bluuebunny/crossref_metadata_2025 huggingface dataset:
A quick-release coupling for a hand auger
Authors: Thompson JM
Published: April 2005

This report describes the design and function of a hand-augering system using a square hollow-section steel tubing and spring-load pins to enable rapid coupling and uncoupling. The report does not attempt to elaborate on auger cutting head design and performance; the Jarrett Auger is used in this report only to illustrate the complete auger assembly.
Thermoluminescence dating of coastal dune sand related to a higher stand of lake woods, Northern Territory
Authors: Hutton JT , Prescott JR , Twidale CR
Published: April 2005

A thermoluminescence age of about 20 000 years (� 3 000) B.P. has been obtained for samples of dune sand from near Lake Woods. This gives the time when the sample was last exposed to direct daylight, and it dates a period of dune building associated with an ancestral Lake Woods. The age is compatible with geomorphological evidence.
A comparison of soil sampling procedures used to monitor soil fertility in permanent pastures
Authors: Friesen DK , Blair GJ
Published: April 2005

Soil testing programs are often brought in disrepute by unexplained variability in the data. The deposition of dung and urine onto grazed pasture brings about marked variation in the chemical status of soils which contributes to this variability. A study was undertaken to compare a range of sampling procedures to estimate Colwell-P, Bray-1 P, bicarbonate K and pH levels in adjacent low and high P status paddocks. The sampling strategies used consisted of 75 by 50 m grids; whole and stratified paddock zig-zag and cluster (monitor plot) samplings. Soil test means for the various parameters did not vary among sampling methods. The number of grid samples required to estimate within 10% of the mean varied from 121 for Bray-1 P down to 1 for soil pH. Sampling efficiencies were higher for cluster sampling than for whole paddock zig-zag path sampling. Stratification generally did not improve sampling efficiency in these paddocks. Soil test means declined as sampling depth increased, but the coefficient of variation remained constant for Colwell-P and pH. The results indicate that cluster sampling (monitor plots) is the most appropriate procedure for estimating the nutrient status of grazed pastures. This sampling method enables a more accurate measure to be taken of the nutrient status of a paddock and should allow more reasonable estimates to be made of the temporal variations in soil test.
The estimated store of soluble salts in the Lake Eyre catchment in Queensland and their possible transport in streamflow to the lake
Authors: Gunn RH , Fleming PM
Published: April 2005

Analytical data from 145 samples of deeply weathered and unweathered rocks and 35 soil samples form the basis for a first approximation estimate of the store of soluble salts in the Lake Eyre catchment covering about 500 x 103 km2 in Queensland. A simple landscape model is defined to estimate the spatial distribution of the soluble chemical constituents of the various rocks and soils. The estimated quantities of soluble sodium and chloride in the catchment are 14x 109 and 25 x 109 tonnes respectively. Some weathered rocks also contain appreciable nitrate and ammonium ions. Available data indicate that bicarbonate, sodium and calcium are the dominant ions in stream flood flows, whereas halite and gypsum are the dominant salts in the lake. Precipitation or reconstitution of degraded clays in the suspended load may account for the absence of carbonates in the lake. It is concluded that the weathered and unweathered Cretaceous sedimentary rocks in the catchment contain large stores of soluble salts, and are the most likely sources of the bulk of the salts in the lake.
Movement of applied phosphorus following the mining and revegetation of mineral sands on Australia's east coast
Authors: Diggle AJ , Bell LC
Published: April 2005

The magnitude of phosphorus movement through a range of mined and unmined sands on Australia's east coast was measured under saturated and unsaturated flow in laboratory columns and in a field experiment of 16 months' duration. Relationships were examined between the amounts of leaching observed and the chemical and physical characteristics of the sands and the rates (0-306 kg P/ha) and forms (KH2PO4,, triple superphosphate and rock phosphate) in which phosphorus was added. Moderate movement of phosphorus was observed in all of the sand types examined, with the greatest movement occurring in A, and stockpiled A, horizon material from a podzol profile and the least being in B horizon material from the same profile. The extent of movement was related to the phosphorus adsorption capacity of the sands, the solubility of the phosphorus source, and the amount and rate of water movement. The adsorption capacity of the sands was positively correlated with the amount of aluminium and iron oxyhydroxides on the quartz grains; the coefficients of correlation (r) between the maximum phosphorus adsorbed and the aluminium and iron extracted by H2SO4- HClO4, were 0.98 and 0.84 respectively. The relevance of the findings to ground water quality and native species regeneration are briefly discussed.
Variations in natural enrichment of 15N in the profiles of some Australian pasture soils
Authors: Ledgard SF , Freney JR , Simpson JR
Published: April 2005

