What the research measured
Independent 2023 results cluster near zero and split by field. Iowa Soybean Association’s six soybean sites averaged −0.5 bu/ac with one significant site at −3.6; Ohio State’s Ashland County corn strips averaged 211 vs 202 bu/ac, not significant at an LSD of 9; Delaware’s irrigated corn showed no product, SOURCE included, significantly different from the check at any N rate; four South Dakota corn fields on one farm ran −10.1, +3.1, +5.3 and +8.2 bu/ac, with the −10.1 and +8.2 results both significant. ISA’s 2021–22 corn sites averaged +1 bu/ac, 10 of 25 showing a gain.
Independent on-farm and university strip trials in Iowa, Ohio, Delaware and South Dakota, 2021–2023, mostly single-season and single-field, plus the company’s own compilation of third-party trials. No peer-reviewed field study and no multi-state replicated small-plot program were found.4 independent sources · 1 manufacturer-authored, labelled.What it is. A foliar-applied chemistry, not a living organism, that the company calls a microbiome activator: it is described as mimicking a plant signal so resident soil microbes supply nitrogen, phosphorus and micronutrients, and is marketed as supplying 25 lb of N and P from a single pass that can ride along with a herbicide or fungicide. SOURCE DC is sold for corn, soybeans, canola, potato and sugar beet and SOURCE XC for wheat, cotton, alfalfa and grass hay; the independent trials here used 0.7 fl oz/ac of DC on corn (at V4 in Delaware) and SC/DC combinations on soybean at R1–R3.
Study conditions and limitations
- Results split by field even on one farm: in South Dakota in 2023 the product lost 10.1 bu/ac in one corn field and gained 8.2 bu/ac in a low-yield zone of another, both significant at 90% confidence, while two other fields were not significant.
- Drought shaped the Iowa 2023 soybean result: April–August rainfall ran 4.6–10.2 inches below the 20-year average, and tissue N and P showed little or no increase after application.
- In Delaware’s 2023 corn, no product (SOURCE included) out-yielded the untreated check at 100%, 80% or 50% N; at 50% N SOURCE trended higher without significance, and the authors call the 50% N rate a net economic loss against the full rate.
- Rates and timings differ by trial: 0.7 fl oz/ac DC on corn, a 0.5 fl oz SC plus 1.25 fl oz DC mix on Iowa soybean at R1–R3, and 1.24 fl oz SC on South Dakota soybean, so the record is not one product at one rate.
- The company’s third-party page reports the same 2023 Ohio State trial as a 9 bu/ac increase; the eFields report prints the two means with the same letter and calls them not statistically significant.
- No independent source in this profile prints a product cost per acre.
Read the sources · 5
- Source Biological Cross-Site Report, 2023 growing season ↗
Six Iowa soybean sites in 2023 with a 50-50 mix of SOURCE SC (0.5 fl oz/ac) and DC (1.25 fl oz/ac) at R1–R3: average response −0.5 bu/ac, site range −3.6 to +5.4, with only one site (−3.6) significant. Earlier ISA work on individual SOURCE products: 25 corn sites in 2021–22 averaged +1 bu/ac (10 with a gain, range −6 to +18) and 13 soybean sites averaged +1.4 bu/ac (10 with a gain).
- 2023 eFields Report: Biologicals – Source, Ashland County ↗
Three replicated 90-ft strips of no-till corn with SOURCE at 0.7 oz/ac averaged 211 bu/ac against 202 untreated; the means share a letter at an LSD of 9 bu/ac (alpha 0.1), and the report states the results were not statistically significant.
- Corn Yield Responses to In-furrow Biological Products ↗
Fourteen biologicals at 100%, 80% and 50% of the N rate on irrigated corn in 2023 (plot averages 265, 260 and 234 bu/ac): no product differed significantly from the untreated check at full N; at 50% N SOURCE, sprayed at V4, trended higher but not significantly; in a non-irrigated field none of the products out-yielded the check at the lower N rates.
- Source DC in corn as part of a corn/soybean rotation (Field 6), McCook County ↗
Five replicated strips with SOURCE DC at 0.7 fl oz/ac foliar: treated corn yielded 10.1 bu/ac less than untreated, beyond the 7.8 bu/ac needed for significance at 90% confidence. Sister fields on the same farm in 2023 ran +3.1 and +5.3 bu/ac (not significant) and +8.2 bu/ac (significant) in a low-yield zone; a soybean field with SOURCE SC at 1.24 fl oz/ac ran −2.0 bu/ac (significant).
- Trusted Independent Analysis: SOURCE third-party data ↗
The company’s compilation reports +9 bu/ac at Ohio State 2023 (211 vs 202), 4–6.6 bu/ac at Purdue, +4.1 bu/ac across five Syngenta sites in KS, IL, WI and IA, +8.5 bu/ac at three Nebraska contract-research sites, +9.1 bu/ac at three Kova sites and +3 bu/ac at Precision Planting in 2022. Company-selected summaries without statistical detail.
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
- October 12, 2026. Every figure shown is printed on the linked page; unit conversions are noted on the chart.
- Company response
- None yet. Sound Agriculture can send corrections, additional trials, or a statement; it is published here, labelled, and never edits the research summary. Send a correction →