into every season. And by capturing an image at peak vegetation with satellite imagery, you can pretty accurately predict the yield potential across the field. So we can mitigate some of those risks of late season weather events really throwing off our final yield data and making that kind of inaccurate for what the field could have done.
Morgan Seger (10:23):
So for that, I think it's a really nice, maybe true, source of data that you can use year over year. I do think it's very important to identify that field at peak vegetation. So you do have to kind of go back in the memory bank and remember what the growing season was like. Because you can't just say you'll take an early June image for each field because some years we have lots of good vegetation, and some years we're just getting the planters back out, maybe for the second or third time. We know lots of things change each year. So you want to make sure that you can identify that peak time to get the most accurate look at what your yield potential is.
Morgan Seger (11:05):
Now, when I am talking about peak vegetation satellite imagery, I am usually thinking of a normalized difference vegetative index of that field, so an NDVI. That will be a score of zero to one to help you understand how much vegetation you have out in your field. And that score will also help you identify at what point that field was at peak vegetation. And then I guess, kind of the third or last thing that I want to highlight about the benefits of satellite imagery is that you can also use bare soil maps.
Morgan Seger (11:39):
So this will be similar information to what you could get from SSURGO. It won't always have the classification and some of the details about the soil. But your soil brightness is a key indicator for organic matter in your field. So as long as you know the crop's history, and you know your tillage patterns, and that type of information that could be affecting your soil brightness, the bare soil satellite image of your field can also be a very powerful layer when you're building a composite map to variable rate seed off of.
Morgan Seger (12:13):
Now, let's talk about some of the watch-outs with satellite imagery. So it is very accessible for every field. One of the downsides is there are satellites going over your field all of the time. So you will have a very large database to sort through, especially if you're doing this on your own, to try to find a good image of your field. The same way there can be noise in yield data, there can be noise with satellite images. One of the main drivers would be cloud cover. So you really want to know how the company you're working with is going to mask for clouds and cut them out of the map, because that could definitely change the way your field is looking.
Morgan Seger (12:56):
And there's also a lot of processing that needs to go into making sure the satellite image is clean. Similar to what you would have to do with yield data. So you want to make sure that you're getting that information from a trusted source, or that you are able to kind of sort out good images from bad images. There will be a lot of images at your fingertips, so you kind of have to sort out which ones you want to use.
Morgan Seger (13:20):
Another downside that you have with satellite images is sometimes you can get vegetation from things like tree lines around the field that then skew your data. So I guess one trick I have for that is if you bring your field boundary in a little bit away from your tree lines, then you'll get a more accurate representation of your field. But lots of times the way the map colors are representing the variability are going to be unique within that boundary. So if you do have really strong vegetation from like some trees, or a weed patch, or something like that, it will then skew the rest of your data. So the colors make it visually easier to understand and comprehend. However, like drilling down to specific NDVI scores within that map may be the most accurate way for you to understand how the rest of the field is really performing.
Morgan Seger (14:10):
The next piece of data that I wanted to talk about when you're looking at building a composite variable rate seeding map would be elevation maps. So you can get general slope information from your SSURGO soil information, but if you really want to understand the elevation differences, or the relief in your field, you'll want to try to access LIDAR maps for your field. So LIDAR stands for Light Detection And Ranging, and they can give you a precise, spatial representation of your field's elevation and that relief.
Morgan Seger (14:42):
So, I mean, growing up in Northwest Ohio, elevation wasn't a huge deal for me because there were no elevation changes. But it definitely impacts yield. Lots of times your elevation correlates very strongly to organic matter, and the way the water moves across your field, and in drainage and things like that. So it definitely can be a very valuable piece of information to include in your composite map that you're building to do a variable rate seeding script.
Morgan Seger (15:09):
Okay. So we've talked about the types of data that we can use to build our composite map to build our variable rate seeding prescription off of. So now let's transition a little and talk about how we're going to use that data together to build the script. When you are looking at your field, oftentimes we create zones based off of productivity. I think that this is a very good place to start, however, I actually encourage the growers that I used to work with to look at the biggest changes in their field.
Morgan Seger (15:41):
So instead of always saying, we have zone one, two, three, and four. One is our highest producing, four is our least producing, and they go in order that way, I actually encourage you to look at what is making that area show up differently year-in and year-out. And there's a couple of reasons for this. Lots of times when we are looking at a field and the way it's performing, you will see areas that stand out every single year as being your highest productivity, and years that are on the low end every year.
Morgan Seger (16:13):
However, when you really start looking at all of the data you have for this field, you'll start seeing some nuances in the data where, just to keep it really simple, on a wet year an area does really well. In a dry year it does really poorly, and vice versa. So when you take a wet year and a dry year data together, that area looks pretty average. But you have to be thinking, what management things could I change to impact that area and really suit it well. Whether it's poorly drained or really well-drained, if it lays wet or if it gets too dry, there are things that you could be changing to manage that area for why it's different, not why it is average. If that makes sense.
Morgan Seger (17:00):
So as we go through the next parts of this conversation, I do think that it makes sense to have your map relatively ranked by productivity, but also be looking at what is causing that productivity to be high or low. Because that definitely can impact the way you are writing your script. I think that's one thing that we often miss in these initial conversations that I really wanted to highlight. From there, it's just spending time looking at these maps, understanding them, and building your prescription.
Morgan Seger (17:31):
Now, once you have established these zones or areas that are going to have different seeding rates, before you take the next step, I want you to think about the product you are putting in the field. So not all corn hybrids and soybean varieties are created equally when it comes to their ability to compete for sunlight and nutrients and water, everything. So you really have to be thinking about the type of plants you're putting into that field before you write a prescription.
