The type of rootzone construction system that fits a particular facility's requirements can be specified and constructed. To do this successfully all things must be considered in determining the objectives of the field, the subsequent expectations, and the anticipated level of use and maintenance. An experienced and qualified sports field designer, with these factors in mind, can help evaluate and meet the sports field requirements for the facility by specifying the component mixtures to be used.

Tackling Compaction

The largest management concern for these types of fields is compaction - because of the varied uses, frequency of use and high intensity of use. 'Frequency' refers to the number of times the field is used; 'intensity' to the level of force or stress per use. For instance, a park type ground and an International stadium may have the same frequency of use, say 3 times per week, but the stadium has the higher intensity because of the more competitive nature of the play.

Controlling the detrimental effects of compaction is achieved in two ways: (1) management techniques, including careful scheduling and timely cultivation (aeration) and (2) construction with compaction resistant materials.

Improvement with construction often is attempted by new construction or complete reconstruction or by differing levels of renovation practices and procedures. Unfortunately the decision whether to renovate or reconstruct multi-use sports turf areas is too often based upon emotional issues or on incomplete information. This information is many times perceived as "free", because it is supplied by a contractor or salesperson who hopes to obtain the contract for the project.

Planning a multi-use field is too important to be approached haphazardly. To avoid costly mistakes, all decisions should be made with the best advice possible. This usually means consulting with a non-biased, experienced sport turf agronomist or designer.

The key to creating a successful multi-use field is to start by answering a series of questions, which tens to fall into three groups.

Level of Use ?

How and how often will the field be used ? In other words, what are the expectation levels for use and performance ? Are those expectations realistic in terms of the budget available for the project and the subsequent maintenance level ? Is the turf manager's level of expertise  adequate to manage the type of field specified ? Is the necessary maintenance equipment available or budgeted for ? Is an objective or the project to improve the field performance for the current frequency and intensity of use, or will frequency and intensity increase following completion of the project.

Field renovation or construction projects may be perceived as total or partial failures when the improved field conditions bring on ever increasing frequency or intensities of use. Even if the field has the potential to tolerate increased use, the necessary management intensity levels may not rise correspondingly.

Safety and Playability

Is one of the objectives of the proposed project to increase playability and safety of the field ? If so, primary considerations for real improvements include :

a) reduced field hardiness and increased traffic tolerance, through compaction-reduction techniques;

b) increased footing or traction, through dense, uniform, strongly knit turf; increased drainage and aeration rates;

c) a reduction in drastic micro-topography changes (such as undulations or holes from settlement of irrigation components and erosion around sprinkler heads etc.);

d) a higher degree of uniformity in the above types of characteristics across the playing surface, making the surface more predictable and playable.

Improved aesthetics can also be considered but should be secondary.

Management Alone ?

Can the level of use and objectives for the field be achieved by a combination of cultural management techniques alone - such as increased aeration, altering the fertility program, managing rootzone moisture differently, or changing wear patterns ?

Can management intensity levels be increased to achieve the desired results ?

Is there a policy in place to limit or cancel play upon the occurrence of field conditions not conducive to use, such as excessive soil moisture ? Will using the field in this condition be severely damaging to the turf's roots-zone system and can the turf manager take necessary steps to avert the damage ?

The rootzone specified for multi-use sports turf areas varies widely. These range from (1) simple installation of drainage systems to (2) recontouring of existing fields using the existing rootzone material to (3) construction or reconstruction with amended rootzone components. Deciding which of these is called for depends on the answers to the questions above.

Many of the materials used as mixture components in rootzone construction can have certain limitations and drawbacks :

• For instance, industrial earthy materials are often high in slats or toxic elements.
• Organics can be tricky because they encompass so many types of materials (manure's, food wastes, sawdust, grain hulls, various kinds of peat and others) and are therefore highly variable in their fibre content, carbon-nitrogen ration and other characteristics.
• Diatomaceous earth and calcined clay raise questions because they have not been thoroughly researched  in all contexts. It may be true that those materials do enhance the soils water holding ability, or it may be that the process of working them into the soil simply increases the soils tilth, which enables water retention. Nor has it been determined how easily they release water or how stable they are.
• The effectiveness of fibres and rubber depends upon weather the pieces touch or interact, types of soil around them, the depth at which they are incorporated, and other factors. The effectiveness of synthetic fibres and fabrics is sometimes limited because they may create shear planes within the soil that may "give" under stress.

If any of the rootzone amendments are used incorrectly or in improper proportions or if the construction is poorly done, the results achieved from the project may be much less than expected. Even worse, the field quality may even decline from the pre-project performance level.

For a better understanding of the complications involved, the two most common methods should be understood in brief.

Native Soil

Many multi-use constructions include a significant proportion of native soil types and may have certain beneficial properties. For instance, native soil based systems generally require a lower management expertise level and may have a lower maintenance budgetary requirement. They may also have a higher frequency use level than say a sand-based system. One reason is that turfgrass plants are more firmly anchored because of the native soil's greater internal strength characteristics.

But native soil systems also have definite limitations. Because they are more prone to compaction, they generally have a much lower intensity use level, particularly under adverse climatic conditions.

Mixing Sand

A common rootzone modification system is to mix various proportions of sand with the existing native soil and then re-install the modified soil mixture. An organic component may or may not be included in the mix.

One problem with this type of modification is the mixing of two contrasting soil types.

Sand-based rootzone constructions are typically composed of 80 to 100 percent of a specified sand with the remaining proportions of the mixture being composed of an organic component or a soil -organic mixture component. A soil component in these sand-based root-zones will often have a detrimental impact ( mainly a clogging effect) on the internal drainage characteristics of the rootzone and is commonly deleted as a mixture component due to these effects.

Although highly complicated, it is possible to build a field that meets the requirements of a multi-use stadium, although that is only half the job. The other half is maintaining the field. If a field is "pushed" beyond its limitations or if other aspects of maintenance are not provided for and adhered to, even the best constructions may fail.