Biostimulants and Crop Responses

Between market fluctuations and changes in climate, no responsible commercial farmer can rest in the idea that what they did last season will be effective in this season — or the next.

Technology is also something that is rapidly changing at all times. It’s vital for the long-term success of any growing operation, of any size, to stay up to date on the latest best practices that have been integrated throughout the industry. 

New additions to growth regimes that have gained a lot of attention — and for good reason — fall under the heading of “biostimulants.” A general definition of a biostimulant is an additive to the soil that works to improve the growing environment for the plants without the use of chemicals. 

Biostimulants, then, are designed to:

  • Enhance bioavailability of nutrition for root structures
  • Improve stress tolerance for plants, especially in saline or moisture-challenged ecosystems
  • Support the genetics of seed stock
  • Help crops improve quality and productivity

But do they actually work better than traditional chemical additives do? Farmers are used to the concept of adding substances that contain nutritional supplements that plants need to grow, but this method goes against the market trend toward organic and chemical-free growing.

Biostimulants approach this problem from another direction. These additives work to improve the health of the rhizospheric level of soil, which then creates a more ideal environment for roots to naturally get the nutrients and water that’s needed for the plants to thrive.

When it comes to biostimulants and crop responses, a review is necessary — or more than one, and from independent researchers who are interested in the long-term viability of the agricultural industry. 

This article will look at the research as well as address the role of biofertilizer in crop production as well as other considerations for commercial use of biostimulants.

Four Types of Biostimulants

There are four main types of biostimulants that are used in modern growing operations. It’s worth noting that, while this article focuses on commercial agriculture, these products are used by backyard hobbyists and farmers with land plots of all sizes. It’s not necessary to oversee large acreage for biostimulants to be a valid addition to your growing regime. 

The four types of biostimulants are:

  1. Beneficial bacteria and fungi

These are some of the most popular biostimulants in part because it’s such an easy concept. People are usually familiar with probiotics that come naturally in yogurts and other fermented products like kefir and kombucha. They know that these “good bacteria” help balance the gut lining for optimum digestion. The concept is the same for growing, except farmers are adding the bacteria to the soil rather than their stomachs.

2. Liquid manure composting

Made by mixing manure water with materials that encourage microbial growth, this liquid can be used as a biofertilizer. Often, town and city officials are willing to work with large landowners to find a mutually beneficial solution for disposing of municipal waste. However, this is a risky operation as so-called sludge can spark community protests and lead to a messy cleanup if problems arise.

3. Seaweed extracts

Available in powders and liquids, seaweed can work well as a biostimulant on land. These nutrient-packed extracts are produced by many different processes and can sometimes be very expensive.

4. Humic and fulvic acids

These acids are the result of the natural decomposition processes of plants, animals, and microbial residues. They are dark in color and can include peat, soft coal, and leonardite. These biostimulants are not always recommended for soils with high salinity and acidity levels. 

Not all of these biostimulants will work well on your land, as the efficiency is highly dependent on other factors. For example, if your soil is too sandy and has a low capacity for holding water, a biostimulant will not be a miracle cure.


plant growth


What the Research Says: Biostimulants and Plant Growth

Frontiers in Plant Science reported that more than 700 scientific papers were published in the last decade on the role of biofertilizer in crop production. Several researchers were able to document improvements in crop productivity, nitrogen use efficiency (NUE), and overall tolerance against abiotic stresses.

For example, research conducted by Calvo et al. that was published in 2014 in Plant and Soil found “growing scientific evidence” that supports the use of biostimulants. The research especially pointed to evidence like increased root growth, enhanced nutrient uptake, and stress tolerance.

A year later, Halpern et al. published in Advances in Agronomy a study that found that fertilizer can be reduced without damaging plant nutrition by instead adding a biostimulant. 

In 2017, S. De Pascale et al. in Italy discovered through their research that biostimulants are able to reduce the gap in yields between organic and conventional yields. Another group of Italian scientists that year was able to hone in on how biostimulants help lettuce tolerant less-than-ideal alkalinity and salinity levels in the soil.

Indeed, the most promising research is related to the use of biostimulants in environments that are subject to extreme temperatures, drought, and salinity. An international 2018 study by Backer et al. showed the value of adding rhizobacteria as a “roadmap” to sustainable agriculture.

Compare the Role of Biofertilizer in Crop Production

Why is plant growth important? Of course, it’s obvious to farmers that plants with high productivity and resiliency can result in greater payouts at the end of the growing season. But conditions for plant growth are varied, and it’s worth testing to see if biostimulants work for your growing beds.

When it comes to biostimulants and crop responses, a review must happen locally as well. That is, just because there are lots of scientists who support this technology does not necessarily mean it’s going to work well on your farm. 

Experts recommend conducting your own trial to determine the role of biofertilizers in crop production in your environment. To do this, simply add a replicated strip trial for a growing season. Use biostimulant products on one strip of your crop, and compare the growth to one where you do not use the biostimulant. 

Look for signs of healthy soils, such as underground critters like worms and fungi, a darker color, crumbly texture that doesn’t stick to roots, and proper water filtration that allows for the absorption of an inch of water per hour.   

Role of Biostimulants in Plants’ Health

The growth in a plant isn’t dependent on just one thing — commercial farmers know the complexity of their work. New growers will soon find out that they must consider many factors when deciding what best practices to follow for a successful season.

Biostimulants can make a measurable difference in your yields. Impello, which offers a proprietary bacterial blend in their microbial inoculants, used an independent, third-party researcher to discover the use of their products resulted in a 15% increase in dry weight yields, a 14% increase in growth rate, and a 16% increase in stem diameter.  

But biostimulants don’t act alone. Farmers should also be aware of additional organic farming practices that help support plant health and increase productivity. 

Crop rotation can play a major role in ensuring the nutritional balance within the soil. Limiting the tillage practices through mechanical disruption is another important practice for the health of the soil. Ripping up the rhizosphere, or the soil layer where roots grow, disrupts the ecosystem that the biostimulants work to support.

Bacteria-based products that help balance the health of the soil can also work in conjunction with other biostimulants. For example, treated manure or dooryard composting can provide enhanced diversity of enzymes and fungi that help root development. Some farmers use biostimulant soil amendments, like Impello’s biofertilizer Lumina


Which Are the Best Biostimulant Products?

You want to use the best plant growth stimulant. Otherwise, you won’t reap the benefits of the biostimulant technology that is gaining such acceptance in the organic and conventional farming communities. 

When comparing products, the first thing to look for is a guarantee. If you test the product compared to your previous methods of growing and find no improvement, you simply shouldn’t have to pay for that product. 

Make sure the products are listed on the Organic Materials Review Institute, or OMRI, and/or certified by the USDA as a bio-based product. 

Finally, you’ll want to make sure you’re using the best biostimulant for your particular desired results. For example, Impello’s Tribus microbial inoculants use a proprietary blend of beneficial bacteria. Tribus Bloom is ideal for the fruiting stage, while Tribus Grow is best for the high-growth period. Tribus Original, meanwhile, is designed to be used throughout the entire cycle of the plant from seed to harvest.

The new technology of biostimulants will help commercial growers overcome the challenges they face from climate changes and market fluctuations that make agriculture an industry that isn’t for the weak of heart and mind. 

By digging into the independent research and conducting tests on your own plots of land, you’ll be able to see the benefits of biostimulants go well beyond the soil. Farmers will discover benefits for their roots, their plants, their yields, and, perhaps most importantly, the community who relies on all their hard work.

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