There's a single change you can make to a piece of land that pays off on two completely different balance sheets at once. Build up the living carbon in your soil, and the ground holds more water — riding out dry spells, soaking up storms. Do the same thing, and that carbon is being pulled out of the air and stored in the ground. One practice, two returns: more water in the dry season, and carbon drawdown the whole time.
That's not a coincidence. Soil holds water for a few reasons — mostly its texture and structure — but the one lever a working landowner can actually build is organic matter, and organic matter is also where soil stores carbon. Improve it and you nudge both up at once.
A sponge landscape is land managed so its soil soaks up and holds water like a sponge instead of shedding it — built by increasing soil organic matter, keeping the ground covered and rooted year-round, and minimizing tillage. Because that organic matter is also where soil stores carbon, the same work delivers two returns: water resilience and carbon drawdown.
New to why land-held water matters so much? Start with the water cycle, broken and how to put it back.
the mechanism: what actually makes soil a sponge
Healthy soil isn't dirt — it's a living structure. Roots, fungi, and microbes bind mineral particles into crumbs with pore spaces between them, and glue those crumbs together with sticky carbon compounds. That structure is what lets water infiltrate and cling instead of running off or draining straight through. Kill the life and pulverize the structure — with constant tillage, bare fallow ground, and no living roots — and the soil collapses into a crust that sheds rain.
So building the sponge is really about feeding soil life. A short list of practices does most of the work:
- keep living roots in the ground year-round — cover crops and perennials feed the microbes that build structure
- keep the surface covered — residue and mulch stop the soil from crusting, baking, and eroding
- minimize tillage — every pass breaks the structure and burns off organic matter
- add organic matter — compost, manure, and crop residue feed the system
- integrate grazing well — managed, moving livestock can build soil where continuous overgrazing destroys it
Do these, and soil organic matter climbs — and with it, how much water the land can hold. We walk through the drought side of this in detail in drought-proofing starts in the soil, not the reservoir; here the focus is what else that same organic matter is doing.
the same work banks carbon
Here's the part that turns a water practice into a climate one: soil organic matter is roughly half carbon — about 58% by the standard (Van Bemmelen) conversion, though the exact factor varies by soil. When you build organic matter, you're moving carbon that plants pulled from the air as CO₂ into the ground. The water sponge and the soil-carbon store are built from the same material.
This is a big part of what "carbon farming" and "regenerative agriculture" describe — though the terms overlap with sponge-building rather than being identical to it. Carbon farming also spans biochar and agroforestry; regenerative agriculture chases soil life, biodiversity, and profit, not just carbon. The shared core is the soil-building that also happens to hold water: the water benefit shows up in the first dry season, and the carbon accrues underground the whole time. (For the case that this kind of drawdown is infrastructure, not just tradable offsets, see carbon removal is infrastructure, not just offsets.)
The one lever a landowner can build to hold more water — soil organic matter — is the same material that stores soil carbon, so on working land, water resilience and carbon drawdown aren't a trade-off. They're two returns on one deposit.
peatlands: the sponge at its most extreme
If mineral soil is a sponge, a peatland is a sponge that never stopped filling. Peat is waterlogged ground where dead plant material can't fully decompose, so it piles up as almost pure carbon, century after century. The result is staggering: peatlands cover only about 3% of the world's land surface but store roughly twice as much carbon as all the world's forests combined (IUCN; UNEP Global Peatlands Assessment).
The biggest peatlands are global — the tropical peat swamps of Indonesia and the Congo Basin, the vast bogs of the boreal north — which makes them one of the highest-stakes surfaces on Earth. Intact peat is a carbon vault; drained peat is one of the most dangerous surfaces there is. Drain a peatland for agriculture or development and it flips from vault to smokestack, oxidizing and releasing centuries of stored carbon. Rewetting it stops the bleed and restores its water-regulating function. It's the wetland story from the most valuable acre in america is a wet one, turned up to its maximum.
one practice, two balance sheets
Stack it up and the sponge earns several ways from a single set of moves:
| what the sponge does | the return |
|---|---|
| holds water | drought resilience, steadier yields, less irrigation |
| stores carbon | soil carbon drawdown; the basis of carbon farming |
| cuts runoff | less erosion, less flooding downstream, cleaner water |
| holds nutrients | lower fertilizer costs, less pollution |
| builds fertility | rising productivity and land value over time |
That's the one repair, many payoffs logic of the whole series, applied underground. It's also why the sponge behaves like improving infrastructure rather than a depreciating asset: the early years of good management add water-holding and carbon fastest, then the gains hold as long as the management does — the opposite of a built asset that degrades from the day it's installed.
the honest caveats
Soil carbon is real, but the market around it is younger and messier than the water benefit, so a skeptic deserves straight answers:
- measurement is hard. Soil carbon varies foot to foot and season to season; verifying a specific tonnage is expensive and uncertain. The water benefit is easier to see than a precise carbon credit is to certify.
