bluuebunny/crossref_metadata_2025 huggingface dataset:
The type and Australian species of the red algal genera Liagora and Ganonema (Liagoraceae, Nemaliales)
Authors: Huisman John M.
Published: March 2003

The type and Australian species of the liagoraceous genera Liagora and Ganonema (Rhodophyta: Nemaliales) are described. Twenty-one species are included, comprising 15 of Liagora and six of Ganonema. Five new species, Liagora walkerae, L. kraftii, L. izziae, L. delicatula and Ganonema borowitzkae are described. The new combinations Ganonema pinnatum (Harv.) Huisman, Ganonema samaense (Tseng) Huisman, Ganonema clavatum (Yamada) Huisman and Ganonema megagynum (Børgesen) Huisman are proposed. Liagora cladonioides Børgesen is shown to be a member of the genus Stenopeltis Itono & Yoshizaki. A key to the world's species of Liagora and Ganonema is provided.
Lactarius (Basidiomycota, Russulaceae) in Papua New Guinea. 3. Two new Lactarius species in subgenus Plinthogali
Authors: Verbeken Annemieke , Bougher Neale L. , Halling Roy
Published: March 2003

Two new taxa Lactarius pudorinus Verbeken & Bougher and Lactarius oomsisiensis Verbeken & Halling, both belonging to the subgenus Plinthogali (Burl.) Singer, are described from Papua New Guinea. A key to all Plinthogali species, so far known in Papua New Guinea, is given.
Australiasca queenslandica gen. et sp. nov. (Chaetosphaeriaceae: Ascomycota) and its anamorph Dischloridium camelliae sp. nov. from Australia
Authors: Sivanesan Asaipillai , Alcorn John L.
Published: March 2003

A new ascomycete, Australiasca queenslandica gen. et sp. nov., belonging to Chaetosphaeriaceae, is described and illustrated from Queensland, Australia with Dischloridium camelliae sp. nov. as its anamorph from Camellia sinensis. This is the first report of a substantiated connection between a teleomorph and a Dischloridium anamorph.
Leptophytum (Corallinaceae, Rhodophyta): To be or not to be?—That is the question, but what is the answer?
Authors: Woelkerling W. J. , Furnari G. , Cormaci M.
Published: March 2003

The question of whether or not Leptophytum (Corallinaceae, Rhodophyta) should be recognised as a distinct genus has been addressed using new data generated from type and other specimens combined with analyses of previously published data from various authors. The results have shown that none of the criteria proposed to separate Leptophytum from Phymatolithon are reliable at generic level. Some lead to the exclusion of type species from genera, others are impossible to assess because information is lacking for virtually all included species, others have character states that intergrade and thus are unsuitable and still others appear to be useful for separating species but not genera. Most of the character states proposed as diagnostic of Leptophytum are unknown or are not present in most of the species that were explicitly included in the recent proposed re-instatement of the genus and, in some cases, species included in Leptophytum show the opposing character state for Phymatolithon. No serious conflict occurs between the holotype fragments of Leptophytum laeve (the type species of Leptophytum) and the designated epitype and the designation of an epitype is fully justified because all of the characters evident in the holotype are demonstrably ambiguous and could apply to more than one species. Moreover, new evidence supports the probable conspecificity of the holotype and the designated epitype and reinforces the conclusion that Leptophytum should not be recognised as a genus distinct from Phymatolithon. Nomenclaturally, the correct authorship of the name of the type species of Leptophytum is L. laeve Adey and not L. laeve (Str�mfelt) Adey or L. laeve (Foslie in Rosenvinge) Adey, and for purposes of priority, the name Leptophytum laeve dates from 1966.
A phylogeny inferred from large-subunit (26S) ribosomal DNA sequences suggests that the family Dasypogonaceae is closely aligned with the Restionaceae allies
Authors: Neyland Ray
Published: March 2003

The Dasypogonaceae is a small Australian family composed of four genera. Previous systematic studies have failed to place the Dasypogonaceae with confidence. The present phylogenetic analysis, inferred from large-subunit (26S) rDNA sequences, strongly suggests that the Dasypogonaceae form a monophyletic group with the taxa referred to as the Restionaceae allies (i.e. Anarthriaceae, Centrolepidaceae, Ecdeiocoleaceae).
Simulating the effectiveness of surface film on water evaporation and ammonia volatilisation
Authors: Zhuang S. Y. , Yin B. , Zhu Z. L.
Published: March 2003

The application of surface films to flooded rice fields is one of the most effective measures of controlling ammonia volatilisation for improving nitrogen use efficiency. The feasibility of using a surface film is determined to some extent by the longevity of the effectiveness and this has never been estimated accurately in the field. The concept of half-life was introduced to estimate the effective life of a surface film by calculation from its effect on water evaporation. A simple laboratory experiment was carried out to validate the usefulness of the half-life concept. The results showed that effects on ammonia volatilisation could be quantified using a logistic equation based on the half-life concept.
The use of Ca-modified, brown-coal-derived humates and fulvates for treatment of soil acidity
Authors: Peiris Damayanthi , Patti Antonio F. , Jackson W. Roy , Marshall Marc , Smith Christopher J.
Published: March 2003

