The Role Of Gypsum In Agriculture: 5 Key Benefits You Should Know

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While farmers have used gypsum (calcium sulfate dihydrate) for centuries, it has received renewed attention in recent years. This resurgence is due in large part to ongoing research and practical insights from leading experts that highlight the many benefits of gypsum.

The latest information on gypsum was the focus of the third annual Midwest Soil Improvement Symposium in Ada, OH, in March. The one-day event was held in conjunction with The Ohio State University’s Conservation Tillage and Technology Conference and sponsored by GYPSOIL — a leading supplier of synthetic gypsum. More than 200 attendees heard from industry representatives, scientists, consultants and growers on the use of gypsum to improve soil structure, reduce nutrient runoff and more.

Advising Growers On Using Gypsum

There is no silver bullet to improving soils. That was the message delivered by two independent crop consultants at the third annual Midwest Soil Improvement Symposium in Ada, OH, in March. And when it comes to recommending gypsum to their grower-customers, Clint Nester of Nester Ag, Bryan, OH, and Greg Kneubuhler of G&K Concepts, Harlan, IN, said it should be part of an integrated systems approach.

“There is no single solution. We prescribe a systems approach that works best for a particular farm and its profitability,” Kneubuhler said. “You have to look beyond just NPK. We’ve been recommending gypsum for a long time because we see great value with it.”

Nester Ag uses adaptive management with its customers, which allows them to better evaluate different management practices and identify and pursue those that are most efficient and cost-effective. “We offer soil tests and on-farm research to helps us determine the best course of action for our customers,” Nester said.

In addition to gypsum, this program often includes using no-till, cover crops and variable rate applications of lime and fertilizer.

Both consultants stress the importance of the 4Rs of nutrient stewardship to their customers, which incorporates the Right fertilizer source, at the Right rate, at the Right time and in the Right place. Kneubuhler even took this philosophy a step further: “I think there should be a fifth “R” — the Right data,” he said. “You need the right data to make good decisions, and soil testing is critical to getting that data.”

Major Benefits Of Gypsum

Here are five key (and overlapping) benefits of gypsum highlighted at the symposium:

1. Source of calcium and sulfur for plant nutrition. “Plants are becoming more deficient for sulfur and the soil is not supplying enough it,” said Warren Dick, soil scientist and professor, School of Environment and Natural Resources, The Ohio State University. “Gypsum is an excellent source of sulfur for plant nutrition and improving crop yield.”

Meanwhile, calcium is essential for most nutrients to be absorbed by plants roots. “Without adequate calcium, uptake mechanisms would fail,” Dick said. “Calcium helps stimulate root growth.”

2. Improves acid soils and treats aluminum toxicity. One of gypsum’s main advantages is its ability to reduce aluminum toxicity, which often accompanies soil acidity, particularly in subsoils. Gypsum can improve some acid soils even beyond what lime can do for them, which makes it possible to have deeper rooting with resulting benefits to the crops, Dick said. “Surface-applied gypsum leaches down to to the subsoil and results in increased root growth,” he said.

3. Improves soil structure. Flocculation, or aggregation, is needed to give favorable soil structure for root growth and air and water movement, said Jerry Bigham, Professor Emeritus, School of Environment and Natural Resources, The Ohio State University. “Clay dispersion and collapse of structure at the soil-air interface is a major contributor to crust formation,” he said. “Gypsum has been used for many years to improve aggregation and inhibit or overcome dispersion in sodic soils.”

Soluble calcium enhances soil aggregation and porosity to improve water infiltration (see below). “It’s important to manage the calcium status of the soil,” he said. “I would argue it’s every bit as important as managing NPK.”

In soils having unfavorable calcium-magnesium ratios, gypsum can create a more favorable ratio, Bigham added. “Addition of soluble calcium can overcome the dispersion effects of magnesium or sodium ions and help promote flocculation and structure development in dispersed soils,” he said.

What Is FGD Gypsum?

While the benefits of gypsum in agriculture were established more than 200 years ago, the practice was lost because gypsum was too expensive to mine and transport, except for certain specialty crops. Today, there’s an alternative, more economical source of gypsum: flue gas desulfurization (FGD) gypsum.

This synthetic gypsum is produced at some coal-fired power plants as a by-product of pollution control measures. The Clean Air Act Amendments of 1990 mandate that electrical utilities install systems for removing (scrubbing) sulfur dioxide (SO2) from flue gases that are generated during the burning of coal. The resulting materials are FGD by-products.

FGD gypsum is generally more pure than mined gypsum. It is a fine white powder that’s damp to the touch, similar to moistened flour or biscuit baking mix.

Source: Gypsoil.com, The Ohio State University Extension

4. Improves water infiltration. Gypsum also improves the ability of soil to drain and not become waterlogged due to a combination of high sodium, swelling clay and excess water, Dick said. “When we apply gypsum to soil it allows water to move into the soil and allow the crop to grow well,” he said.

Increased water-use efficiency of crops is extremely important during a drought, added Allen Torbert, research leader at the USDA-ARS National Soil Dynamics Lab, Auburn, AL. “The key to helping crops survive a drought is to capture all the water you can when it does rain, he said. “Better soil structure allows all the positive benefits of soil-water relations to occur and gypsum helps to create and support good soil structure properties.

5. Helps reduce runoff and erosion. Agriculture is considered to be one of the major contributors to water quality, with phosphorus runoff the biggest concern. Experts explained how gypsum helps to keep phosphorus and other nutrients from leaving farm fields. “Gypsum should be considered as a Best Management Practice for reducing soluble P losses,” said Torbert, who showed studies on how gypsum interacts with phosphorus.

Darrell Norton, retired soil scientist at the USDA-ARS National Soil Erosion Research Laboratory at Purdue University, added: “Using gypsum as a soil amendment is the most economical way to cut the non-point run-off pollution of phosphorus.”

Hopkins is Senior Online Editor for the CropLife Media Group at Meister Media Worldwide.
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3 comments on “The Role Of Gypsum In Agriculture: 5 Key Benefits You Should Know

  1. Ron Chamberlain

    The symposium speakers included spporting data in their presentations. You can find videos of all the presentations given at the 2013 symposium by going to the GYPSOIL website at this link:http://www.gypsoil.com/improving-your-soil/midwest/midwest-soil-improvement-symposium/2013-symposium
    Also, GYPSOIL maintains a large Research Library of peer-reviewed research papers; proceedings, bulletins and research reports; slide sets and popular press articles at the link below. It is easy to search the Library for specific topics pertaining to gypsum such as water infiltration, aluminum toxicity, sulfur, erosion, etc. You can also search by state and researcher name. Find the Library at this link: http://www.gypsoil.com/research-library?&filterCrop=&filterFocus=&filterState=&filterCategory=&filterKeyword=&pagenum=6