Autumn renovation on natural turf facilities

Laurence Gale MScOct 01, 2004in Consultancy

By Laurence Gale MSc

This month's feature article is on the autumn renovation of summer sport natural turf playing surfaces, which generally includes the following sports - flat/crown green bowling, cricket, tennis, croquet and, in some cases, rugby league facilities. After a long hard season of play many of these facilities will require varying degrees of repair and renovation to restore and rejuvenate playing surfaces.

Autumn renovation is vital in providing a good playing surface for next season. Failure to complete autumn renovations or undertake vital repairs will only result in further deterioration of playing surfaces. It is also imperative to complete the works quickly to make good use of warm soil temperatures that will aid seed germination.

Autumn renovation involves a series of operations and inputs that are initiated in sequence and complement one another. The success of autumn renovation is dependant on a number of factors:-

The type of facility - bowls, tennis, cricket, croquet, rugby.
The playing standards of the facility - school, Local Authority, club, County or International standards.
The current state of the sward and soil profile will determine and prioritise the extent and nature of the renovation works required.
Groundsman/Greenkeeper's knowledge and experience.
Resources available - machinery, staff.
Water resources.
Availability of materials and products.
Availability of specialist services - contractors, consultants.
Planning and time - the window of opportunity.
Costs/Budgets.
Weather and soil conditions.

The following activities are generally implemented during autumn renovation:-

Mowing the sward, preparing surfaces for renovation.
Scarification, removal of unwanted debris.
Aeration, decompaction of soil, improving gas exchange in soil.
Soil exchange/top dressing, restores levels and improves surface drainage.
Overseeding, restores grass populations.
Fertilising, provides nutrients for grass growth.
Brushing to incorporate dressings and to help the grass stand back up.
Watering/Irrigation and the use of germination sheets to promote seed establishment.

A turfgrass sward will decline during the playing season for a number of reasons - lack of cultural practices, drought, weeds, diseases, shade, poor soil, neglect, abuse and over use. All natural sports turf pitches and facilities will encounter wear from play and the effects of compaction. Even on well constructed pitches and greens the re-arrangement of soil particles and accumulation of organic matter can all influence the physical performance of the surface layer in terms of it's drainage and playing qualities.

The aim of autumn renovation is to help restore turf health and quality after a season of play.

Mowing:

The grass is usually mowed prior to starting any renovation works. The objective of mowing is to clean and prepare the grass surface, removing unwanted top growth. Grass growth can be uneven and varied. Mowing the grass to a lower, uniform height will help prepare the surface, making it easier for scarification and topdressing operations.

Cuttings should be boxed off and removed, and the height of cut will depend on the type of surface you are preparing. For fine turf, golf greens and bowling greens the cut may be down to 5-6mm, for tennis and cricket outfields 8-12mm, and for rugby league 15-20mm.

Cylinder or rotary mowers can be used as long as they are able to collect the cuttings.

Scarifiying:

During growth the grass plant produces a lot of dead material that accumulates above and below ground level.

Above ground (Thatch layer): dead and decaying leaf and root material develops and accumulates to form a thatch layer of matted material. This layer of thatch can create a microclimate that is detrimental to turf, preventing water infiltration and providing ideal conditions for fungal and disease establishment.

Below ground (Mat layer): root growth involves increased biomass of the root system and, like the grass shoots above the ground, this matter dies back leaving a dead mass of root material which can often prevent and restrict new root growth and affect gaseous exchange in the soil. It is important to remove this debris too.

Scarifying is the term used to remove this unwanted vegetation. There are many different ways and methods of scarifying turf surfaces. The process usually involves a raking/cutting action to clean out the thatch debris, and can be done manually using spring tine rakes or mechanically using specially designed rotorakes and/or knife action machines such as the Graden.

The choice of method and type of machinery used will be dependant on:-

Size of the area to be scarified.
Location and aspect of site.
Type of surface - fine turf or outfield turf.
Depth of operation.
The amount of debris to be removed.
Surface damage.
Time allowed.
Soil type.
Grass type.
Retention of organic matter.

It is important to validate what you are trying to achieve and what will be the consequences if you over do it. Modern Groundsmanship errs on being ruthless during this operation, cleaning the surface thoroughly of organic material.

There are many different types of machines designed and available for scarifying turf, all offering different cutting depths, with different power and speed variations, with and without collection boxes. Machines can come in many shapes and sizes, some are pedestrian, some tractor/prime mover mounted.