Previous workers have demonstrated the amelioration of soil acidity with Ca-saturated, at least slightly soluble, organic materials. This study investigated the effectiveness of a new source of such materials, the humate- or fulvate-rich products of oxidation (hydrogen peroxide) of Loy Yang brown coal. The products were characterised by physical and spectroscopic measurements and by elemental analysis. Two products, one approximately half fulvate (fulvate-rich), the other predominantly humate (humate-rich) were mixed with CaCl2 and then used to treat columns of an acid red podzol soil from Book Book, NSW. Leachate fractions were collected and analysed for pH, ionic strength, and concentration of Ca, Mg, K, Mn, Fe, and Al. After leaching (3 pore volumes), each soil column was sectioned and exchangeable Ca and Al contents were determined. The results were compared with those obtained from lime-treated and untreated columns.The Ca-fulvate-rich product was the most effective in lowering the exchangeable Al content of the soil whilst increasing exchangeable Ca and soil pH. About 90% of the reduction in exchangeable Al was due to loss of Al in the leachate rather than immobilisation. The pH increased over the top 15 cm of the column from 3.8 ± 0.1 to 4.5–5.4. The Ca-humate-rich oxidised product was less effective in ameliorating soil acidity, as expected from its chemical properties, but it increased soil pH (to 4.0–4.7) and exchangeable Ca in the top 6 cm of the column and decreased exchangeable Al in the top 12 cm. More of the reduction in exchangeable Al than for the treatment with Ca-fulvate-rich material was due to conversion to an immobile form. This material was superior to lime, which only gave significant improvement near the soil surface. The leachates from treated columns contained the same amounts of Mg, Mn, and K as a control, but more Fe was leached from treated columns, particularly that treated with the Ca-fulvate-rich product.
Assessing the viability of recharge reduction fordryland salinity control: Wanilla, Eyre Peninsula
Authors: Dawes W. R. , Gilfedder M. , Stauffacher M. , Coram J. , Hajkowicz S. , Walker G. R. , Young M.
Published: March 2003

The emerging paradigm to manage the spread of dryland salinity is the manipulation of farming practice to provide both a reduction in recharge and a commercial return to farm enterprises. Recent work has attempted to classify the groundwater systems across Australia into distinct provinces, with the implication that the flow processes, and therefore remediation strategies, of catchments within each province are similar. This paper presents a case study of the Wanilla catchment on the Eyre Peninsula in South Australia. This catchment is in the groundwater province that includes 60% of the dryland salinity expression in Australia. The results of conceptual and numerical modelling of the catchment suggest that the land management for reduced recharge paradigm may be less effective in this groundwater province than in others. The scale of expression and salinity history of such catchments provides further impediments to management options aimed at controlling or reversing existing dryland salinity.
Diversity and symbiotic effectiveness of Rhizobium leguminosarum bv. trifolii isolates from pasture soils in south-western Australia
Authors: Collins M. T. , Thies J. E. , Abbott L. K.
Published: March 2003

The abundance of the Australian inoculant strain of Rhizobium leguminosarum bv. trifolii for subterraneum clover (WU95) and the diversity of naturalised rhizobia were assessed in 3 subterranean clover pastures in the Albany region of south-western Western Australia. Most probable number, enzyme linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR) techniques were used. A putative strain similar to inoculant strain WU96 was uncommon at one site (South Stirling) and not isolated at 2 other sites. Randomly amplified polymorphic DNA (RAPD) PCR fingerprinting using the RPO1 primer identified 45 different profiles amongst the 208 isolates examined. RAPD-PCR fingerprinting using the primers RPO4 and RPO5 confirmed most groupings based on RPO1 fingerprint patterns and revealed further genetic diversity within some groups. Overall, 54 putative strains were defined by RAPD-PCR fingerprint profiles across the 3 sites. Subterranean clover rhizobia at the Manypeaks and Mount Shadforth sites were dominated by isolates with 1 or 2 RPO1 RAPD profiles at 2 sampling times, while the population at South Stirling was much more diverse. The symbiotic effectiveness of 11 rhizobial isolates, representing the major RPO1 RAPD profile groups within naturalised rhizobial populations, were compared in pot culture with those of the 2 commercial inoculant strains for subterranean clover, WU95 and TA1, on 3 cultivars. Differences in effectiveness among 3 of the 11 isolates were observed in comparison to both the commercial strains and other naturalised isolates. The nitrogen fixing effectiveness of 8 isolates representing different subgroups from one RP01 group was not the same. The use of all 3 primers increased the precision in defining putative strains of Rhizobium leguminosarum bv. trifolii, and although naturalised rhizobia from these pastures are saprophytically competent, their dominance in nodules does not appear to be linked to symbiotic effectiveness.
Effect of soil variability, within and between soil taxonomic units, on simulated nitrate leaching under arable farming, New Zealand
Authors: Lilburne L. R. , Webb T. H.
Published: March 2003

