Biostimulants: Importance, Types, Impact and Effectiveness

Biostimulants are a group of natural organic compounds that are added to the soil in order to enhance nutrient uptake and activate the role of fertilizers. They are also added with fertilizers and foliar pesticides for the same purpose and to resist factors of plant stress.

Despite the rapid growth of the biostimulants market, many professionals and farmers still lack a comprehensive understanding of biostimulants, how they are used, their benefits, and their dangers.

The biostimulants market has witnessed substantial growth, although it is recent. It is growing annually at a significant rate compared to the rest of the agricultural input sectors. The market size exceeded $2.6 billion in 2019 and is expected to record a compound annual growth rate of over 11.24% between 2020 and 2025. The increase in using new agricultural technologies, due to the limited availability of arable lands, has opened new pathways for further growth of the biostimulants industry. The increased focus on boosting productivity, along with rapid soil degradation, is likely to push the market further during the forecast period. Moreover, sustainable agriculture and organic agriculture practices encourage the expansion of biostimulants use.

The need to use safe means to increase and improve production through sustainable agriculture processes leads to further developing the biostimulants sector in the coming years. Three groups will be largely expanded: amino acids, seaweed extracts, and beneficial microorganisms.

The multiple functions of biostimulants include: enhanced nutrient uptake, improved metabolism, water holding capacity, and chlorophyll production. Biostimulants enhance the antioxidant activity of the plant, thus reducing environmental stress, and help greatly in combating climate change. They also enabled seasonal crops to be produced for longer periods of time and enhanced crop yields in the market.

Low environmental footprint and non-toxic nature are key advantages of biostimulants. Water and soil pollution and other environmental hazards due to the excessive use of chemical fertilizers are among the critical issues faced by the fertilizer industry in the world. This problem doesn’t occur when using biostimulants that are safe for the environment and human health.

Types of Biostimulants

Amino acids

Humic acids

Fulvic acids

Seaweed and seaweed extracts

Microorganisms such as mycorrhizae and trichoderma, and plant growth-promoting bacteria such as nitrogen-fixing and element-dissolving bacteria

Enzymes and yeasts

Silicon compounds

Others

Main Plants on Which Biostimulants Are Used

Based on the plants that consume the most biostimulants, field crops such as corn, wheat, barley, soybeans, and cotton are at the forefront of the US market.

Importance and Characteristics of Biostimulants

• Biostimulants are easy to use: They can be sprayed on plants, added to the water used for irrigating the root zone, or used for seed treatment. Foliar applications are used for some biostimulants, while others are applied directly to the soil (or during growth) or used for seed treatment.

• They stimulate natural processes: There are many processes in which biostimulants affect plant development, especially when certain types of amino acids are available for example, or stimulate the production of hormones in plants. Other processes also occur in the soil (or during growth) around the plant. Their effect in soil may be particularly relevant to soil microbial organisms, lixiviates, humic acids, derivatives of organic matter, etc., which are often also utilized when biostimulants are used in the soil and not sprayed on the leaves.

• They enhance nutrient uptake and efficiency: Nutrient uptake (major and minor fertilizers) is related to their efficiency and quality. Therefore, it is very important to choose good fertilizers to be mixed with good biostimulants in order to get great results. Biostimulants may allow further nutrient uptake, whether by foliar spraying or soil irrigation, and they may also activate and improve soil microorganisms (if used by irrigation), which increases the bio-fixation of nitrogen or phosphorus dissolution, for example.

• Biostimulants have been of particular interest to fertilizer manufacturers as using factory mixes of biostimulants and fertilizers has proved to be a good way of providing better products, even if the products are standard. The introduction of biostimulants into products has enabled many manufacturers to create products with new standards and efficiency higher than if they were a manual mix of generic products. The same could be true for some pesticide formulations, but the practice is less widespread compared to the fertilizer industry.

• They enhance abiotic stress tolerance: They affect the general condition of plants, making them more adaptable to the harsh growing conditions. Specific products may also provide the plant with specific tolerance to abiotic stresses, such as drought, salinity, high temperatures, or frost.

• Biostimulants improve crop quality: Like all products related to plant nutrition and soil fertility, biostimulants may directly affect crop quality in several ways: for example, by enhancing the plant’s essential nutrients uptake, reducing the energy the crop uses in times of stress, or by providing peptides and amino acids, which saves the plant a lot of energy and time to produce them.

• Regardless of their nutrient content, biostimulants may contain nutrients that act as fertilizers, but they are usually in low quantities. Thus, the benefit of the biostimulants cannot be attributed to the effect of the fertilizers in it. Trials can actually prove that these nutrients are not the cause of the observed effect, but rather their combined presence with the biostimulants has increased the plant’s ability to benefit from them, even if in small amounts.

• Many biostimulants have proven to be effective at improving crop health and resilience to pests. As a result, the budget that previously was spent solely on pesticides may be spread across other areas too, such as pheromone traps and biostimulants to improve crop health. In other cases, even without the removal of registered pesticides, the results achieved on crop yield by using a biostimulant might be so impressive that it could compete with a pesticide for the set amount of funding that a farmer may spend on agrichemicals. However, this is only likely for pests/diseases that cause minor damage and for biopesticides with a strong effect.

