Free Grower Resource
Crop Yield Improvement Report
Grow More on the Same Acres With High-Purity CSD
How calcium sulfate dihydrate corrects the hidden limits on yield — sulfur shortfall, calcium demand, poor water entry, and nutrient loss — and why mineral purity decides the payoff.
Heal the Soil, Feed the Earth
Calcium sulfate dihydrate (CSD) — also commonly known as “gypsum” in its lower-grade, less-refined form — is one of the
most valuable mineral tools in modern agriculture. Throughout this guide we use its precise scientific name, CSD, because
purity and mineral quality determine how well it performs. CSD is roughly 22% calcium and 18% plant-available sulfur and,
unlike lime, does not change soil pH.
WHY YIELDS STALL EVEN WHEN YOU FERTILIZE
Most yield-limiting problems are not a shortage of nitrogen or phosphorus — they are the soil’s inability to deliver water and nutrients to the root. When the surface crusts and water runs off, the crop is droughted and starved even in a wet year, and the fertilizer you applied leaves
with the runoff. High-purity CSD attacks four of these limits at once: it supplies the calcium and sulfur modern soils lack, it rebuilds structure so water and roots can move, and it holds nutrients in the root zone. Because CSD releases its nutrients only as it dissolves, a purer product delivers more
of what you paid for.
22% Ca
Calcium supplied for structure & nutrition
18% S
Plant-available sulfate sulfur
pH-neutral
No unwanted pH swing like lime
22% Ca
Calcium supplied for structure & nutrition
18% S
Plant-available sulfate sulfur
pH-neutral
No unwanted pH swing like lime
WHAT THE YIELD RESEARCH SHOWS
— BY CROP
Extension trials are consistent on one point: calcium sulfate pays best where a real limit exists (low sulfur, calcium demand, sodium, crusting, or acidic subsoil). Where those limits are present, yield gains are commonly reported.
| CROP | WHY CSD HELPS | DOCUMENTED RESPONSE |
|---|---|---|
| Corn | Sulfur demand (~0.1 lb S/bu); better infiltration on tight soils | Yield increases where soil pH, organic matter, or S was low (Ohio State; MSU) |
| Soybean | Economical sulfate source on deficient acres | Corrects S deficiency; vigor and yield gains reported (MSU Extension) |
| Peanut | Calcium in the pegging zone prevents “pops” and pod rot | ~1,000 lb/acre at early bloom; higher grade & seed Ca (UGA) |
| Alfalfa | Calcium/sulfur; helps acidic subsoils | Significant yield increases on some soils (UGA/CAES) |
| Almond / tree & vine | Water-run CSD improves infiltration & water management | Infiltration up to 3× at 1–2 tons/acre (UC ANR) |
Honest Expectation
Older reviews (1933–2008) found no yield benefit in many cases where soils were already well-structured and sulfur-sufficient. CSD is a targeted tool, not a blanket rate — and a low-purity product wastes tonnage on inert filler. A soil test tells you whether the limit it fixes is present on your ground.
THE FOUR MECHANISMS
BEHIND HIGHER YIELD
1. It feeds two nutrients soils now lack
Since the Clean Air Act, atmospheric sulfur deposition has fallen more than 80% in some regions — from roughly 10–15 lb/acre/year historically to under 2 lb today. High-analysis fertilizers (urea, DAP, potash) add none. High-purity CSD restores plant-available sulfate; 100 lb supplies about 18 lb of sulfur per acre.
2. It opens the soil so water reaches the root
Calcium flocculates dispersed clay and displaces sodium, preventing the surface crust that sheds rain and irrigation. UC ANR research documents infiltration increasing as much as threefold after 1–2 tons/acre.
3. It keeps fertilizer where the crop can use it
CSD binds soluble phosphorus into less-mobile calcium phosphate that stays plant-available, cutting dissolved-P runoff 40–70% (Ohio State). Nutrients retained in the root zone are nutrients your yield can convert.
4. It builds deeper rooting
Calcium moving into the subsoil improves structure at depth, letting roots explore more water and nutrients — the buffer that protects yield in a dry finish. Texas A&M AgriLife Research has shown that surface-applied CSD carries calcium and sulfate into acid subsoils, reducing aluminum toxicity so roots proliferate into zones they previously could not use (Chessman, Leonard & Haby).
1. It feeds two nutrients soils now lack
Since the Clean Air Act, atmospheric sulfur deposition has fallen more than 80% in some regions — from roughly 10–15 lb/acre/year historically to under 2 lb today. High-analysis fertilizers (urea, DAP, potash) add none. High-purity CSD restores plant-available sulfate; 100 lb supplies about 18 lb of sulfur per acre.