A Monte Carlo approach was used to predict the effect of soil variability on nitrate leaching from 8 soil series, encompassing a wide range of drainage, texture, and age of soil development characteristics. A database of soil physical properties consisting of a minimum of 9 profiles per soil series was used to derive correlated probability distribution functions of key soil properties. The distribution functions were then used for random sampling to derive input soil-data for the GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) simulation model. Variability in soil properties found within single soil taxonomic units (depth/stoniness phases of soil series) resulted in an appreciable range of predicted leaching of nitrate. Leaching from soils with greatest variability (generally shallow and stony phases) had an inter-quartile range of predicted leaching of up to 19 kg N/ha in 1992. Sensitivity analysis indicated that organic matter content, depth to the base of the upper 2 horizons, and available water storage were important drivers of variability within soil taxonomic units. Despite wide variation within soil taxonomic units, there were still clear differences between them. Effective soil depth accounted for most of this variance, which was attributed to differences in total profile available water storage. Soil drainage had some effect on risk of leaching. This effect would probably have been greater if water table effects had been accounted for. Soil series distinctions related to soil age had no significant effect of leaching risk. These results indicate that nitrogen leaching risk assessment using GLEAMS is dependent upon soil maps with accurate identification of soil depth/stoniness phases and organic matter content.
Soil and soil solution chemistry of a New Zealand pasture soil amended with heavy metal-containing sewage sludge
Authors: Percival H. J.
Published: March 2003

The disposal of wastewater treatment sewage sludge onto agricultural land in New Zealand has led to the development of guidelines for the upper limit concentrations for total heavy metals in the underlying soil. However, those soil biological and biochemical processes now known to be most sensitive to environmental change are being used internationally to set new soil limits. The soil solution chemistry of a pasture soil amended with heavy metals has been used to assess the bioavailability of several important heavy metals. Field trial plots were treated with both spiked (Cu, Ni, or Zn) and unspiked sewage sludge to raise total soil metal concentrations, both above and below the current New Zealand guideline values. Soils were sampled pre-amendment in 1997 and post-amendment in 1998, 1999, and 2000. Soil solutions were extracted by centrifugation and analysed for pH, for concentrations of heavy metals, major cations and anions, and dissolved organic carbon. Heavy metal speciation was calculated with the GEOCHEM-PC model.Soil solution concentrations of Cu, Ni, and Zn increased with increasing levels of metal in the spiked sludge, reflecting increases in total soil metal concentrations. Cu concentrations changed little with time, but those of Ni and Zn tended to decrease. Cu was much more adsorbed by the soil than was Ni or Zn. The free metal ions, Cu2+, Ni2+, and Zn2+ (representing the most 'bioavailable' fraction), were the dominant metal species in the soil solutions. Variations in free metal ion percentages with metal-spiking level depended on the balance between organic and sulfate complexation for Cu, but on sulfate complexation alone for Ni and Zn. Cu and Ni free metal-ion activities in soil solution were relatively low even at the highest metal loadings in the soil, but may be high enough to cause toxicity problems. Zn activities were very much higher, and at the regulatory limit for zinc likely to affect sensitive biological and biochemical properties of the soil.
Organic carbon and soil porosity
Authors: Emerson W. W. , McGarry D.
Published: March 2003

The %C within the top sandy 0.15 m of a sodic Hydrosol under native trees consisted of a constant %C in uncharged organic matter and a %C in negatively charged organic matter decreasing linearly with depth, as did the specific volume of the soil. The kaolinitic clay present was strongly bonded together. In an adjoining canefield cleared 10 years earlier, incorporation of burnt cane residues to 0.35 m had more than doubled the CEC of the soil, but had not generated structural porosity. The clay in the top 0.15 m remained strongly bonded together. The rate of increase in the specific volume of the sandy soil under trees with %C was twice that reported for surface aggregates of a silty soil from rotation plots on a Chromosol, and of sectioned clay cores from a Ferrosol under softwood scrub.The rate of increase in the specific volume of pores ≤30 μm diameter with %C was measured by the water retention of aggregates at 10 kPa suction, and was 50% more for the sandy soil than for the silty soil. The difference is ascribed to the dominance of mycorrhizal fungi under trees compared with bacteria under grass. Both agents are presumed to link particles together through acidic polysaccharide gel. Subsequent air-drying then leaves pores stable to wetting and drying. It is suggested that the increase in the plastic limit of silty soils is mainly due to pores stabilised in this way. Pores in decomposing plant residues coated with inorganics could also contribute.
Sediment yields and soil loss rates from different land uses on Triassic shales in western Sydney, NSW
Authors: Erskine Wayne D. , Mahmoudzadeh A. , Browning C. M. , Myers C.
Published: March 2003

Sedimentation surveys of small dams demonstrate that land use is the dominant factor generating high sediment yields in the ungullied shale catchments of western Sydney where rainfall erosivity and soil erodibility are relatively constant. A single urban catchment produced 6.5 t/ha.year and cropped catchments an average of 6.7 ± 1.99 t/ha.year, whereas grazed woodland/forest and grazed pasture exported averages of only 2.5 ± 0.57 and 2.9 ± 1.02 t/ha.year, respectively. These yields are high by Australian standards and the farm dam sediments are enriched in both clay and phosphorus, in comparison to catchment topsoils. Empirical soil loss equations based on the Universal Soil Loss Equation (USLE) [Modified Universal Soil Loss Equation (MUSLE), Soiloss and Revised Universal Soil Loss Equation (RUSLE)] accurately predicted the measured sediment yields, with Soiloss being the most accurate. Although Soiloss is the only empirical equation to use Australian data, it is only marginally better than MUSLE, a simplified version of the USLE used for teaching. RUSLE predictions of soil loss rates were closely correlated with measured sediment yields but required inputs for poorly defined parameters. European land uses in the South Creek catchment, the largest shale catchment in western Sydney, have probably increased mean annual sediment yield by 4.4 times over that in 1788. Further increases are likely with increasing urbanisation.
An improved calibration curve between soil pH measured in waterand CaCl2
Authors: Henderson B. L. , Bui E. N.
Published: March 2003