Morgan Seger (18:02):
There are lots of ways to access this information. I generally recommend that you talk to the person who is selling you the seed to get their recommendations. But things like for corn, obviously, if the ear is going to be a fixed ear, a flex ear, a semi flex ear will help you understand how much room you have in your population swings for soybeans. You know, is it a tall plant? Is it a short plant? Is it a bushy plant, or is it a thin line plant? You need to know those things. So that way you're really maximizing your plan based off of the plant you're putting into that area.
Morgan Seger (18:36):
Once you have a good handle on, I guess, the min and max populations that plant would do best at, then you can start building your prescription based off of the zones that you have created. So take time to individually place that hybrid into the field, and then at the population best suited for that hybrid, based off of what you know about the field. Before we could do variable rate seeding, there were growers who would often set the population so that, in their worst areas, they would still have a growing crop. They might have really high productivity areas that they could have been pushing the population, but they would back it down so they didn't have to go over an empty knob.
Morgan Seger (19:19):
The benefit of variable rate seeding is you really can tailor your prescription to the field. So you have crop across the field and you're not missing out on that top end yield. So lots of times growers will use variable rate seeding in order to get really aggressive in areas of their field. So in very high productivity areas that you know you have good drainage and good fertility, that's where you can push your populations and let the plants do some work. And then back it off in the areas where you know drainage might be an issue, or it might burn up, things like that, in summer.
Morgan Seger (19:55):
At the end of the day, generally speaking the average population is still pretty close, within a couple of thousand plants usually, of what the grower would have flat rated across the field. So that's the benefit of variable rate seeding, is it doesn't cost more seed or save you a ton of money on seeding generally. But it does help you to better fit that field, be more aggressive, whether that's increasing or decreasing your populations based off of what the field needs.
Morgan Seger (20:23):
Now, when it comes to corn and soybeans, you definitely have two different approaches. Generally speaking, for corn in higher productivity areas, you're going to increase your population. In tougher areas, you're going to decrease your population. In soybeans, it's almost exactly opposite. So in your high productivity areas, sometimes beans can get little tall. They might start to lodge. So backing down your population will allow that plant to better express itself. Lots of times you'll see it bush more, put on more side branches and fill those up with pods, instead of having all of that plant-to-plant competition. And then you can still increase your population. Say you get up on a clay knob and you need some plant height, increasing your population and the competition around that plant might give you that height you're looking for. So it's just the opposite of what we generally see in corn when you're building a soybean recommendation.
Morgan Seger (21:20):
Then as we're kind of wrapping up our discussion today, there's just a couple of things that I want to make sure that we're talking about, or at least giving you some food for thought when you have your prescription planted. If this is the first time you're doing variable rate seeding, you'll also want to be thinking about the impacts this could have on the fertility in those areas. So you'll want to make sure if you're increasing your population, that those plants are still getting fed. This can be kind of a tricky conversation because lots of times you're putting it where you have more height, where you have higher organic matter, and maybe more available nitrogen to begin with. But you still want to make sure those plants are being fed appropriately as you're increasing and decreasing population across the field.
Morgan Seger (22:00):
The second thing I want to talk to you about is how you use your yield data, and any data really, moving forward after you start variable rate seeding. It's kind of like the example I gave on whether or not you would use historical data before and after adding drainage to your field. You are impacting your field's ability to yield once you start doing variable rate seeding.
Morgan Seger (22:27):
So you do want to keep that in mind as you transition into this new way of farming, how it's going to impact your yield data, or your satellite imagery. Because you should be setting your field up to perform at its best. And I don't know if you'll see things even out or become more extreme. It really depends on the field and how you're managing it, but it definitely could impact your yield data moving forward. So just keep that in mind when you go to build your composite the next year.
Morgan Seger (22:56):
I know this is a lot right now, but I do think that after you have your initial field variable rate script set up, it does get easier. So you spend a lot of time in this initial setup phase to really understand, not only your field's performance, but why it's performing the way it is. And then you start managing for that. Year over year, it does get a little bit easier to kind of reevaluate your prescription, see if you need to change any zones or modify anything. But you'll definitely want to revisit every year and make sure your seeding recs are aligned with the hybrid or variety that you're putting into that field.
Morgan Seger (23:34):
So then the next step, which we will get to in a later episode, is what do you do when you start throwing in multiple hybrids? I've been talking this week with some people that are doing variable rate seeding with variable rate hybrids, and the level of complexity is almost overwhelming when you're trying to sit at a table and plan it all out in the winter. So I'm excited to hopefully bring you some of that information here in the near future.
Morgan Seger (24:00):
In the meantime, I am so grateful that you tuned in to another episode of Precision Points. We love having the opportunity to talk to you and share these ideas. And we would love, if you have a minute, for you to go to precisionagreviews.com, check out our show notes and our other expert advice available on our blog. From there, you can read other growers reviews or leave a review of your own. We would love any comments or feedback that you have on how you create your variable rate seeding map, what levels of data you use, and how you make your decisions. Let's grow together.
Speaker 2 (24:33):
Thanks for tuning in to today's episode. To hear more podcasts like this, please rate, review, and subscribe to Precision Points. Visit precisionagreviews.com for show notes from this episode, and read expert advice on the blog, share your experience with the precision ag products you use, and check out our network of farmer reviews. Let's grow together.
Host: Morgan Seger
Morgan Seger grew up on a small farm in northwest Ohio before studying agriculture at The Ohio State University. She spent 10 years working with ag retail – specifically in ag tech – prior to hosting the Precision Points Podcast. She lives and farms in western Ohio with her husband Ben and their four children. Morgan has her own blog, Heart and Soil, where she talks about her experience farming, gardening, and raising her family.