2. It opens the soil so water reaches the root
Calcium flocculates dispersed clay and displaces sodium, preventing the surface crust that sheds rain and irrigation. UC ANR research documents infiltration increasing as much as threefold after 1–2 tons/acre.
3. It keeps fertilizer where the crop can use it
CSD binds soluble phosphorus into less-mobile calcium phosphate that stays plant-available, cutting dissolved-P runoff 40–70% (Ohio State). Nutrients retained in the root zone are nutrients your yield can convert.
4. It builds deeper rooting
Calcium moving into the subsoil improves structure at depth, letting roots explore more water and nutrients — the buffer that protects yield in a dry finish. Texas A&M AgriLife Research has shown that surface-applied CSD carries calcium and sulfate into acid subsoils, reducing aluminum toxicity so roots proliferate into zones they previously could not use (Chessman, Leonard & Haby).
A SIMPLE YIELD-IMPROVEMENT PLAN
- 1. Soil test for sulfur, calcium, base saturation, sodium (ESP/SAR), and texture.
- 2. Match the rate to the limit: nutrition/structure maintenance often 500–1,000 lb/acre; reclamation or heavy crusting 1–2+ tons/acre (per NRCS 333, do not exceed 5 tons/acre/year).
- 3. Insist on purity — above ~90% CSD — so more of each ton dissolves and is absorbed.
- 4. Verify with strip checks and follow-up tests, and ask about NRCS/EQIP cost-share.
PROVEN RESULTS THROUGH
LAND‐GRANT UNIVERSITIES
The value of calcium sulfate dihydrate is documented by the land-grant universities serving the two largest farm states in the country — the same institutions growers trust for unbiased, research-based guidance.
Texas — Texas A&M AgriLife
Texas A&M AgriLife Extension recommends calcium sulfate to loosen heavy clay soils and make them more workable, and lists soluble calcium
(CSD) as the primary chemical amendment for reclaiming sodic soils. Texas A&M AgriLife Research (the Texas Agricultural Experiment Station)
has shown that surface-applied CSD moves calcium and sulfate down into acid subsoils, reducing aluminum toxicity and supplying Ca and S
so roots can proliferate deeper and extract more water and nutrients (Chessman, Leonard & Haby).
California — University of California (UC Davis / UC ANR)
University of California research established the gypsum-requirement standard used nationwide for sodic-soil reclamation — roughly 1.7 tons
of pure CSD per acre-foot of soil for each milliequivalent of exchangeable sodium (J.D. Oster and colleagues). UC ANR field work in the San
Joaquin Valley documents CSD increasing water infiltration up to threefold on tight and clean-water-affected soils (UC ANR, Can Gypsum
Improve Water Penetration?).
Texas — Texas A&M AgriLife
Texas A&M AgriLife Extension recommends calcium sulfate to loosen heavy clay soils and make them more workable, and lists soluble calcium (CSD) as the primary chemical amendment for reclaiming sodic soils. Texas A&M AgriLife Research (the Texas Agricultural Experiment Station) has shown that surface-applied CSD moves calcium and sulfate down into acid subsoils, reducing aluminum toxicity and supplying Ca and S so roots can proliferate deeper and extract more water and nutrients (Chessman, Leonard & Haby).
California — University of California (UC Davis / UC ANR)
University of California research established the gypsum-requirement standard used nationwide for sodic-soil reclamation — roughly 1.7 tons of pure CSD per acre-foot of soil for each milliequivalent of exchangeable sodium (J.D. Oster and colleagues). UC ANR field work in the San Joaquin Valley documents CSD increasing water infiltration up to threefold on tight and clean-water-affected soils (UC ANR, Can Gypsum Improve Water Penetration?).
Why The Source Matters
When a recommendation comes from Texas A&M AgriLife or the University of California — not a product brochure — you can act on it with confidence. EcoGEM® builds its CSD program on exactly this body of public, peer-reviewed research.
THE CSD DIFFERENCE: WHY PURITY MATTERS
Not all calcium sulfate dihydrate is created equal — and this is where a mineral-science company parts ways with a run-ofmine gypsum supplier. common mined gypsum ranges roughly from 60% to over 95% calcium sulfate; the remainder is inert, insoluble material such as dolomite, quartz, and clay that dissolves poorly, delivers no calcium or sulfur, and is simply hauled and spread as filler.
Because CSD releases its calcium and sulfate only as it dissolves, purity directly governs how much of what you apply actually becomes plant available. Ohio State University Extension analyses found that high-purity CSD left under 3% insoluble residue after dissolution, while lowergrade mined material left as much as ~19% undissolved (Dontsova et al., OSU Extension ANR-20). Higher-purity CSD — above roughly 90% — therefore puts a greater share of each ton into the soil solution, where roots can absorb it, and does so faster because finer, high-grade material dissolves more readily.
