From Dairy Waste to Dairy Fertilizer: A Tulare County Circular Economy Story

A Tipton dairy farmer allowed HydroSoil Renew to conduct a fertilizer trial on his fields out of curiosity. What he found changed his approach farming.

When Tipton dairy farmer Frank Mendonsa agreed to let us conduct a trial by planting HydroSoil Renew on his corn and wheat fields, he wasn't expecting to change how he farmed, but that's exactly what happened.

HydroSoil Renew is a novel soil amendment, and Mendonsa's fields were a logical place to test its effectiveness. The fertilizer starts with a resource most people think of as a disposal problem: the wastewater left over from dairy food processing. A few miles from Mendonsa's farm, Tulare-area plants turn milk into the cheese, yogurt, butter, and ice cream that show up on grocery shelves under national brands. That process leaves behind nutrient-rich water that normally has to be treated and disposed of. HydroSoil Renew captures those nutrients, combining the processed dairy byproduct with other inputs, including biochar, into a granulized fertilizer that can be applied like any standard dry product.

For Mendonsa, the results were promising, especially in an industry where margins are thin and every bushel counts. And the fact that the fertility came, in part, from dairy processing water that would otherwise need to be disposed of made the outcome land differently for him. The circular economy wasn't an abstraction. It was happening on his own fields.

What the formal field trial found

Mendonsa's experience occured during a controlled field evaluation conducted on winter wheat and corn silage at Mendonsa Farms during the 2024–2025 growing season, comparing HydroSoil Renew against the farm's grower standard practice.[1] That trial measured notable gains:

• Winter Wheat (36.75-acre trial)

• Yield increased 4.7–7.5% over the grower-standard treatment, depending on application rate

• Crude protein rose from 9.8% to 11.6% at the higher HydroSoil rate, enough to clear the 11% threshold commodity buyers pay a premium for

• Nitrogen use efficiency rose sharply compared with the grower-standard treatment

• Corn Silage (68.1-acre trial)

• Total tonnage increased a modest 2.0%

• Crude protein (dry-matter basis) increased 12.5%

• Digestible protein (dry-matter basis) increased 33.3%

That last number is the one worth sitting with. A silage crop that's only a little bigger but meaningfully more digestible is exactly the kind of trade a dairy operation wants: more usable protein per acre, without a corresponding jump in inputs or acreage.

Why this matters beyond one farm

Mendonsa's fields sit at the intersection of two things Tulare County has in abundance: dairy processing byproducts and cropland that feeds those same dairies. HydroSoil Renew closes part of that loop, turning a processing-plant output back into an input for the corn and wheat that end up in a feed ration a few months later.

For a farmer like Mendonsa, the appeal wasn't a new system to learn or new equipment to buy. It was a soil amendment he could apply the same way he'd apply any other dry fertilizer with a result he could see in a field that hadn't grown much of anything before, and in yield numbers on the fields that had.

[1] HydroSoil: Transforming Agriculture Through Biological Soil Enhancement — Field Performance Evaluation, Winter Wheat and Corn Silage Trials at Mendonsa Farms, Tipton, California, 2024–2025 Growing Season. Prepared by Christopher R. Ott, P.E., Central Valley Resource Recovery LLC, a subsidiary of Hydros AgriTech, Inc., in collaboration with Richard Mead, Agronomist, Nutrien Ag Solutions. Report No. CVRR-2025-001, November 2025.