Using Gypsum to Grow Better Alfalfa

Alfalfa is a popular forage crop grown across the world. To grow better alfalfa, farmers must manage soil conditions and nutrition well. EcoGEM® gypsum can help. It improves soil structure and provides calcium and sulfur.

Alfalfa is well-adapted to the intermountain west’s climate and soils. In the drier, sunnier conditions, growers produce alfalfa that remains greener and more appetizing after it is baled. It has relative feed values (RFV) exceeding 200. This makes western alfalfa a highly sought after product in the beef, dairy and horse markets.

Alfalfa removes large quantities of nutrients from the soil. Historically, phosphorus and potassium are required in the greatest amounts followed by sulfur and boron. Nutrient deficiencies reduce yield, quality, and stand life. So, annual applications are a must.

With proper management, fertility, and irrigation, alfalfa yields can reach 8 to 10 tons per acre. Maintaining good soil drainage and supplying the correct amounts of nutrients are important management strategies to grow better alfalfa, increase yield, and increase profit.

Download the printable version of Growing Better Alfalfa with Gypsum (pdf).

Why Apply EcoGEM® Gypsum

EcoGEM® gypsum is an all-natural, OMRI-listed fertilizer and soil amendment. The mineral is also known as selenite or calcium sulfate dihydrate (CaSO4 •2di style=”font-family: Georgia, serif; font-size: 48px; font-weight: 700;”v0).

Gypsum contains 20-21% calcium and 17-18% sulfur (in the sulfate form). It is as soluble as other dry fertilizer, much more soluble than lime, and plants take up the sulfate form directly.

You can grow better alfalfa by using gypsum as a soil amendment, source of calcium, and source of sulfur.

Gypsum as a Soil Amendment

Gypsum is well known for its ability to remediate sodium buildup in the soil.

Sodium disperses soil particles, breaking down structure and allowing the particles to come together. This reduces porosity.

Gypsum naturally flocculates soil particles, which increases porosity and builds resilience against compaction.

Gypsum is an excellent soil amendment because its calcium displaces sodium in the soil’s cation exchange sites. Then, the water-soluble sodium can be flushed below the root zone by rainfall or irrigation.

Benefits of Improved Porosity
  • Better water infiltration and retention
  • Increased aeration
  • Reduced runoff
  • Greater microbial activity (when you have available calcium and sulfate)
  • Better soil health
Gypsum as a Source of Calcium

Calcium is essential for many plant functions. It helps with cell wall integrity, plant metabolism, and warding off disease.

However, calcium isn’t very mobile in the soil and is immobile in the plant. In the soil, it easily ties with carbonates and phosphates and quickly become unavailable. In the plant, it is deposited into cell walls and cannot be recycled into new growth.

Gypsum is an excellent source of calcium (Ca). Applying gypsum on an annual basis replenishes the soil and provides a continuous available supply. Read more about the calcium cycle.

Gypsum as a Source of Sulfur

Sulfur is an essential component in two amino acids—cysteine and methionine. These are building blocks of key proteins, including storage proteins that improve crude protein in forages and structural components of various enzymes that drive metabolism.

Applying sulfur as fertilizer has become more common today for several reasons:

  • A shift from low-purity to high-purity fertilizers (with sulfur byproducts removed)
  • Higher yielding varieties and production systems
  • Reduced atmospheric sulfur deposition due to introduction of the Clean Air Act
  • Declining soil reserves as soil organic matter is depleted and not replenished
S deficient alfalfa Brian Lang ISU
The lush alfalfa on the left was treated with sulfur; the sparse alfalfa on the right is sulfur-deficient. Photo: Brian Lang/ISU.

Gypsum is also an excellent source of sulfur (S). Gypsum is preferred because it is already in the plant-ready sulfate form (-SO4). It is also soluble once applied and watered in by irrigation or rainfall. While elemental sulfur has a higher analysis (90% vs. 18%), it can take years to break down in the soil and become available to plants.

Alfalfa is one of the crops most sensitive to a sulfur deficiency. Deficient plants are smaller with thinner stems and lighter green color. Sulfur shortages can affect forage production and quality long before you see visual symptoms.

Alfalfa is responsive to supplemental sulfur, so it is simple to prevent a deficiency.

Gypsum Application Rates

Gypsum is an excellent way to improve soil structure, while providing necessary calcium and sulfur. Annual applications are recommended as calcium will be tied up and sulfate is vulnerable to loss from leaching over time.

Meeting Sulfur Needs

Alfalfa requires 6 lbs. of S per ton of production. Production levels of 8 to 10 tons require 48 to 60 lbs. of S annually.

When a sulfur shortage is expected, Utah State University recommends applying 50 lbs. sulfate-sulfur (SO4-S) per acre, which is equivalent to 300 lbs. of gypsum per acre annually.

Meeting Calcium Needs

Improving soil structure requires a single larger dose of gypsum from 500 lbs. per acre annually to 2000 lbs. per acre every 3-4 years. A rate of 500 lbs. provides 100 lbs. Ca and 90 lbs. SO4-S; a rate of 2,000 lbs. provides 400 lbs. Ca and 360 lbs. SO4-S.

Download a free report: Grow Better Alfalfa with Gypsum by EcoGEM

Using gypsum for alfalfa is a great way for farmers to stretch their dollar and use a product that serves them in multiples ways.

Want to Grow Better Alflafa with EcoGEM® Gypsum?

Our agronomists can help you determine what application rates will work best for your alfalfa or other crops. Contact us today at (303)804-0100 or [email protected].

Dr. Dan Davidson, Ph.D. is a farmer, production agronomist, and international consultant for sustainable farming and agriculture.

He studied agronomy and crop science, earning his Bachelors of Science at University of Nebraska-Lincoln, his Masters of Science at University of Missouri-Columbia, and his Ph.D. at Washington State University.

Photo Credits: Alfalfa field by Wesley Haun. Cattle eating alfalfa by Lance Cheung, USDA. Sulfur deficient comparison by Brian Lang, Iowa State University Extension and Outreach Field Agronomist.