New Developments for Autumn Renovations...

Martin Wardin Consultancy

Symbio's Martin Ward says that, as our understanding of soil biology increases, autumn renovations may be improved and simplified by adopting new technologies and products to employ a more holistic approach to grass management.

In this article, he details new methods for the renovation of cricket squares and bowling greens

Cricket and bowls renovations have the great advantage of up to six months without play, and our progressively warmer winters mean a lot more can be achieved in the close season, especially if we combine all three disciplines of biology, chemistry and physics in the soil to improve results.


Cricket clubs have a huge variety of budgets, machinery and management practices, so I will limit this article to commenting on improving the health of the rootzone and improving perennial rye grass growth.

Irrespective of the available budget and machinery, the aim of the autumn renovation is constant for all clubs, and that is to remove all the thatch that has built up over the season to create a sound surface and rootzone by topdressing, and to overseed and create a dense sward with good strong roots that will prevent moss invasion and form the foundation of the pitch for the following season.


The first job is to remove thatch from the top few centimetres before topdressing. The problems caused by burying thatch have been well documented and discussed. Scarifying is essential to create a key for future topdressing and a seed bed. However, if thatch cannot be removed by scarification, or is buried too deep to remove mechanically, it is now possible to add thatch degrading microbes either as a granular or liquid or in compost teas or added to autumn fertilisers. If the problem is deep seated, then several applications of a liquid will probably be needed.

Aeration is essential if thatch is to be degraded biologically; this can usually be achieved by using a sarel roller every two to three weeks during the close season. The tines must reach the bottom of the thatch layer. If the organic material is buried too deep for tine aeration, there are liquids on the market which release oxygen atoms for microbial metabolism.

HAC Cricket Renovations2

Growing a dense sward

Give grass the mycorrhizal advantage

Mycorrhizal fungi act like extra roots by extending the root area of the grass. They solubilise locked up nutrients, especially phosphate, in the soil and make nutrients available to the grass plant as and when needed for optimum growth. The great advantage for the plant that accesses nutrients via mycorrhizal fungi is that fertiliser inputs are reduced, avoiding boom and bust fertilisation, and the plant can access the nutrients it needs when it needs it.

Mycorrhizae also take up water into the plant and form a barrier against some turf diseases. Mycorrhizal inoculated grass grows much faster, so mixing spores of mycorrhizal fungi with seed when overseeding is a great way to increase the density and root mass of your sward.

Autumn nutrition

To develop a dense sward in the last two or three months of the growing season, when light is low and nights are cold, takes considerable skill and a bit of luck.

Young plants need phosphate, which is made available by the mycorrhizae or can be added in a fertiliser, plus nitrogen and other macro and micro elements - preferably in organic form - to prevent salts building up in the rootzone. They also need carbohydrates and sugars, which are in short supply on cricket squares but are found in fertilisers derived from sugar cane or sugar beet, or in biostimulants derived from molasses, seaweed and fish hydrolysate. The biostimulant that is most effective at promoting growth in low light, cool season conditions is fulvic acid, which is present in some organic fertilisers and humates or may be purchased by itself in liquid or dissolvable granular form.

If inorganic fertilisers are used with mycorrhizae, you should apply a fertiliser low in phosphate and also apply carbohydrate and protein as a biostimulant on a monthly basis through the remaining growing season to achieve similar results.

The combination of mycorrhizae and the correct nutrition can promote very rapid growth as described in the cricket case study and illustrated left.

Bowling Greens

Many of the accepted practices for sports turf maintenance and solutions to the problems of wear, moss, thatch build up, disease and poor drainage are not practical for many bowling clubs due to lack of access for large coring machinery, limited budgets and sometimes limited experience of the members that carry out the tasks.

The demand for improved surfaces has led bowling clubs and contractors to look for new ways to provide excellent results on a limited budget. They have started to look at all aspects of plant health, the soil chemistry, biology and physical structure required to provide a better playing surface without the need for hollow coring and frequent disruption of the surface.

Soil Chemistry

Over twenty years of conducting soil analysis of bowling greens has thrown up some common problems. Very often, levels of available and total phosphate and iron are excessive, they have been over applied to make up for deficiencies in other nutrients.

Llanstrisant 1.9.15 2

Often in short supply are calcium, one of the most important elements for healthy plants and nutrient availability, and magnesium. If pH is too acidic, i.e. below 5.5, then calcium carbonate CaCO3 may be applied to add calcium and raise pH. If the pH is at an acceptable level, then calcium can be applied as calcium sulphate CaSO4 which will not significantly raise pH. Magnesium may be applied as Kieserite 16% MgO.

Ideally, the base saturation ratio between Ca:K:Mg for optimum nutrient availability should be about 7-10:2:1, with magnesium greater than 60ppm. These elements are the cations that form the greater part of alkaline or base ions in the soil. On your soil analysis, the above ions should equal more than 75% of the total base saturation; if the figure is lower, then the elements should be added to get the above ratio.

Calcium and magnesium in greens grade granular form is relatively inexpensive and can be added at the time of autumn or spring renovation. As a rough guide, 150kg of CaSO4 with 32% calcium will increase calcium levels in the top 10cm of rootzone by about 200ppm and 30Kg Kieserite 16% MgO will increase MgO in the top 10cm by about 30ppm.

These nutrients should be added and brushed into the tine holes before applying topdressing.

Soil biology, thatch, disease and percolation rates

Soil biology is responsible for thatch degradation and the friability of the soil. If you get a good balance between soil biology and chemistry, it is no longer necessary to hollow core most greens to remove thatch and create friable rootzones because the microbes do the work for you.

