Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper says it is critical for plant health to build soil structure with the right soil environment, where beneficial soil micro biota populations flourish naturally, providing all the benefits that are claimed by inoculants.

Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper says it is critical for plant health to build soil structure with the right soil environment, where beneficial soil micro biota populations flourish naturally, providing all the benefits that are claimed by inoculants.

Do we really need to use inoculants?
On face value your answer might be unequivocally, YES.
And you might back that up with another question: Aren’t inoculants, which are beneficial microorganisms, good for plant health and able to control pests and improve the quality of the soil?
Yes and no, says Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper.
Yes, microorganisms are crucial for plant health, growth and improving the soil but, like natural soil biota, existing in the right environment is critical to their ‘performance’.
“If the soil is run down and low in organic matter, inoculants won’t work,” Dr Roper said. “And the same is true if soil pH is below 5.5pH.”
This quickly turns us full circle to the need to build soil structure and the right soil environment, which is Ausplow’s hypothesis of the BioFurrow™, more widely known as near-row sowing.
According to Dr Roper, in the right soil environment, beneficial soil micro biota populations flourish naturally, providing all the benefits that are claimed by inoculants. And it’s free. But these natural microbial populations may take time to develop.
The right soil environment can be described as soil with organic matter, structure, the right pH, moisture and oxygen.
“Arguably the most widely known natural inoculant is rhizobium in legumes which fix nitrogen,” Dr Roper said. “But these inoculants have the advantage of residing within a plant where they are protected from adverse environmental conditions and other microbial competitors. Such organisms are called ‘endophytes’ which means ‘inside-plants’.
“There are other soil microbes which can colonize plants as endophytes and these are likely to be the most successful inoculants. Inoculants that target the bulk soil, generally, have very poor survivability.
“Soil microorganisms include bacteria, fungi, protozoans (microscopic animals) and algae.
“One group of bacteria (actinobacteria) are very common in soils, survive well in our extreme WA soil environments and produce various bioactive agents including antibiotics, enzymes, and vitamins.”
In a good soil environment, collectively, there are between one and two tonnes a hectare of microbes in the top-soil with around 70 per cent in the top 10 centimetres, equating to more than 10 billion microbes in a kilogram of soil with literally kilometres of fungal hyphae.
Fungal hyphae spread like a network to capture mineral nutrients and in a highly complex symbiotic relationship, bacteria and fungi provide nutrients to plant roots while accessing food in the form of exudates from the roots.
A classic visual of this process is the ‘dreadlock’ roots you find on healthy plants.
According to Dr Roper, what science is now showing, through on-going trial research, is a better way to grow healthier crops and protect them from disease, by using microbial communities and root systems in the soil.
“This is not the conventional crop establishment we are witnessing in our era,” Dr Roper said.
“Ironically before World War Two farmers focused on what we now regard as ‘organic farming practices’ focusing on building organic matter which cycles nutrients for plant use and increases water-holding capacity. This encouraged plant roots to explore the soil profile to access nutrients rather than relying on localised fertilizer inputs.
“After the war, there was an excess of ammonium nitrate which had been used in the manufacture of bombs and this was sold to farmers to create a boon in crop production.
“Extensive use of nitrogen fertilizer results in rapid vegetative development of crops and increased yields.
“But the downside can be a deficiency of mineral nutrients because uptake of these mineral nutrients does not keep pace.
“And an unintended consequence of the over-use of nitrogen fertilizers has been acidification of soils world-wide.
“And the incidence of plant diseases has increased.
“Ideally we want plants to expend early energy in exploring the soil profile so they can associate with the soil micro biota and capture plant-available nutrients for healthier growth and better protection against diseases.”
Crops with balanced nutrition (of a range of mineral nutrients – not just nitrogen) will result in healthier crops and higher quality grains with great benefits for human and animal nutrition.”

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Publish Date: 
Wednesday, October 27, 2021