For an effective, vigorous scarifying, the blade should be at least 3 mm wide. Scarifying in at least two directions (in fact four or five directions is regularly practiced), at an angle of less than 90 degrees, gives the most vigorous working. Scarifying at right angles has the tendency to cause severe damage, with small squares of turf being ripped from the surface. To restore the playing surface after vigorous scarifying will require an application of top dressing materials to restore levels and provide a seed bed for grass seed.

In general, the level and quality of scarification is dependant on the type of machinery available. Not all groundstaff have their own machines and, if they do, may have a particular type that can only achieve a certain level of working depth and performance. Hiring can be beset with problems. The machines may not be available when you want them, so it is important to check availability and book early when hiring. If hiring machines make sure they are serviced and the blades are not worn.

If purchasing, then the choice of machine is critical. It is no good spending money on a machine that does not or cannot remove the quantity of debris desired or achieve the depth of penetration required. It is best to seek advice and ask for demonstrations of different manufacturers' machines. This will enable you to find one that meets both your facility needs and budget.

Below are a few example of the types of scarification equipment available:


Fine turf scarifier, removes and controls thatch on all fine turf areas.	Heavy duty powered scarifier, de-thatcher and linear aerator.


All surface scarifier for vigorous renovation.	Combined de-thatcher and linear aerator with collection for larger areas.

Within the last couple of years we have seen the development of new turf renovation machinery, particularly the Koro Field Topmaker. For quick turf rejuvenation, the tractor-mounted Field Topmaker has blades that can be set from 4cm above ground to 6cm below, to skim off the top layer of vegetation. At a higher setting, the Field Topmaker will fraise mow the ground removing thatch, organic material and shallow rooting grasses, leaving the roots of the desired species, like perennial ryegrass, intact for re-growth. The Field Topmaker can be fitted with deep vertical scarifying blades to carry out linear aeration up to 2". Simultaneously, the material is removed on to the hydraulically driven conveyors into a trailer alongside. By cutting through and removing much of the thatch, water, air and nutrient permeation is encouraged and, because vertical blades sever lateral growth, conditions for a healthier and more active sward are provided.

Koro machines are becoming very popular with a number of cricket clubs who are now using the Koro Fraise mowing technique for removing the surface vegetation from their squares (organic matter/thatch and Poa grass species all in one go). Slightly deeper koroing enables ends to have saddles removed in one easy operation. Once the surface vegetation is removed the process of spiking, top dressing and overseeding can be carried out in the normal way.

Aeration:

Aeration is a vital part of the renovation programme. Not only does aeration remedy any compaction problems by restoring and improving air movement in the soil profile, it also provides channels and openings for the top dressing materials to integrate, particularly if hollow tines are used. The benefits of aeration are:

Improves soil surface drainage (water infiltration).
Helps to increase soil temperatures.
Increases soil pore space.
Allows gaseous exchanges in the soil (oxygen, carbon dioxide) that improves root depth (growth and development).
Aids integration of top dressings into soil profile.
Aids the removal and breakdown of thatch /organic matter.
An aid to promoting better surface levels that will increase ball roll /speed.
Aids surface firmness/dryness thus increasing ball bounce and surface grip.

Types of aeration are as follows:

Using solid tines (hand forks, pedestrian and tractor mounted machinery).
using hollow coring tines that remove soil cores from the soil.
Using flat slit/star tines.
Drill and fill techniques.
Disc/blade implements (linear aerators).
Compressed air and water systems.

The variety and choice of implements and devices now available are excellent, providing different tine sizes, operating widths and shattering features that can meet the requirements of any facility and, more importantly, do not disturb the playing surface, and allow play to continue after use. With the demand for higher quality, all year round playing surfaces, turfgrass managers are always interested in trying out new techniques to keep playing surfaces aerated. In recent years we have seen the development of pressure air and water aerators that can offer deeper aeration than conventional aerators.

In the main solid tine and slit tine spikers are primarily used during autumn renovations to relieve compaction. However, hollow tines are generally used when rectifying problems or wanting to change a percentage of the soil medium in the playing surface.

Traditionally hollow tining on fine turf facilities was carried out every year. However, with the development of verticutting and grooming units being used on a regular basis throughout the year thatch levels have been reduced dramatically reducing the need for regular hollow coring operations.

