Organic Bio-fertiliser Effects on the Soil and Plant Health Functions


Bio-fertiliser is a substance which contains living microorganisms which, when applied to the plant, seed or soil, colonise the interior of the plant and the region of soil that is directly influenced by root secretions and associated soil microorganisms (rhizosphere). This promotes growth by increasing the supply or availability of primary nutrients to the plant.

Below Dr Stephanus Malherbe elaborates on the 17 micro-organisms contained in ExploGrow™ and their specific functions and effects on the soil and plant health functions, also describing how some of the microbes may enhance the plant's resistance to certain diseases. The use of this particular blend of bio-fertiliser promotes sustainable agriculture due to its formulation that includes nitrogen-fixing bacteria that even fixes atmospheric nitrogen, a potent phosphate solubiliser, microbes with soil balancing properties and more (see below). This enables the farmer to replace petrochemical fertilizer by over 50% with a natural plant growth stimulant that is more than simply environmentally friendly since it also improves the condition of the soil.

By Dr Stephanus Malherbe, BSc, BSc Hons., MSc (Microbiology), Pr.Sci.Nat. (Agricultural Science).

The microbes listed below are 100% organic, highly complex micro-organisms. They are environmentally friendly soil ameliorants and plant growth stimulants, with increased soil microbial balance properties.

Azospirillum humicireducens

A free-living nitrogen fixer (therefore suitable for non-legumes); grows under anaerobic conditions, which means it can function in waterlogged heavy soils); optimum pH is 7.2; optimum growth temperature is 30° C.

Azotobacter vinelandii

A free-living nitrogen fixer (therefore suitable for non-legumes); grows under aerobic conditions; known for the secretion of phytohormones and vitamins into the soil; is an ideal 'plant growth promoting bacterium'.

Bacillus licheniformis

A saprophytic soil bacterium; plays a major role in nutrient cycles in the soil; is ideal for use in agro-ecological and low-input production systems where crop nutrients are supplied via the organic matter of the soil.

Bacillus thuringiensis

A classic insect biological control bacterium; various formulations and variants are commercially available around the world; has no effect on beneficial insects (like bees, etc.). There are several subspecies, each attacking different types of insects.

Ensifer fredii

A nitrogen fixer that forms nodules on legumes; earlier known as but was recently
reclassified as spp. (this means literature can be used for marketing).

Flavimonas oryzihabitans

Also known as ; known for the control of root knot nematode (spp.) and Fusarium wilt on tomatoes; Pseudomonads are known for their versatility and usefulness in the agricultural context as biological control agents, phosphate solubilisers and plant growth promoting bacteria.

Rhizobium radiobacter

Little information is available about this organism; it is linked to improved plant growth through secretion of compounds that stimulate plant growth. Strains from the genera and are among the most potent phosphate solubilisers.

Trichoderma aureoviridi

All the Trichoderma species were found to produce different extrolites and enzymes responsible for the biocontrol activities against the harmful fungal phytopathogens that hamper in food production. This potential indigenous Trichoderma spp. can be targeted for the development of suitable bioformulation against soil and seedborne pathogens in sustainable agricultural practice.

Trichoderma harzianum

A classic and the most well-known biological control fungus; it parasitizes other fungi and is used for biological control of fungal diseases; different formulations are available that determine under what conditions the organism will be effective (e.g., soil versus leaf surface applications).

Azorhizophillus paspali

Nitrogen fixing from atmosphere. This organism is efficient in plant growth-promotion, and most of its beneficial effects to crop productivity can be attributed to nitrogen fixation, phytohormones production, and biocontrol of phytopathogens. Plant inoculation of cereals and grasses with this organism, can lead to strong promotion of the development of the root system with increases in density and length of root hairs and in the number and volume lateral roots; significant increases in nutrient absorption by the host plant (K+ , Ca2+, PO4 3-, H2O), increase in plant resistance to water stress (drought resistance), acceleration of N-mobilization of seed and plantlet growth (increased precocity) and early flowering.

Trichoderma inhamatum

Like all the other Trichoderma species it is found to produce different extrolites and enzymes, which are responsible for biocontrol activities against various harmful fungal phytopathogens that hamper in food production. This potential indigenous Trichoderma spp. can be targeted for the development of suitable bioformulation against soil and seedborne pathogens in sustainable agricultural practice.

Ensifer numidicus

Symbiotic properties of isolates showed diversity in their capacity to nodulate their host plant and to fix atmospheric nitrogen.

Sinorhizobium americanum

Is a predominant symbiont that nodulates and fixes nitrogen.

Bacillus cereus

Plants benefit from the presence of because often prevents plant diseases, and can enhance plant growth. benefits by gaining shelter in the plant roots.

Ensifer meliloti 

Benefits plant growth in drought conditions. Lucern benefits greatly from this microbe.

Trichoderma virens

Increased biomass production and stimulates lateral roots. 

Pseudomonas japonica

Calcium ion binding.

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