What Are Biostimulants?
You may have heard some buzz around biostimulants recently. But are they a scientifically advanced new way to increase yields and sustainability on a farm, or are they just a whole lot of talk? And for that matter, what exactly are biostimulants?
Don’t be worried if you don’t have a deep idea of what this product class is. The category is actually still without a legal definition in the United States. In Europe, which has the largest market for biostimulants globally, biostimulants have been defined by the European Biostimulants Industry Council as:
“Contain[ing] substance(s) and/or micro-organisms whose function when applied to plants or the rhizosphere is to stimulate natural processes to enhance/benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, and crop quality.”
It’s important to note that biostimulants act only a plant’s vigor, offering no direct action against diseases, insects, or weeds. And biostimulants are not Plant Growth Regulators, which are a different class and are regulated by EPA.
Categories of Biostimulants
There are seven main categories of biostimulants according to the scientific journal Scientia Horticulturae (vol. 196, 2015):
Amino-acids and peptides mixtures obtained by chemical and enzymatic protein hydrolysis from both plant sources and animal wastes. The plant-based peptides in particular are the most interesting of the biostimulants due to their multifunctional activity.
HUMIC AND FULVIC ACIDS
Organic acids that occur naturally in soil, resulting from the decomposition of plant, animal and microbial residues. These acids can also come from soil microbe activity.
SEAWEED EXTRACTS & BOTANICALS
Seaweed is the more established extract, having been used for hundreds of years as a fertilizer and to improve soil structure. However, the biostimulant effects of seaweed extracts are a relatively new development. Extracts from other plants are increasingly being studied and used.
CHITOSAN & OTHER BIOPOLYMERS
Several uses have been developed over the years, usually focused on plant protection against fungal pathogens, but recently studies also point toward tolerance to various plant stresses.
These are minerals such as silica, selenium, cobalt and others which promote plant growth, the quality of plant products and tolerance to abiotic stress.
Sometimes regarded at plant “probiotics,” these are complex to understand and their results in the field are difficult to replicate consistently.
Benefits of Biostimulants
- Improving the efficiency of the plant’s metabolism to induce yield increases and enhanced crop quality;
- Increasing plant tolerance to and recovery from abiotic stresses;
- Facilitating nutrient assimilation, translocation and use;
- Enhancing quality attributes of produce, including sugar content, colour, fruit seeding, etc;
- Rendering water use more efficient;
- Enhancing soil fertility, particularly by fostering the development of complementary soil micro-organisms.
A new frontier in biostimulant research in the USA is the use of biostimulants to alleviate stress caused by the application of postemergent herbicides over the top of crops.
Because biostimulants are relatively new, metrics and data are necessary to sort out the reliable technologies from the gimmicks. Biostimulants are lightly regulated. Many product claims are made from a wide variety of merchants and all sorts of concoctions that purport to be a biostimulant. Make sure you are given an explanation as to “why” something works. If not, find another product or supplier.
The science around biostimulants is advancing rapidly, and careful measurement of results is key to determining what products can create real results for growers. Next time you apply product, take a look at our detailed guide to getting the most out of your farm's applications.