Variability in the natural enrichment of 15N in total nitrogen (N) and several N fractions was examined for profiles of pasture soils differing in parent material and period under Trifolium subterraneum. The natural enrichment of 15N in the total N of surface soils (0-5 cm) within a 400 km2 catchment ranged from 2.55 to 6.79�(expressed as �15N with respect to atmospheric N2). There was no relationship with parent material, period under T. subterraneum or concentration of total N in the soil. In one soil, lateral variations in �15N over a 12 m2 grid were within the range of 5.01 to 7.95�. The �15N of total soil N always increased with depth in the soil profiles. This was associated with an increase in the stable clay-sized humus fraction, which had a higher �15N than the less humified organic N in sand and silt-sized fractions. One soil was separated into four depth layers in which �15N in the inorganic N, mineralizable N, plant-extractable N and total soil N were determined. The first three parameters all had lower �15N values than the total soil N. The �15N of total N increased with soil depth, whereas there was no change with depth in the other three parameters.
Reactions of copper with soil affecting its availability to plants. III. Effect of incubation temperature
Authors: Brennan RF , Gartrell JW , Robson AD
Published: April 2005

The effect of soil temperature on the reactions between applied copper and soil constituents was examined in a black calcareous sand from Dongara. The uptake of copper by wheat plants was estimated after the soil had been maintained at field capacity at different soil temperatures (10, 15, 20, 25, 30�C) for 30 and 60 days after copper had been applied. The higher the temperature at which the soil was incubated (over the range 10-30�C), the lower was the amount of copper subsequently taken up by the wheat plants. A non-linear decay function adequately described the effects of the interaction between time and temperature on copper uptake by wheat plants.
The short-term fate of urea applied to barley in a humid climate. I. Experiments
Authors: Mohammed IH , Scotter DR , Gregg PEH
Published: April 2005

The fate of 15N labelled urea and potassium bromide applied to a mole-tile drained silt loam soil, sown to barley, was investigated using microplots and small weighable lysimeters. Two irrigation treatments, corresponding to normal and high rainfall conditions, were imposed on the lysimeters. After 35 days approximately 90% of the applied nitrogen (N) was recovered from the lysimeters, in the soil, plants and leachate, indicating gaseous losses were not large. Approximately 50% of the urea N was hydrolysed within 3 days of application, and a similar percentage was present as organic N in the soil after 20 days. Six per cent of the fertilizer N was leached from the normal lysimeters and 14% from the wetter lysimeters. In contrast, 76% of the applied bromide was leached from the wetter lysimeters. Plant uptake into shoots and roots of fertilizer N was 32% and 22% of that applied in the normal and wetter lysimeters respectively, leaching losses being largely at the expense of plant uptake. Native soil N was also measured. It is suggested that process-oriented studies of the kind described can assist in the interpretation and extrapolation of results from conventional fertilizer, trials, particularly when used to develop simple mechanistic models.
The short-term fate of urea applied to barley in a humid climate. II. A simple model
Authors: Scotter DR , Mohammed IH , Gregg PEH
Published: April 2005

A simple model describing the transformations, leaching and plant uptake of the nitrogen (N) in urea fertilizer applied to a barley crop is presented. The model considers the root zone as a single compartment and uses daily time steps, and so can be run on a small programmable calculator. It consists of separate submodels for water, fertilizer N and native soil N. Data from a field experiment described in a companion paper were used for parameterization, and the model was then tested on another data set from that experiment. The model successfully predicted the effect, on the leaching and plant uptake of fertilizer N, of a large increase in rainfall plus irrigation from 103 mm to 186 mm in the 35 days following sowing and urea application. As an example of the model's utility, it is used to predict that if 30 mm of drainage occurred within 24 h of fertilizer application, about 33% of the fertilizer N would be leached from the root zone in the silt loam soil studied. However, the same amount of drainage occurring a week after fertilizer application would result only in about 8% of the fertilizer N being leached. The complementary roles that process-oriented field experiments and simple mechanistic models can play in soil fertility research are discussed.
Effects of irrigation and soil management for fodder crops on root zone conditions in a red-brown earth
Authors: Mason WK , Small DR , Pritchard KE
Published: April 2005