A new pH water to pH CaCl2 calibration curve was derived from data pooled from 2 National Land and Water Resources Audit projects. A total of 70465 observations with both pH in water and pH in CaCl2 were available for statistical analysis. An additive model for pH in CaCl2 was fitted from a smooth function of pH in water created by a smoothing spline with 6 degrees of freedom. This model appeared stable outside the range of the data and performed well (R2 = 96.2, s = 0.24). The additive model for conversion of pHw to pHCa is sigmoidal over the range of pH 2.5 to 10.5 and is similar in shape to earlier models. Using this new model, a look-up table for converting pHw to pHCa was created.
Short-term effects of incubated legume and grass materials on soil acidity and C and N mineralisation in a soil of north-east Australia
Authors: Marx M. , Marschner B. , Nelson P. N.
Published: March 2003

Perennial grass growth forms the basis of beef production systems in northern Australia. To improve pasture productivity the woody legume Stylosanthes has been introduced into these native pastures. However, the growth of legumes has been recognised to be a major factor in soil acidification, thereby reducing soil fertility. In order to determine impacts of Stylosanthes scabra (stylo) or Urochloa mosambicensis (urochloa) residues on soil pH, acid neutralising capacity (ANC), and C and N mineralisation, their tops and roots were incubated at a rate equivalent to 10 t dry matter/ha at 25�C for 25 days in topsoil samples of a Mottled-Subnatric Yellow Sodosol from a long-term field experiment under urochloa or under stylo cover. The amount of CO2-C released during the first 2 days of incubation was correlated with the decrease in dissolved organic C. Plant material addition immediately raised the pH and ANC relative to the control. This was related to the amount of ash alkalinity of the plant residues added to the soil. Since the ash alkalinity is a measure for the organic anion content of plant material, it was concluded that the pH buffering was due to protonation of organic anions. During incubation, net N mineralisation was only observed in the urochloa soil amended with stylo leaves. In all other treatments, N added in the residues was immobilised by microorganisms due to the high availability of easily degradable C-sources. Consequently, there was no further change in pH or ANC during incubation, since no significant amounts of H+ were produced or consumed during N conversion processes.
Improvements to peroxide oxidation methods for analysing sulfur in acid sulfate soils
Authors: McElnea Angus E. , Ahern Col R. , Menzies Neal W.
Published: March 2003

Improvements to peroxide oxidation methods for analysing acid sulfate soils (ASS) are introduced. The soil solution ratio has been increased to 1 : 40, titrations are performed in suspension, and the duration of the peroxide digest stage is substantially shortened. For 9 acid sulfate soils, the peroxide oxidisable sulfur value obtained using the improved method was compared with the reduced inorganic sulfur result obtained using the chromium reducible sulfur method. Their regression was highly significant, the slope of the regression line was not significantly different (P = 0.05) from unity, and the intercept not significantly different from zero. A complete sulfur budget for the improved method showed there was no loss of sulfur as has been reported for earlier peroxide oxidation techniques. When soils were very finely ground, efficient oxidation of sulfides was achieved, despite the milder digestion conditions. Highly sulfidic and organic soils were shown to be the most difficult to analyse using either the improved method or the chromium method. No single analytical method can be universally applied to all ASS, rather a suite of methods is necessary for a thorough understanding of many ASS. The improved peroxide method, in combination with the chromium method and the 4 M HCl extraction, form a sound platform for informed decision making on the management of acid sulfate soils.
Soil organic matter as influenced by straw management practices and inclusion of grass and clover seed crops in cereal rotations
Authors: Curtin D. , Fraser P. M.
Published: March 2003

In New Zealand, cereal straw has traditionally been burned to facilitate seedbed preparation for the succeeding crop. Because of concerns over the decline of organic matter and the associated deterioration in soil structure, farmers are interested in incorporating crop residues as a means of maintaining organic matter levels. In a 6-year trial on a Wakanui silt loam on the Canterbury Plains, we evaluated the effects of 3 straw management practices (i.e. straw incorporation, burning of straw, and straw removal) on total and labile soil organic matter. A fourth treatment was included to evaluate the local practice of including seed crops (grass and clover) in cereal rotations. The seed crops were grown every second year, the crop sequence being cereal–ryegrass–cereal–clover–cereal–clover. The rate of straw (wheat) decomposition was determined using a litter bag technique, with the bags being buried at a depth of 15 cm for intervals of up to 19 months. In the straw-incorporated treatment, about 25 t/ha of straw (~11 t C/ha) was returned to the soil during the trial. However, there was no significant effect (P > 0.05) of straw management treatments on total soil C (or N), or on labile organic matter pools, although there was a tendency for higher levels of mineralisable C and N where straw was incorporated. Measured straw decomposition rates were consistent with predictions of the Douglas-Rickman residue decomposition model. Under the relatively warm conditions of the Canterbury Plains (thermal time typically >4000 degree-days per year, calculated as the sum of daily degree-days above a base temperature of 0�C), about three-quarters of incorporated straw decomposed within a year. Of the 11 t C/ha of straw-C incorporated, we estimated that only about 1 t C/ha would remain in the soil at the time of sampling. An increase in soil C by this amount would not be detectable (total soil C was about 55 t/ha in the upper 15 cm). Growing seed crops every second year increased several of the labile organic pools (mineralisable C and N, light fraction C and N, microbial biomass) in the 0–7.5 and 7.5 cm soil layers and this may have beneficial effects (e.g. improved N supply) on the succeeding cereal crop. However, the seed crops did not significantly increase total soil organic matter within the 6 years.
The rapid assessment of concentrations and solid phase associations of macro- and micronutrients in alkaline soils by mid-infrared diffuse reflectance spectroscopy
Authors: Bertrand I. , Janik L. J. , Holloway R. E. , Armstrong R. D. , McLaughlin M. J.
Published: March 2003

