Did your soil struggle to support your corn or soybean crop last season? If so, you might be considering soil amendments this year.
But where do you start? With the exception of fertilizer, almost every material added to soil to improve its properties and processes falls under the broad category of soil amendments.¹
With so many options available, how should you choose soil amendments, and what benefits and risks should you consider when amending your soil?
Learn how inputs such as lime, animal manure and gypsum can control soil pH, improve soil structure, add nutrients and more.
What to do before starting soil amendments
- Test your soil: Testing your soil before making amendments is critical. If you skip soil testing, your application of soil amendments may end up doing more harm than good, inadvertently limiting certain nutrients and reducing your yield.
- Choose amendments carefully: Use your soil test results to determine specific aspects of your soil you want to improve, and consider how long the amendment will last in the soil.
- Consider soil components: Understanding soil texture, and factors such as corn/soybean sensitivity to salt, alongside the potential amendment’s components will help you properly leverage your chosen amendment.
- Consider complementary management practices: Growing cover crops to improve soil productivity can complement amendment application.
Common soil amendments for corn and soybeans
Lime
Using lime as a soil amendment neutralizes yield-limiting soil acidity and adds calcium and magnesium to the soil, correcting low nutrient availability of calcium and magnesium and potentially changing soil structure. As lime dissolves, it raises soil pH levels, enabling greater nutrient uptake as most nutrients are most available at a pH between 6.0 and 7.0.
However, one downside to using lime as a soil amendment is that the full payoff from liming may require three to four years to show up, especially in calcareous soils. Additionally, yield increases from lime amendments are typically greater with soybean than with corn.²
Animal manure
Animal manure is a common soil amendment, especially in operations that have livestock, providing an excellent source of nitrogen, phosphorus and potassium.
In operations where manure is readily available, applying with a P-based manure application rate may make the most long-term economic sense.³
One limitation of using manure is that the proportion of nutrients in manure is typically not the same as the proportions of nutrients crops require, and manure application based on one nutrient may over- or under-supply other necessary crop nutrients.
It is recommended to supplement with commercial fertilizers to balance out these unintentional imbalances. Additionally, similar to lime’s delayed effects, nutrients from manure are not fully available in the first season.
Gypsum
Gypsum provides a soluble source of calcium and sulfur (in sulfate form) that can be used as a plant nutrient source.
Additionally, research indicates that gypsum can minimize the loss of dissolved P in surface water runoff from row crop systems as well as hayfields.⁴
Since gypsum decreases soil pH in high-pH soils, beware of applying gypsum when soil pH is less than 5. This can be harmful to plants present at the time of the application. To avoid damage, apply lime to correct soil pH, and then reevaluate for gypsum application as needed.
Since gypsum is costlier than lime, it is best used in specific situations such as an identified need for sulfur, aluminum toxicity in acidic subsoils, or surface crusting in higher clay soil types.⁵
Experts are available to help you make your decisions. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.
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Endnotes
- Maharjan, Bijesh, et al. “Soil Amendments.” CropWatch, 4 Dec. 2024, cropwatch.unl.edu/2020/soil-amendments. Accessed 5 Dec. 2024.
- Maharjan et al. “Soil Amendments.”
- Wilson, Melissa. “Guidelines for Manure Application Rates.” Extension at the University of Minnesota, 2022, extension.umn.edu/manure-management/manure-application-rates#non-irrigated-corn-1858660. Accessed 5 Dec. 2024.
- “Gypsum As a Best Management Practice for Reducing P Loss from Agricultural Fields.” Livestock and Poultry Environmental Learning Community, 5 Mar. 2019, lpelc.org/gypsum-as-a-best-management-practice-for-reducing-p-loss-from-agricultural-fields/. Accessed 5 Dec. 2024.
- “Amending Soils with Lime or Gypsum (NRCS 333).” AgBMPs, agbmps.osu.edu/bmp/amending-soils-lime-or-gypsum-nrcs-333. Accessed 5 Dec. 2024.
