The present study characterized biochemical properties root zones of two keystone native plant species (Acacia chisolmii, leguminous and Triodia pungens, spinifex) under subtropical and semi-arid climatic conditions. Results suggested the importance of native leguminous acacia in contributing N rich plant litter for nutrient cycling in infertile soil, altering microbial community by increasing fungal:bacterial ratio, microbial biomass and enzymatic activities, compared to spinifex. These provide the basis for engineering growth media to rehabilitate acacia-spinifex communities across mined landscapes.

Plant available water in clay-delved soil was evaluated by mixing sand and clay-rich subsoil of different clod sizes at different quantities. We measured soil physical properties of the mixtures and found subsoil clay increased plant available water up to additions of 40% subsoil by weight, beyond which it declined. Smaller subsoil aggregates were less effective at rates in the practical range of <20% so we caution against excessive post-delving cultivation.

Soil erosion is a dynamic environmental process that influenced by multiple factors. The back-propagation (BP) neural network modelling and grey relational analysis were used to rank the influencing factors. The predicted total runoff and total sediment by BP model closely tracked the experimental data. Runoff and sediment yield depend most strongly on rainfall intensity and vegetation coverage.

Tropical forests play a key role in the global carbon cycle, but little is known about carbon cycling in the substantial portion of tropical forests that are low-lying, with shallow and fluctuating water tables. We found that emissions of CO₂ from soil in a riparian rainforest in Queensland, Australia, were significantly related to soil temperature, water content and depth to water table. Models of soil respiration in lowland tropical forests should take into account depth to water table, a factor that has been little considered to date.

As common processes in arable soils, drying and rewetting (DRW) events are vital in soil nutrient cycling, but the effect of DRW stress on microbiological characteristics and carbon (C) and phosphorus (P) dynamics remains unclear. We found that soil microbial biomass C, extractable organic C, soil microbial biomass P, and NaHCO₃-extractable P each responded differently to different frequencies of DRW stress and that parameter fluctuation became less with increasing frequency of DRW cycles. There may be links among soil moisture, microbial activity and nutrient bioavailability that are critical to water and nutrient management.

Hydrogeological Landscape (HGL) units are used to facilitate appropriate land-management actions for issues such as dryland salinity and climate change. We show that HGL units, commonly manually defined by bringing together multiple spatial datasets, can be automatically constructed using Self-Organising Maps (SOM), an unsupervised statistical learning algorithm. SOM-derived HGL units indicate both additional complexities within individual HGL units and broad similarities between distant HGL units that will aid land-management decision-support systems based on the HGL framework.

Variably aged hairy vetch biomass was incorporated in paddy soil to estimate global warming potential (GWP). The emissions of methane, carbon dioxide and nitrous oxide were monitored in closed-chamber. Incorporation of 3 Mg ha^–1 biomass of 204 day-old hairy vetch minimized GWP without sacrificing rice yield.

The photogrammetry (PHM) method was used to determine the volume of soil aggregates with diameter ranging between 1 and 8 mm. The PHM results were compared with those obtained with the Archimedes’ principle, and was subsequently used to calculate the aggregate bulk density, ρ, under different tillage treatments. Tillage management and aggregate sizes had a significant influence on ρ.

Applicability of TDR under naturally distributed stone fragments in a multilayer profile of a 30-m-deep well was investigated. A semi-empirical mixture model was employed in order to convert bulk Ka to bulk θv to be compared with θv by the conventional Topp equation. An improvement in model performance was observed. This approach for converting the in-situ measured Ka to the θv can be applied based on the determined stoniness.