Scientists at Wageningen University in the Netherlands have concluded that the grass length and irrigation of a surface do lower the ambient temperature. The scientists benefitted from the hot summer, which allowed them to study their test fields to their full potential.

The research programme is a public-private partnership between the university, the government, bodies representing the golf and sports surfaces market and industry, as well as grass seed producers in the Netherlands.

With an estimated 4.5% (approx. 1,515 ha) of the Dutch land area consisting of grass, this can make a significant contribution to reduce the effects of climate change, like urban heat islands, water shortage or nuance, carbon sequestration and to reverse the decline in biodiversity.

Last year, the scientists sowed a plot with eight different monoculture grasses and four mixtures that are commonly used for sports or recreational grass surfaces. Half of the plot was watered twice a week to maintain a moisture level of at least 15%. In the period between July and August, moisture levels for the other half hovered between 4 and 7%. The grass was also kept at different lengths. Half of the plots were maintained at 3 cm. The other half were allowed to grow to 6 cm maximum.

Moisture, surface temperature and NDVI were captured in spring as well as during summer. They will be recorded again in autumn.

With summer having come to an end, scientist Leon Mossink has drawn his first conclusions. “Irrigation will have more effect on reducing the ambient temperatures than the length of the grass. Ambient temperature for all irrigated fields remained consistent at around 30 degrees Celsius, while reference temperatures over a concrete slab went up to over 40 degrees Celsius,” he says. “We also noticed that the ambient temperature over longer grass was lower than over grass that was consistently cut to 3 cm.”