Introduction

In their natural environment, plants are part of a rich ecosystem that includes numerous diverse microorganisms in the soil. It has been long recognized that some of these microbes, such as mycorrhizal fungi or nitrogen-fixing symbiotic bacteria, play important roles in plant performance by improving mineral nutrition. However, the full range of microbes associated with plants and their potential to replace synthetic agricultural inputs has only recently started to be uncovered.

Although plant physiologists sometimes view soil as simply a source of nutrients to plants, it is actually a complex ecosystem hosting bacteria, fungi, protists, and animals. Plants exhibit a diverse array of interactions with these soil-dwelling organisms, which span the full range of ecological possibilities (competitive, exploitative, neutral, commensal, mutualistic).

Throughout modern plant science, most interaction studies have focused on alleviating pathogenic effects such as herbivory and infection, or attenuating abiotic stress conditions. However, there has also been longstanding interest in characterising the positive ecological interactions that promote plant growth. For instance, mycorrhizal fungi as well as the bacteria present in nodulated legumes were both recognized as root symbionts from the second half of 19th century.

Already in the 1950s, crop seeds were coated with bacterial cultures (Azotobacter chroococcum or Bacillus megaterium) to improve growth and yield. By the 1980s many different bacterial strains, mainly Pseudomonas but also Azospirillum, had been described as having plant growth promoting effects. Since the 2000s, research focus has somewhat shifted away from individual microbial strains, and toward documenting the abundance and diversity of the root microbiome through metagenomics. Results from such sequencing studies have shown that the rhizospheric niche is a hotspot of ecological richness, with plant roots hosting an enormous array of microbial taxa.

Three mechanisms are usually put forward to explain how microbial activity can boost plant growth:
      1. Manipulating the hormonal signalling of plants
      2. Repelling or outcompeting pathogenic microbial strains
      3. Increasing the bioavailability of soil-borne nutrients.

In natural ecosystems, most nutrients such as N and P are bound in organic molecules and are therefore minimally bioavailable for plants. To access these nutrients, plants are dependent on the growth of soil microbes such as bacteria and fungi, which possess the metabolic machinery to depolymerize and mineralise organic forms of N and P. The contents of these microbial cells are subsequently released, either through turnover and cell lysis, or via protozoic predation.

This liberates inorganic N and P forms into the soil, including ionic species such as ammonium, nitrate, phosphate, and sulfate that are the preferred nutrient forms for plants. In natural settings, these microbial nutrient transformations are key drivers of plant growth and can sometimes be the rate-limiting step in ecosystem productivity.

TM – Nestle Soil Analysis Results

A significant increase in the following variables can be seen from the analysis of soil samples with the application of TM Agricultural as compared to the untreated samples.

Mycorrhizal Fungi

The soil analysis results showed an average increase of 525% in terms of mycorrhizal count was also noted in the TM Agricultural treated soil samples compared to the control samples.

Mycorrhiza, which means “fungus-root,” is defined as a beneficial or symbiotic relationship between a fungus and the roots of its host plant. This relationship is a natural infection of a plant’s root system in which the plant supplies the fungus with sugars and carbon and receives water and/or nutrients in return. This type of relationship has been around since plants began growing on land about 400 to 500 million years ago.

The main benefit mycorrhizal fungi provide is access to large amounts of water and nutrients (particularly nitrogen, phosphorus, zinc, manganese and copper). This is because the hyphae increase the root surface area of absorption from soil. The mycorrhizal hyphae are smaller in diameter compared to plant roots and can reach areas unavailable to the roots.

Nitrogen Fixing Bacteria (NFB)

The soil analysis results also show an average increase of 21% of nitrogen fixing bacteria on TM Agricultural treated soil samples compared to the control samples.

Nitrogen is abundant in the atmosphere, but plants cannot utilise it in its gaseous form. NFB, such as Rhizobium, Azotobacter, and Cyanobacteria, play a vital role by converting atmospheric nitrogen into ammonia, which plants can readily absorb. The reliance on synthetic nitrogen fertilisers can negatively affect environmental sustainability, contributing to issues like soil degradation and water pollution. NFB, on the other hand, can naturally enrich soils with nitrogen, reducing the need for chemical inputs and promoting more sustainable farming practices.

