Over the years, the Iowa Soybean Association (ISA) has tested 6 different biofertilizers with the help of Iowa farmers: Source by Sound Ag, a foliar-applied, nitrogen-fixing and phosphorus-solubilizing bacteria for corn and soybeans; PROVEN 40 by Pivot Bio, an in-furrow N-fixing bacteria for corn; EndoPrime by Valent BioSciences, an in-furrow mycorrhizal fungi for corn and soybeans; Vertex-IF by Terramax, in-furrow N-fixing and P-solubilizing bacteria that adheres to corn roots; Envita by Azotic North America, an in-furrow N-fixing bacteria for corn; and Utrisha N by Corteva, a foliar-applied N-fixing bacteria for corn and soybeans.

ISA presented results from trials of 4 of the 6 products during a recent Innovation TO GO webinar. They are summarized as follows:

1. Source by Sound Ag

ISA tested Source by Sound Ag in soybeans in 2021. The product was sprayed at R1-R3 on soybeans following corn in 9 no-till and conventional tillage fields. Some of the test plots were lower-yield environments in the 50-55 bushel range, while others were high-yielding fields pushing 85 bushels per acre. On average, Source provided a 1 bushel-per-acre increase. One trial resulted in a 2.7 bushel advantage with Source, but Drew Clemmensen, ISA field services program manager, says the plots were not statistically different.

Iowa Soybean Association trial results for Source in soybeans

Iowa Soybean Association trial results for Source in corn

In the corn trials, Source was sprayed at V4-V6 in 10 no-till and conventional fields. Yields in those fields ranged from 160 bushels per acre to 240-250 bushels per acre historically. The 10 trials resulted in an average drop of 2.2 bushels per acre with nothing statistically different among the plots.

2. PROVEN by Pivot Bio

ISA worked with 3 growers who had purchased Pivot Bio’s PROVEN on their own to conduct trials in corn following soybeans in 2021. The farmers applied the biological in furrow when planting April 29-30 and kept their N rates consistent for research purposes, despite PROVEN’s claim that it can reduce N rates.

The results indicated PROVEN provided a 11.7 bushel advantage in the lowest-yielding field, raising bushels per acre from 223.2 to 234.9. It also increased yield by 6 bushels in a field that typically yielded 246.7 bushels per acre. The highest yielding field, which typically averages 258.7 bushels per acre, declined by 0.1 bushels with the application of PROVEN.

Iowa Soybean Association trial results for PROVEN in corn

3. Vertex-IF by Terramax

ISA also compiled results from 3 farmers who tried Vertex-IF in 2020. The biological was planted in furrow April 21, April 28 and May 2 in corn following soybeans in 2 trials and corn following corn in the third. The plots treated with Vertex-IF showed a decline in yield in all 3 trials. The largest decrease was 4.8 bushels per acre in a field that averaged 141.5 bushels per acre untreated. The highest-yielding field, which produced 236.6 bushels per acre untreated, lost 2 bushels per acre with Vertex-IF. Clemmensen notes that the 3 locations were 6-10 inches below average precipitation in 2020.

Iowa Soybean Association trial results for Vertex-IF in corn

4. EndoPrime by Valent BioSciences

Finally, the ISA tested EndoPrime, a mycorrihizal product, in 11 trials of corn following soybeans from 2017-18. The biological was applied in furrow during planting from April 25-May 11. Yield environments ranged from 155 bushels per acre to more than 250 bushels per acre. The trials averaged a 0.5 bushel loss. The biggest gain and decline happened in 2018. One trial resulted in a 3.4 bushel per acre loss, while another increased 6.2 bushels.

Iowa Soybean Association trial results for EndoPrime in corn

ISA is continuing to test biologicals with more Source trials and trials of AMVAC's iNvigorate, a liquid in-furrow product meant to improve absorption of N,P and potassium, planned for the future. Clemmensen says farmers who want to try biologicals for themselves should prepare for multiple years of trials to determine the products' true value. He also recommends using them as part of an integrated system, not as a substitute for key nutrients. 

Click here to view past ISA biological trial results. 

Related Content

Building a Better Biological Habitat by Extending the Life of Applied Nutrients

Biologicals Are the Final Frontier of Soil Management

How Mineral Nutrition & Humates Boost Your Bottom Line with Jim Hoorman