Land management is one of the major issues facing the planet in the 21st century. As a result of climate change, droughts are becoming longer and more intense and severe floods are getting worse.
Land degradation due to human activity and extreme weather is increasing the spread of deserts, reducing biodiversity, hampering the production of agricultural crops and increasing water scarcity.
The search for solutions is urgent, and mounting evidence suggests there is a role to be played by the humble dike — a simple structure that has been used by farmers for thousands of years.
“Dikes” are barriers designed to keep a liquid out or keep a liquid out. They can be made of natural or man-made materials and appear in many contexts—for example, a wall around a chemical storage facility in case of a leak, or a sloping embankment around a road or railroad to control the flow of chemicals. Water.
The most basic ones consist of clay. In terms of geoengineering, they are low-tech, but when built strategically, their impact on the environment can be profound.
Separate programs in climates as disparate as Tanzania and Northern Ireland are demonstrating the dyke’s regenerative power — and the results could benefit both humans and nature.
Putting techniques in the hands of Tanzanian farmers
In Tanzania, a collaboration between the non-profit organizations Justdiggit and the LEAD Foundation is working with local communities to dig tens of thousands of dikes in arid lands to collect rainwater, as part of a massive UN-backed reforestation effort.
Angelina Tarimo, coordinator of the LEAD Foundation, has been working with local communities in places like Pembamoto, a village in the Dodoma region, where desertification is a growing threat.
“When you ask the elders what was happening in the past, they will tell you that the rains were there; it was much greener than what we’re seeing now,” she says. “You completely know something has gone wrong somewhere.”
Agriculture has had a negative impact on the land in Tanzania, says Tarimo, with farmers cutting down native trees and plants for cultivation, or allowing pastures to become overgrazed.
This damages the soil structure and makes it more prone to erosion. Because the soil is drier, when rain falls, water is more likely to run off the surface rather than seeping into the soil, washing away the fertile soil and perpetuating a drying cycle.
In 2018, Justdiggit and the LEAD Foundation worked with the village to transform a 50-acre barren test site by digging a network of raised perimeter semi-circular dikes around a shallow trench into which the seeds were sown. The dikes, about five meters by two meters wide, were placed in a pattern of overlapping fish scales with their depression facing upwards to capture rainwater flowing from the land, slowing its movement and allowing it to penetrate the ground. Earth.
As part of the program, the Pembamoto community agreed to leave the land untouched for two years.
“They were really skeptical of seeing any kind of results, because they haven’t seen any grass growing in the area for years,” says Tarimo.
But after two years, such was the success that they decided to extend the fallow period (rest of the soil from agricultural activities). Not only did the grass seed grow, but other dormant seeds germinated and the small mammals returned.
The vegetation extended far beyond the perimeters of the bunds, covering the previously degraded landscape. “After three years, the grass was taller than I was!” says Tarimo.
In August 2021, the community started to sustainably harvest grass for forage and sold the surplus to neighboring villages, with the money earmarked for community development, says the LEAD coordinator.
Justdiggit has other projects in Central Tanzania, where it says hundreds of villages are working to restore more than 303,514 hectares through various methods. Between sites in Tanzania and southern Kenya, more than 200,000 dikes have been dug to date.
Justdiggit’s global director of communications, Wessel van Eeden, says it’s vital to put reforestation techniques in the hands of farmers.
Along with its partners’ outreach programs, which include roadshows, brochures and radio slots, Justdiggit collaborated with other nonprofits to create the digital platform Greener.land, which details 20 geoengineering interventions to restore degraded areas.
“There are potentially 350 million smallholder farmers in sub-Saharan Africa,” says van Eeden. “The techniques… are super low-tech, low-investment, so they’re scalable. All we need to do is tell the right story to the right farmer through the right platform.”
Restoring Peatlands in Northern Ireland
A grouping of dikes — creating an enclosed space with dikes — has been used around the world for thousands of years to create watertight pockets of land ideal for growing rice. In recent years, tests have been carried out to see if it can restore peatlands in Northern Ireland.
As part of the €4.9 million Source To Tap project, Northern Ireland Water and its partners established that peatland restoration could be a sustainable and cost-effective method of improving drinking water quality.
Nearly 70% of drinking water in Northern Ireland and the Republic of Ireland comes from peat bogs, which act as a natural filter, explains project manager Diane Foster. If the peatland is degraded, “this can cause challenges,” she adds.
Trees planted in peatlands intercept rain and lower the water table, reducing the moisture available for sphagnum moss, the essential building block for new peat. As a result, it can cause fluctuations in water color and cloudiness, explains Foster.
On land belonging to the Northern Ireland Forest Service in Tullychurry, County Fermanagh, peat bogs were used for a pine plantation.
The trees were harvested at a test site in 2019, and in late 2020, two diggers worked for 11 weeks to create 145 bunds of rectangular cells on just over six hectares.
The clustering method seemed to work “very, very quickly,” says Foster, remembering some cells overflowing. A team from the University of Ulster collected water samples between February and December 2021.
“We don’t have huge amounts of data,” admits Foster, adding that he would like to secure funding for future studies. Results are expected to be published later this year.
“That area is now left to restore further,” she adds. “We’ve put the mechanism in place to keep the water level high… We’re seeing it getting greener. We saw the sphagnum mosses come back.”
While the test was set up with humans in mind, the benefits of restoring peatlands are manifold. “This would support many different ecosystem services,” says Foster, including “biodiversity, water supply, flood storage, and especially carbon storage.”
Northern Ireland Water is already implementing the technique elsewhere. At Lough Bradan, a lake that is a source of drinking water, between eight and ten hectares of trees planted in peat bogs were felled along the west bank of the reservoir and cells were installed, creating a peat bog to slowly filter the water flowing into the reservoir. the lake.
“It’s really exciting to see him at this drinking water catchment,” says Foster. “It will take a while for the sphagnum mosses and everything else to colonize, but the process is ongoing.”
Source: CNN Brasil