Chemical analysis is a crucial but often expensive and time consuming step in the characterisation of soils. Mid-infrared diffuse reflectance (MIR-DRIFT) spectroscopy coupled with partial least square (PLS) analysis was used to determine macro- and micronutrient concentrations of a range of alkaline soils from southern Australia. Solid phase associations of macro- and micronutrients were also investigated using the mineralogical information contained in the infrared spectra of soil samples. Results showed that MIR-PLS analysis is a powerful and rapid technique for the accurate prediction of more than 15 chemical properties from each soil sample spectrum. Correlation coefficients for MIR derived concentration versus laboratory determined values were greater than R2 = 0.80 for soil moisture, calcium carbonate concentration, total concentration of Mg, K, S, Fe, Al, Mn, Zn, Cu, and oxalate- extractable Al, Fe, Mn, and Si. In calcareous soils, sulfur was associated with carbonate and conversely Mg was more related to the clay concentration of soils. Micronutrients such as Fe, Zn, Mn, and Cu were positively associated with smectite/illite in the clay fraction and negatively with kaolinite. The potential use of these results in partitioning model to assess plant available micronutrients pools is discussed.
A field study on persistence and mobility of metsulfuron-methyl in three tropical agricultural soils
Authors: Ismail B. S. , Tet-Vun Chong
Published: March 2003

Studies on the persistence and mobility of metsulfuron-methyl in 3 soil types (Lating, Sungai Buluh, and Serdang Series) were conducted under field conditions. Two weeks after treatment (WAT), metsulfuron-methyl applied at 30 g/ha leached downward to the lowest depth of the soil profile of 30–40 cm in the Sungai Buluh and Serdang soils, but not in the Lating soil. At the recommended treatment rate (15 g/ha), no metsulfuron-methyl residue was detected in the lowest depth for the Lating series soil studied. At 1 WAT, a high percentage of the metsulfuron-methyl residue had accumulated in the top layer of the Lating soil compared with the other 2 soil types studied. The residue in the upper layer decreased as the period from application increased. The dissipation rate of metsulfuron-methyl was greater at the recommended rate than at double the recommended rate. The half-life of metsulfuron-methyl, at the application rate of 30 g/ha, was shorter in the Lating (approximately 8.2 days) than in the Sungai Buluh and Serdang soils (13.4 and 13.4�days, respectively) for the whole profile. However, the half-life of metsulfuron-methyl when applied at the recommended rate was shorter than when applied at double the recommended rate.
Hydraulic properties of rain impact surface seals on three clay soils—influence of raindrop impact frequency and rainfall intensity during steady state
Authors: Foley J. L. , Silburn D. M.
Published: March 2003

This paper investigates the influence of rainfall intensity, and its components drop size and impact frequency, on steady state flow through sealed soils. Infiltration rates are often observed to increase with greater rainfall intensity. There appears to be no consensus in the literature on the reasons for this behaviour, making it difficult to incorporate in infiltration models. Seals were formed on 2 swelling Black Vertosols and a contrasting non-swelling Brown Sodosol, under simulated rainfall treatments with a range of rainfall intensities, drop sizes, and drop size distributions. For Vertosols, aggregate size composition of the seal, sub-seal moisture content, and suction were similar across rain treatments and between soils. Steady infiltration rate and conductivity increased 3-fold as rainfall intensity increased from 30 to 120 mm/h for Vertosols. The component of intensity responsible for this trend was isolated, with a strong positive linear relationship found between conductivity and raindrop impact frequency (R2 = 0.87). This trend was attributed to increased water entry by hydraulic penetration of drops through pores in the seal as the frequency of drop impacts increased, on more porous Vertosol seals. In contrast, rain intensity and drop impact frequency had little effect on steady infiltration rates and conductivity for the Sodosol. Abundant fine particles in the seal decreased porosity, apparently leaving few pores of large enough diameter to allow hydraulic penetration. While hydraulic penetration was suppressed, other seal properties for the Sodosol were influenced by rainfall characteristics. Larger, more energetic drops produced seals with lower moisture content and higher subseal suction than seals formed under other treatments. Results of this study indicate that water entry through sealed surfaces may consist of an actively driven component associated with hydraulic penetration of water through larger pores (jetting), as observed elsewhere in early stages of surface sealing. Water entry by this mechanism continues through to steady state on soils where significant numbers of larger pores remain open at the soil surface. This mechanism would act alone, or in addition to other mechanisms such as erosive stripping or microrilling of seals, to explain widely observed increases in infiltration rates with increasing rainfall intensity.
The measurement of actual acidity in acid sulfate soils and the determination of sulfidic acidity in suspension after peroxide oxidation
Authors: McElnea Angus E. , Ahern Col R. , Menzies Neal W.
Published: March 2003

