The role of soils in provision of energy

Thermodynamic characterization of LF, H, and mineral soil layers from oak forest ecosystems: Exploring the role of proximate analysis

Studying the thermodynamic properties of soil organic matter is a developing field that involves the measurement of the energy stored by the soil. Quantifying soil energy content is still challenging despite different methodological approaches are available to calculate that value. One of the options is the proximate analysis following the guidelines for the energetic characterization of biomass. However, proximate analyses are still unexplored for soils. In this paper, we investigate the potential of this analysis to contribute to study soil from a thermodynamic perspective. With that goal, 31 soil samples collected in mature oak forests following a depth transect were used for elemental, thermal and proximate analysis. Proximate analyses and energetic characterization were performed by simultaneous thermogravimetry and differential scanning calorimetry. These methods allowed fragmentation of the soil organic matter in water content, volatile matter, fixed carbon, and ash, as well as the quantification of the soil organic matter and energy content. Pearson's correlation showed significant relations among the proximate, the elemental components of soils and the energy. The equations relating all of these variables were calculated for soils from oak forests by partial least squares analysis. Equations representing the relationship between energy and the proximate fractions provide an additional alternative to calculate the heat of combustion of the soil organic matter. This value is the essential step for the thermodynamic characterization of soils.

The role of soils in delivering Nature's Contributions to People

This theme issue provides an assessment of the contribution of soils to Nature's Contributions to People (NCP). The papers in this issue show that soils can contribute positively to the delivery of all NCP. These contributions can be maximized through careful soil management to provide healthy soils, but poorly managed, degraded or polluted soils may contribute negatively to the delivery of NCP. Soils are also shown to contribute positively to the UN Sustainable Development Goals. Papers in the theme issue emphasize the need for careful soil management. Priorities for soil management must include: (i) for healthy soils in natural ecosystems, protect them from conversion and degradation, (ii) for managed soils, manage in a way to protect and enhance soil biodiversity, health, productivity and sustainability and to prevent degradation, and (iii) for degraded soils, restore to full soil health. Our knowledge of what constitutes sustainable soil management is mature enough to implement best management practices, in order to maintain and improve soil health. The papers in this issue show the vast potential of soils to contribute to NCP. This is not only desirable, but essential to sustain a healthy planet and if we are to deliver sustainable development in the decades to come. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

Soil-derived Nature's Contributions to People and their contribution to the UN Sustainable Development Goals

This special issue provides an assessment of the contribution of soils to Nature's Contributions to People (NCP). Here, we combine this assessment and previously published relationships between NCP and delivery on the UN Sustainable Development Goals (SDGs) to infer contributions of soils to the SDGs. We show that in addition to contributing positively to the delivery of all NCP, soils also have a role in underpinning all SDGs. While highlighting the great potential of soils to contribute to sustainable development, it is recognized that poorly managed, degraded or polluted soils may contribute negatively to both NCP and SDGs. The positive contribution, however, cannot be taken for granted, and soils must be managed carefully to keep them healthy and capable of playing this vital role. A priority for soil management must include: (i) for healthy soils in natural ecosystems, protect them from conversion and degradation; (ii) for managed soils, manage in a way to protect and enhance soil biodiversity, health and sustainability and to prevent degradation; and (iii) for degraded soils, restore to full soil health. We have enough knowledge now to move forward with the implementation of best management practices to maintain and improve soil health. This analysis shows that this is not just desirable, it is essential if we are to meet the SDG targets by 2030 and achieve sustainable development more broadly in the decades to come. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.