Technical - Soil Biology
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Inoculating the roots of newly sown grass with mycorrhizal fungi have been shown to more than double the early growth rates, substantially reducing the grow in time
they are fungi that act like roots. These fungi act as an extended root system massively increasing the root area of the plant, allowing it to take up more water and nutrient to speed up its growth. Mycorrhizal fungi also have the ability to produce enzymes that solubilise nutrients, especially phosphate, and make locked up nutrient available to the plant.
Mycorrhizal fungial spores, or propagules, are available in granular, powder or liquid form and can be added to the rootzone either as part of a granular inoculant or applied to the surface of the rootzone immediately before seeding or turfing, or as a seed coat or added to hydroseeding solutions.
Inoculating the roots of newly sown grass with mycorrhizal fungi have been shown to more than double the early growth rates, substantially reducing the grow in time.
Mycorrhizal fungi live on the roots of the grass so do not need any other organic matter or biostimulants to survive. Once the grass is inoculated with mycorrhizal fungi, it should stay colonised by these friendly fungi. Mycorrhizae can be killed by systemic fungicides, but are more often reduced by over fertilisation, especially excess phosphate.
Soil Bacteria and Fungi
There are many thousands of different bacteria and fungi that live on the plant roots and in the soil. They all perform many functions and are essential for nutrient uptake and retention, plant hormone production, defence against disease, good soil structure, humus creation and buffering pH. Perennial grasses grow best when colonised by mycorrhizal fungi in low phosphate with an approximately equal amount by weight of soil bacteria and fungi in the rhizosphere.
A complete range of microbes can be applied by adding aerobic compost to the rootzone material to give an 80:20 or 70:30 ratio of sand:organic matter, but this is a temporary solution and may adversely effect drainage. The best way to apply a broad spectrum of bacteria and fungi, protozoa and nematodes suited to
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the pH of the rootzone is to apply compost tea, immediately before seeding and monthly thereafter through the growing season. Where the application of compost tea is not possible, then a restricted range of bacteria and fungi can be applied as an inoculant.
Biostimulants
Sand based sports turf rootzones are not designed to support soil microbiology, so microbial food has to be applied. The recent article
https://www.pitchcare.com/magazine/biostimu lants.html explains how biostimulants work and which one to choose once the sward is established but, for rapid grow in, different combinations are needed.
In the early stages of growth, especially if sown in spring or autumn when there is less light for photosynthesis, the plant and microbial community needs a ready supply of protein and carbohydrate, humates and humic and fulvic acid, which can be obtained from molasses based fertilisers, which are also excellent food for soil bacteria and humic and fulvic acid compounds.
Fungal food can be obtained from liquid seaweed and fish hydrolysate, which also provide essential trace elements and plant hormone elicitors.
The immediate financial benefit of following the above suggestions is that the surface can be brought into play faster and generate income. There are a number of longer term benefits to consider.
Excessive mineral fertiliser applications appear to work well enough in the short term, but create the conditions for poa annua and heavy thatch growth, this means higher costs for thatch removal and overseeding, topdressing, fungicides and seed. These elements will continue to be required, but in lower amounts, so over the lifetime of the facility these extra costs will be substantially reduced.
Initial high inputs of phosphate, iron, and other mineral salts become locked up in the soil,
eventually they form layers and root breaks which, in turn, require either intensive aeration or biological intervention to break down.
Apart from the subsoil preparation, the same techniques can also be used for the rapid transformation when overseeding and converting poor swards to good quality perennial grass playing surfaces.
In short, if you can take the standard specifications for rootzone materials and create the correct chemistry and biology for healthy plant growth, you will achieve an excellent playing surface more quickly that is both easier and less expensive to manage in the long term.
Martin Ward
Symbio is dedicated to researching solutions to restoring the natural biological activity in soils and growing media essential to ensure the long term sustainability of food production and amenity plant
resources for the world’s increasing population.
E:
martin@symbio.co.uk T: 01428 685762 W:
www.symbio.co.uk
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