ProPopulus Team, April 29, 2025
The Vega de Granada aquifer is the province’s main groundwater reserve, supplying 39 municipalities. However, nitrate concentrations frequently exceed the legal limit of 37.5 mg/L, a by‑product of intensive farming.
A study conducted under the EU‑funded LIFE Wood for Future project, coordinated by the University of Granada, shows that poplar plantations act as living filters, preventing these compounds from reaching the water table.
How nitrates are removed
Between 2020 and 2022, the Institute of Agrifood Research and Training (IFAPA) compared poplar plots in Purchil under three irrigation regimes—every two weeks, every three weeks, and every four weeks—with adjacent uncultivated soils.
“Analyses revealed that nitrate levels are far higher in uncultivated, unirrigated plots, and that they decline in poplar‑planted plots—especially those receiving the most frequent irrigation,” explains IFAPA specialist María Ángeles Ripoll. “For trees to uptake nitrates, they must first dissolve in water.”
In more sparsely irrigated plots, nitrates accumulated in deeper soil layers, though always at concentrations below those found in bare soils.
In irrigated areas without trees, the lack of vegetation encourages nitrate leaching into lower horizons, heightening the risk of aquifer contamination. This contrast underscores the protective function of poplar plantations against subterranean pollution.
Beyond filtration: the ecosystem services of poplars
Beyond nitrate removal, poplars capture up to 20 tonnes of CO₂ per hectare yearly—vastly outperforming herbaceous crops. Their broad canopies can cool summer air by 3–6 °C and boost humidity, while their roots stabilise soil and foster biodiversity along riverbanks and streams.
Poplars (Populus spp.) are exceptionally fast‑growing, reaching heights of 20 metres within a decade. Their lightweight wood and extensive root systems explore multiple soil strata, efficiently harvesting water and nutrients.
Their dense foliage also traps dust and airborne pollutants, and their high transpiration rates temper heat and raise ambient moisture levels.
LIFE Wood for Future and the green bioeconomy
The LIFE Wood for Future project (LIFE 20 CCA/ES/001656), funded by the EU’s LIFE programme, unites the University of Granada, the Provincial Council, COSE, the University of Santiago de Compostela, 3edata, and IberoLam Timber & Technology.
Alongside agronomic trials, it has launched Marjal—a cooperative of nearly 100 producers—and helped establish a wood‑based industry and novel materials for sustainable construction.
“The findings of this research, combined with the use of reclaimed water promoted by the Andalusian Government, greatly benefit the sustainability of the poplar sector, public health, and the biodiversity of our river corridors, as they ensure that aquifers and springs are recharged with clean water,” says Antolino Gallego, LIFE Wood for Future coordinator.
He adds that the next step should be for authorities to formally recognise this ecosystem service and compensate farmers by including poplar cultivation within agricultural aid programmes.