Energy Grass Project – Water-Resilient Natural Grass for Sports Fields

The managers of sports complexes face major challenges. The chemical control of pests and weeds has been phased out and the leaching of fertilizers has to be reduced. At the same time, the strain on those complexes is rising due to population growth and the simultaneous decline in water availability. Sports fields, like other green infrastructure, provide important ecosystem services in the urban environment. Rainwater can infiltrate and evaporation provides as a cooling effect during hot periods. However, natural grass is prone to damage when there is excessive utilisation by field sports and it is therefore increasingly being replaced by artificial turf. Both sports associations and municipal authorities want to conserve and, where possible, introduce more fields with natural grass. A major challenge here is the changing climate. Although climate change means that grass grows and recovers for longer during the winter, recovery when a competition stops is not guaranteed because of the increasing probability of hot and dry periods during the summer. In addition, specifically during hot and dry periods, there are restrictions on irrigation using groundwater and surface water, and less consumption of drinking water is needed. As a result, the fields may not be available for full utilisation when the competition starts. The question, then, is whether water savings are possible without affecting the playability, health and quality of the pitch.

Objective

Current pitches are designed for optimal playability in relatively cool and humid conditions. As a result of climate change, alterations in the design, monitoring and control of both drainage and irrigation are needed, both to conserve irrigation water and improve playability. In this project, we are improving our understanding of relationships between playability and water-conservation measures, and investigating how the use of innovative measures to improve the soil can make natural grass fields more resilient to wear and dry periods (for example by improving the fibres in the root zone). We are developing a system for the effective monitoring and management of irrigation to deliver water savings (or water circularity) and optimal grass growth in natural grass fields.

Challenge

We are developing a new grass sports field system with improved soil physical properties with the use of innovative (natural) fibres in combination with improvements in the control of drainage and capillary irrigation. Our research into new fields therefore covers:

• the relationship between playability and water conservation measures using an innovative online sensor and control system;

• soil improvement measures and their effects on extending playability duration and the health of the grass;

• the effect on water conservation, water circularity and grass growth of a fibre/granulate-enhanced root zone in combination with a water retention and irrigation system in the subsurface of the field;

• how the technology can be used to allow worn areas to recover and, where necessary, to improve growth conditions in weak spots.

Solution

Sports fields are no longer simply outdoor areas for sports but integral components of the climate-adaptive, water-sensitive and energy-aware management of entire sports parks. A healthy, robust pitch and innovative drainage irrigation system is the basis for meeting those challenges. The ultimate goal is for the Netherlands to maintain its position in the vanguard of 1) the innovative irrigation and drainage of sports fields, 2) reducing water consumption in the summer and (3) implementing forms of sustainable energy supply. The Water-Robust Natural Grass Sports Fields differ from conventional natural grass sports fields in the following respects:

– a fibre-reinforced and improved soil structure in which more water can be retained is available through the capillary system and is less prone to wear;

– a retention and capillary subsurface irrigation system that is water-circular and saves irrigation water in the foundation of the field, combined with innovative on-line monitoring and the control of the water management system;

– the option of extracting heat from the field and irrigation water for heating the clubhouse and for shower water.

Intended impact