Ten tips for evaluating soil biological products |
| By Matt Yost |
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The author is an associate professor and agroclimate extension specialist with Utah State University.  Farmers currently have more options for crop inputs than ever before. There are hundreds, if not thousands, of crop inputs on the market, including fertilizer, seed genetics, pesticides, soil amendments, and more recently, biological and nanotechnologies. Wading through this sea of inputs and knowing which will result in a positive return on investment (ROI) is one of the most challenging parts of farming. The purpose of this article is to provide 10 tips for considering which biological products to trial and use on your farm. Many of these tips will apply to crop inputs in general and can serve as a guide for approaching and conducting your own on-farm research. Why should we care about soil bacteria and fungi? Some say they are the most important “livestock” on the farm or ranch. These organisms provide a host of benefits to crop production. Here are just a few:
A large number of players Given these benefits, improving the health of soil biology should be a priority on all farms. As we approach this conversation about biological soil additives, it is important to cover a few basics of soil biology. A gram of soil can have about 500 million bacteria. There are thousands of known species of bacteria, and they can reproduce in as little as 30 minutes. There are about 900 million grams of soil per acre in the top 6 inches. Taken together, this equates to about 45,000,000,000,000,000 (4.5 x 1016) bacteria per acre. Now, let’s say a soil biological product recommends a rate of 1 million bacteria per acre. That would represent about 0.0000000022% of the bacteria already present in the soil. This example highlights the challenge of significantly altering the biology of soil by applying bacteria and fungi. Other factors that influence the temperature, moisture, and habitat for soil biology such as tillage, living roots, fertilizer, amendments, and residue management can rapidly and greatly alter the amount and diversity of biology. These factors should be the first focus when seeking to improve soil biology. It should be noted, though, that the right biological input in the right place can make a large difference. A prime example of this is rhizobium bacteria coated on legume seed. This placement significantly impacts a legume’s ability to nodulate and fix nitrogen. Biological products in the right place can make a difference but will require extreme care to ensure effective outcomes. A lot to ponder As you consider which biological products to trial on your farm, it may be wise to remember these 10 tips: 1 Focus on foundational inputs first. With so many new and exciting products on the market, it can be easy to forget or question the value of the foundational inputs of water and plant nutrition. Before exploring new biological products, ensure that your irrigation systems and management (if applicable), fertility program, and agronomic practices are fine-tuned and maximizing your return on investment. If these inputs are limiting, other efforts to improve crop production may prove futile. 2 Feed and water soil biology. It is wise to first fine-tune the practices that influence biology the most. Continuously adding organic matter (crop residues and amendments) with low carbon-to-nitrogen ratios provide food for bacteria and fosters growth and activity. Biological activity is also promoted by growing healthy plants with healthy roots, reducing soil saturation by avoiding over-irrigation, and having proper soil drainage. 3 Maximize biological activity. Minimizing or eliminating tillage reduces soil disturbance and can maintain higher levels of arbuscular mycorrhizal fungi. Keeping the soil covered and managing residue helps provide a more ideal soil temperature (around 85°F) to support bacteria and fungi activity. Where possible, keep soil pH between 6.0 and 7.2. Avoiding excessive soil salinity will also promote biological activity in the soil. 4 Pay due diligence. There are a lot of biological soil additives or inoculants on the market. It will not be possible to test all of them on your farm. Thoroughly investigate a product before trialing. Check for independent, nonbiased research on the performance of the product and be on the lookout to avoid products with extremely lofty claims, incredible testimonials, and no data on product performance. Ask other farmers for data on how the product has worked for them. 5 Know what’s inside. The first thing to check when evaluating a product is what’s inside. Read and know the ingredients. If a company will not disclose the ingredients, you may want to steer clear. This is especially important for biological products because they are living organisms that can change during handling and storage. Some products claim certain quantities and types of bacteria and fungi that are not present when an independent analysis of the ingredients is conducted. 6 Request or test ingredient analysis. Biological products are living organisms. Living organisms can evolve and die during product development, storage, and handling. Ensure that there is live, desirable biology (bacteria and/or fungi depending on the product) by requesting a product analysis by the manufacturer or by conducting your own independent analysis. Applying a bottle full of dead bacteria or fungi is sure to have no effect on your crop production. 7 Follow storage and application instructions. Many biological products have special requirements for handling and application. This often includes avoiding excessive temperatures and priming the bacteria for a 24- or 48-hour period before application. 8 Do not bet the farm. This saying is used a lot by extension personnel and cannot be overstated. Once you’ve identified reputable products to start testing, it is wise to start small and test products using best on-farm research practices (see extension.usu.edu/crops/research/on-farm-research-guide for more details). This includes having replicated treated and nontreated strips or sections of a field with careful yield monitoring to measure how the product influences yield and ROI. 9 Focus on return on investment. If the product costs only $5 per acre, but the yield increase was only worth $3 per acre, then the product is not a good investment. Yield gains alone sometimes inaccurately become the ultimate focus. Be sure to track the cost of the product and the returns to that investment to ensure it is positive. 10 Ask for a second opinion. It can be difficult to know which products have potential and are good investments. University extension services, crop advisers, and other professionals are available to help you sort through options, connect with resources and previous research results, and conduct on-farm trials. A simple phone call or email can save you a lot of stress and money. Biological inputs for agriculture are a relatively new frontier. There is still much to learn about how to support and improve soil biology through soil management and biological additives. Following these 10 tips should help as you sift through current and future products. Ensure that you test and invest in those biologicals that will improve your soil and profit margin. This article appeared in the April/May 2024 issue of Hay & Forage Grower on pages 10-11. Not a subscriber? Click to get the print magazine. |
