University of Western Australia

About: University of Western Australia is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Poison control. The organization has 29613 authors who have published 87405 publications receiving 3064466 citations. The organization is also known as: UWA & University of WA.

Biochar-mediated changes in soil quality and plant growth in a three year field trial

Abstract: While many laboratory studies have focused on the short term effects of biochar addition to soil), there have been comparatively few tracing its longer term effects in the field. This study investigated the multiyear impact of biochar on crop performance and soil quality with specific emphasis on carbon (C) and nitrogen (N) cycling over a 3 y period. Biochar was added to an agricultural field at 0, 25 and 50 t ha(-1) and planted with maize (year 1) and grass (years 2 and 3). Biochar addition affected plant performance in the grass crop with significant increases in foliar N (year 2) and above-ground biomass (year 3). Below-ground, biochar increased soil respiration, fungal and bacterial growth rate and turnover in year 2. This change coincided with a shift toward a bacterial dominated decomposer community, suggesting a decrease in the potential for microbially mediated C sequestration. Biochar did not affect dissolved organic C (DOC) and N (DON), NO3- or NH4+ pool sizes. Similarly, biochar addition had limited effects on the turnover of C-14-labelled SOC (plant litter), DOC (sugars and organic acids) and DON (amino acids) and no long term effect on N mineralization, NH3 volatilization, denitrification and NH4+ sorption. After 3 years in the field, the alkalinity associated with the biochar had been fully neutralized and biochar lost most of its cations (K, Na, Ca) but had built up an associated microbial community. We conclude that biochar addition to soil causes small and potentially transient changes in a temperate agroecosystem functioning. Importantly, many of the short-term effects of biochar on plant growth and soil behavior reported from laboratory studies were not observed in the field emphasizing the need for long term field trials to help inform agronomic management decisions involving biochar. (C) 2011 Elsevier Ltd. All rights reserved. (Less)

Salinity tolerance of crops – what is the cost?

Abstract: Soil salinity reduces crop yield. The extent and severity of salt-affected agricultural land is predicted to worsen as a result of inadequate drainage of irrigated land, rising water tables and global warming. The growth and yield of most plant species are adversely affected by soil salinity, but varied adaptations can allow some crop cultivars to continue to grow and produce a harvestable yield under moderate soil salinity. Significant costs are associated with saline soils: the economic costs to the farming community and the energy costs of plant adaptations. We briefly consider mechanisms of adaptation and highlight recent research examples through a lens of their applicability to improving the energy efficiency of crops under saline field conditions.

C:N:P ratios of benthic marine plants1

Abstract: The median C:N:P atomic ratio of benthic marine macroalgae and seagrasses is about 550:30:1. Benthic plants are much more depleted in P and less in N, relative to C, than phytoplankton. The amount of nutrients required to support a particular level of net production is much lower for benthic marine plants than it is for phytoplankton.

Modern Robust Statistical Methods An Easy Way to Maximize the Accuracy and Power of Your Research

Abstract: Summary Most researchers analyze data using outdated methods.Classic parametric tests, effect sizes, and conÞdence inter-vals around effect size statistics are not robust to violationsof their assumptions, and violations seem to occur fre-quently when real data are analyzed. Researchers relyingon statistical tests (e.g. LeveneOs test) to identify assump-tion violations may frequently fail to detect deviations fromnormality and homoscedasticity that are large enough toseriously affect the Type I error rate and power of classicparametric tests. We recommend that researchers bypassclassic parametric statistics in favor of modern robustmethods. Modern methods perform well in a much largerrange of situations than do classic techniques. The use ofmodern methods will result in researchers Þnding morestatistically signiÞcant results when real effects exist in thepopulation. Using modern methods will also reduce thenumber of Type I errors made by researchers and result inmore accurate conÞdence intervals around robust effectsize statistics. A range of accessible texts about modernmethods is available (e.g., Wilcox, 2001, 2003), as well asa wide range of software to perform modern analyses.Given the wealth of resources available, researchers have atremendous opportunity to engage in modern robust statis-tical methods.

Detrital Zircon Analysis of the Sedimentary Record

Abstract: The composition of “heavy,” or accessory, detrital minerals in sediments and sedimentary rocks has been a topic of quantitative study for at least the last seventy years, beginning with the first issue of the Journal of Sedimentary Petrology in May 1931 (Tyler 1931, Pentland 1931). Zircon has since played a prominent and complex role in interpreting the composition and history of modern and ancient sediments. Because zircon is highly refractory at Earth’s surface, it occurs in virtually all sedimentary deposits and so provides a critical link in understanding the source history of a deposit. Twenhofel (1941), in a pioneering paper on the frontiers of sedimentary mineralogy and petrology, noted that the simple presence of detrital zircon would be of little value in determining its source: “Zircons from a half dozen sources with as many different properties may be present in a sediment and merely be identified as zircon. Parent rocks cannot be positively identified on such data . The variety or varieties must be identified and their optical properties determined.” From very early on, then, it was recognized that detrital zircon would be a powerful tool in understanding provenance, and thus, sedimentary dispersal systems. Interpretive goals matured considerably in the subsequent decades, especially with major advances in microscopy, mineral chemistry, isotope tracer geochemistry, and geochronology, each addressing different aspects of provenance, sedimentation, and Earth history. The hundreds of published studies utilizing detrital zircon in the last 20 years indicate the increasing success in assessing provenance, paleogeography, and tectonic reconstructions. Selected studies are highlighted in this review to illustrate ways in which detrital zircon can be used for interpreting the stratigraphic record, and thus, the past surface conditions of Earth. In it we will outline the quantitative techniques involved in the sampling protocol and interpretation of data and then …