Soil Health Lab presentation: frequent testing, cover crops and regenerative practices can cut fertilizer use

Eric Morgan, representing the Soil Health Lab, told the panel that detailed soil nitrate testing and a regenerative approach to fertility can materially reduce the amount of nitrogen growers need to apply. "We cut the fertility budget in half," he said of a commercial example, adding that one citrus grower was producing with about 30 pounds of applied N per year because the soil was supplying much of the crop's needs.

Morgan outlined the laboratory and sampling protocol he uses: replicate cores across the bed, homogenize samples in the field, extract with potassium chloride, and measure nitrate‑N using a Timberline ammonia analyzer. He said a commonly used interpretive threshold is about 20 parts per million nitrate‑N in the top two feet for many cool‑season vegetable systems; below roughly 10 ppm growers may start to see deficiency symptoms.

He described agronomic results and caveats: high‑biomass crops such as broccoli can leave substantial residue N in the soil that later crops access; residual N and irrigation water nitrate must be accounted for when recommending in‑season applications. Morgan cautioned that rainfall can be a wild card and that technology (for example, laser‑induced spectroscopy) may permit more frequent and lower‑cost monitoring in the future.

Panelists pressed Morgan on the economics and methodology; he said his lab had observed commercial operations producing lettuce on as little as 20 units of applied N following a high‑residue crop, and that careful in‑season testing and water management were critical to avoid leaching. Morgan recommended increased grower education and incentives for practices that build soil N cycling and retention.

Attribution: Direct quotes and paraphrases are attributed to Eric Morgan and to panelists who questioned him during the public session.