Global soils

Soil is a declining resource for a variety of reasons such as conventional agricultural practices and overexploitation of forests. Soil loss and erosion – half of the topsoil on the planet has been lost in the last 150 years – has a huge impact on our ability to produce food and, due to erosion, around 30% of the world’s arable land has become unproductive in the last 40 years. Tipped as an environmental problem second only to population growth, sustainably managing our soils should be a global priority.

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On the 4^th of December, the Montpellier Panel published its latest report ‘No Ordinary Matter: Conserving, restoring and enhancing Africa’s soils’, this time focusing on the importance of soils to global food security. The report explains the contribution of soil to alleviating many of today’s pressing challenges is overlooked. The report finds that soils have become politically and physically neglected, triggering land degradation and recommends the following action be prioritised:

1. Strengthen political support for sustainable land management
2. Increase financial support for investment in land and soil management.
3. Improve transparency for land and soil management.
4. Attribute a value to land degradation.
5. Start a ‘Big Data’ Revolution on soils.
6. Create incentives, especially secure land rights.
7. Build on existing knowledge and resources.
8. Build soil science capacity in Africa.
9. Embrace integrated soil management (ISM).
10. Climate smart soil helps agricultural systems become more resilient.

Soil biodiversity and ecosystem function

It has long been recognised that organisms living in the soil are important for making nitrogen available to plants and for storing carbon in the soil but a new paper in PNAS by de Vries et al, Soil food web properties explain ecosystem services across European land use systems, investigated the impact of communities of soil organisms on the overall functioning of ecosystems.

The study is the largest of its kind, involving researchers from across Europe, and is the first time whole communities of soil organisms have been investigated. Spanning 60 sites across 4 countries and three types of land uses (intensive wheat rotations, extensive rotation and permanent grassland), the study marks a significant piece of evidence for the importance of soil biodiversity.

Researchers found a strong link between soil biodiversity and the performance of ecosystems, in particular on carbon and nitrogen cycling. Indeed soil biodiversity was a greater predictor of C and N cycling than land use. Intensive wheat rotation was found to reduce soil biodiversity across the food web in all countries. The authors hope that this and other research will lead to the development of sound land management practices that support soil biodiversity, in turn increasing the productivity of land while mitigating climate change.

The study concludes that we require more research into soil food webs and in particularly how they might alter in response to changes in land use and climate change. Soil biodiversity is understudied, perhaps because of its scope, but it is under increasing threat from, for example, urbanisation, climate change, pollution and agriculture. Mapping and conserving soil biodiversity is urgently needed if we are to include their roles in C and N cycling models, which will in turn help us to better understand the likely impacts of climate change.