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Research Highlights
Turning By-products into Products: Can Acidic Soils be Amended from Sugarbeet Lime?

A crew of students from North Dakota State University hand-apply beet lime within the orange hoops in the spring after soil was sampled and soybeans were planted. Just prior to harvest, the hoops are removed, and soil samples are taken again after harvest.

By Carol Brown

Farming systems in each state have their own identity because of the soil types, precipitation amounts and topography. These factors affect what crops are grown in the state or region. North Dakota is no exception. In addition to soybeans, corn, and wheat, sugarbeets are a prominent crop grown in the state. There are approximately 30 beet sugar processing plants in the United States, seven of which are in or near North Dakota.

Soil scientist Chris Augustin, at North Dakota State University’s Research Extension Center in Dickinson, is looking at whether beet lime can be used to improve acidic soils in the state. The work is funded by the North Dakota Soybean Council.

“Beet lime is a by-product of making beet sugar,” says Augustin, Dickinson REC director. “For this research project, we’re using beet lime from Sidney Sugars, Inc. in Sidney, Montana. They have mountains of it. For us, beet lime is much less expensive than ag lime, as it is costly to get ag lime delivered to western North Dakota.”

NDSU soil scientist David Franzen and Augustin began exploring whether beet lime could be used as an amendment to reduce soil acidity in areas of the state. If they could improve the soil pH using beet lime, how would that impact soybean yield?

“We know that under extreme acidic soil conditions of less than 5.5 pH, crop nutrients  and activity of the nitrogen-fixing rhizobia bacteria can decrease. These are yield-limiting factors,” Augustin says. “After a couple years of this study, we haven’t seen a yield response or a quality response in soybeans. But North Dakota has been abnormally dry for four or five years now, which could be something that’s curbing the response.”

Augustin led the project last year, which was conducted on 12 farms mainly in the western portions of North Dakota. And based on the soil tests from these soybean field sites, the results could indicate how much lime is needed to alter the soil pH.

“We are waiting for results from the 1,200-some soil samples we collected,” he says. “From these results, we’ll get a pH response curve to see how much lime we should be putting down.”

Just because Augustin hasn’t seen soybean benefits yet, it doesn’t mean he never will.  Variable factors in agriculture could be affecting soybean non-response. In addition to dry conditions, no-till management could play a role. No-till has many benefits, says Augustin, such as improving soil organic matter, reducing soil erosion, and reducing fertilizer inputs, and it is prevalent in western North Dakota. But he’s found some soil stratification in long-term no-till soils.

“Where people have been applying fertilizer year after year, we can find zones of extreme acidity two to three inches down in the soil profile,” he says. “It doesn’t matter the fertilizer type; all fertilizers will slowly acidify. A benefit of soybeans is we can greatly reduce fertilizer inputs, which can slow down the acidification process and save the producer money by reducing input costs.”

In addition to weather and tillage methods, crop rotations could play a factor in soil acid levels, which is why he is expanding the tests and seeking support from other commodity groups such as the North Dakota Wheat Commission and the North Dakota Corn Council.

“Our thought is that soil pH impacts all crops. We’re trying to cast a wider net to look for variability in the western half of North Dakota,” says Augustin. “It may take longer to see yield response in soybeans; and beet lime may impact other crops more effectively. I want to conduct some longer-term studies and use different crops to test these variables.”

The agriculture industry in North Dakota may benefit from beet lime as a soil amendment and the sugarbeet industry may benefit from the utilization of this by-product. Augustin is hoping his research results could find a synergistic solution for both.

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.