Improvements to the routine methods for the determination of actual acidity in suspension for acid sulfate soils (ASS) are introduced. The titratable sulfidic acidity (TSA) results using an improved peroxide-based method were compared with the theoretical acidity predicted by the chromium reducible sulfur method for 9 acid sulfate soils. The regression between these 2 measures of sulfidic acidity was highly significant, the slope of the regression line not significantly different from unity (P = 0.05) and the intercept not significantly different from zero. This contrasts with results of other workers using earlier peroxide oxidation methods, where TSA substantially underestimated the theoretical acidity predicted by reduced inorganic sulfur analysis. Comparison was made between the 2 principal measurements from the improved peroxide method (TSA and SPOS), with SPOS converted to theoretical sulfidic acidity to allow comparison. The relationship between these 2 measurements was highly significant. The effects of titration in suspension, as well as raising titration end points to pH 6.5, were investigated, principally with respect to the titratable actual acidity (TAA) result. TAA results obtained by KCl extraction were compared with those obtained using BaCl2, MgCl2, and water extraction. TAA in 1 M KCl suspensions titrated to pH 6.5 agreed well with titratable actual acidity measured using the 25-h extraction approach of the Lin et al. (2000a) BaCl2 method. Both BaCl2 and KCl solutions were ineffective at fully recovering acidity from synthetic jarosite without repeated extraction and titration. The application of correction factors for the estimation of total actual acidity in ASS is not supported by the results of this investigation. Acid sulfate soils that contain substantial quantities of jarosite or other acid-producing but relatively insoluble sulfate minerals continue to prove problematic to chemically analyse; however, an approach for estimating this component is discussed.
Is there evidence of arsenic movement at cattle tick dip sites?
Authors: Kimber Stephen W. L. , Sizemore Delton J. , Slavich Peter G.
Published: March 2003

Soils at cattle tick dip sites in Australia have been contaminated by a range of chemicals, including arsenic (As). To determine if significant off-site migration of As from dip sites has occurred, 28 dip sites were surveyed to assess both surface and subsurface As transport. Although previous studies using sequential extraction techniques indicated a risk of As leaching at these sites, no evidence of such movement was found in the field from this study.The As concentration in shallow groundwater (2 m) at clay textured sites was below detection level of 1 μg/L.�At sandy textured sites, groundwater immediately adjacent to the dip bath contained significant levels of soluble arsenic, but declined sharply with distance (c. 20 m) from the bath.The distribution of As at the soil surface was consistent with disposal methods used (pumping out used fluid from the dip). No sites showed significant transport and redeposition of As.Arsenic speciation in groundwater revealed As (V) as the dominant species in all sites. As (III) was found in detectable quantities at one site only.Most dip sites in New South Wales are located on heavier textured soils rich in iron oxides that adsorb As. These sites pose a negligible risk of contaminating groundwater. However, a few dip sites also occur on coastal sand relics. These sites have potential to contaminate groundwater within small distances (c. 20 m) from the dip bath. Lack of significant surface movement of residues was attributed to good vegetation cover at the sites surveyed.
Changes in bicarbonate-extractable phosphorus over time when P fertiliser was withheld or reapplied to pasture soils
Authors: Burkitt L. L. , Gourley C. J. P. , Sale P. W. G.
Published: March 2003

Field studies were established on 9 different soil types used for pasture production in the high rainfall zones of southern Victoria. Sites were selected to represent a range of phosphorus (P) buffering capacities (PBC) and were analysed for a series of chemical and physical properties before receiving P fertiliser treatments. A single application of P fertiliser in the form of triple superphosphate (TSP), single superphosphate (SSP), or TSP and lime (5 t/ha) was applied at amounts ranging from 0 to 280 kg P/ha at the start of the experiment, whilst treatments of 35 and 70 kg P/ha were reapplied at 6-monthly intervals. Soils were analysed for bicarbonate-extractable P concentration, using both the Olsen P and Colwell P methods, 6, 12, 18, 24, and 30 months after P fertiliser was applied. A strong positive linear relationship existed at all sites and time periods between the amounts of P applied as a single application and both the Olsen P and Colwell P concentrations. The slopes of these relationships measured the change in extractable P concentration per unit of P applied (ΔEP) and the rate of decline in ΔEP values represented the decline in the effectiveness of the P fertiliser with increasing time from application. The decline in these ΔEP values varied with soil type. The ΔEP values of some low to moderate P buffered soils remained 2–3 times higher compared with the most highly buffered soils, after 30 months. Despite this, the decline in ΔEP values between 6 and 30 months was difficult to predict using a single soil property. Multiple linear regressions involving a measure of PBC and either organic carbon or exchangeable hydrogen were useful methods of predicting the decline in ΔEP values across the 9 field sites examined in this study. In general, the reapplication of P fertiliser every 6 months resulted in significantly higher extractable P concentrations compared with the same rates applied in a single application, across all sites and rates of P applied. The application of SSP, TSP, and TSP and lime had little impact on ΔEP values 18–30 months after treatments were applied.
Mineral sources of potassium to plants for seven soils from south-western Australia
Authors: Pal Y. , Gilkes R. J. , Wong M. T. F.
Published: March 2003

