Scientific Research

Introduction

Microbe Plus™ fertilisers – essence and proven qualities

Fertilisers from the Microbe Plus range are based on a precise combination of microorganisms. The formulations include a significantly diverse set of beneficial fungi (Chaetomium brasiliense, Chaetomium globosum, Chaetomium spinosum, Chaetomium virescens, Farrowia longicola, Farrowia seminuda, Trichoderma harzianum, Trichodermalongibrachiatum, Trichoderma viride, Phanerochaetae chrysosporium) and bacteria (Bacillus subtilis).

Products containing beneficial microorganisms have a number of advantages over synthetic mineral fertilisers (Figure 1). It is established that they increase plant productivity and crop quality. They enhance absorbability of mineral elements, stimulate the metabolism of plants, supplying them with vitamins and hormones that promote growth and activate the enzyme defense system of crops.

The microbes used in our products form mutualistic symbiosis with plants (Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other).

Plant growth–promoting rhizobacteria (PGPR) are classified into two groups:

The first group includes bacterial strains that have the capability of synthesizing plant growth–promoting substances, fixing atmospheric nitrogen, solubilizing inorganic phosphate or iron, and of improving plant stress tolerance to drought, salinity, metal toxicity, and pesticide load. The second group includes the bacteria which are able to decrease or prevent the deleterious effects of phytopathogenic microorganisms.

Figure 1: Effect of beneficial fungi and bacteria in the leaf. They will not only increase the efficiency in plant nutrition but also they will provide with protection against other pathogens

The bacteria used in GrowGreen products has effects on both of the above features as it can promote plant growth through stimulating phytohormones, solubilization and mobilization of phosphate, production of antibiotics, and induction of plant systemic resistance to pathogens.

The fungi added to our products colonize root intercellular spaces and thus they can protect plants against diseases and environmental stresses such as salinity and drought, and an improve plant growth and development In return, plants can secrete up to 30% of their fixed carbon via root exudates, thereby feeding their symbiotic partners.

Representatives of the Bacillus genus synthesize a wide range of enzymes that degrade proteins to amino acids as well as other important organic macromolecules. Some strains of Bacillus subtilis synthesize enzymes that break down poorly digestible phosphate sources, which increases the content of mobile phosphorus in the soil. A similar effect has also been reported with respect to other food macro and microelements. Higher is the content of mobile potassium as well as that of magnesium. Better mineral nutrition leads to increased growth and higher yields. Increased growth of both the ground mass (a prerequisite for better photosynthesis) and the development of a more powerful root system (capable of covering a larger volume of soil, respectively more mineral elements and more water) is observed. This overall strengthening of the plants treated with Bacillus subtilis makes them more resistant to the adverse environmental factors (Figure 2).

Figure 2 – Treated field / Untreated field

The powerful root system is particularly important in the early stages of crop development, especially in those grown by seedlings (ensuring better interception of young plants) (Figure 4). Useful bacteria in Microbe Plus also synthesize growth regulators (gibberellins, cytokinins, abscisic acid).

Several beneficial fungi are included in the products. Representatives of the genus Chaetomium are common soil occupants. Their action is associated with the synthesis of special enzymes – celluloses that degrade cellulose. These mushrooms are able to synthesize mycotoxins with antibacterial properties and thus suppress the development of a number of causes of economically important diseases of crop plants. Chaetomium sp. protects plants from the negative effects of heavy metals on the soil. Representatives of the genus Trichoderma live in symbiosis with the roots of the plants. These beneficial fungi synthesize substances that cause plant systemic and local resistance to pathogens. This is due to their ability to synthesize enzymes that degrade the cell walls of phytopathogenic organisms. The tolerance to the adverse factors of the medium in the treated plants also increases. Mushrooms of the genus Phanerochaetae have the ability to break down the lignin (in the tree species and in the underlying tissues). All these positive qualities that our microbiological products possess make them extremely effective. They can be successfully combined with conventional mineral fertilisers. Their use would contribute to reducing the amount of the most widely used fertilisers based on better absorption of food macro- and microelements and the overall strengthening of plants, their improved physiological status and resistance to biotic and abiotic stress factors.