The irrigated red-brown earths in northern Victoria have traditionally been considered unsuitable for intensive cropping owing to unstable soil structure. This experiment was established to determine whether management systems for continuous double cropping or crop/lucerne rotations could be developed for these soils. A range of tillage levels, flood or furrow irrigation treatments and organic matter additions were imposed in December 1981. Soil strength, measured with a field penetrometer, has been significantly reduced by both surface soil management and deep ripping. The stability of surface soil aggregates has been significantly increased by reducing tillage, by avoiding the rapid wetting associated with flood irrigation and by the addition of organic matter. However, there has been no increase in rooting depth or activity of maize crops, as indicated by soil water extraction patterns and midday leaf water potential data, in response to the treatments imposed. However, lucerne rapidly developed an active root system, deeper in the profile than maize. This deeper root system increased the soil water supply for lucerne by approximately 50 mm.
The influence of rock weathering on the genesis of gypsum and carbonate in some Australian arid zone soils
Authors: Akpokodje EG
Published: April 2005

Some chemical and mineralogical properties of soils and rocks (fresh and weathered) from a part of the Australian arid region, were examined. The bicarbonate ion is dominant over the chloride ion in both the groundwater, the surface runoff, and the soil salt solution. This lack of similarity of ionic ratio with sea water indicates the negligible influence of oceanic salts. Most of the halite, gypsum, and secondary carbonate, were formed by the chemical weathering of the pyritic, calcareous and dolomitic phyllitic shales. Aeolian activities are partly responsible for the deposition of the locally derived salts in the soils that overlie the quartzites and sandstones.
Water retention, transmission and contact characteristics of ludas sand as influenced by farmyard manure
Authors: Kumar S , Malik RS , Dahiya IS
Published: April 2005

Small cylinders were filled to a depth of 20 cm with a sandy soil to which farmyard manure (F.Y.M.) had been added up to a maximum rate equivalent to 846 t/ha. The cylinders were set in the ground and kept moist. At the end of 10 months samples were taken for measuring water retention and saturated hydraulic conductivity as well as the rate of horizontal infiltration for 0.01 M CaCl2, and alcohol. An apparent contact angle was calculated from the last two measurements. The application of F.Y.M. caused a progressive increase in the volume of water retained at a given suction, together with a small increase in available water. Hydraulic conductivity was decreased. Cumulative horizontal infiltration of 0.01 M CaCl2 decreased markedly with increase in F.Y .M. applied. This decrease is attributed mainly to an increase in the contact angle. Values are also given for the increase in cation exchange capacity and linear shrinkage due to the treatments.
Toxic concentrations of boron in a red-brown earth at Gladstone, South Australia
Authors: Cartwright B , Zarcinas BA , Mayfield AH
Published: April 2005

Severe leaf blotching in a crop of barley growing on a red-brown earth (Calcic Rhodoxeralf) was closely associated with high concentrations of boron in the soil. No infection by fungal pathogens capable of accounting for the symptoms was found. Of 14 elements determined in the plants only accumulation of high-concentrations of boron was associated with the disorder. Boron concentrations in saturation extracts of subsoil ranged up to 17.9 �g boron/cm3 under plants that were severely affected, and plants sampled just prior to anthesis contained up to 96 fig boron/g (mean 62.4). Plants that were only slightly affected contained less than 15 �g boron/g (mean 13.8). Grain yield was depressed by 17% due to the boron toxicity. This is only the second report of boron toxicity due to naturally occurring boron in Australia, and the first for a red-brown earth.
The retention of elements in mineral pseudomorphs in lateritic saprolite from granite — a weathering budget
Authors: Anand RR , Gilkes RJ
Published: April 2005

Saprolite formed by lateritic isovolumetric chemical weathering of granite contains pseudomorphs of primary mineral grains which can be separated and analysed. For most elements the chemical composition of rock and saprolite matches the sum of the contributions by the separated primary mineral grains in the rock and their pseudomorphs in saprolite. This agreement allows an element 'budget' to be calculated, which shows that the behaviour of some elements during alteration of granite is determined by the mineralogy of the primary mineral grains and their various alteration products. Most of the Si, Ba, Sr, Pb and Cu present in feldspars in granite was lost on weathering to halloysite, whereas Ga, Al and V were retained. Most of the Zn, Mn and Co that was present in biotite in granite was also lost during alteration, whereas the pseudomorphs retained Fe, Cr and Ni. Zn, Fe, Mn, Cr and V present in magnetite were wholely retained within the hematite pseudomorphs, whereas Ni was lost. Thus Zn and Mn exhibit a mobile behaviour when initially present in biotite and a residual behaviour when present in magnetite. Ni shows an opposite behaviour; it is mobile in magnetite but residual in biotite. These differences are a consequence of the formation of different alteration products from the primary minerals.
The movement of septic tank effluent through sandy soils near Perth. I. Movement of nitrogen
Authors: Whelan BR , Barrow NJ
Published: April 2005