This investigation was conducted with surface horizon samples from 7 south-western Australian soils and their 3 size fractions (sand, silt, and clay). The K release of these materials was measured for several extractants; the highest amounts of K were released from the clay (<2 μm) fraction. The presence of sand-size feldspars and incomplete removal of attached organic matter resulted in sand releasing significant amounts of K. The proportions of total K released in boiling 1 m HNO3 by the sand, silt, and clay fractions ranged from 0.4 to 3.4%, 2.6 to 36.3%, and 11.2 to 51.4%, respectively, and from 2.0% to 22.9% for the whole soils. Cumulative K uptake by 6 harvests of ryegrass over 260 days ranged from 0.26 to 1.23 cmol/kg soil.The clay fraction released higher proportions of total K to acid compared with the sand and silt size fractions because of the high specific surface area of the clay and because it contained proportionately higher amounts of illite, which releases K by both ion exchange and dissolution, whereas K release from feldspars requires congruent dissolution of the silicate structure. The differences in contents of StepK (relatively available fraction of the non-exchangeable K) and CRK (constant rate K) for 1 m HNO3 dissolution of these soils and size fractions reflect differences in mineralogical composition between the soils and size fractions. The low contents of StepK for the sand fraction indicated that K was strongly retained by feldspars. The soils with high CRK values had significant amounts of illite in the clay fraction. Values of CRK were positively related to cumulative K uptake and cumulative dry matter yield of ryegrass.
Sorption of pesticides used in banana production on soils of Ecuador
Authors: Cáceres Tanya , Ying Guang-Guo , Kookana Rai
Published: March 2003

There is concern about the migration and adverse impact of pesticides used in banana production systems in Ecuador on aquaculture and ecosystem health. Therefore, we studied the sorption of chlorothalonil, fenamiphos, and its 2 metabolites (fenamiphos sulfone and fenamiphos sulfoxide), by batch method on 6 surface soils from the Guayas River Basin (1–3�S, 79–81�W), a major banana production area of Ecuador. The sorption of chlorothalonil on the 6 soils was high and varied considerably as shown by the Kd values ranging from 68.50 to 152.60 L/kg. The sorption coefficients normalised with the organic carbon content of soil (Koc) for chlorothalonil ranged from 2330 to 7336 kg/L, with a mean value of 4012 kg/L. These Koc values are higher than those previously reported in the literature. The sorption of fenamiphos and its metabolites to the 6 soils varied among soils in a similar pattern. The Kd values ranged from 5.66 to 14.31�L/kg for fenamiphos, from 2.81 to 8.79 L/kg for fenamiphos sulfone, and from 0.77 to 4.00 L/kg for fenamiphos sulfoxide, respectively. In all of the soils the sorption coefficients of both metabolites of fenamiphos were lower than that for the parent compound. The Koc values ranged from 220 to 515 kg/L (mean value 371 kg/L) for fenamiphos, from 29 to 141 kg/L (mean value of 76 kg/L) for fenamiphos sulfoxide, and from 79 to 334 kg/L (mean value of 191 kg/L) for fenamiphos sulfone. Chlorothalonil had much stronger sorption than fenamiphos and its metabolites on the Ecuadorian soil. Due to lower sorption and therefore greater mobility and longer persistence of the fenamiphos metabolites, these compounds need adequate consideration during residue monitoring and assessment of potential off-site impacts on ecosystem health and aquaculture in the Guayas River Basin.
Layer charge characteristics of smectites from Vertosols (Vertisols) of New South Wales
Authors: Singh Balwant , Heffernan Susan
Published: March 2003

Premature senescence in cotton has been attributed to K deficiency in the cotton soils of Australia. The availability, release, and fixation of K+ in soils are mainly dependent on the clay mineralogy and layer charge characteristics of 2 : 1 clay minerals. There is a little information on the mineralogy and charge characteristics of the cotton growing soils (Vertosols) of Australia. The aims of this study were to determine the clay mineralogy, the layer charge density, and layer charge distribution of some cotton growing soils by chemical and X-ray diffraction methods.Most soil clays contain abundant smectite associated with small amounts of mica, kaolinite, and an interstratified mineral. The total layer charge as determined by the alkylammonium method ranged between 0.55 and 0.67 mol(–)/(O10(OH)2), indicating a high interlayer charge density. The layer charge of smectites from different valleys and for different size fractions was similar. The Greene-Kelly test showed that most of the charge originated in the tetrahedral sheet. The chemical analysis indicates that the smectite is an iron-rich beidellite, which has possibly formed from the weathering of mica.
Laboratory and field studies on the degradation of fipronil in a soil
Authors: Ying Guang-Guo , Kookana Rai
Published: March 2003

Degradation of a new insecticide/termiticide, fipronil, in a soil was studied in the laboratory and field. Three metabolites of fipronil (desulfinyl, sulfide, and sulfone derivatives) were identified from soils after treatment. Laboratory studies showed that soil moisture content had a great effect on the degradation rate of fipronil and products formed. High soil moisture contents (>50%) favored the formation of a sulfide derivative of fipronil by reduction, whereas low soil moisture (<50%) and well-aerated conditions favored the formation of fipronil sulfone by oxidation. Microorganisms in soil accelerated the degradation of fipronil to sulfide and sulfone derivatives. The third transformation product, a desulfinyl derivative, was formed by photodecomposition of fipronil in water and on the soil surface under sunlight. The desulfinyl derivative degraded rapidly in field soils with a half-life of 41–55 days compared with an average half-life of 132 days for fipronil. The half-life of the 'total toxic component' (fipronil and its metabolites) in field soil was 188 days on average.
Reduced leaching of nitrate, ammonium, and phosphorus in a sandy soil by fly ash amendment
Authors: Pathan S. M. , Aylmore L. A. G. , Colmer T. D.
Published: March 2003

