The objective of this Forum article is to argue that one of the key justifications for developing theories and models of soil processes is that these theories are needed to determine what it is relevant to measure in soils. Without these theories and models to guide us, in particular if we rely on machine-learning and artificial intelligence methods to make progress, we are navigating in the dark, and are likely to base decisions on mere correlations that do not reflect true mechanisms.

The current global context, marked by this year's intense El Niño, underscores the growing severity and destructive consequences of climate change, particularly across the Pacific Rim. With a noticeable increase in the frequency and severity of climate-related disasters, there is a profound and pressing need for effective strategies to enhance regional resilience and mitigate future risks.

How can carbon be stored in red soils? Our 18-yr manure application reveals that applying manure stabilizes soil carbon through two key mechanisms: it helps soil particles clump together, physically shielding the carbon, and it improves soil conditions to promote minerals that act like glue, binding the carbon chemically. This research provides a sustainable strategy for enhancing soil fertility and mitigating climate change.

This manuscript studies the potential of paludiculture to reduce greenhouse gas emissions (GHG) in rewetting peatlands. Results showed that the potential to mitigate GHG emissions could be maximized in nutrient enriched areas, while in low nutrient areas it might be more beneficial not to harvest the biomass. Results also showed that peatland heterogeneity and water table dynamics should be considered to accurately estimate emissions from rewetting peatlands.

To understand how warming will change the dynamics of roots across soil profile, we took usage of a long-term field warming experiment and incubated ¹³C-labelled roots at three different depths. After 3 years of incubation, at compound class level, the effects of warming on decomposition of root-derived hydrolysable lipids were compound class specific. At monomer level, warming effects on suberin-derived monomer decomposition were depth-dependent and their resistance increased with chain length.

Agrogeophysics harnesses geophysical methods for non-invasive, multiscale mapping and monitoring of soil properties and processes in the plant-soil-atmosphere continuum, which are responsible for climate regulation, food production and water security. Here, we present an overview of advances in Agrogeophysics in the last decade and discuss how the contributions to the Special Issue “Agrogeophysics: Illuminating soil’s hidden dimensions” help addressing agricultural and environmental challenges.

We looked at soil carbon storage in bioenergy crop fields that had different levels of plant diversity over 12 years. We discovered that biopores – small holes in the soil formed as roots grow, die, and decompose – are closely linked to the amount of organic carbon in the soil. When there are more biopores, there’s more surface where roots touch the soil, which helps carbon from plants spread out and get stored better.

Soil erosion threatens landscapes worldwide, and understanding how surfaces change over time is key to addressing this issue. We developed a new camera-based system that automatically captures and analyzes daily surface changes on a hillside over several years. Triggered by rain and a clock, the system showed how weather and farming impact the land. Our method offers a powerful way to monitor surface changes and can help improve predictions and solutions for soil erosion.

Alpine soils store much carbon but warming and changes in vegetation could reverse this by turning them into carbon sources. In a one-year laboratory study, we examined alpine forest and pasture soils and added fresh grass litter marked with a carbon tracer to track decomposition under different temperatures. Our findings reveal that fresh plant material drives soil breakdown more than temperature alone, offering new insights into how climate change may affect carbon storage in mountain regions.

The study evaluated how soil properties affect vivianite efficiency as a phosphorus (P) fertilizer. With phosphate rock reserves declining, alternative P sources are crucial. Soil pH and P availability influence the effectiveness of vivianite as a P fertilizer. Higher solubility in acidic soils and low P availability can enhance plant and microbial mobilization, thereby improving its efficiency. Findings highlight the need to consider soil properties for optimal use of alternative P fertilizers.

Regenerative soil management reduced bulk density, increased carbon stocks, and influenced aggregate stability with time. Soils were observed to become proportionally more enriched in stable aggregates and store more carbon with time. Stable aggregates provided physical protection (occlusion) to labile carbon stocks. When considered alongside recalcitrant carbon, these carbon stabilisation mechanisms may provide further opportunities to deliver robust long term carbon sequestration outcomes.

This study demonstrates that municipal solid waste biochar (MB) is a highly effective amendment for Ni immobilization in contaminated calcareous soils, outperforming both individual and combined applications of compost and bentonite. These findings provide valuable insights for developing remediation strategies in Ni-contaminated agricultural soils, emphasizing the potential of biochar as a sustainable and efficient immobilization agent.

Improved management practices such as rotational grazing, grazing exclusion, and legume enrichment can boost climate change mitigation and adaptation in grasslands. We studied the effects of these practices on soil organic carbon (SOC) stocks and fractions in semi-arid grasslands. Rotational grazing increased SOC, especially mineral-protected fraction, while exclusion reduced particulate organic carbon stocks. These outcomes were linked to changes in plant traits, soil microbes, and nutrients.

Soil acidity below the plow layer harms crops and is difficult to correct with surface lime applications. Adding organic matter may help lime move deeper, but its effectiveness remains uncertain. We set up column leaching experiments to identify the mechanisms of subsurface liming. We found that combining lime with organic amendments can improve deeper soil conditions, but only in soils that do not strongly retain organic carbon. These insights can help develop better soil management strategies.