Use of marble gravel mulching for tomato production inside a Mediterranean naturally ventilated solar greenhouse

The albedo, or fraction of incident solar radiation reflected by a surface, influences the availability of shortwave radiation and the energy balance on this surface.
In the case of greenhouses, soil albedo can affect the microclimate and production.
Gravel mulching has also long been widely used in agriculture to reduce surface evaporation from the soil.
The traditional “enarenado” sand mulching inside greenhouses of Almeria (Spain), allows to increase the shortwave radiation reflected towards the plants.
White plastic mulching is also used in greenhouses to increase the available light during periods of low radiation and thus benefit plant growth.
Black mulching is used to increase solar absorption and increase soil and air temperature in cold periods.
With the objective of reducing solar radiation absorbed by the soil and avoiding the reflection of direct radiation, in September 2022 a white marble gravel mulch was installed in the western half of a multispan greenhouse with a tomato crop inside in Almería.
In the East sector, a black polypropylene plastic mulching was maintained.
In the West sector, a weaker whitewashing was carried out that allowed to have 10% more photosynthetic active radiation (PAR). The increase of solar radiation reflection, from the 11% produced with the plastic black mulching to the 44% obtained with the marble mulching, allowed reducing a 13.5% the net radiation at 2 m height.
As consequence, the PAR was increased at the level of the tomato leaves reducing temperature of the air and the plants.
Photosynthetic activity was 9.1% higher in plants with the marble gravel mulching (5.1 μmol CO₂ m^‑2 s^‑1) compared to the standard black polypropylene mulching (4.7 μmol CO₂ m^‑2 s^‑1). As consequence, cumulated marketable tomato yield was 7.6% greater with the marble gravel mulching (6.37 kg m^‑2) compared to the standard black mulching (5.92 kg m^‑2).

International Symposium on New Technologies for Sustainable Greenhouse Systems: GreenSys2023

F.D. Molina-Aiz, M.N. Honoré, P. Marín-Membrive, C. Galindo-Rodríguez, D.L. Valera

soil albedo, protected crops, whitewashing, energy balance, airflow, photosynthesis

https://doi.org/10.17660/ActaHortic.2025.1426.13