The mocement and transformation of nitrogen under seven septic tank installations was studied. Samples of the effluent and of the soil solution beneath the discharge systems were taken and analysed for ammonium, nitrate and pH. Most of the nitrogen came from household toilets, and after passage through a septic tank, the nitrogen was mostly in the ammonium form. It remained in this form while it was in the ponded effluent above the slime layer in the absorption systems. Once it had passed through the slime layer into the unsaturated, aerobic soil below, it was usually oxidised to nitrate within 0.5 m. This was accompanied by a drop in pH of about two units. However, in one case in which the distance between the top of the slime layer and the water table was less than 0.8 m, ammonium was not oxidized to nitrate. This was taken to indicate that the saturated zone extending below the absorption system overlapped the capillary fringe and consequently the soil was anaerobic. Accumulation of organic nitrogen was restricted to the 0.5 m slime layer which accumulated on the sandy base of the soak wells and leach drains. The low cation exchange capacity of the soil and the high rate of conversion of ammonium in the effluent to nitrate in the unsaturated soil resulted in almost all of the nitrogen from the septic tanks entering the groundwater except that lost to plant uptake.
The movement of septic tank effluent through sandy soils near Perth. II. Movement of phosphorus
Authors: Whelan BR , Barrow NJ
Published: April 2005

The potential of seven septic tank installations in the Perth (Western Australia) metropolitan area to contribute phosphate to the groundwater was investigated. The phosphate concentration in the soil solution below the soak wells and leach drains was measured using immiscible displacement and compared with the phosphate concentration of the water flowing into the systems. The phosphate sorbing properties of the subsoils were measured, and these were found to vary up to 100-fold within the same profile. A very strong correlation was established between a laboratory measure of the ability of the soil to sorb phosphate and the phosphate sorbed in the soil profile below leach drains and soak wells. The correlation held only for those systems for which little further phosphate was removed by reaction with the soil, and the phosphate in the soil solution was at or near the same concentration as the phosphate in the effluent. For a system receiving water from the bathroom, laundry and kitchen the phosphate concentration was as low as 8 �g P/ml. For a system receiving water from a toilet only, the concentration was as high as 29 �g P/ml. In systems receiving water from both sources the values were intermediate. For systems that had been installed for more than a few years, the concentration of phosphorus in the soil water down to 6 m below the soak well and leach drain was similar to that in the effluent being discharged into the soil.
Temporal fluctuations in biochemical properties of soil under pasture. I. Respiratory activity and microbial biomass
Authors: Ross DJ , Orchard VA , Rhoades DA
Published: April 2005

Temporal fluctuations in respiratory activity (CO2 production) and two indices of microbial biomass (biomass carbon and mineral-nitrogen flush contents) were determined in topsoil, predominantly a Typic Haplaquoll, from a site under grazed pastures in the Wairarapa area. Samples, with organic carbon contents averaging 6.7 and 3.6%, were taken from two separate plots at c. 4-weekly intervals for over a year. Biomass indices were estimated by the chloroform fumigation technique. The suitability of a physiological procedure for indicating biomass fluctuations was also investigated. Correlations between properties were calculated with plot effects removed. Rates of CO2 production by field-moist soil, and soil at a standardized water potential, were lowest in samples taken at the driest time of the year and correlated significantly with field-moisture content. In contrast, biomass carbon estimates were generally highest in late summer and autumn, and lowest in winter, and were correlated negatively with soil moisture content. Mineral-nitrogen flush fluctuations were less marked, and not significantly related to soil moisture or biomass carbon content. In the physiological procedure, using field-moist soil, neither rates of CO2 production by soil + glucose, nor net glucose response values, were correlated significantly with biomass carbon estimated by the fumigation technique. This procedure therefore appears unsuitable for estimating temporal fluctuations in the biomass of an individual soil under pasture.
Corrigenda - Temporal fluctuations in biochemical properties of soil under pasture. I. Respiratory activity and microbial biomass
Authors: Ross DJ , Orchard VA , Rhoades DA
Published: April 2005

