Plants will grow in sterile conditions but will thrive in richly biological soils where they co-exist with a host of mutually beneficial organisms that include bacteria, fungi, worms, insects etc. Many of the plant’s natural partners live in and around the root zone. They process or produce nutrients for the plant and in return use the carbohydrate rich root exudates as a food source. This balance of give and take is of particular importance in making available to the plant a whole range of major nutrients (N:P:K) and trace elements. These may well be present in the soil but do not get taken up by the plant if they are not rendered into a form that the roots can utilize. In addition to this there is also the consideration of the amount of root that a plant produces. Good healthy well developed root systems are encouraged by the presence of microbes in the root zone and this occurs as a result of the production of plant growth stimulants by the microbes and microbial conversion of phosphates which promotes root growth.
Over and above these direct effects there is also the contribution made in the root zone by mycorrhizae. These specialised fungi have co-existed with plants for millions of years. They not only have the ability to produce growth stimulants but most importantly they form a web of threads (mycelia) throughout the root zone. These threads act as root extensions bringing in to the plant far more nutrients than could be obtained with its root system alone.
When there is a combination of mycorrhizae with other beneficial bacteria and fungi the potential availability of nutrients is significantly increased. This applies to the amount and to the range of nutrients. Obviously this benefit is passed on in the form of a more nutritious plant to the animal or human that consumes it. UK trials have shown the following nutrient increases in cereals and similar increases in grass for grazing animals
Phosphorus + 80%,
Potassium + 64%,
Calcium + 36%, Iron + 56%
Copper + 118%
Magnesium + 52%
Manganese + 97%
On pastureland the grass is not only more nutritious but also grows more robustly and produces 40% more dry matter per hectare. These results were obtained by adding mycorrhizal cultures at the time of planting
Why add mycorrhizal cultures?
On soils which have been farmed intensively the microbiology of the soil is often badly out of balance and mycorrhizae may be totally absent. Placing them where they are needed will enable them to re-establish i.e. placement in the planting furrow where the plant’s roots will grow.
How can this be done?
Until recently mycorrhizal products were mostly sold as retail packs or as root dip gels to landscapers for tree planting; now however there are forms available which are suitable for use in agriculture and horticulture.
Biotechnica are leading the field in the development of mycorrhizal inputs. Straight granular products are available to mix with grass seed for forage sowing and granules fortified with beneficial microbes and humates are available to sow with seed potatoes.
Most recently pure spore based products have been introduced that are water soluble and can be trickled into the planting furrow together with vegetable and salad crop seeds. These soluble grades also contain beneficial microbes to protect against fungal diseases, and humates to promote root growth.
What goes on biologically in the soil and particularly in the root zone of any plant has a bearing on the health and nutritional status of the plant. There should be a thriving community of mutually beneficial life forms ranging from bacteria and fungi up through nematodes, worms and insects. These synergistic relationships play a part in the processing and cycling of nutrients and in particular in protecting the plant against diseases. A major part of the biological population of the root zones of plants in undisturbed eco-systems consists of mycorrhiza. These specialised fungi form an extensive network of their mycelial threads around the root zone and in many cases actually penetrate the roots. Mycorrhizae are not spread by airborne spores, and when they have been depleted or destroyed they cannot return unless they are purposely replaced. Regular soil disturbance together with the widespread use of fungicides, herbicides and other chemical inputs has reduced mycorrhizal populations in agricultural soils significantly.
When mycorrhizae are present they effectively increase the plant’s ability to obtain nutrients. This happens because the fungal threads spread through the soil and connect the plant to a much bigger area. They also work with other soil microbes to make nutrients such as phosphate available. Mycorrhizae and their attendant microbes produce root growth stimulants and suppress potential pathogens. Where mycorrhizal cultures have been sown together with grass seed some remarkable results have been achieved. Establishment and root development is faster and more extensive. This results in significant improvements in the nutrient content with average increases in the order of 50% in phosphorous, potassium, calcium etc. and similar increases in micronutrients, such as manganese and zinc. Dry matter increases of 40% have also been observed.
Adding mycorrhizae back into the soil results in a more nutritious diet for animals and for people.
Mycorrhizal products are re-establishing the relationship that should exist in a healthy soil/plant environment. The benefits in health and nutritional value pass along to animals grazing in the pasture or via silage and also directly to humans.
Mycorrhizae also contribute to carbon sequestration in the soil adding a further eco-benefit.