This study is restricted to soil physical aspects of soil quality and health with the objective to define procedures with worldwide rather than only regional applicability, reflecting modern developments in soil physical research and focusing on important questions regarding possible effects of soil degradation and climate change.

In this paper, we quantify the global-level relationship between soil organic matter and crop yield. We find that greater concentrations of soil organic matter are associated with greater yields and that increases in yields saturate around 2 % SOC. Using the relationship that we generate, we then provide an estimate of the potential for soil organic matter management to reduce global yield gaps for two of the most important staple crops (maize and wheat) grown worldwide.

Weathering rates in forest soils are important for sustainable forestry but cannot be measured. In this paper, we have modelled weathering with the commonly used PROFILE model as well as with the dynamic model ForSAFE, better suited to a changing climate with changing human activities but never before tested for weathering calculations. We show that ForSAFE gives comparable weathering rates to PROFILE and that it shows the variation in weathering with time and works well for scenario modelling.

By coupling an OA-ICOS with hydrophobic but gas-permeable membranes placed at different depths in acidic and calcareous soils, we investigated the contribution of abiotic and biotic components to total soil CO₂ release. In calcareous Gleysol, CO₂ originating from carbonate dissolution contributed to total soil CO₂ concentration at detectable degrees, probably due to CO₂ evasion from groundwater. Inward diffusion of atmospheric CO₂ was found to be pronounced in the topsoil layers at both sites.

Forest management may lead to long-term soil acidification due to the removal of base cations during harvest. By means of the HD-MINTEQ model, we compared the acidification effects of harvesting with the effects of historical acid rain at three forested sites in Sweden. The effects of harvesting on pH were predicted to be much smaller than those resulting from acid deposition during the 20th century. There were only very small changes in predicted weathering rates due to acid rain or harvest.

Digital soil mapping has been widely used as a cost-effective method for generating soil maps. DSM models are usually calibrated using point observations and rarely incorporate contextual information of the landscape. Here, we use convolutional neural networks to incorporate spatial context. We used as input a 3-D stack of covariate images to simultaneously predict organic carbon content at multiple depths. In this study, our model reduced the error by 30 % compared with conventional techniques.

The role of soil aeration in carbon sequestration in arable soils has only been explored little, especially at the farm level. The current study, which was conducted on 30 fields that belong to individual farms, reveals a positive relationship between soil gas transport capability and soil organic carbon content. We therefore conclude that soil aeration needs to be accounted for when developing strategies for carbon sequestration in arable soil.

We measured net fluxes of OCS from nine soils with different land use in a dynamic chamber system and analyzed for one soil RNA relative abundance and gene transcripts. Our data suggest that indeed carbonic anhydrase (CA) plays an important role for OCS exchange, but the role of other enzymes might have been underestimated. Our study is the first assessment of the environmental significance of different microbial groups producing and consuming OCS by various enzymes other than CA.