There have been many questions regarding biologicals use for soil fertility. There are many products in the marketplace. There are so many, it is not feasible to test all of these.

There is a regional publication summarizing research information across Midwest universities compiled by NCREA 103 committee. The publication can be found by googling “Performance of Selected Commercially Available Asymbiotic N-fixing Products in the North Central Region.” This is the latest research on many of the common biological products.

The category of biologicals which are beneficial bacterial is typically called biostimulants. These are bacterial that are already found in most of our soils. These are free-living nitrogen fixers that are located in the rhizosphere and use root exudates and source of food and then allows them to fix nitrogen from the air.

Most research indicates that there is little benefit from these products. Our soils are already active biologically. But to determine if these products will work in your field, set up comparison of replicated strips of treated and untreated strips. In MU’s strip trial program, we use a minimum of five strips. Data can be misleading if you are using a comparison of one strip, that is, one treated compared to an untreated.

As far as biologicals, we already have experience with Bradyrhizobium japonicum, which is used to inoculate soybean seed. The bacteria form a symbiotic relationship with the soybean plant.   The soybean plant obtain nitrogen from the bacterial, the plant provides the bacteria with carbohydrate.

Studies from Iowa State several years ago showed no significant difference among inoculants compared to the control. Soybeans are typically inoculated when soybeans have not been grown in a field for greater than five years.

Biologicals are not a replacement for good agronomic management. Researchers suggest not decreasing your corn nitrogen fertilizer rate.

For more information, contact Wayne Flanary, Field Specialist in Agronomy, University of Missouri Extension at 816-279-1691.