Low ionic sorption capacities and high hydraulic conductivities of sandy soils contribute to the potential for leaching of nutrients applied to these soils. Batch sorption experiments were used to examine NO3–, NH4+, and P sorption/desorption isotherms for Karrakatta sand and Kwinana fly ash. Column experiments assessed leaching of these nutrients from this sandy soil, when amended with 4 rates (0, 5, 10, and 20%, wt/wt) of fly ash. The sorption of NO3–, NH4+, and P was higher for fly ash than the sandy soil. Phosphorus sorption was greatest for unweathered fly ash, followed by weathered fly ash and then the soil; for example, sorption from a solution containing 20 mg/L P was 90%, 28%, and 14%, respectively. Desorption of P was much slower in the unweathered fly ash than weathered fly ash or the soil. Leachates collected from columns containing fly ash amended soil (5, 10, and 20%, wt/wt) generally had lower concentrations of NO3– and NH4+ than leachates from non-amended soil. Prior to adding fertiliser, the concentration of P was greater in leachate from fly ash amended soil than from the native soil, due to fly ash (weathered) itself containing 92.5 mg/kg of extractable P. However, from day 35 onwards, the concentration of P was lower in leachates from soil amended with 10% or 20% fly ash than from non-amended soil. Thus, fly ash amendment retarded NO3–, NH4+, and P leaching in the sandy soil and may therefore be a useful tool for improvement of nutrient management in sandy soils.
Afforestation of pastures with Pinus radiata influences soil carbon and nitrogen pools and mineralisation and microbial properties
Authors: Ross D. J. , Tate K. R. , Scott N. A. , Wilde R. H. , Rodda N. J. , Townsend J. A.
Published: March 2003

In New Zealand, Pinus radiata D. Don is frequently planted on land under pasture primarily for production forestry, but with the added advantage of potentially offsetting carbon dioxide (CO2) emissions from energy and industrial sources. Conversion of pasture to P. radiata plantations can, however, result in lowered contents of soil carbon (C) at some sites. We here examine the effects of this land-use change on soil C and nitrogen (N) pools, and on microbial properties involved in the cycling of these nutrients, at 5 paired sites, each with an established pasture and P. radiata plantation. Four sites had first-rotation trees aged 12–30 years and the other site second-rotation trees aged 20 years. In mineral soil at 0–10 cm depth, total and microbial C and N, extractable C, CO2-C production, and, generally, net mineral-N production were lower under P. radiata than under pasture; differences were significant (P < 0.05), except for total and extractable C at 2 sites. Differences between these land uses were less distinct in soil at 10–30 cm depth. On an area basis, total C in 0–30 cm depth soil was lower under P. radiata than under pasture at most sites, but significantly lower at only one site. Total N, microbial C and N, and CO2-C and net mineral-N production were, however, again generally significantly lower under P. radiata. These ecosystem differences were less marked, although still present, except for CO2-C production, when forest litter (LFH material) was included in the area calculations. Overall, our study suggests that afforestation with P. radiata leads to a reduction in total N, microbial biomass, and microbial activity, but a less consistent effect on soil C storage after one rotation.
Chemical characteristics of phosphorus in alkaline soils from southern Australia
Authors: Bertrand I. , Holloway R. E. , Armstrong R. D. , McLaughlin M. J.
Published: March 2003

This study was performed to better understand the chemical behaviour of P in a variety of alkaline soils from southern Australia. To do so, surface soil samples of 47 alkaline cropping soils from Upper Eyre Peninsula in South Australia and from western Victoria were collected. The 22 soils collected from Eyre Peninsula were Calcarosols, and those from western Victoria were Vertosols, Alkaline Duplex soils, Sodosols, and Red Brown Calcareous soils. Parameters included total and amorphous Al and Fe, organic C, organic P, CaCO3 content, P sorption characteristics, phosphorus buffer capacity, calcium lactate (Ca-Lac) extractable P, bicarbonate-extractable (Colwell) P, water-extractable P, anion exchange membrane extractable P (AEM-P), and isotopically exchangeable P (labile P). Concentrations of micronutrients in the Calcarosols were relatively low, considered to be a function of low clay contents. Given very low background Cd concentrations in the soils, it was estimated from Cd measurements that the majority of total P in the soils was derived from previous fertiliser applications. Phosphorus buffer capacities (PBCs) were relatively high in the Calcarosols and moderately high in the other alkaline soils. P sorption behaviour in the Calcarosols was a direct function of CaCO3 content, although in the other alkaline soils, amorphous Al and Fe oxides were the principal determinants of the P sorption behaviour. Both Colwell and Ca-Lac extractants dissolved non-labile P in the highly calcareous soils, whereas AEM appeared to only remove surface-adsorbed P. In addition, Colwell P values were positively related to PBC and to the slope term in the Freundlich model (Kf) when Kf > 10. It is suggested that AEM-P may be a better predictor of P availability in highly calcareous soils compared with the other extractants.