• Improving the action of pesticides:

There are several ways in which a biostimulant can improve the action of a pesticide. The biostimulant may be combined with the pesticide during formulation or, more commonly, during tank mixing. One proposed mode of action for improving pesticide action for a number of botanical extracts, such as seaweeds, is the improved retention of an active ingredient on the leaf surface, either by forming micro-colloids of polysaccharides or an ionic charge held by the biostimulant. Another mode of action that may be present in many extract biostimulants is the metabolic stimulation of beneficial microbes that have been applied as biopesticides. This can be due to the presence of organic carbon sources in the extracts, but could also involve the activation of specific extracellular enzymes in the microbe that are key to the control of a pathogen, such as chitinases. Furthermore, many humic acid products carry a number of claims relating to improved absorption of active ingredients and micronutrients. Whilst these are all important functions, you will still need to ensure that you comply with local regulations covering adjuvants. Some commercial compound biostimulants don’t mix with some plant protection products, so be careful and read the label before starting work.

Note: It is known that biostimulants will not always improve the action of pesticides; at times, they may have no significant effect or may even reduce the effectiveness of the pesticide. Potential negative effects could include the precipitation of the active ingredient of the pesticide out of the solution, or having an antagonistic effect. They could also include providing a source of organic carbon nutrition that aids the growth of a facultative sapotroph pathogen that uses biostimulants to grow before entering the necrotrophic growth phase. Another potential negative interaction is providing an antioxidant effect on the leaf surface during the pathogen invasion period when the plant is producing reactive oxygen species (ROS) to combat the attack. This could include the presence of antioxidants, such as mannitol (present in very high levels in some seaweed extracts).

• Biostimulants and pesticides provide a launchpad for new biopesticides: After several years on the global market, end-users often report that a biostimulant has shown positive effects in protecting against a specific pest or disease. A number of successful biostimulant companies have taken these unexpected reports from the field and have studied them in greater depth to understand why this effect occurred. In some cases, this has resulted in the development of a biopesticide that is refined or extracted from a single compound biostimulant. These new products have then been registered as biopesticides in their own right. This includes chitosan, which is registered as an organic biopesticide in the European Union, commensal fungicides, such as Trichoderma harzianum, and biofertilizers, such as phosphorus-dissolving bacteria.

When are Biostimulants Necessary?

• When plant stress is expected to occur, plant resistance must be enhanced by specific types of biostimulants. Treating the results of stress also requires using biostimulants.
• When the consumer market demands fast agricultural production, growth must be accelerated by using biostimulants.
• When you want a successful investment in the land in the shortest period of time and with the best production.
• When the land is unsuitable for traditional agriculture for some reason, such as salinity, drought, or others.
• To obtain a distinctive quality of production under difficult conditions.
• The net agricultural benefit, after considering the positive and negative impacts of the biostimulant, should be large enough to justify its use.
• The benefit from using the biostimulant should be appropriate for the plant and for the purpose for which the product is to be used.
• The biostimulant is used as a key component in an integrated crop management (ICM) program.
• They are essential in specialized agriculture, such as organic agriculture and sustainable agriculture.
• The most important thing in our country is that when all kinds of mineral fertilizers are not used properly, or when the crop service operations are not performed in an ideal manner (irrigation, fertilization, control), then using biostimulants is necessary to try to maintain the same level of crop or quality.

Field Testing

Field trials provide essential information about biostimulant effects under real-world conditions. However, for some claims, such as salt stress or cold stress, it is difficult to artificially create the appropriate field conditions. In such cases, repeated field trials will be more on the “holistic” benefits of the biostimulant in terms of yield/quality, while a specific biostimulant claim related to its mode of action (for measurable matters such as early production, early flowering, faster growth, increased production) can (and must) be demonstrated in controlled conditions. For example: one can demonstrate that a specific biostimulant helps produce crop one week earlier in controlled greenhouse or laboratory conditions when it is used early, and demonstrate the overall general benefit to the farmer in terms of improved yield and/or early production when field testing of the same product. A farmer is not interested in a specific product or mode of action if it doesn’t result in tangible on-farm benefit.

A respected company, like Debbane, conducts multiple trials in several regions before launching a new biostimulant product in the market. The company verifies the statements of the manufacturer by performing dozens of field tests on several crops, under multiple conditions, and with expanded possibilities. When we make sure of the effectiveness of the biostimulant, we proceed with the registration and importation procedures; otherwise, the product is not launched in the market. Where the data indicate that there are inconsistencies in the performance of a product, the reasons for these inconsistencies should be explained and solutions or ways to develop the product should be found. The instructions for use and local test results should enable the user to identify the conditions under which the product will provide optimal performance, as well as any factors that may have an impact on effectiveness. In all cases, the label shall be made in accordance with the results of the field tests and the recommendations of the manufacturer. Therefore, the user must follow the instructions on the label. Transparency is critical to allow farmers to make informed decisions in order to obtain clear and verified results.

What are the Most Important Countries that Produce Plant Biostimulants?

Four regions of the world:

– USA and Canada

– Spain, France, and Italy

– China and India

– Chile and Mexico.

The rest of the countries are still striving in this field, although their development is also rapid.

Notes

Biostimulants have no direct action on against pests, and therefore do not fall within the legal regulatory framework for pesticides. Many biostimulants indirectly help plants with pest control.

Biostimulants differ from plant growth regulators (hormones), especially synthetic hormones.

Vegetables and field crops have a higher rapid response to biostimulants than fruit trees, especially when used as seed treatment.

Plants grown with excellent service methods have limited response to plant biostimulants under natural conditions, because they have reached the peak of growth and health.

Next time, we will talk about each type of biostimulant separately: seaweed, amino acids, biofertilizers, and more. Wait for us.

by W. Al Matni