Soil texture is one the most important properties of soil that determine its capacity to hold water and nutrients. The terms sand and silt, as constituent particles of soil, are parts of the common jargon, but there is not consistence in the particle size boundaries between them. This work proposes a mathematical model to transform Australian textural classes to the ones used by USDA and FAO (used in most parts of the world). This will generate a ‘common language’ within the scientific community, improving the efficiency of knowledge flow.

Variation in soil temperature at 5cm depth affects the rate of plant and insect development and other chemical reactions in the soil. There is a daily cycle with a rapid rise through the morning followed by a rapid fall to a transition point then a slower fall to the minimum, fitting an exponential decay function. Use of the minimum and maximum alone to estimate daily temperatures will overestimate the average by about 6%.

The study of soil physical properties is important to preserve soil quality in semi-arid regions. The study area is dependent on irrigation, and there is evidence of soil degradation resulting from intensive use and inappropriate management; the soils with more intensive cultivation experienced major degradation. These areas should be managed using no-till management and/or crop rotations to increase soil quality, especially if they are expected to be used in the long term for agricultural purposes.

Burnings is widely used as a management tool in opening up new agricultural areas or as a pasture management practice, which may promote changes in soil physical properties and also generate hydrophobic substances which accumulate and result in the formation of water-repellent layers thus reducing the water infiltration in soil. This study investigated the induction of hydrophobicity by burning and changes in soil hydro-physical properties. The soil surface layer showed an increase in water repellency after burning, which affected soil organic matter content, air permeability and hydrophobicity.

Only sodium salts in soils and irrigation water are currently considered to affect soil structure overlooking the effects of potassium and magnesium salts. We have established the effectiveness of the new cation ratio of soil structural stability (CROSS) in accommodating the differential effects of all these salts. We have derived, in relation to this ratio, threshold salt levels and also dispersive potentials of soils which will predict the quantity of amendments to improve soil structure in salt-affected soils.

Waterlogging is a widespread problem for crop production, especially in the duplex soils and loamy clay soils of Australia and the sodic/alkaline soils of India. Reductions in plant growth and grain yield of wheat caused by waterlogging are accompanied by sharp reductions in redox potentials and increased concentrations of Mn, Fe and other elements in soils. These studies support that wheat varieties tolerant to the element toxicities or pH extremes in soils have a greater capacity to tolerate higher concentrations of microelements under conditions of waterlogging.

Soil respiration comprises the second-largest terrestrial carbon flux. We show that elevated atmospheric ozone (O₃) significantly decreased soil respiration in a soybean-winter wheat rotation cropland, with a larger effect observed in soybean. This study implicates that the important effects of O₃ on soil respiration should be included in soil carbon cycle models.

This study applied different manure rates in combination with chemical fertiliser to overcome some of the problems caused by the inappropriate use of manure. The medium manure rate (15000 kg/ha) in combination with chemical fertiliser improved the soil properties and increased the crop yield. The medium level of manure application is the most appropriate soil fertiliser rate for dryland maize production.

Coral and seagrass communities in the Great Barrier Reef World Heritage Area can be adversely affected by the entry of pollutants, such as phosphorus, from waterways discharging into the GBRWHA. This study investigated if phosphorus escapes from farms during rain storms into waterways near the GBRWHA. It found that significant amounts of phosphorus can be lost from farms in this way, possibly due to over-fertilisation with phosphorus fertilisers. In the long term, this may have consequences for the ecology of the GBRWHA unless farm management practices are changed.