Fall gypsum improves soil for next crop

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Farmers who apply gypsum to their fields in the fall can increase sulfur and calcium in their soils for their next crop, an Ohio State University scientist explains.

Warren Dick, a soil biochemist in the university’s College of Food, Agricultural, and Environmental Sciences, says in a recent paper that  applying flue gas desulfurization (FGD) gypsum to crop fields in the fall after harvest can result in improved soils that lead to higher yields.

Gypsum is an abundant byproduct from coal-burning power plants, said Dick, who holds an appointment with the Ohio Agricultural Research and Development Center, the research arm of the college.

“Growers typically apply gypsum in the fall after harvest,” he said. “When the gypsum is applied to soils low in available sulfur or with poor physical properties, improved crop vigor and increased yields for corn, soybeans, alfalfa and wheat are commonly observed during the next growing season.

“Growers need to be aware, however, that the benefits are not always immediate, as time is needed for the reactions in soil to take place. As rain droplets contact gypsum-treated soil, the gypsum particles dissolve and begin to move slowly into the soil profile.”

FGD gypsum is powdery, resembles flour and generally can be applied using conventional farm spreaders designed for spreading ag-lime and/or litter. Growers apply it to soils for several reasons, Dick said, including supplying sulfur when the element is limiting crop yields, and improving soil chemical and physical conditions.

According to Dick’s research, sufficient sulfur from gypsum, applied at rates of 0.5 to 2 tons per acre commonly used by producers, remains present in the upper soil profile for several years after application.

“Gypsum is also used to improve soils high in sodium and in some cases magnesium, as such soils can become dense or crust,” he said. “Adding gypsum to these soils will improve water infiltration and aeration.”

A typical application rate is 1 or 2 two tons per acre every 1-2 or three years, Dick said. A growing number of farmer co-ops sell it. When applying gypsum to soils, there are several factors growers need to consider, he said, including:

  • Gypsum doesn’t dissolve all at once or move though all soils at the same rate. Its solubility is impacted by the source, particle size distribution and the environment surrounding the material once it is applied.
  • Gypsum movement into the soil profile is also influenced by soil texture, amount of organic matter, surface soil structure, residue, compaction, soil moisture condition, and the timing and volume of rainfall.
  • Crop nutrient needs vary depending on the type of plant, but most agricultural crops require 30-70 pounds per acre of applied sulfur. Most producers add more than this amount to their soil when applying gypsum.
  • Plants can use sulfur only in the sulfate form, the form supplied by gypsum.
  • Fall applications of gypsum to tight clay soils at recommended rates can be expected to provide adequate sulfate-sulfur and calcium to the following spring-planted crop. Over time, improvements to soil structure can also be achieved.
  • Gypsum contributes to a variety of improvements to soil quality beyond fertility, including increased water infiltration and reduced losses of topsoil and nutrients.

Dick said gypsum has multiple benefits, including the ability to reduce phosphorus runoff from high phosphorus soils. More details are available in an OSU Extension bulletin (Bulletin 945), “Gypsum as an Agricultural Amendment,” available for $7.50 here.

Dick recommends that growers research those benefits to decide if applying gypsum is the right choice for them.

“Applying gypsum in the fall can be worth it, but it is not a silver bullet,” he said. “It is a tool in the farmer’s toolkit that, if used properly on the right soils and with the right crops, can provide both economic and environmental benefits.

“The benefits depend on the soil and the crop, so growers should evaluate their soils and crop management options and goals.”



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Arthur Welser, Cornell "74"    
Albany NY  |  December, 16, 2013 at 05:18 PM

Plough! Something that is still being done in much of Europe! You know, that age old practice of incorporating soil amendments!

Shuler Houck    
Cameron,SC  |  December, 16, 2013 at 07:03 PM

Gypsum has beneifits on soils that it fits. In the Southeast with our lighter land we do get into problems with it at times that no one seems to want to point out. The first is that the people that market it as well as most extension people insist that it does not change the pH. NOT TRUE. It probably will not change it the first year except on light land and heavy rainfall. The sulfur will leach away much faster than the calcium and you are left wondering how your pH went over 7 with the lime you applied. The calcium saturation will run up to 65% + and all the other cations, especially potash, will leach even easier. An imbalance can occur resulting in a need of higher potash levels to avoid deficiencies.

Eugene Edens    
Hillsboro, Texas  |  December, 17, 2013 at 06:36 AM

Shuler, It Is With Respect To University And Extension Individuals That I Make The Following Comments To You. Yes, You Are Correct Gypsum Will Decrease The Soil pH. Always Remember This To Be True, A Sulphate Always Decreases The pH, Where As A Carbonate Increases The pH. When Applying Finely Ground Calcium Carbonate In A Water Suspension, the Carbonate Is What Neutralizes The Hydrogen In The Soil. I Get Very Concerned When I Hear The Word "TONS" Of A Sulphate Being Added To The Lighter Soils In The Southeast. When Adding Calcium To A Soil With A Light To Medium Clay Content, It Would Be Best To Go The Lime Method For Increasing The Calcium Level In The Base Saturation Level Of The Soil. I Am Not Denying That Sulphur Isn't Needed In The Southeastern Soils. Be Very Careful When Applying Large Amounts Of Gypsum Per Acre, Because You Run The Risk Of Increasing The Soil pH To A Level Which Would Tie Up The Herbicide In The Soil. For The Last 20 Years, I Have Been Involved With Using A 200-Mesh Or Finer Limestone In A Water Suspension For Soil pH Correction. One Of The Most Limiting Factors In Agriculture Production Is Low Soil pH. I Have A FREE Liquid Lime DVD Available Upon Request. I Also Have Available The Research Work Conducted With Liquid Lime On A University Level.

Trent Tiemann    
Illinois  |  December, 17, 2013 at 08:10 AM

From a retailer standpoint this stuff is horrible to spread to the point that a higher price to spread it should probably be considered. Which in turn cuts down on the cost savings that were achieved as it being purshaced as a by product.

Curt Walker    
Alberta  |  December, 17, 2013 at 09:31 AM

I would be interested in viewing your lime video as well as reading the research paper on liquid lime. Thanks.

Scott Vanderventer    
Louisville, KY  |  December, 19, 2013 at 01:12 PM

I agree that gypsum is horrible to spread. Try our product, SUL4R-PLUS.com We have a premium product that spreads and blends perfectly with other Ag sized granular fertilizers. Our price point is higher but to your point you get what you pay for.

NICK EVANS    
FAIRMONT NC  |  December, 26, 2013 at 08:27 AM

I WOULD LIKE TO SEE YOUR LIQUID LIME DVD ALONG WITH THE RESEARCH DATA THANK YOU NICK

Eugene Edens    
Hillsboro, TX  |  July, 05, 2014 at 08:10 AM

Nick, I am so sorry about the delay in responding to your request for the Liquid Lime DVD. I just now found your request. Please send your mailing address to my email, eugeneedens@sbcglobal.net and I will be glad to mail you the DVD. What type of agricultural business are you associated with? Eugene

Eugene Edens    
Hillsboro, TX  |  July, 05, 2014 at 08:14 AM

Curt, I am so sorry about the delay in responding to your request for the Liquid Lime DVD. I just now found your request. Please send your mailing address to my email, eugeneedens@sbcglobal.net and I will be glad to mail you the DVD. What type of agricultural business are you associated with? Eugene


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