Planting in Cold Soil

Every once in a while during our Farm Basics time, we like to talk about some of the things that are misconceptions out there. For example, our topic today is, the soil temp has to be warm for you to go plant. And unless it's at least 50 degrees, you're crazy to do your planting. When Brian and I were growing up, we didn't normally do a whole lot of planting in April. A lot of our planting happened in the early part of May. But that has completely flipped. And a lot of farmers in our area look at the crop insurance date as the first date they target planting. So for us in our area, the crop insurance date is April 10th for corn. So after April 10th, you can insure the crop. Well, at April 10th, the soil temperature is a little different, Brian, than three weeks later, May 1st. Ok, a couple of things here. First of all, crops actually can grow when the soil temp is in the 40s. Many can grow when the soil temp is in the 40s. But here's the other big thing, and I didn't realize this until we got a weather station on our farm. South Dakota State University has a weather station right at the Ag PhD field day site, and we can see the soil temperature down at 4 inches, and deeper than that too, but at 4 inches deep. Every day, it varies 5 to 10 degrees. Some days it's 15 to 20 degrees variance. So what I'm saying is, just because, oh it's 50 today, well it might be 40 tomorrow, might be 60 tomorrow, we just don't know. There's a lot of variance out there. Well, the biggest two things that have changed, besides the planting date, are the seed treatments that are on the seed, and then of course, the cold germination score. That's something in the past, well, farmers hadn't been too concerned about. They looked at the warm germination score on the seed bag, well that was run at 77 degrees. It's obviously not 77 degrees when we're planting. So unfortunately, your seed company most likely is not going to tell you what your cold germination score is. So what we do on our own farm is, we get the seed in early, we send it into a lab, and then we run that test at 40 degrees. We want to see, can we plant at 40 degrees? Are we safe? In most cases, we're at 85, 90 percent cold germ, even at 40 degrees. Yes, corn can grow when the soil temp is in the 40s. But the other thing is the seed treatment, Brian, and this also makes a huge difference. Multiple fungicides on the seed to protect against a variety of diseases, and then also insecticide on the seed to stop any seed attacking bugs. Now, the number one reason why a lot of people don't want to plant real early is they're worried about a late spring frost, and that can happen. Ok, I don't care what crop it is, but you also have to understand, what are the differences with the crops? For example, with soybeans, all the growing points are above ground as soon as you see leaves. So, in other words, if we freeze off all those growing points, the plant's dead. With corn, on the other hand, the growing point remains below ground until you hit about V6. So, in other words, you can see a bunch of leaves above ground, you could freeze off, heck, you could mow off that plant, that plant's still going to grow because the growing point is still below ground. So, there's a big difference and a big reason why we are always planting corn before soybeans. So, in the past, there were farmers that just looked at, well, what's the soil temp if it's at least 50 degrees? They got a pretty good chance of most seeds making it out there, but now with advanced seed treatments, also with other tests like the cold germination to tell us how that seed will do in even colder soils than 50 degrees, it allows farmers to plant a little earlier. Yeah, so the two things we look at, number one, what's the date on the calendar, and number two, is the soil dry? If we're past our crop insurance date and the soil's dry, we're going. I don't care how early it is, I don't care how cold that soil is, it doesn't matter, it's going to be fine. Well one time that I'd like it to be a little warmer than 40 degrees, though, is when I'm out spraying weeds like our Weed of the Week. Can you identify this week's weed?