Temporal fluctuations in respiratory activity (CO2 production) and two indices of microbial biomass (biomass carbon and mineral-nitrogen flush contents) were determined in topsoil, predominantly a Typic Haplaquoll, from a site under grazed pastures in the Wairarapa area. Samples, with organic carbon contents averaging 6.7 and 3.6%, were taken from two separate plots at c. 4-weekly intervals for over a year. Biomass indices were estimated by the chloroform fumigation technique. The suitability of a physiological procedure for indicating biomass fluctuations was also investigated. Correlations between properties were calculated with plot effects removed. Rates of CO2 production by field-moist soil, and soil at a standardized water potential, were lowest in samples taken at the driest time of the year and correlated significantly with field-moisture content. In contrast, biomass carbon estimates were generally highest in late summer and autumn, and lowest in winter, and were correlated negatively with soil moisture content. Mineral-nitrogen flush fluctuations were less marked, and not significantly related to soil moisture or biomass carbon content. In the physiological procedure, using field-moist soil, neither rates of CO2 production by soil + glucose, nor net glucose response values, were correlated significantly with biomass carbon estimated by the fumigation technique. This procedure therefore appears unsuitable for estimating temporal fluctuations in the biomass of an individual soil under pasture.
Changes in soil physical properties under grazed pastures
Authors: Willatt ST , Pullar DM
Published: April 2005

Soil compaction caused by animal treading in grazing of pastures has not been considered a serious problem in Australian soils. However, recent circumstantial evidence suggests that in northern Victoria compaction does occur. In an experiment conducted at the Hamilton Pastoral Research Station (western Victoria) in 1973, grazed pastures with various stocking rates showed increases in bulk density and bearing capacity of the soil, and decreases in hydraulic conductivity occurred with increasing stocking rate. Some change in pasture composition was also noted.
The use of high energy moisture characteristic to assess soil stability
Authors: Collis-George N , Figueroa BS
Published: April 2005

The laboratory method of determining aggregate stability introduced by Childs in 1940 is reconsidered. A convenient and quick method of interpreting the experimental results is presented and provides the structural index for a given soil treatment. The ratio of the structural indices for two soil treatments provides the stability ratio, which is of relevance to erosion and pedogenetic studies of structure. Illustrative results show that pretreatments such as air drying, grinding and sieving affect the structural index and stability ratio.
Some physico-chemical properties of an exposed B horizon of a red-brown earth treated with gypsum
Authors: Greene RSB , Wilson IB
Published: April 2005

Physico-chemical properties of a red-brown earth B horizon (Goulburn clay loam) were studied for three years following exposure and treatment with gypsum. In the first year irrigation and rain caused considerable leaching of soluble salts to 80 cm in both the control and gypsum treated plots. Gypsum was found to enhance the leaching of chloride by increasing the hydraulic conductivity in the upper soil profile. After three years soluble salts had returned to within 30 cm of the surface in the control plots, due to the occurrence of a perched water table. No similar increase occurred in the gypsum plots. Calcium-sodium exchange due to gypsum was slow to occur, and was mainly limited to the 0-10 cm layer. The exchange of calcium for magnesium was the dominant exchange reaction in this layer.
Radiocarbon dating of groundwater in tertiary sediments of the Eastern Murray basin
Authors: Drury LW , Calf GE , Dharmasiri JK
Published: April 2005

The Tertiary sediments located in the eastern part of the Murray Basin contain one of the most important low salinity groundwater resources in New South Wales. This has been especially apparent during recent years as increasing demands on the resource are being made by irrigators and municipal water suppliers. It is therefore imperative that the hydrogeoloical environment in which the groundwater occurs be thoroughly understood to allow adequate management of the resource.
As part of a systematic exploration of the Tertiary aquifer systems, the Australian Atomic Energy Commission, in association with the Water Resources Commission of New South Wales, carried out a radiocarbon dating project on 37 groundwater samples from bores screened in these unconsolidated sediments.
The results indicate water ages in the range 'modern' to 15 800 years. Groundwater recharge areas are indicated and rates of groundwater recharge and movement determined. The latter shows close correlation with velocity values quantitatively determined by Darcy's law.
Determination of the swelling characteristics of a soil using neutron and gamma density meters
Authors: Jayawardane NS
Published: April 2005

