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News About Soil Additives and Biologicals

So much is being written/disseminated about soil health and how soil additives/biologicals may promote it that an article that provides an up-to-date view of the current status of these materials is warranted. The following narrative is an attempt to do that.

There is no doubt that soybean producers are looking for every edge to increase yield and profit, and to increase the sustainability of production in their fields. One of the more tempting avenues is to use inputs that are touted to improve the soil environment that provides the medium for soybean roots. Hopefully the following narrative will shed some light on how soil additives and/or biologicals might be a future input to accomplish this.

A soil amendment or additive is any material added to a soil to improve its physical characteristics such as water retention, permeability, water infiltration, drainage, aeration, and structure, and/or its microbial activity. The goal from adding any soil amendment is to provide a better or improved environment for plant roots.

There are two broad categories of soil amendments–organic and inorganic. Organic amendments are derived from something that was alive, while inorganic amendments are either mined of are man-made. Organic amendments increase soil organic matter (SOM) which is an important energy source for microbes and other living organisms in the soil.

Soil amendment applications can benefit growers in several ways that include: 1) increased nutrient availability and retention due to increased organic matter; 2) increased water holding capacity and water infiltration into soil; 3) enhanced soil microbial activity; 4) enhanced soil carbon storage; and 5) more sustainable crop production systems.

Four Farm Progress articles provide information about the availability of and technology associated with the development and use of biologicals in agricultural settings. Links to those articles and a brief summary of each one’s content follow.

•    “Firms partner to bring ‘bio’ to crop production” by Willie Vogt appears in a Mar. 10, 2021 article. This article reports that FMC and Novozymes Biologicals will collaborate to research, co-develop, and commercialize biological enzyme-based crop protection products that will potentially boost efficacy of crop protection chemicals. It is touted that this technology will complement synthetic chemical products that are used to control insects and fungi.

•    “Biologicals: Know what you’re using before diving in” by Chris Torres appears in a Mar. 25, 2021 article. This article provides a list of categories of biologicals, how they work, and how they must be matched to a field environment.

•    “FBN is newest supplier in biologicals business” by Willie Vogt appears in an Apr. 9, 2021 article. This article provides information about the expansion of the Farmers Business Network (FBN) into the biologicals market. FBN Biological’s lineup includes 1) prebiotics that contain molecules that will stimulate soil microbial activity, 2) probiotics that are live microorganisms with targeted functions when applied to the soil, 3) foliar-applied stimulants that are designed to enhance a crop’s photosynthetic capacity, 4) carbon sources that provide soil benefits, and 5) biologically enhanced micronutrient fertilizers.

•    “Are microbes the next carbon crop for farmers?” by Mindy Ward appears in an Apr. 21, 2021 article. In this article, the work Pluton Biosciences is doing to find microbes that will aid in sequestering carbon in the soil is briefly described. Basically, the company envisions applying microbes as a cover crop–i.e., they will be sprayed onto the soil as an amendment at harvest, at burndown, or at planting. The company will be attempting to identify and develop microbes that can store carbon and nitrogen in the soil.

There are two approaches to improving soil microbial health and/or activity. First, beneficial microbes can be added to the soil to potentially increase soil microbial activity and the subsequent benefits that should be derived from that increased activity. Such is the approach outlined in the above Farm Progress article that highlights the work of Pluton Biosciences. Second, microbes that are already in the soil can be enhanced by increasing the food supply available to them. This can be done by increasing crop residues or adding an organic material such as poultry litter that will provide a carbon source for these microbes, or by directly applying carbon amendments to the soil. There is anecdotal evidence that liquid products–e.g. organic carbon, humic acid–will provide a soybean yield enhancement, presumably by increasing soil microbial activity that complements soil processes that increase nutrient availability to soybean roots that mine the soil for those nutrients.

A good short summary of why agricultural biologicals are important, how they can promote diversity in current agricultural practices, and how they might provide an alternative to chemical agricultural products is provided here. The ultimate goal from using effective agricultural biologicals and soil amendments is to enhance the growing environment of crops and to enhance soil health.

Factors that should be considered when selecting a soil amendment are: 1) the expected length of time the amendment will persist in the soil–i.e., will it have a long- or short-term effect; 2) soil texture at the site receiving the amendment since this will dictate the goal from adding a soil amendment–i.e., for sandy soils the goal is to increase water and nutrient holding capacity, while the goal when adding an amendment to a clayey soil might be to increase porosity, permeability, aeration, and drainage; 3) soil salinity and plant sensitivity to salts–i.e., ensure that a soil amendment will not add to the salt content of a soil that is already high in salt; 4) salt content and pH of the amendment–i.e., do not add an amendment that will exacerbate these soil properties that may be problematic in soil at the site of its proposed addition; 5) how and when should the amendment/additive be applied to ensure its maximum effect; and 6) the analysis of considered soil amendments to ensure their properties/components will in fact be sufficient to affect the intended process at the site of application.

There is evidence that biological control agents (BCA) can be used to lessen the effects of diseases that affect soybean. For example, an article titled “Trichoderma isolates inhibit Fusarium virguliforme growth, reduce root rot, and induce defense-related genes on soybean seedlings” [Plant Disease 104:1949-1959 (2020)–click here for a summary of this research] provides information about how BCAs such as Trichoderma spp. can be used to suppress F. virguliforme (pathogen that causes sudden death syndrome or SDS) populations in the soil and thus reduce SDS severity in soybean. The authors cautioned that for successful introduction of BCAs into crop production systems, the method of application of the BCA is crucial because this can affect how the BCA may interact with the plant and targeted pathogen. They stated that research is needed to develop optimized BCA delivery systems that will allow the BCA to have a competitive advantage against the targeted pathogen.

Unfortunately, the information provided here cannot be used to provide a recommendation to producers about what new products should or should not be applied to soybean fields to increase yield and profit from the enterprise. Rather, each individual producer will have to decide whether or not to spend the money on any of the myriad soil additives with the hope that they will provide a positive return from their addition, or will contribute to long-term improvement in soil health. The current upward trend in the soybean commodity price gives producers the opportunity to explore using inputs that might not otherwise be considered; however, producers are cautioned to have a distinct goal in mind if/when the decision is made to add any of the many “soil health” products that are touted to enhance crop production sustainability. Otherwise, it will just be adding an expense that may not contribute to increased profits or a more sustainable production system.

As with any new technology, time will be needed to conduct research that will provide results to either validate or dispute the claims that are made for new biologically-based soil amendments and products. However, this in no way negates the fact that soil amendments that will improve soil health, whether it be by improving physical, chemical, or microbial properties, are needed to either replace or complement synthetic additives that are currently being applied. Results from sound research that will be conducted with this new technology and its application in crop production systems will provide the final answer.

Composed by Larry G. Heatherly, June 2021,