9 March 2023

Soil transplanting allows regeneration of degraded lands

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Transferring a healthy soil mass to a degraded area can ensure rapid restoration, explain researchers at the Netherlands Institute of Ecology. An important finding in the global scenario. But more studies are needed

by Matteo Cavallito

 

Transplanting healthy soil can significantly contribute to the regeneration of damaged land, according to a study by the Netherlands Institute of Ecology (NIOO-KNAW). The investigation, published in the Journal of Applied Ecology, compared 46 field experiments in 17 countries on four different continents, says a statement of the institute, revealing how areas in need of natural restoration benefit from this type of intervention.

“From the tropics to the tundra’s, soil transplantation substantially improves the chances of restoring vegetations with species of high conservation value. Particularly when applied over large areas,” said Jasper Wubs, the researcher who led the international team of scholars who joined the Netherlands-based institute in the work.

The experiments

From grasslands to rainforests, there is a wide range of natural sites in need of restoration. Soil transplanting involves transferring a healthy soil mass – which includes its entire biodiversity, including microorganisms and plant seeds – to an area prone to degradation. In this way, the scientists explain, rapid restoration can be ensured. To test the validity of the hypothesis, the authors recorded plant composition and its changes at experimental sites.

“We found that soil translocation leads to plant community development further away from the control and more towards the reference plant communities compared with treatments where only plant propagules (ovvero semi, spore e altri elementi in grado di generare la vita, ndr) were introduced (i.e., seeds, spores and other life-generating elements, ed.),” the research states.

The results were variable, however, highlighting, therefore, the importance of some key factors. The researchers, for example, found that “restoration success was more likely on loamy soils and when translocation treatments were implemented over larger spatial areas (>180 m2).”

Transplanted soil adds organic matter and other properties

On balance, however, higher plant abundance and more significant species richness were shown in soils subjected to transplanting when compared with areas treated with traditional restoration methods. “For heavily degraded sites, for example, mine tailings or construction sites, higher plant abundance in the soil translocation treatments could be due to the fact that the added soil provides a substrate for plant establishment and growth,” the research explains.

Moreover, “The translocated soil adds organic matter, as well as other chemical and physical properties (e.g. water retention) necessary for germination and survival of plants.”

“Ecological recovery is tricky and often unpredictable. People tend to only look above at above ground recovery, but we have demonstrated that the key to success is laid below ground,” Wubs said. “We are now able to restore biodiverse ecosystems in places where natural regeneration is not enough. But at the same time, we need to explore why restoration is more successful in some cases than in others.”

90 percent of the Planet’s soils at risk

The development of new regeneration techniques becomes critically important in a highly problematic global context. “World’s soils have been ignored for so long that as of today, 33 percent are degraded, and if management practices continue as they are today and action is not taken to protect this important resource, it is estimated that this percentage could reach more than 90 percent in 2050,” Lucrezia Caon, FAO Land and Water officer and coordinator of the Global Network of Soil Laboratories (GLOSOLAN), said at the latest General States of Soil Health.

The situation is also worrying in Europe. Today 60-70% of EU soils show some form of degradation. In the Continent, in particular, there are an estimated 2.8 million contaminated sites. While for 65-75% of agricultural soils, nutrient inputs reach levels that create possible eutrophication and affect biodiversity. In addition, 25% of soils in southern, central and eastern Europe are at high or very high risk of desertification. The costs associated with soil degradation in the EU are estimated to exceed 50 billion euros per year.