For more information see

If the thatch does not degrade and convert to humus, even with regular aeration, it means that the fungi and bacteria needed to break it down are missing from the thatch layer. They can be added with compost teas, or with inoculants of thatch-eating fungi and bacteria. Compost teas add a lot more soil biology than inoculants which helps create friable rootzones. The best time to start applying is after scarification and before overseeding. If liquid inoculants and/or compost teas are used, apply just before or after overseeding then monthly whilst the soil temperature is above 5OC

When thatch degrades, it forms humus which acts as a substrate for soil microbes, increases the nutrient holding capacity of the rootzone, improves water retention when dry and increases percolation rates in times of heavy rain, because the combination of humus and soil microbiology create the correct air and water spaces between soil particles for optimum root and shoot growth.

As a general rule, it is better for the sward and less expensive to degrade thatch and convert it to plant nutrient and humus than dilute it with sand. Topdressing only needs to be applied to provide an even surface and substrate for the newly sown seed.

Again, aeration is essential because thatch degradation is an aerobic process. A mixture of solid tining and sarrel rolling - at least monthly through the close season - will pay dividends next summer.

Llanstrisant Dec 2015

Overseeding and nutrition

With the correct chemical balance and the rootzones' physical structure sorted out, we can now look at overseeding and nutrition. By the end of the season, most bowling greens will have a variety of bare patches - the after effects of heavy use, dry patch and fairy rings and possibly some disease scars - all of which will allow moss to invade which, if not treated, will carry over to next year as an uneven sward. Filling in these bare patches with new seed is the main aim for October and November.

Where the grass has worn away, there is unlikely to be any mycorrhizal fungi in the soil so, to encourage rapid growth of new seedlings on bare patches, seed should be coated with mycorrhizae for maximum effect.

If you are breaking down thatch, the organic matter released will act as the main biostimulant, so inorganic or organic fertilisers may be used.

If, however, there is limited thatch, then best results are usually obtained by using organic fertilisers rich in proteins and carbohydrate, or by applying complex carbohydrates as a biostimulant.

The NPK value of the fertiliser will be determined by the soil analysis; usually, more potassium than nitrogen is needed in autumn, and, if applying mycorrhizal fungi, little or no phosphate is required, except on very new constructions.

If the soil analysis shows that Cation Exchange Capacity is low, i.e. below 7 meq/100cm, it will be increased over time by converting thatch to humus; but, if budget allows, a quick fix can be obtained by brushing zeolites into the tine holes. This will help prevent nutrients from leaching and make fertilisers last longer.

Fulvic acid is not only a good, low light and cool season biostimulant but, when applied as a liquid, is an excellent chelating agent and can be mixed with most fungicides and liquid fertilisers to get them more effectively into the plant.

Climate change is giving us a much extended growing season so, in some years, it is possible to apply an additional feed in November or even December. At this time of year, when fusarium is rife, it is usually prudent to apply an inorganic turf hardener to prevent fusarium or snow mould from utilising any excess organic matter for its own growth.

The renovation programme may be different from that usually recommended, but the combination of the three disciplines of biology, chemistry and physics, as nature intended, will get natural processes working for you to reduce inputs and improve results.

Bowling Green Case Study

Llantrisant Bowls Club, Rhondda Cynon Taff

Supplied by Christian Page and Mark Harper of Absolute Grass Care

"We took on the contract at Llantrisant Bowls Club on September 1st 2015 and, as you can see from the picture abovr, it was suffering from fungal dry patch and severe wear, with many bald patches on the ends. Drainage and disease was made worse by a thatch layer up to 5cm deep across the entire green.

Phase 1 of the autumn renovations commenced by scarifying to a least 10mm to clean the surface, we solid tined to 100mm and sarrel rolled two ways. We conducted a chemical soil analysis, which indicated levels of calcium and magnesium were very low, whilst phosphate was excessive. We brushed 150kg of greens grade gypsum CaSO4 & 50kg of Kieserite 16% MgO into the surface and tine holes, before topdressing and, while the surface was open, we applied 150kg of TraceOlite (zeolite) to help improve the Cation Exchange Capacity CEC.

To degrade the thatch and clean up the rootzone, we applied Symbio's Fungal Additive with compost teas to start the process of degrading the thatch levels and releasing the nutrients locked up in the rootzone.

Phase 2 of renovations started two weeks later with an overseed of fescue/bent coated with Symbio Mycorrhizal Seed Coat and an application of Symbio 5:0:28 MycoGro Fertiliser, which contains mycorrhizal fungi and phosphate solubilising bacteria to make the locked up phosphate available to the grass. This was followed by a light topdressing, especially on the bare areas, to cover the seed.

Compost teas applications and sarrel rolling continued on a monthly basis through the winter.

The second bowls picture above was taken in early December after a cut at 10mm."

Cricket case study

Managed by Daniel Ratling BSc

The square was physically prepared in the usual way, before overseeding with ryegrass coated with Mycorrhizal Seed Coat, followed by topdressing. Symbio Caviar 10:0:4 (containing fulvic and amino acids and complex carbohydrates) was applied at 50gms per square metre in mid-September. The photograph was taken on 22nd October showing complete regrowth on all worn areas.

Daniel comments of the success of combining biology with traditional practices; "I have successfully used Symbio Caviar 10:0:4 fertiliser and mycorrhizal seed coat or inoculant on my cricket square renovations for the last four years. Rapid and healthy seedling development, prodigious rooting and mycorrhizal infection of the roots have all been witnessed post renovation. For loam soils with adequate levels of phosphorus, I have not found a better combination of products for establishing seedlings."