05/29/25 Managing Acidic Soils for Soybean Success
You're listening to In The Pod, soybean updates, a weekly trek into the latest soybean information from NDSU Extension. Where does acidic soil come from, and how does it affect soybeans? Managing acidic soils can be challenging. Here to guide us is Victor Gomes, NDSU Extension cropping system specialist. Victor, some farmers have to deal with it. Where does it even come from?
Victor Gomes:Acidic soils for the longest time have not been a major concern in North Dakota agricultural soils. They've become a thing within the last couple decades as a result of not only the clay mineralogy in certain parts of the state where you can see more of a kaolinite clay content in the soil as opposed to a smectite content in the soil. There's a very clear divide there the Missouri River, Western of the Missouri River you're going to see more of those kalinite rich soils as opposed to the Eastern side of the state. So those soils they usually have naturally a lower buffering capacity that is they have a lower resistance to changes in soil chemistry that will impact in a change in soil pH. But also there are some anthropogenic factors long term no till associated with high rates of nitrogen over time have aggravated this condition in the soil. And since Western North Dakota has adopted no till as their pretty much their conventional soil management practice nowadays for so long you can see that these areas are more prone to the soil acidification out here in Western North Dakota.
Bruce Sundeen:When does it become a concern? What level does it have to get to?
Victor Gomes:Soil acidity in itself wouldn't be as much of a problem if it wasn't for the aluminum that is released in the soil. So, usually, when the soil pH drops below 5.5, you start to see more aluminum being released in the soil solution. That aluminum will ultimately cause toxicity to plants, and that's when you start to see a huge problem. But again, there are some factors, some intrinsic factors within the soil chemistry like organic matter or the soil buffering capacity that will dictate how much of a problem that aluminum content in the soil or that low soil pH is. So as a rule of thumb, knowing your soil very well is where you should shoot for if you suspect you have a low soil pH issue.
Bruce Sundeen:What kind of effect does acidic soil have on soybean growth and yield?
Victor Gomes:You're gonna see stunted growth on soybean plants. Some nutrient deficiency symptoms can also be observed as aluminum tends to tie up phosphorus in the soil as an example. So you might see symptoms of phosphorus deficiency. But below the ground you're also going to see some symptoms there in soybean plants. You're going to see lower root growth, lower number of lateral roots and also very importantly you're going to see lower nodulation happening because the rhizobia is also sensitive to those low soil pHs. So that's a first sign that you might have an acidic spot in your property.
Bruce Sundeen:Victor, how do you manage something like that?
Victor Gomes:So for low soil pH, the best strategy is to lime the soil, apply a substance that has calcium carbonate in it. Unfortunately, North Dakota doesn't have a source of lime, agricultural lime within the state. We don't have a lime quarry here. So what our growers have been using here in Western North Dakota is sugar beet waste lime that's coming from a sugar beet processing plant across from us in Montana. That approach, however, is costly and will depend on a number of factors whether it's going to be feasible or not such as do you own the land or do you rent it? And if you're renting it, for how long are you tied into that contract? So those are all things that you should keep in mind when approaching the low soil pH management. If liming is not an option for you, crop selection or cultivar selection can also have a huge part on it since some cultivars can be more tolerant to that aluminum toxicity than others.
Bruce Sundeen:Thanks, Victor. Our guest has been Victor Gomes, NDSU Extension cropping system specialist. You're listening to In The Pod, soybean updates, a weekly trek into the latest soybean information from NDSU Extension supported by the North Dakota Soybean Council.
