This paper reviews the literature on nitrate leaching and nitrogen runoff under intensive dairy pasture systems in Australia and highlights that nitrate leaching loads are generally lower than those measured in New Zealand. However, few data are available, particularly following urine application, to make a thorough comparison. Similarly, more research is needed to quantify surface N runoff and leaching following effluent application and dissolved organic forms of N loss, particularly with the continued intensification of the Australian dairy industry.

Tree removal and agricultural practices have exposed the surface soils of Australian temperate woodlands to high rates of moisture loss.  Returning missing coarse woody debris (fallen trees and branches) is shown to reduce soil moisture loss by increasing drying times by around 40% in soil adjacent to the coarse woody debris.  Such reduced rates of soil moisture loss would be advantageous for organisms, especially during extended dry periods.

Despite the importance of silicon for biogeochemical processes in soils, quantitative data on non-crystalline Si phases in soils are still fairly rare. For the first time, the recently developed method for sequential Si extraction from soils was tested on six different soil types of temperate-humid climate. The tests proved that the new method enables the quantification of important Si phases in soils. Furthermore, they revealed that the most abundant non-crystalline phase in the topsoils is biogenic origin.

Little is known about the fate of nitrogen leaching from urine patches out of the root zone, through the unsaturated zone, and into the saturated zone (groundwater). Despite laboratory studies having indicated significant potential for nitrate removal in the unsaturated zone, this study showed that this potential is not realised under field conditions. Accordingly, reduction of leached nitrogen is only likely to occur where suitable conditions exist in the saturated zone.

Acid sulfate soils (ASS) occur in coastal and inland environments in Senegal and West Africa and represent a major threat for sustainable land use. This work investigated the genesis and mineralogy of coastal ASS in the Saloum River basin, west central of Senegal and demonstrated the importance of environmental factors (topography, hydrology, soil acidity and salinity) on ASS formation and distribution. Such knowledge may help develop sound soil-management strategies, including optimising water management, at local and regional level.

Information regarding topsoil biogenic and physicogenic aggregates formation is a simple indicator of soil quality. Biogenic aggregates were more sensitive to impacts caused by natural and anthropogenic processes, and also more efficient in increasing soil fertility and carbon content of soil organic matter fractions than were physicogenic aggregates. This was confirmed by the absence of biogenic aggregates in the conventional tillage system than a no-till system, forest and pasture areas.

Oil palm plantations are expanding rapidly throughout the humid tropics. To conserve biodiversity and limit greenhouse gas emissions, conversion of grasslands is preferable to conversion of forests, but the effects on soil fertility were unknown. We found that soil structure and fertility were maintained in the desirable range after 25 years of oil palm cultivation on former grasslands. Slight acidification and loss of exchangeable magnesium occurred but this can be readily managed to ensure long-term sustainability of soil fertility.

Biochar addition can affect soil biological properties. This study showed that biochar addition increased soil carbon mineralization rates and soil enzyme activities at the early incubation stage. The results should be useful to better understand biochar’s effects on soil carbon mineralization and sequestration from the biological point of view.

Widespread land use change and conservation agriculture has reduced wind erosion but few SOC sequestration studies have separated the effects. Here we show that SOC sequestration in conservation agriculture trials was over-estimated relative to conventional tillage without considering SOC redistribution. We conclude that reduced SOC erosion and/or SOC dust accumulation by vegetation–crop cover must be included when considering SOC sequestration induced by changes in land use and management.

Sediments, especially fine particles such as clay, are major surface water pollutants. Interactive effects between polyacrylamides (PAMs) and clays on clay flocculation and PAM adsorption were studied using various types of clays and PAMs. Results showed that PAMs were effective in flocculating clay particles and clarifying water. Widespread use of PAMs in surface water treatment and clarification of runoff water has great potential in improving surface water quality and therefore the wellbeing of aquatic organisms.