The table below depicts some of the aeration machinery used on different types of surfaces. There are many more makes and types of equipment available, including hand held tines, forks, pedestrian aerators and large tractor mounted aerators.

Bowling greens / Croquet / Cricket Coring machine and pedestrian solid tine spikers


Fine turf Solid tine Compact Vertidrain Verticore machine

Sports fields Vertidrain Linear Aerator

Click on this link for details of companies who sell Aeration machinery

Top Dressing:

The application of a good quality top dressing, in combination with a suitable aeration programme, will go a long way to counter the ravages of play. In addition, on sites where the original soil is not necessarily suited for sporting activity, the use of appropriate topdressing materials can contribute significantly to the production of an acceptable playing surface by making progressive changes in the composition of the surface layer. Sand companies and top dressing suppliers offer a wide range of materials for use on sports areas.

Benefits of top dressing:-

Restores surface levels.
Stimulates new root and shoot growth.
To cover seed (soil/seed contact to initiate germination).
Increases/decreases water holding capacity of the soil.
Improves soil structure.
Increases nutrient retention.
Improves surface drainage.
Increases air filled porosity (air pores in the soil).
Increases ball bounce/ ball roll.

Choice of top dressing materials will be determined by a number of factors:-

Existing soil type.
Type of facility construction -i.e. Loam square/court or specialist sand constructed sports field.
Different sand types - to improve surface drainage.
Organic Materials - composts.
Cost.

It is important to evaluate the existing soil/sand composition of your facility. This can be achieved by sending soil/sand samples away for testing. Using the wrong dressing material, creating a layering effect, can cause severe drainage and rootbreak problems. To help choose the correct top dressing material, it is often best to seek advice from top dressing suppliers or qualified consultants or agronomists.

Choosing and using top dressings is a complex subject, in that, if you choose to change and use inferior materials you may reap a series of problems in the future. A problem often seen on cricket squares is caused by a change in loam quality. The type of loam can often influence (amongst other things) the characteristics of play (reducing or increasing ball bounce on the pitch).

However, and this is important, loam should be chosen because of its mechanical makeup, not because of its name. With a soil analysis of your square, you are armed, knowing the proportions of sand, clay and silt that are in its composition. Make sure that you ask your loam supplier for a similar type, so that there will be cohesion between the existing and newly applied loams.

The choice of loam material should be judged/based on a number of reasons:

The level of play anticipated.
The compatibility of existing soil profile.
Relevant experience and knowledge of the grounds staff.
The ability to manage the type of loam chosen (time, machinerypitch protection facilities).

Another problem often associated with cricket square renovations is the problem of layering, a build up of different soil layers in the profile.

A build up of soil layers often causes a number of problems:

The forming of root breaks.
Decreasing infiltration properties of the soil profile.
Affecting the dynamics of the soil (ball bounce, the ability to compact the soil).

One of the most common problems seen on cricket squares is when clubs have applied loams on top of ill-prepared surfaces. It's important that thatch layers are effectively removed. Top dressing on top of spongy surfaces will lead to a sandwich of loam and thatch being formed, This layer will affect ball bounce on the square and prevent you achieving the results you desire in producing a consistent, safe and durable surface.

The success of top dressing will also be influenced by the amount applied and how well it has been worked into the turf surface. Applying too much dressing will have a detrimental affect, smothering existing grasses and increasing the likelihood of disease.

The amount of top dressing required will depend on the depth of material required x the surface area of the site.

Click on the link for details of companies who sell Topdressers/spreaders

There is a range of machinery that can transport and spread top dressings accurately:


Spinner for light regular top dressings.	Precision brush top spreader.


Barrow pedestrian top dresser.	Pedestrian spreader.

Click on the following links to buy top dressing materials direct on line from the shop or view top dressing suppliers. Pitchcare shop Topdressing materials or Loam suppliers or Topdressing/sands

Overseeding:

It is not cost effective to use cheap or old grass seed stock, as germination and establishment is likely to be poor. Buy your seed from a reputable company which specialises in developing and marketing quality grass seed mixtures. These seed varieties may be more expensive but they do guarantee quality and performance.

Overseeding rates will depend on a number of factors:

Type of seed.
Condition of existing turf (how bare).
Type of seed spreader/drill machine used.
The number of passes (sowing the seed in different directions).
Cost.

