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Soil physical measurements are essential for solving many natural resource management problems. This operational laboratory and field handbook provides, for the first time, a standard set of methods that are cost-effective and well suited to land resource survey. It provides: practical guidelines on the soil physical measurements across a range of soils, climates and land uses; straightforward descriptions for each method (including common pitfalls) that can be applied by people with a rudimentary knowledge of soil physics, and guidelines on the interpretation of results and integration with land resource assessment. Soil Physical Measurement And Interpretation for Land Evaluation begins with an introduction to land evaluation and then outlines procedures for field sampling. Twenty detailed chapters cover pore space relations, water retention, hydraulic conductivity, water table depth, dispersion, aggregation, particle size, shrinkage, Atterburg limits and strength. The book includes procedures for estimating soil physical properties from more readily available data and shows how soil physical data can be integrated into land planning and management decisions.

S. (2017). High-frequency monitoring of catchment nutrient exports reveals highly variable storm event responses and dynamic source zone activation. Abstract Storm events can drive highly variable behavior in catchment nutrient and water fluxes, yet short-term event dynamics are frequently missed by low-resolution sampling regimes. In addition, nutrient source zone contributions can vary significantly within and between storm events. Our inability to identify and characterize time-dynamic source zone contributions severely hampers the adequate design of land use management practices in order to control nutrient exports from agricultural landscapes. Here we utilize an 8 month high-frequency (hourly) time series of streamflow, nitrate (NO 3-N), dissolved organic carbon (DOC), and hydroclimatic variables for a headwater agricultural catchment. We identified 29 distinct storm events across the monitoring period. These events represented 31% of the time series and contributed disproportionately to nutrient loads (42% of NO 3-N and 43% of DOC) relative to their duration. Regression analysis identified a small subset of hydroclimatological variables (notably precipitation intensity and antecedent conditions) as key drivers of nutrient dynamics during storm events. Hysteresis analysis of nutrient concentration-discharge relationships highlighted the dynamic activation of discrete NO 3-N and DOC source zones, which varied on an event-specific basis. Our results highlight the benefits of high-frequency in situ monitoring for characterizing short-term nutrient fluxes and unraveling connections between hydroclimatological variability and river nutrient export and source zone activation under extreme flow conditions. These new process-based insights, which we summarize in a conceptual model, are fundamental to underpinning targeted management measures to reduce nutrient loading of surface waters.

This study evaluated the accuracy of pressure plate apparatus for measuring soil water retention at −0.5 and −1.5 MPa matric potential. Samples from 35 contrasting Australian soils were wetted with distilled water and drained on pressure plate apparatus at −0.5 and −1.5 MPa. The soil matric potential of each sample was then determined using a thermocouple psychrometer, and water content was measured. Water content at exactly −0.5 and −1.5 MPa matric potential was determined independently by interpolating between replicates of matric potential–water content data measured using a thermocouple psychrometer. Water content of the soil samples at apparent equilibrium on pressure plates was compared with these “target” water contents. The 35 samples on pressure plates at −1.5 MPa equilibrated, on average, to 0.3% (w/w) wetter than the target water content, with mean matric potential of −1.10 MPa. Fifteen samples were significantly wetter than the target values. Soil samples on pressure plates at −0.5 MPa equilibrated, on average, to 0.2% (w/w) wetter than the target water content, attaining a mean matric potential of −0.48 MPa. Mean error in water content at −1.5 MPa on pressure plates was reduced from >0.5 to <0.1% (w/w) in a subset of 10 samples prone to dispersion by wetting with 0.01 mol L−1 CaCl2 Water contents of samples equilibrated on pressure plates at −1.5 MPa were good estimates of “true” −1.5 MPa water content for the nonswelling soils tested, provided CaCl2 was used to minimize dispersion. Vapor equilibrium measurement methods are recommended for swelling soils.

The sustainability of agricultural practices is enhanced when vegetation makes optimal use of natural hydrological processes. For example, planting tree belts where slope gradient sharply decreases can enable harvesting of run-on water. This can be beneficial for example in reducing water logging and enhancing tree production. There is a need for rapid and low cost identification of water flow paths and conceptualisation of hillslope hydrology so that local landuse planning can reflect such opportunities. The collection of detailed hillslope hydrological data is prohibitively expensive for such applications and so the use of soil morphology and visual observation of topography and surface condition is evaluated as an alternative.At a study site in south eastern Australia the soil physical profile was described down a hillslope with additional measurements of the hydraulic conductivity, bulk density, cation exchange capacity, electrical conductivity, and particle size distribution of the key horizons. This data was used to identify the perceived significant hydrological flow paths down the hillslope. Measurement of the surface runoff, subsurface lateral flow, and the distribution of saturation measured in piezometers were subsequently used to test the conceptual hydrological model. Soil morphology, particularly the soil colour and presence of redox concretions were useful in identifying the locations and depths where saturation and lateral flow occur. The morphology provides an integrated reflection of the dominant hydrological conditions, but care must be taken to ensure that the observations reflect the current hydrological environment and not relic conditions. Other collaborating information such as the history of geomorphological events at the site, a validation of plausible water sources for the potentially transmitting layers, surface soil condition and landholder observations give improved confidence. Combining soil morphological understanding with visual observations of other site characteristics enabled rapid conceptualisation of hillslope hydrological behaviour as needed for local landuse planning.