Best known as the core material in drywall, gypsum has multiple benefits for growers and the agricultural industry. Even though there are multiple advantages of using gypsum in agriculture, we will cover five of those advantages.
1. Improves Soil and Plant Structure
Gypsum’s scientific name is calcium sulphate dihydrate. In layman’s terms, that means it consists of calcium (nutrient), sulphate (a central sulphur atom surrounded by four equivalent oxygen atoms), and dihydrate (two water molecules). Basically, gypsum is made up of nutrients, salt, oxygen, and water which are all beneficial to soil structure.
Agricultural gypsum helps water management, adds nutrients to the soil, breaks up compacted particles through a process called flocculation, reduces soil acidity, and prevents runoff and erosion. Gypsum, in addition to prevention and correction of sodicity, include greater stability of soil organic matter, more stable soil aggregates, improved water penetration into soil, and more rapid seed emergence.1
By improving soil structure, gypsum simultaneously improves plant structure. Flocculation allows plant roots to penetrate subsoil, enabling roots to move deeper and spread out, providing sturdier positioning. Not only this, but because of the calcium found in gypsum, the plant absorbs the nutrient making it stronger. The sulfate that is taken up by plants and metabolized releases the associated oxygen which is a source of oxygen to plant roots although a limited source.2 With improved plant structure, a plant is more likely to produce more, resulting in better yields. Gypsum can also help lessen phosphorus and nitrogen losses due to runoff.
In a survey done by Marvin Batte, PhD at the University of Kentucky and D. Lynn Forster from the Ohio State University, the results of farmers who used gypsum on their fields concluded the soil amendment improvements included better plant fertility, improved crop yield, provided needed sulfer and calcium nutrients, improved soil structure, improved plant root depth, improved seedling emergence, enhanced biological activity, increased soil water retention, improved soil tilth, reduced soil compaction, and, lastly, reduced soil crusting. “Gypsum users had a mean gross sale nearly $300,000 greater than non-adopters.”4
2. Works Well with Lime
Agricultural lime, or CaCO3, is crushed limestone. It is a soil amendment used in agriculture. It reduces the acidity of soil, provides calcium, and provides magnesium. Gypsum has no effect on the pH of soil so, if one were to use agricultural lime to reduce soil acidity, adding gypsum will not additionally affect the soil’s pH. Both gypsum and lime add calcium to the soil, but gypsum also adds sulfur, another nutrient that plants need.
Lime itself is insoluble in water. For the most part it isn‘t able to move throughout the soil. When applied at first, lime can harden the surface, decreasing water’s ability to penetrate the soil. As mentioned before, one of lime’s effects on soil is that it reduces its pH. However, because lime is relatively immobile, it doesn’t travel much deeper than topsoil. Lastly, when applying lime to fields, it can be very dusty and airborne. Although lime is non-toxic, it can be an irritant to humans and animals.
With all that said, gypsum can help with all the areas where lime falls short. For example, gypsum is up to 200 times more soluble than lime and is very mobile in soil. Using gypsum in addition to lime will help the lime move past the topsoil, having a positive effect on the soil underneath and providing better soil structure for plants. As mentioned, lime can often harden the surface of soil, but gypsum is able to break down the hardened soil particles, having an opposite effect to the lime. Gypsum, unlike lime, is neutral to the pH of the soil, so it won’t increase it or decrease it. “If aluminum toxicity is an issue due to acid subsoils, the gypsum will also react with the aluminum to offset its effect. As a result, root depth will be greater and nutrient availability will be improved.2 As an added benefit, gypsum doesn’t take as long to break down as lime does because it dissolves quicker, resulting in faster results.
3. Fast acting – results within a year
Although gypsum is beneficial for most soils, it is great for clay soils. Gypsum breaks up soil particles, improving water management, and is a soil amendment adding calcium and sulfur to the soil. Gypsum also is non-toxic, and you can apply it to existing plants, and it won’t burn or kill them. Although gypsum doesn’t work overnight, results are seen quicker than lime alone. Some studies have shown improvement on soils within the first year of application. Gypsum is also useful in changing the soil structure of heavy soils which have been impacted by heavy traffic, flooding, over cropping, or simply overly weatherized.3
Although it is known that response times of different crop species varies, there have been studies that show results of better soil structure within a year. Quicker results, better yields, and healthier plants result in more money for the farmer.
4. Easy application methods
Gypsum can be applied before, during, or after crop planting whether it is in the form of powder or pellets. The right way to apply gypsum, especially over a large area like a field, is with a spreader. This allows you to lay an even coat of gypsum throughout the field with the correct amount. Although there are typical pound rates per acre, it varies due to what the soil needs.
5. Renewable resource when recycled
The main use of gypsum is for the construction industry in which wallboard manufacturers use gypsum to make drywall, a necessary component in building. Gypsum is a renewable resource, but only if it is recycled. Because it comes straight from the mine, there is a limited quantity of it in the earth. However, if it is recycled, it becomes renewable and can be used for years to come. At Urban Gypsum, we have done just that. We take unused wallboard for construction companies, run it through our unique process, then sell it for agricultural use. We are dedicated to closing the loop on gypsum so instead of being thrown in a landfill, it is recycled and reused, reducing our environmental impact.
1. “Central Missouri Turf Management Incorporated.” Gypsum - Central MO Turf Management – Serving Jefferson City, Columbia, Lake Ozarks and Surrounding Areas with Lawn and Fertilization Services., www.cmtmi.com/gypsum.asp.
4. Batte, Marvin & Forster, D. (2015). Old is New Again: The Economics of Agricultural Gypsum Use. Journal of the American Society of Farm Managers and Rural Appraisers. 56-74.