>90%
Purity EcoGEM® targets for reliable absorption & reactivity
<3%
Insoluble residue for high-purity CSD (OSU ANR-20)
~19%
Undissolved filler in lower-grade mined material
22% Ca
Calcium supplied for structure & nutrition
18% S
Plant-available sulfate sulfur
pH-neutral
No unwanted pH swing like lime
The practical result of higher purity: more plant-available calcium and sulfate per ton, faster and more complete dissolution, better nutrient absorption by the crop, and less inert material to transport and apply. As a mineral-science company, EcoGEM® supplies high-purity calcium sulfate dihydrate (CSD) — not lower-grade, run-of-mine gypsum.
APPLICATION & HANDLING BEST PRACTICES
Getting the agronomy right is only half the job — how CSD is sourced, spread, and followed up determines the return. These
practices apply across every use in this guide.
Texas — Texas A&M AgriLife
Texas A&M AgriLife Extension recommends calcium sulfate to loosen heavy clay soils and make them more workable, and lists soluble calcium
(CSD) as the primary chemical amendment for reclaiming sodic soils. Texas A&M AgriLife Research (the Texas Agricultural Experiment Station)
has shown that surface-applied CSD moves calcium and sulfate down into acid subsoils, reducing aluminum toxicity and supplying Ca and S
so roots can proliferate deeper and extract more water and nutrients (Chessman, Leonard & Haby).
California — University of California (UC Davis / UC ANR)
University of California research established the gypsum-requirement standard used nationwide for sodic-soil reclamation — roughly 1.7 tons
of pure CSD per acre-foot of soil for each milliequivalent of exchangeable sodium (J.D. Oster and colleagues). UC ANR field work in the San
Joaquin Valley documents CSD increasing water infiltration up to threefold on tight and clean-water-affected soils (UC ANR, Can Gypsum
Improve Water Penetration?).
Source quality matters most
Agricultural calcium sulfate comes as mined natural material and as synthetic (FGD) material recovered from power-plant emissions; USGS notes synthetic sources now supply a large share of U.S. tonnage. What matters for your field is purity, low contaminants, and a particle size that spreads evenly and dissolves on schedule. EcoGEM®, as a mineral-science company, supplies OMRI-listed high-purity CSD rather than variable, run-of-mine gypsum.
Spreading and incorporation
- Even coverage beats high rates — calibrate the spreader and overlap correctly.
- Water it in. CSD needs moisture to dissolve and move calcium into the profile; rainfall or irrigation after application activates it.
- Surface-applied is fine for infiltration and phosphorus goals; light incorporation can speed nutrient objectives.
- Water-run option: in flood/surface irrigation, finely sized high-purity CSD can be metered into the water (studied by UC ANR in almonds).
Stewardship guardrails
Follow NRCS Practice 333: do not exceed 5 tons/acre in a single year for these purposes, and base rates on a current soil test. CSD is pHneutral — it does not replace lime where a pH correction is needed, and it will not harm soils already at target pH.
GROWER FAQ
Yes — calcium sulfate dihydrate (CSD) is the precise scientific name for the mineral commonly sold as “gypsum.” The important difference is grade: much of what is marketed as gypsum is lower-purity, run-of-mine material. EcoGEM® supplies high-purity CSD, so more of every ton is active, dissolvable mineral.
Yes. Because CSD delivers calcium and sulfate only as it dissolves, inert impurities are dead weight. Ohio State Extension found high-purity
material left under 3% insoluble residue, versus up to ~19% for lower-grade mined product (ANR-20). Higher purity — above ~90% — means more plant-available nutrient absorbed per ton and less filler hauled and spread.
No. Calcium sulfate is pH-neutral — that is its advantage over lime. It supplies calcium and improves structure without raising pH, so it is safe on soils already at the right pH. Where you need to correct acidity, use lime; the two can be used together.
It depends on the goal. Nutritional (Ca/S) needs are often met annually per soil test; the phosphorus-binding and structural effects have been documented to persist 20+ months, so infiltration and runoff programs may run on a multi-year cycle. Sodic reclamation may require repeated applications over several years.
Often, yes. CSD is USDA-NRCS Conservation Practice 333. Federal EQIP cost-share and state water-quality programs such as Ohio’s H2Ohio provide financial assistance because it keeps nutrients on the field and out of waterways. Ask EcoGEM® and your local NRCS office about eligibility.
Ready to put high-purity CSD
to work on your ground?
EcoGEM® is a mineral-science company supplying OMRI-listed, high-purity calcium sulfate dihydrate (CSD) — plus soil & water analysis, custom application rates, and NRCS-practice guidance. Ask how your acres may qualify for conservation cost-share.