Review of soil data in government databases in Australia has identified many data quality issues. These issues, coupled with a lack of quality coding systems, limit the efficient and effective use of the data. The solutions we propose should form the beginning of a long-term goal of improving the quality of soil data in Australia.

Spatial distribution of soil properties provides essential information for ecological modelling, environmental prediction, precision agriculture, and natural resources management, as well as land-use planning. The aim of the study was to predict spatial distribution of soil properties based on environmental variables by using geographically weighted regression. The model could deal with varying relationships between soil properties and environmental variables and its performance was improved by reducing spatial autocorrelation in model residuals.

Fertilisation affects key soil physical properties related to soil tilth. We studied several soil physical properties after 120 years of contrasting fertiliser rate and type and found that crop-yield-optimised rates of mineral fertiliser appear to sustain soil physical properties almost as well as manure, whereas long-term suboptimal fertilisation compromises soil physical properties. Thus, the results illustrate the importance of ensuring an optimal crop growth to sustain soil physical properties.

Most soils used for crop production in Western Australia are acidic, and ameliorating acid soils with lime can change the requirement for fertilisers by crops. The present study showed that a lime-induced reduction in aluminium toxicity reduced the amount of fertiliser P required at one site and a lime-induced potassium deficiency constrained the response to P fertiliser at another site. Grain producers may need to adjust phosphorus and potassium fertiliser application after liming to maximise productivity.

The effects of manure and/or gliricidia on soil organic matter were examined. High-quality, N-rich organic fertilizers reduced the more labile matter organic of soil. The techniques tested were good indicators of soil organic matter quality in our site.

Soil organic carbon loss is an important process for C cycle studies, which may contribute to various disciplines. The current study area is at risk owing to hilly topography, soil conditions facilitating water erosion and inappropriate agricultural practices such as excessive soil tillage and cultivation of steep lands – this makes the area typical of Mediterranean environment. Thus, this study will be a guideline for similar future studies in the Mediterranean region as well as other parts of the world.

Additional soil organic carbon (SOC) can potentially mitigate climate change; however, our estimates of SOC change remain uncertain owing to natural change through time. We examined land use systems across northern NSW to quantify changes in SOC in 2008–11. No SOC change was detected under agricultural systems; however, non-agricultural (native woodland) systems showed a significant SOC increase in response to high rainfall in 2010–11. We conclude that SOC has natural variability and responds rapidly to rainfall; however, this change is moderated by agricultural activity.

Prediction of the required draft force of tillage implements is important for designing an efficient machine. In the present study, an analytical model was developed to calculate draft force of a winged subsoiler based on soil mechanics and dynamics laws. The findings indicate that the model developed herein is able to predict the draft force of the machine if the required parameters of soil, machine, and working state are known.

Soil is the largest land-based reservoir of carbon on Earth; it is important for mitigating global warming and extreme weather. Subsoil organic carbon storage is approximately two-fold greater than that of A horizon soils. Thus, the results about spatial distribution and storage of subsoil carbon can provide useful information for estimating global carbon cycle rationally.