Holding water back instead of letting it run: the Slow Water method

At Ellbach, in the Napf region of canton Lucerne, the meadows around Urs Burri's farm are burnt like almost everywhere else in late July. In the middle of them, though, sits a pond dug this spring, with two smaller retention basins. The water neither stands still nor is drained away: it leaves slowly through drainage pipes and keeps the soil beneath it moist.

Burri runs a biodynamic family farm with dairy cows, pigs, poultry, turkeys and bees, plus eighty standard fruit trees. The problem, he explains, is not the amount of rain but its distribution: it pours for a few hours, then nothing falls for weeks. For a farmer the soil is the capital, and soil that produces nothing means no fodder and no income.

For about two and a half years his farm has taken part in "Slow Water", a project run by the Federal Office for Agriculture and co-financed by the cantons of Basel-Landschaft, Basel-Stadt and Lucerne. Around 110 farms are involved across the pilot regions. The programme runs from 2024 to 2030 and has set itself measurable targets: cutting the use of external water by more than 30 per cent in crop production and by more than 20 per cent in livestock farming.

Fifteen measures are planned, in two families. On one side the hydrotechnical works: ponds, retention basins, infiltration channels, adjustable drainage, keyline. On the other the farming practices: reduced tillage, humus building, undersowing, hedgerows, agroforestry systems. Burri has cut keyline furrows some forty centimetres deep along the contour lines, which slow erosion and carry water towards the drier ground, and has planted fodder trees alongside them: the roots hold the soil, the canopies give shade, the leaves supply minerals to the animals.

Those without an alternative

Oliver Schilling, professor of hydrology at the University of Basel and a researcher at Eawag, sums the project up in two aims: reducing soil erosion and keeping water in the landscape as long as possible, so it can be used when it is scarce. His distinction is political as much as technical. The Plateau can rely on large rivers, lakes and groundwater; the Pre-Alps, the Jura and the mountain regions have no plan B during a long drought. Retaining water, he notes, reverses what was done in the past, when wetlands were drained to gain farmland.

Results do not show up in a single season. Burri's pastures are covered with sensors measuring rainfall, soil moisture, water levels and run-off, with untreated control plots beside the treated ones. Schilling's group is using that data to build a national map of which measures work best in which region, and says it is close to the target.

The context, meanwhile, is getting worse. Between April and June this year Switzerland received 56 per cent of the thirty-year average rainfall, and with July the drought stands comparison with those of 1976, 2003 and 2018. In some regions milk production has fallen by up to 30 per cent. In June and July almost 70,000 cattle excluding calves were slaughtered, against about 60,700 last year: more than fifteen per cent up. Burri says he hopes for a wet end of summer, one that lets him make enough hay and spares him from selling animals. His son is training as a farmer.