FAQ: Agricultural Biologicals

What are agricultural biologicals?

Agricultural biologicals are crop inputs derived from living organisms, natural substances, or biological processes that help support plant growth, nutrition, stress tolerance, or pest and disease management. They are often grouped into categories such as biostimulants, biofertilizers, and biopesticides.

What is the difference between a biostimulant, biofertilizer, and biopesticide?

A biostimulant supports plant processes such as nutrient efficiency, abiotic stress tolerance, or quality traits. A biofertilizer helps make nutrients more available, often through microbes such as nitrogen fixers or phosphorus solubilizers. A biopesticide helps manage pests or diseases and is regulated by EPA when pesticidal claims are made.

How do biological products work?

Biological products can work in many ways: improving nutrient availability, supporting root growth, activating plant stress pathways, increasing tolerance to heat or drought, improving soil biology, or helping plants respond to pests and diseases. Their effects are often system-level rather than single-cause, single-effect.

Are biologicals fertilizers?

Some are, but not all. Biofertilizers directly or indirectly improve nutrient availability, while many biostimulants support plant function without supplying meaningful nutrient levels. Biopesticides are regulated separately when they are intended to control pests or diseases.

Are biologicals pesticides?

Only some biologicals are pesticides. EPA defines biopesticides as naturally occurring substances, microorganisms, or plant-incorporated protectants that control pests. Biological products that do not make pest-control claims may instead be regulated as fertilizers, soil amendments, biostimulants, or other product categories depending on composition and claims.

How are biological products regulated?

In the United States, regulation depends heavily on what the product is and what claims are made about it. Products making pesticidal or plant-regulator claims may fall under EPA/FIFRA, while fertilizer and soil amendment products are often regulated at the state level. EPA has issued guidance to clarify when plant biostimulant claims may cross into plant-regulator or pesticide territory.

Why have biologicals sometimes been called “snake oil”?

There are simple and complex reasons for this. A simpler reason is that historically, there were a lot of not great biological products that suffered from inconsistent performance, poor formulation, and weak field validation. A more complex reason is that biologicals are living and adaptive tools and so they sometimes require better timing, placement, and storage than conventional inputs. An additional challenge is that with living organisms, adaptive behavior can be both feature and bug. That is, microbes often adapt to their surroundings, so some features of a product might change under certain circumstances. For example, if you put a nitrogen-fixing microbial into a system in which N is being constantly added in large amounts, the microbes might turn off their N-fixing capacity for a time. However, even in this case, microbes will still do what they do best and most consistently: improve the root system. But, ironically, this is another contributing factor to why biologicals don’t always get the recognition they deserve: one of the biggest benefits that have all the time is literally hidden underground in most systems. 

Why is that changing?

The biologicals industry is changing because modern products are increasingly supported by better strain selection, fermentation, formulation, field testing, genomic tools, and clearer agronomic recommendations that are inline with the benefits that biologicals actually have. The category is also growing rapidly as growers look for tools that improve sustainability, resilience, nutrient efficiency, and crop quality.

Do biologicals replace conventional crop inputs?

Usually, no. Biologicals are most effective when integrated into a broader agronomic program. They can complement fertility, irrigation, crop protection, and soil health practices by helping plants and soils function more efficiently. Farmers have a difficult job and they need all of the tools in the toolbox.

When should biologicals be applied?

Most biologicals work best when applied proactively, before stress or disease pressure peaks. Microbial products often need time to colonize roots or influence the rhizosphere, while biostimulants and elicitors are often most useful when used before predictable stress windows. 

Why do results vary with biologicals?

Results vary because biology is context-dependent. Soil type, crop, weather, irrigation, fertility, tank mix compatibility, timing, storage, and microbial adaptation all influence performance. This is why good biological companies focus heavily on technical recommendations, field validation, and realistic use guidance.