How do the bacteria and fungi work with the plant?

GrowGreen fertilisers are microbiologically active. Soil and/ or foliar applications of our products will have the following effects:

  • Inoculates the Rhizosphere or Phyllosphere with beneficial bacteria and encourages growth of beneficial fungi.
  • Phyllosphere’s microbes behave similarly to Rhizosphere microbes in that they:
    • Fix nutrients, particularly N-fixing;
    • Produce plant beneficial exudates including vitamins, enzymes, pathogen toxins, growth hormones, and nutrients in organic forms
    • Facilitate faster nutrient transport
    • Compete against pathogenic Phyllosphere microbes
  • Additionally, Phyllosphere microbes “breath out” CO2 localized near the leaf which stimulates stomatal response which in turn promotes more rapid nutrient up-take and CO2 uptake that fuels photosynthesis.
  • Reduce plant sensitivity to ultraviolet light.
  • Reduce transplant shock and aids recovery. Help stabilize and improve soil structure.
  • Encourage healthy growth to help resist adverse weather, disease and pest attack.
  • Provide major nutrients, vitamins and trace elements.

It is shown that nutrients are absorbed into the leaf metabolic processes faster with foliar spray.

A test conducted on turf by the University of Nebraska shows that within 6 hours after foliar spray vs liquid irrigation, nutrient absorption is up to 5 times faster for N and 1.5 -2 times faster on P and K, a range of 1.5 to 10 times faster for micronutrients depending on the micronutrient.

How do the bacteria and the fungi work in the soil?

The bacteria included in GrowGreen products belong to the PGPR family (Plant Growth Promoting Rhizobateria). The Rhizosphere (Figure 1) includes the soil connected to the plant roots and often extends a few millimetres off the root surface, being an important environment for the plant and microorganism interactions.

The PGPR belong to a beneficial and heterogeneous group of microorganisms that can be found in the rhizosphere, on the root surface or associated to it, and are capable of enhancing the growth of plants and protecting them from disease and abiotic stresses (Figure 2). The mechanisms by which PGPB stimulate plant growth involve the availability of nutrients originating from genetic processes, such as biological phosphate solubilization, stress alleviation, and production of phytohormones and siderophores, among several others.

Our fungal species secrete into the rhizosphere some growth stimulants, thereby speeding up seed germination, uniformity of germination, growth, flowering, fruit setting and yields. But also, they have been successfully utilised for biological control and other fungi.

Are our microbes aerobic or anaerobic?

The cocktail of microorganisms added to our products have an aerobic respiration. Also during our manufacturing process, we add specific preservatives that will inhibit the growth of molds or other anaerobic species.

Figure 4: Effect of GrowGreen fertilisers in soil

Effect of GrowGreen fertilisers in soil

For its growth and development, plants need nutrients in an easy digestive form. Many nutrients require the involvement of various organisms in the soil (and on the leaves) to become accessible to the plants.

When the processes in the soil are balanced, the plants can develop their maximum potential. They need proper nutrition as well as a need to grow in healthy soil.

Soil – a major source of nutrients for plants

The main source of mineral elements for plants is the soil. Its properties are determined by a variety of physical, chemical and biological factors. Plants are not capable of directly digesting substances firmly attached to soil components. These nutrients pass into a form accessible to plants by the so-called ion exchange. Elements adsorbed on the surface of soil particles form the so-called soil absorption complex (SAC). They are more difficult to access, but they are a stable and lasting food stock for plants. This SAC is a set of organic, mineral and organic-mineral substances including mainly soil humus and clay (Figure 3).

