What the research measured
Published results vary by site and nitrogen rate. The ten-state review reported significant yield increases in 0 of 15 PROVEN 40 site-years; Wisconsin reported none in five trials. The Illinois study reported a mean increase of about 1.8 bu/ac across four site-years. Kentucky and manufacturer studies report additional responses under their tested conditions.
Multi-year, multi-site independent trials: a ten-state land-grant review, five Wisconsin sites, Nebraska on-farm research and a peer-reviewed four-site-year Illinois study.4 independent sources · 1 manufacturer-authored, labelled.What it is. Gene-edited nitrogen-fixing bacteria (Klebsiella variicola and Kosakonia sacchari) applied in-furrow at 12.8 oz/ac or on the seed, marketed as supplying up to 40 lb N/ac so growers can cut synthetic nitrogen by that amount.
Study conditions and limitations
- Any response shows up at low to moderate N: in Illinois the gain appeared at 45–135 kg N/ha and vanished at 0 and 225 kg N/ha, and the fertilizer-N equivalent fell from 38.5 kg/ha at V8 to 11.5 kg/ha for grain yield.
- Kentucky saw a significant gain in 2023 and, in 2024, only at 215 lb N/ac under heavy rye residue; the Kentucky authors say they cannot predict where or when a product will work.
- Cutting N without an untreated reduced-N check can hide a loss: a 2022 Nebraska comparison at 106 lb N/ac plus PROVEN 40 yielded 195 bu/ac against 235 bu/ac for a 142 lb N/ac check.
- Handling is strict: use within 24 hours of opening, non-chlorinated water, add it last, and avoid 7-21-7, ATS or UAN as a carrier.
- Gene-edited bacteria are not OMRI-listed, so it is not an option for organic corn.
- The manufacturer’s own 2024 Northern Plains strip trials (20 locations) reported −0.4 bu/ac with 38.5 lb/ac less N; that is company data, not independent.
Read the sources · 5
- Performance of Selected Commercially Available Asymbiotic N-fixing Products in the North Central Region ↗
Land-grant trials in ten states through 2022: 59 of 61 corn site-years showed no yield increase from any product over the N rate alone. The review reported a significant yield benefit for PROVEN 40 in 0 of 15 site-years and Utrisha N in 0 of 11.
- Soil inoculation with nitrogen-fixing bacteria to supplement maize fertilizer need ↗
Four Illinois site-years (2019–21): the PROVEN 40 inoculant raised grain yield by an average 0.11 Mg/ha (about 1.8 bu/ac), with the gain at 45–135 kg N/ha and none at 0 or 225. The authors calculate a 2–6 bu/ac gain is needed to profit at $25–75/ha and conclude the effect did not warrant replacing fertilizer N.
- Biological N Fixation Products for Corn: An Update ↗
Kentucky 2023: PROVEN 40 plots averaged 200 bu/ac at both 140 and 180 lb N against 199 and 191 without, a significant difference the authors report as 9 bu/ac; in 2024 it helped only at 215 lb N under heavy rye residue. Regionally, 2 positive site-years out of 61.
- Biological Nitrogen Fixation in Corn: Wisconsin Trial Results ↗
Five 2023 Wisconsin N-rate trials (0–280 lb N/ac) found neither corn grain yield nor the yield response to N was affected by PROVEN 40 at any site. The authors see no significant current evidence that a gene-edited N-fixer can meet corn N needs in Wisconsin.
- Genetic remodeling of soil diazotrophs enables partial replacement of synthetic nitrogen fertilizer with biological nitrogen fixation in maize ↗
In 58 commercial fields (2021), cutting N by 35–40 lb/ac with PROVEN 40 produced no significant yield reduction, and isotope measurements estimated 21.2 kg N/ha from fixation by VT–R1, about 11% of plant N. This study was authored by the manufacturer with university co-authors.
Before you buy, ask
- Is the formulation and application method I would buy the one that was tested?
- Was the comparison a yield gain at the same nitrogen rate, or held yield with less fertilizer?
- What happens to my result if I cut nitrogen and the product does not fix enough?
Record
- Sources checked
- September 26, 2026. Every figure shown is printed on the linked page; unit conversions are noted on the chart.
- Company response
- None yet. Pivot Bio can send corrections, additional trials, or a statement; it is published here, labelled, and never edits the research summary. Send a correction →