To support and maintain diverse soil micoorganisms, regenerative farmers are turning away from synthetic
fertilisers (standard purchased NPK plus trace element fertilisers having soluble and insoluble components), or at least very much reducing their use, and are switching to biostimulants. Examples of biostimulants are worm juice,
compost tea (carefully prepared), fish emulsion and seaweed-based liquids, etc. Many are available commercially, but you can make your own.
By applying synthetic fertilisers farmers are interfering with the communication between plants and soil, and soil microbes are being killed. If you pull up a plant and the main root can be seen clearly, then your soil is not healthy. The roots should be surrounded by soil called rhizosheaths containing mycelium (microscopic filaments of myccorhizal fungi). Rhizosheaths help the soil to stick to the roots.
Plants will send signals into the soil to get whatever nutrients they need (nitrogen and phosphorus from the soil as organic N, and organic P, calcium, boron, silicon etc.), and specialised bacteria working in a symbiotic manner with the plant will bring the required nutrients into the plant through the plant root tips. There is a bi-directional flow – carbon going out of the plant, supplying energy to the bacteria, mycorrhizal fungi, etc. to source what is needed from the plant root exudates and the soil – and water and nutrients going into the plant. Of all the mineral nutrients, nitrogen contributes most to plant and crop growth. Nitrogen-fixing bacteria get nitrogen from the atmosphere and from the breakdown of organic material. In agriculture, the most important and efficient symbioses of nitrogen-fixing bacteria and plants occur in the legume family where the bacteria live in nodules along with the plant roots. The symbiotic activities of several nitrogen-fixing bacteria allow Acacias to live in some of the most nutrient-poor soils on the planet. An Acacias’ nitrogen-fixing contribution helps to regenerate soils.
Inorganic nitrogen fertilisers destroy soil carbon and inorganic soluble phosphorus suppresses the activity of soil microbes. Plant root exudates are influenced poorly by nutrient deprivation (particularly nitrogen and phosphorus). Similarly, fungicides, herbicides, insecticides, and pesticides interfere with a healthy soil microbiome and can destroy many soil microbes. Once the plant’s natural resistance to pests and diseases has been interfered with, poisons continually need to be applied to defend the plant, and fertiliser needs to be applied because the plant will not be supported by mycorrhizal fungi.
On a Montana ranch, 80 acres were sprayed with a biostimulant (fish-oil emollient, molasses, and a small amount of sea salt) and several things happened. “Horses in another pasture smelled the spray and broke through a barbed-wire fence to get to the site and graze the grasses. Then a squadron of dung beetles flew in and went to work so that the horse dung, instead of drying into hard pellets, was buried in the ground by the next day. This typically doesn’t happen in a climate that averages [250 to 300 mm] of precipitation per
year”. (See Dung Beetle article in this edition
Biostimulants support seed germination, plant…