Figure 3

When the elements are poorly fixed on the soil components, but there is a risk of being easily washed into deeper soil layers or reaching groundwater. The mineral elements contained in the soil solution that fills the soil capillaries and the spaces between the soil particles are most easily absorbed. In „healthy“ soils, the ratio of cations (positively charged ions) and anions (negatively charged ions) is physiologically balanced. Soil (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), hydrogen (H+), aluminum (Al3+) and ammonium (NH4+) are found in soils as exchange cations. The most common cation exchange is calcium. Good supply of alkaline earth cations, especially calcium, is an important condition for soil formation with good structure, high moisture retention, aeration, volatility, etc. Calcium-exchanged soils are characterized by a neutral or near-neutral reaction with the greatest durability of the absorption complex and the best buffering (resistance against acidification and alkalization). For a soil to be fertile, it must contain some quantities of other exchange cations. The reason for this is that the soil solution is physiologically balanced when, along with calcium cations, it also contains cations of magnesium, potassium and others. This is only possible if these cations are contained in the swallowing complex in an exchange form.

Soil humus is of great importance for soil fertility. It is the main source of nutrients for plants and, on more dry conditions, improves the water regime of the soil. The role of microorganisms in the process of humus formation is to decompose the resulting plant residues (cellulose, pectic substances, lignin, proteins, etc.). An important role in this complex biological process also play the soil-climatic conditions – mainly soil type and moisture. In soils with a high content and plant residues and a high humidity due to the active microbiological activity is formed more humus back into soil less plant residues and low humidity, due to the reduced microbiological activity accumulates less humus. Micro-organisms also play an important role in the process of cloud formation, which is an important property of the soil. The structural soil under processing is degraded on macro-aggregates (buckets) with a diameter of 0.25-10 mm, and the non-structural – small particles (micro aggregates) with a diameter of less than 0.25 mm. The soil structure is most advantageous when soil aggregates have a diameter of 1 to 10 mm.

The structure of soils is of great importance for their fertility and for the efficiency of imported fertilisers. The favorable water, air and heat regime of the soil are key factors for the maximum absorption of nutrients from the plants and hence for the maximum.

Shelf life of GrowGreen microbes in the soil

When our microbes are exposed to adverse conditions (high/low pH, high/ low temperature, low aeration, etc.) they will form resistance structures e.g. spores, sclerotia (fungus). Under this resistance structures, our microbes can remain as “dormant” for years. When the conditions change into favourable, they will become active again.

GrowGreen interaction with tillage

Tillage systems influence physical, chemical, and biological properties of the soil. Different tillage practices cause changes in soil physical properties, such as bulk density, water holding capacity, pore size distribution, and aggregation. Stratification of soil organic matter and differences in nutrient distribution have also been observed in long-term conservation tillage systems. Thus, altered soil physical and chemical conditions under conservation tillage create significantly different habitats for microorganisms and result in shifts of soil microbial community structure. That’s why soil application of GrowGreen products should be done after tillage.

The timing for the soil application of GrowGreen fertilisers is preferred before seeding, as the biostimulants properties of the products will help the seeds to increase the percentage of germination and seedling survival.

In Australia, where farmers have the technology of adding GrowGreen fertilisers at the same time of seeding, it has been proven positive results in seedling nutrition and as a consequence in higher growth.

Efficiency of GrowGreen with different soil pH

The ideal pH value in the soil is around 6.5; at this pH the majority of the nutrients are available for the plant. The response of the plant to GrowGreen products is enhanced when the conditions are far from ideal.

Our fertilisers assist plants growing under stress due to the following parameters:

  • In poor soil situations, going foliar is an advantage.
  • Due to the microbial digestion, our nutrients are readily available to the plants.
  • Our products contain hormones and other molecules with plant stimulatory effect this will help plants to better deal with any soil related stress.
  • If soil pH locks nutrients, GrowGreen microbes will help in unblock nutrients for plant nutrition. Again, it is an advantage to supply to the leaves nutrients with low mobility within the plant, e.g. Calcium.
  • Once the GrowGreen’s microbes find the plant roots, they will start transforming the Rhizosphere in order to create more appropriate conditions for their survival. Due to the organic acid production by our microbes, the conditions around the roots can be modified and hence better assist in plant nutrition.