Most seed suppliers will recommend sowing rates but, as a rule of thumb, it will generally be about 35grams of seed per sq/m. Temperatures above 12°C, a moist, well-aerated seedbed, close seed/soil contact are primary requirements for rapid grass seed development. Machinery designed to sow grass seed include disc, direct drilling, oscillating and broadcasting mechanisms. The best results are achieved when the seed has direct contact with the soil, and preferably below the soil surface. Seed that is left lying on the surface and not in direct contact with soil is prone to drying out and being eaten by birds. Ensure moisture is available for germination.


The Proseeder performs four tasks during seeding, making holes, injecting seed, covering with top dressing and brushing materials into the surface.	15 disc Overseeder for seeding large areas, capable of overseeding six football pitches in a day.

Sisis Variseeder	Spaldings Pedestrian seed spreader

Selection of grass seed is important. There are many varieties of seed now commercially available, offering different performance characteristics and growing habits. New varieties have been introduced for specific requirements, sport related dwarf rye grasses for cricket and tennis, bents and fescue grasses for fine turf golf and bowling greens, and shade tolerant grasses for stadia use. See link for details of STRI Turfgrass Seed Book 2004.

It is vitally important to buy your seed from an approved seed company that can verify the quality and performance of its seed mixtures, with relevant certification and documentation. This prevents you buying seed and finding out it has been contaminated with weed seed or inappropriate grass varieties which, in turn, affects the quality and performance of your sward.

Click on the following links to buy turf grass seed mixtures direct on line from the shop or view seed suppliers Pitchcare Shop Amenity Seed Suppliers

Fertilising:

Prior to applying any fertilisers it is essential to obtain the nutrient and pH status of the soil. This can be achieved by sending soil samples to a soil laboratory which will carry out a nutrient analysis of the sample. Once obtained you will be able to choose a product that offers you the correct N P K fertiliser ratio for your soil.

Many of the leading fertiliser manufacturers offer a balanced fertiliser for autumn renovation. The benefits of applying N P K fertilisers are:

Stimulates seed growth.
Increases tillering and shoot growth.
Increases root growth.
Balances grass growth.
Increases grass plants vigour and resistance to disease.
Improves grass colour.

These fertilisers can be supplied in granular or liquid form. Granular products tend to be more widely used because they are easier to handle and distribute. Over dosing or applying granular fertilisers without enough soil moisture being present may result in the grass becoming scorched, resulting in scarring or death of the grass plant. Fertiliser application is only effective if you ensure uniform coverage. Granular fertilisers can be applied with either a drop (gravity) spreader or a rotary (centrifugal) spreader.


Tractor mounted spreader	Pedestrian rotary spreaders

Click on links for details of fertiliser products in the Pitchcare shop Granulars or Liquids or companies who sell Fertilisers

Brushing / Dragmatting / Luting:

Once all top dressings, grass seed and fertiliser materials have been incorporated into/onto the surface, it is important to work the material into the profile by brushing, dragmatting or luting. These operations ensure the materials are worked in evenly, and prevent any excess material remaining on the top. This operation is best done when the surface is dry, enabling the material to distribute itself easily.


Lute	Dragmat


Dragbrush	Tractor drawn brush

Covers/Germination sheets

Once all the renovation processes have been completed, it is beneficial to cover the area with covers/germination sheets to retain soil temperatures and encourage rapid germination and seedling establishment. Check regularly under the covers to make sure that there is no disease, generally sheets should not stay down for more than four or five days. With the advent of frosts, but warm sunny days, it may be worthwhile to use the covers during the night, removing them each day to allow the warmth of the sunlight onto the ground.

Irrigation / watering:

To renovate successfully, adequate water must be available from seeding through to completion of germination and grass establishment. Do not allow newly overseeded areas to dry out once watering has commenced. Initially, maintain a constantly moist seedbed with frequent waterings of short duration. As newly germinated seedlings begin growth, decrease the frequency, and increase the duration of watering to encourage deeper rooting.

Conclusion:

Autumn renovation is often a time consuming and expensive exercise. Successful renovation requires detailed planning and programming, to ensure the right materials and equipment are available and working throughout the renovation process. Generally, most renovation programmes have to be completed in a short period, between 1 and 4 weeks, usually during September/October.

However, when successfully implemented, the results of the Autumn renovation should promote and produce a healthy turf sward capable of withstanding the onslaught of next year's playing season.

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