Speaker 1: With the recent rains that we’ve had this spring, now is a good time to assess your soil for compaction. Joining us now is Jason Warren, our soil management specialist. Jason why now this year?
Jason: A lot of times people ask me about compaction and they generally wait until the summertime because particularly wheat farmers are off. They’re not busy harvesting or planting or managing the crop. They’re just trying to get ready for the following crop.
The summertime is probably one of your worst times because our soils tend to be dry. But now that we’ve had all this nice rain in a lot of the state and then hopefully we’ll continue to get some nice rains throughout the rest of the spring. Our soils will be well suited to assess compaction. When we look at compaction we don’t want to look at dry hard soils. We want to look at our moist soils and see if when under moist conditions, is that compaction sufficient to limit root growth.
When we look at compaction we can visually observe horizontal layers or horizontal root growth or we can use something like this. It’s a penetrometer or even, this is a $200 deal, you could just have a pointed steel rod with a t-handle on it and make you own penetrometer and kind of feel around for dense layers in the soil.
But anytime you do any kind of penetration resistance, is what they call this, we certainly want to do it when the soil is wet, because as soon as this hits the ground, just like anybody know from digging post holes or any kind of hole, dry soil is hard and roots aren’t going to go through it regardless. So we want to do it when the soil is wet like it is today here in Stillwater.
Speaker 1: You kind of dug a little hole here and did a test. What kind of things did you find with this particular soil that we know has gotten lots or rain lately?
Jason: First thing we do is we can push it down, and whether you are using a steel rod or a penetrometer like this, you want to slowly push it down and slowly push it down until you start to see resistance.
Essentially the resistance of a soil is more where it stops to move downward. You look at the reading and you can keep pushing it. We want to, on a penetrometer, if the penetration resistance is greater than 300 PSI than we can limit root growth. What I find is about, I can get penetration resistance there of around 300 and that’s about six inches, on my rod here. So what I’ve done is dug down there to kind of get an idea what that might be.
Because you can have, plow pan would be common at six inches. Clay pans could also be common there. Had we not had six inches in the last two weeks here we possibly have dry soil, but what we find is an increase in clay content.
You see this pad is nice and shiny where this one is kind of dull. It’s got sparkling sand grains in it, but the surface isn’t shiny. From visually that shiny surface tells me there’s more clay in it than what’s in the surface. When you start to put it between your thumb and finger you can see it sticks together real readily and starts to kind of shine. It’s more the feel than the look, but that look is what you can see there on tv.
So what we know is there about six inches we may have a plow pan there, because this is cultivated crop land. We also certainly have an increase in clay that has got something to do with that penetration resistance.
So then the question becomes, do we want to try to physically remove that compaction? On a heavy clay soil or subsoil like that it’s going to cost you a lot of money to run a deep ripper through it. So I would probably say no, I’d let nature take its course and throughout the summer the soil will shrink and expand and break apart and probably do just as well as running some kind of heavy equipment through here.
Speaker 1: Okay. For wheat farmers you can kind of do, and canola I’m sure, kind of do this after harvest as well.
Jason: Yeah. In fact, the nice thing about wheat and canola is as they dry down or [Inaudible 04:22], they’re going to slow down their water use. You’re going to continue to accumulate more water if you’re not already full on that profile. From now until after harvest your soil should be in pretty good shape to take penetration resistance readings and dig some holes.
If you find resistance, dig some holes and see what’s down there. Look again for horizontal structure, which I didn’t see in this location. Then, just as importantly, is horizontal root growth or an abrupt change in the density of roots within your profile, indicates some compaction issues. Then you need to decide whether you want to live with them or try to alter that field come this summer with deep tillage or cover crop management or something like that depending on your system.
Speaker 1: Okay. Jason Warren. Good information. Thanks a lot.