Reducing purchased nitrogen is often discussed as a rate-cutting exercise. John Kempf frames it differently: first build the soil and plant processes that can supply, cycle and retain more nitrogen, then reduce external inputs as evidence allows.

The pace of any reduction should follow measured crop performance over time.

Listen to this part of the conversation #

Suggested section: 48:30–51:18. The player begins at 48:30; pause when you reach the end of the suggested section.

Listen for Kempf’s answer about BioCoat Gold, the wide variation in reported nitrogen contribution and his caution against treating a field-observation range as a dependable fertilizer credit.

Originally published on 3 April 2026 as Podcast Extra: Adjusting Nitrogen Management with John Kempf and MSHC. Full episode: 1:00:54. Audio is streamed from Libsyn.

What must be functioning #

Biological nitrogen contribution depends on more than the presence of nitrogen-fixing organisms. The system may also require:

• suitable carbon or energy sources;
• adequate moisture and aeration;
• compatible pH and mineral nutrition;
• micronutrients involved in nitrogen metabolism;
• living roots and effective rhizosphere exchange;
• fertilizer placement that does not overwhelm the organisms being encouraged.

Kempf also notes that biological nutrient delivery may remain valuable when free soil water is limited, based on field observations of crop resilience. The scale and reliability of that effect need local verification.

BioCoat Gold as an example #

Kempf discusses AEA’s BioCoat Gold as one tool intended to support biological nitrogen contribution. He reports that contributions around 35-40 pounds of nitrogen are commonly observed under suitable conditions, while clearly cautioning that not every farm achieves that result.

That distinction is crucial. The reported range should not be entered into a fertilizer budget as a guaranteed credit. Soil carbon, starter-fertilizer proximity, climate, crop and existing biological function can materially change performance.

Build evidence before taking credit #

A staged trial might include:

1. the existing nitrogen program;
2. the biological treatment with the existing program;
3. the biological treatment with a modest, agronomically defensible nitrogen reduction;
4. repeated measurements across more than one season where possible.

Track total nitrogen from every source, soil moisture at sampling, plant nitrogen status, yield, quality and economics. Where testing biological activity or soil carbon-to-nitrogen relationships, record sampling conditions so results are comparable.

Before assigning a nitrogen credit, check whether the reduced-input treatment maintains performance across repeated comparisons.

Questions to take into the field #

• What evidence shows that biological nitrogen supply is functioning on this farm?
• Are moisture, aeration, carbon, pH and mineral conditions suitable for the organisms involved?
• How will total nitrogen from every source be measured?
• What modest reduction can be tested without treating a reported contribution as a guaranteed credit?
• Can the response be repeated across seasons before a permanent budget change is made?

What this evidence can—and cannot—show #

Biological nitrogen fixation and cycling are established processes. The quantity credited to a particular commercial treatment is context-dependent. Kempf’s 35-40 pound figure is a reported field-experience range and needs independent, local validation.

The practical takeaway #

Build and measure biological contribution before relying on it to replace purchased nitrogen.

Further reading #

• Original recording and episode notes
• Minnesota Soil Health Coalition
• Advancing Eco Agriculture: Regenerative Nitrogen Management

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Source: John Kempf, Regenerative Agriculture Podcast, Podcast Extra: Adjusting Nitrogen Management with John Kempf and MSHC, published 3 April 2026.

Evidence note: Biological nitrogen fixation and cycling are established processes. The quantity attributed to a particular commercial treatment is context-dependent speaker experience and needs independent, local validation before it is entered into a nitrogen budget. The podcast is produced by Advancing Eco Agriculture, and AEA products mentioned in the wider recording should be understood in that commercial context.

Listen to the original episode.