Bacteria like Rhizobium, found in leguminous plants, or free living bacteria such as Azospirillum, can fix atmospheric nitrogen and make it available for plant growth. These bacteria vary in presence and efficiency depending on the soil type and environmental conditions. NFB produce enzymes like nitrogenase, which help break the strong triple bond in N₂ molecules. By utilising biological nitrogen fixation, farmers can enhance soil fertility, support plant growth, and minimise reliance on synthetic fertilisers, contributing to better environmental and soil health in the long term.

Phosphate Solubilising Bacteria (PSB)

The soil analysis results also show an average increase of 145% of phosphate solubilising bacteria on TM Agricultural treated soil samples compared to the control samples.

Phosphorus is an essential macronutrient for plants, yet a significant portion of soil phosphorus exists in insoluble forms, making it unavailable for plant absorption. Phosphate solubilising bacteria (PSB), including species such as Pseudomonas, Bacillus, and Rhizobium, are capable of transforming insoluble phosphates into soluble orthophosphate through biochemical processes. The application of chemical phosphorus fertilisers can lead to environmental degradation, such as eutrophication in aquatic ecosystems. The use of PSB offers a more environmentally sustainable alternative by naturally increasing the bioavailability of phosphorus, thereby reducing dependency on synthetic fertilisers.

PSB achieve phosphate solubilisation through the secretion of organic acids (e.g., gluconic acid, citric acid) and enzymes, which lower the pH and release phosphorus from minerals such as apatite or calcium phosphate. These microbial processes, including chelation, acidification, and enzymatic activity, enhance phosphorus mobility in the rhizosphere. The abundance and activity of PSB vary based on soil composition and environmental factors, yet they play a significant role in phosphorus cycling. Incorporating PSB into agricultural practices not only improves phosphorus uptake by plants but also mitigates the environmental risks associated with conventional phosphorus fertilisation, promoting a more sustainable and efficient nutrient management system.

Potassium Solubilizing Bacteria (KSB)

The soil analysis results also show an average increase of 1282% of KSB on TM Agricultural treated soil samples compared to the control samples.

Naturally, soils contain K in larger amounts than any other nutrients; however most of the K is unavailable for plant uptake. Application of chemical fertilisers has a considerably negative impact on environmental sustainability. It is known that potassium solubilizing bacteria (KSB) can solubilise K-bearing minerals and convert the insoluble K to soluble forms of K available for plant uptake.

Many bacteria such as Acidothiobacillus ferrooxidans, Paenibacillus spp., Bacillus mucilaginosus, B. edaphicus, and B. circulans have the capacity to solubilize K minerals (e.g., biotite, feldspar, illite, muscovite, orthoclase, and mica). KSB are usually present in all soils, although their number, diversity, and ability to solubilise K vary depending on the soil and climatic conditions. KSB can dissolve silicate minerals and release K through the production of organic and inorganic acids, acidolysis, polysaccharides, complexolysis, chelation, and exchange reactions. Hence, the production and management of biological fertilisers containing KSB can be an effective alternative to chemical fertilisers.

Conclusion

From the information and observations made to-date, TM Agricultural (a biological activator) would appear to have the following characteristics:

      1. Increases microbial diversity & activity
      2. Improves the efficiency of nutrient uptake
      3. Promotes N fixing leguminous nodules and probably the free-living N fixing bacteria
      4. Increases soil carbon
      5. Helps to neutralise acidic soils
      6. Promotes plant growth
      7. Promotes the root system
      8. Decreases the susceptibility to insect/pest attack
      9. Reduces the use of insecticides, pesticides and fungicides
      10. Helps to buffer and improve the efficiency of herbicides/insecticides/fungicide sprays
      11. Acts as a nutrient regulator – for example, reducing high Na levels
      12. Acts as a soil conditioner − Improves soil structure, porosity, colour & air capacity of the soil
      13. Promotes crop vigour and persistence
      14. Decreases water repellency (soil hydrophobicity)
      15. Reduces the susceptibility of crops and pastures to frost damage

The above 15 points provide an interesting list of characteristics, any one of which would justify the detailed investigation of the soil, plant, economic and environmental performance of farms using TM under different climate zones, soil types and land uses. Collectively, the above characteristics would provide farmers and agricultural consultants with a powerful tool to significantly lift on farm performance while at the same time decreasing a farm’s environmental footprint, both in terms of reducing nutrient loss, greenhouse gas emissions and sequestering soil carbon.