Soils from a field trial with diverse treatments (long-term pasture; arable cropping rotation; long-term bare fallow) were used in a case study to (1) examine the association between soil organic matter (SOM) solubility (in hot water) and bioavailability and (2) evaluate whether water-insolubility is a defining feature of the recalcitrant fraction of SOM.

Land use and management practices must be oriented to convert soils into carbon sinks. Different methods were applied to estimate the carbon sequestration capacity of Pampean soils in the fine soil fraction. Potential carbon sequestration was higher in fine textured soils, in soil surface layers and in humid and colder environments. Cropland soils had higher carbon sequestration capacity than grassland or lowland soils. Pampean soils can potentially sequester double their actual carbon content.

Soil microbial biomass is a key property in both agricultural and environmental monitoring contexts, routinely estimated using the chloroform fumigation–extraction method. The existence of nonmicrobial organic matter in the fumigation flush, potentially contributing to biomass overestimation, has never been excluded. In the current study, fluorescence spectroscopy was found potent in discriminating non-microbial ‘humic-like’ material from microbial ‘protein-like’ material in the fumigation flush. A conceptual framework for assessment and alleviation of interference from humic substances in microbial biomass estimation is presented.

Soil organic carbon (SOC) content increased for tableland, sloping land, and gully in a watershed after implementation of the ‘Grain-for-Green’ program. The variation magnitude of SOC differed for different topographic types from 2002 to 2018. Topography, vegetation, edaphic variables, and their interactions affected the SOC spatial variability.

Vertosols are widely used for cotton production globally. This study investigated the change in characteristics of Australian Vertosols due to the impact of rainfall, seasonal variability, and John Deere 7760 cotton picker traffic. Measurements of soil physical properties (soil water content, dry bulk density, and soil penetration resistance) were carried out in the 0–80 cm depth profile during the study period.

A simple power law relationship was derived to relate electrical conductivity (EC) with unsaturated hydraulic conductivity (K) of sands through laboratory experiments. The parameter of exponent β value described the EC–K relationship very well and acted as a lumped factor accounting for pore tortuosity, pore connectivity, shape of pore space, and fluid EC. The developed relationship could lead to a direct estimation of the spatial and temporal unsaturated K using the measurements of SWCC and a geophysics approach.