Representative grassland soils in south east NSW were sampled to provide an overview of agronomic phosphorus requirement and phosphorus environmental risk for pastoral land uses. From soil Colwell P and phosphorus buffering index (PBI) values, 20% of the sites was considered to present a significant environmental risk to water quality. Routine use of soil PBI analysis with Colwell P tests could improve land management practices to reduce diffuse pollution from agriculture.

With a single residue addition, the reduction in soil respiration with increasing salinity was smaller in soils amended with rapidly decomposable residues (low C : N ratio) compared with slowly decomposable residues (high C : N ratio). With rapidly decomposable residue, the reduction of cumulative respiration with increasing salinity was smaller with repeated addition than with only a single addition. However, this was not the case with slowly decomposable residue.

A ‘hybrid approach’ consisting of determining magnitude and cause(s) of yield gap to estimate costs of soil constraints to the Australian agriculture was proposed and demonstrated at farm scale. Multi-year spatiotemporal analysis of remotely sensed data provided a rapid and accurate assessment of areas that are consistently low-yielding over several years, indicating the presence of at least one unamended soil constraint factor. A ‘bottom-up’ approach was proposed to upscale the hybrid approach from local to national relevance.

Polyethylene film and biodegradable polymer film mulch had significant effects on soil temperature, water conservation, maize yield and water use efficiency when compared with the uncovered control. However, no significant differences were observed between the liquid membrane and control during the entire growing season. The biodegradable polymer film could potentially replace polyethylene film during agricultural production in Loess Plateau, China.

Conservation tillage practices are necessary to stop the decline in soil fertility and crop productivity under tropical smallholder farming conditions. We assessed the long-term impact of reduced tillage and crop residue retention on soil quality and crop productivity, and our results indicate a positive influence on physical soil properties. However, there is need to maintain higher levels of crop residue to counter the negative effects of reduced tillage to enhance crop productivity.

Available water holding capacity was increased by decreasing the layer thickness in the layered soils. Decreasing layer thickness increased fine root distribution in the finer textured soil layers. Alfalfa water consumption and biomass increased in the layered soils relative to the homogeneous soils.

Knowledge of the spatial pattern of soil water temporal stability is important in hydrological research. This study evaluates the uncertainties in predicted spatial patterns of temporal stability and shows that the uncertainty due to the limited number of sampling points used for interpolation of soil moisture is more important than the uncertainty due to the limited number of sampling days used for calculating temporal stability. Additional sampling sites rather than additional sampling days should be developed to reduce prediction uncertainty.

In Queensland, Australia, the clearing of large tracts of native vegetation for agriculture has changed the hydrology of the landscape. This study found that clearing brigalow (Acacia harpophylla) increased peak run-off rate by an average of 96% when cleared and cropped and 47% when cleared and grazed. This knowledge can be used to improve hydrological modelling of landscape processes and to assist with catchment management.

Controlled traffic no-till (NTCT) was associated with a substantial improvement in soil organic matter, total N and available P. NTCT treatment decreased the soil bulk density in the deep soil layer (10–30 cm) relative to the conventional tillage (CT) treatment. Maize and wheat yields were significantly higher under NTCT than under CT and random traffic no-till treatments.

A two-year field study on N₂O emission was conducted in a wheat ecosystem. Nitrogen fertiliser stimulates N₂O emission under reduced tillage practice. With increasing nitrogen fertilisation levels, nitrogen use efficiency was found to decrease irrespective of the tillage practices. A 25-% reduction in nitrogen fertiliser reduced N₂O emission in conventional tillage practice without sacrificing the wheat grain productivity.