- additionality is the real bar. For soil carbon to count as a credit — or as a corporate Scope 3 / SBTi FLAG reduction — you have to show it wouldn't have happened anyway and measure it against a defensible baseline. That's a genuine hurdle the water benefit simply doesn't face.
- it's reversible. Carbon built over years can be released in a single season of tillage. Soil carbon is a rented store that must be maintained, not a one-time deposit — an argument for durable funding, not against the practice.
- gains saturate. Soil fills toward a new equilibrium over a few decades and then holds rather than climbing forever. The early years add the most.
- results vary. Climate, soil type, and management all move the numbers; regenerative practices are principles to adapt, not a formula to copy.
None of this undercuts the core point: the water benefit alone justifies building the sponge, and the carbon is a real — if harder to measure and monetize — second return.
who funds the transition
The barrier is timing. Cover cropping, reduced tillage, compost, fencing for managed grazing, and the yield dip during transition all cost money now, while the water and carbon returns arrive over years. That gap stops a lot of good management before it starts.
Ensurance is built to close it. It prices the full stack of returns from building the sponge — water resilience, carbon, reduced runoff — using a natural-capital accounting method, and lets the beneficiaries fund the transition upfront. The claim they hold is priced off the flows the ground produces: its natural cap rate — the annual value of those services relative to cost — so as the soil's water and carbon services grow, so does what the claim represents. The farmer gets capital to make the switch; the funder holds it as a certificate for a named place or a coin across many.
Crucially, that funder can be a corporation whose supply chain depends on this exact ground. A food, apparel, or beverage company sourcing from a watershed can fund the soil-building in its own supply shed and — where it's properly measured and additional — count insetting-grade carbon in its own footprint, rather than buying disconnected offsets elsewhere. It turns "the transition is too expensive to risk" into "the beneficiaries funded it, and everyone holds a stake in the sponge."
how to start
if you work the land — farmer, rancher, or steward
Start where disturbance is highest: add cover, cut tillage, keep living roots in the ground, and integrate grazing well, then measure organic matter as a baseline. Fund the transition without absorbing the whole multi-year cost alone — and, for a watershed, pool the other beneficiaries and build the sponge at landscape scale. Explore specific ensurance for your ground → · talk through an operation →
if you fund the land — corporation or investor
Soil that holds more water and more carbon is improving natural infrastructure most balance sheets have never priced. A corporation can fund it in its own supply shed as water-risk reduction plus insetting-grade carbon; an investor can hold the restored capacity as an asset whose returns stack. See how the funding works → · see specific ensurance certificates →
frequently asked questions
what is a sponge landscape?
A sponge landscape is land managed so its soil absorbs and holds water like a sponge rather than shedding it — achieved by building soil organic matter, keeping the ground covered and rooted year-round, and minimizing tillage. Because that organic matter is roughly half carbon, the same practices also store carbon, so the land holds more water and more carbon at once.
how do you increase soil's water-holding capacity?
Build soil organic matter and protect soil structure: plant cover crops and perennials to keep living roots in the ground, leave residue to keep the surface covered, minimize tillage, add compost or manure, and use managed rather than continuous grazing. These feed the soil life that builds the crumb structure and pore space water needs to infiltrate and cling.
is carbon farming the same as building a sponge landscape?
They overlap heavily but aren't identical. Carbon farming and regenerative agriculture both center on the soil-building — more organic matter through cover, roots, and less tillage — that also makes soil hold water, so building the water sponge and storing soil carbon are largely two results of one practice. But carbon farming also includes methods like biochar and agroforestry, and regenerative agriculture pursues soil life, biodiversity, and profit beyond carbon alone.
why are peatlands so important for carbon?
Peatlands are waterlogged soils where dead plants don't fully decompose, so carbon accumulates for centuries. They cover only about 3% of land but store roughly twice the carbon of all the world's forests. Intact, they're a massive carbon vault and water regulator; drained, they release that stored carbon rapidly, which is why keeping them wet matters so much.
does building soil carbon really pay off?
The water benefits — drought resilience, steadier yields, lower input and irrigation costs — show up reliably and justify the practice on their own. The carbon is a real second return, though harder to measure and monetize, and reversible if the soil is disturbed again. Funding the transition upfront and holding the returns (the ensurance approach) is what makes the multi-year payback workable.