Impact of annual biofuel crops (corn, sorghum) and perennial grasses (switch grass, miscanthus, prairie mix) were assessed on soil properties and soil organic carbon (SOC) stocks in Central Ohio. Perennial energy crops improved soil properties in terms of lower soil bulk density, higher porosity, improved water-stable aggregates and higher mean weight diameter compared to annual crops maize and sorghum. The SOC stock in the 0–10 cm layer was significantly higher under switch grass and miscanthus than that under sorghum.

We analyse the value of soil organic carbon (SOC) in cropping systems of the south-west of Western Australia in terms of agronomic benefits from increasing productivity (through increased plant-available water-holding capacity) and reducing fertiliser use (due to increased mineralisation of nitrogen), as well as sequestration benefit if landholders were able to participate in a carbon-sequestration program. We estimate the marginal value of SOC to be AU$7.1–8.7/t C.ha.year, depending on rainfall zone and crop type.

To accurately estimate mean soil CO₂ emission in a mature oil palm plantation, a high measurement point density was necessary (>24 points across the 38.5 m2 repeating unit). At each measurement point, emissions were greater than plant-derived carbon inputs. The difference may be due to inaccurate assumptions in calculation of below-ground inputs or to unknown fluxes, perhaps geologically derived CO₂, because the study site is in a tectonically active area.

Transient salinity (salinity associated with decreased soil hydraulic conductivity) is an important constraint to cropping in Australia but is rarely studied. We examined the causes of transient salinity in the cropped areas of Western Australia using four datasets collected at scales varying from the entire south-west of Western Australia to that of a single paddock. Transient salinity (EC_1:5) was most strongly correlated with increased exchangeable sodium and with soil alkalinity.

Studies at 3 sites showed that 30 years of sugarcane production produced marked changes in the topsoils with organic carbon, CEC and exchangeable bases most affected. Soils at 30–40 cm also showed changes in OC, CEC and bases, while at 70–80 cm changes were much smaller, but with significant increases in OC. Management of topsoils is critical for maintaining soil fertility in such systems.

Soil gravels can reflect past soil formation processes, so we studied the composition and fabric of different gravels within a Plinthic Haplustox in Brazil. Pedogenic and lithopedogenic gravels varied in morphology, genesis and mineralogy, but were all marked by impregnation by Fe and Al. We conclude that such differentiation was the result of multiple cycles of soil formation and argue against the conventional classification of all such gravels as ‘ironstone’.

Rice husk in the form of biochar (BC) and fly ash (FA) for soil application is a potential opportunity for waste management. Biochar, in combination with FA can be utilized for crop production. Beneficial effects of BC and FA on soil properties and rice yield was exhibited when applied in addition to fertilizers. Even 50% N application with BC and FA produced a similar yield as that of 100% N.

Soil biological indices and potato growth are sensitive to Cadmium (Cd) toxicity. Cd threshold depends on its concentration and duration to accumulate. Soil biological and potato physiological parameters are stress indicator.