GrowGreen products in flooded areas

Flooding affects both above- and below-ground ecosystem processes. While the below-ground changes may be less obvious, they are as important as the above-ground changes. Soil microorganisms are sensitive to disturbance, and shifts in soil microbial community structure are expected when anaerobic conditions develop from flooding.

Soil inundation or saturation depletes soil oxygen. This loss of soil oxygen is the greatest challenge to established plants.

Fungi are less prevalent in inundated soils. Reduction reactions may result in changes in phase or solubility. For example, reduced Fe and Mn are more soluble; these reduced ions move through the soil resulting in areas with either a depletion or surfeit of Fe and Mn. GrowGreen fertiliser effects in flooded crops:

  • The stimulating effect will help the plant to better deal with the stress.
  • Plant roots will be colonized by our aerobic bacteria.
  • As our nutrients can be absorbed directly by the plants (by both the roots and leaves) the stressed plants will need less energy for the nutrient consumption. Therefore, plants will take nutrients with less energy consumption.

Figure 5

Chelation only affect to positively charged ions (as calcium, magnesium) but has nothing to do with negatives as sulphates. Due to the microbial digestion, the originally added nutrients in our fertilisers are partially quilted. As microbes profiler in our liquids they segregate organic substances with chelating properties. The segregation of these organic molecules has two consequences:

  • Plant nutrients are easily absorbed by roots or leaves.
  • Due to the “sticky” nature of these substances, the nutrients can be attached to the soil particles more effectively, which eventually reduces the leaching effect.

Plant-growth-promoting-rhizobacteria (PGPR) can improve the plants’ tolerance to many abiotic and biotic stresses, including drought stress. PGPR improve water retention and soil aggregation around the plant’s roots. Some PGPR have the enzyme 1-aminocyclopropane-1-carboxylic-acid (ACC-deaminase).

The resistance to environmental stresses including water stress of plants treated with plant growth promoting bacteria can be increased. The mechanisms that have been suggested include reduction of stress ethylene production via the action of ACC deaminase and increased expression of the ERD15 gene, which is responsive to drought stress. Under stress conditions, ACC deaminase-containing bacteria that restrain the production of ethylene may be effective in alleviating a portion of the stress effect.

Fungi and bacteria are present in all of GrowGreen range of fertilisers. When adding our cocktail with different species of fungi and bacteria the initial concentration is up to 106 cfu/ml (Colony Forming Units). However, this number will change with time, increasing or decreasing with favourable or not conditions. When the container is stored for long periods, the natural process of the microbes is to form resistance structures. Once the conditions change (aeration, addition of molasses) they will become active and the total population will increase.

GrowGreen is not a replacement or substitution alternative. We always work in conjunction with other plant fertiliser solutions. One of the keys of our success is that when stimulating the plant with hormones or other organic bioactives contained in our products, the plant will use with increased efficiency any other source of nutrition.

GrowGreen liquid fertilisers have been shown to be compatible with all the fertilisers proven so far.

Interactions of GrowGreen with UAN

Immediately after fertilization with UAN, high concentrations of ammonia temporarily inhibit soil microbes in the fertiliser retention zone. Bacteria are sensitive to ammonia and are affected by this to a greater extent than fungi. After few days up to couple of weeks, ammonia concentrations gradually decline as the ammonia adheres to soil particles or moves with water away from the application site. As ammonia concentrations decrease, the application of GrowGreen biofertilisers will help to repopulate the affected area. This is achieved because:

  • Our products are loaded with fungi and bacteria that will help in the microbial population increase.
  • But also, the stimulatory (hormones, bioactive molecules, etc) effect as well as the different key nutrients (as molasses) included in our products, will help to boost the natural microbial population of the affected soil.