In-situ measurement of swelling characteristics of soils are required in soil physics and engineering studies. The combined use of neutron and gamma meters for making such measurements was evaluated. The regression of gamma ratio (�) on neutron ratio (n) was calculated by combining the calibration equations of the neutron and gamma meters with the swelling characteristics of the different soil layers in a transitional red-brown earth. The slope of the calculated regression of � on n was correlated with the extent of swelling in the soil layers. Close agreement was found between wet bulk densities calculated from measured � and n values at two adjacent sites. These densities were also very similar to the wet bulk densities obtained from the calculated regression lines of � on n for the transitional red-brown earth, allowing for soil heterogeneity of the field sites. Equations were derived for calculating the bulk density-moisture content relationship of a soil using the measured regression of � on n, and the calibration equations for the neutron and gamma meters. Equations were also developed for calculating the moisture content and the dry bulk density at a given depth in a swelling soil from a single gamma count. The use of the measured regressions of � on n to evaluate uniformity in swelling characteristics with depth in field soils is discussed. These regressions can also be used to determine the heterogeneity in swelling characteristics between field experimental sites of any soil.
Field rainfall simulator studies on two clay soils of the Darling Downs, Queensland. III. An evaluation of current methods for deriving soil erodbilities (K factors)
Authors: Loch RJ
Published: April 2005

Simulated rain has been widely used to derive soil erodibility (K) values for the Universal Soil Loss Equation (USLE). Because of concern that recent work using smaller plots may not give realistic results, this paper considers the effects of plot length and erosion process on values of K derived from rainfall simulator studies. It also highlights problems in the calculation of K from rainfall simulator data, using the factors of the USLE. Rainulator data on slope length/erosion process interactions were used to calculate soil losses and K for plot lengths of 10.7 and 22.5 m tilled up and down the slope, on two soils, both on 4% slope. K showed up to threefold variation with changes in plot length, because different erosion processes contributed to soil loss. The results also showed major differences between single-event and annual average responses of erosion to slope length, leading to the conclusion that the annual average factors of the USLE cannot be used to analyse single-event rainfall simulator data. Instead, rainfall simulator data must be converted to average annual soil losses, which can then be validly analysed, using the factors of the USLE, to derive K. The procedures presently used to calculate annual average soil losses from rainfall simulator data do not take into account erosion process/runoff rate interactions, and are therefore unsatisfactory. Single-event soil loss models may provide a means for producing better estimates of annual average soil losses suitable for the derivation of K.
Laboratory study of transformation and recovery of urea-N in three Queensland soils
Authors: Campbell CA , Myers RJK , Catchpoole VR , Vallis I , Weier KL
Published: April 2005

Recovery, movement and transformations of urea-15N applied to three cultivated Queensland soils were measured as the soil dried out from two initial moisture contents. The soils were a Prairie Soil, a Grey Clay and a Red Earth, providing a range of pH (6.6-8.1) and cation exchange capacity (7-42 C/g). Urea was applied by banding and mixing into the top 2.5 cm layer of soil. Ammonium sulfateJ5N was applied to a second set of soil samples. The soil was incubated at 35�C for 21 days. Recovery of urea-15N was 93-103% of the amount applied in the Prairie Soil, 72-92% in the Grey Clay, and 55-83% in the Red Earth. The larger recoveries were for banding urea into dry soil and the smaller for mixing it into moist soil. Some 15N moved into the 2.5 to 5.0 cm layer of soil, the amounts averaged 21%, 18% and 12% of the amount of 15N recovered in the Red Earth, Grey Clay and Prairie Soil respectively. Transformations of urea-N into ammonium-N approached completion after 3 days when urea was mixed into moist soil, but only 55% of completion after 21 days when it was banded into dry soil. The sequential losses of 15N and changes in the ammonium-N content in the soil demonstrated a strong affinity for ammonia by the Prairie Soil, a moderate affinity by the Grey Clay and a weak affinity by the Red Earth. Special precautions needed in the field to achieve efficient use of urea fertilizer therefore increase in importance from the Prairie Soil to the Grey Clay to the Red Earth.
Properties of Australian fly ashes relevant to their agronomic utilization
Authors: Aitken RL , Campbell DJ , Bell LC
Published: April 2005

Of the 13 fly ashes from Australian power stations, all were dominated by both amorphous and crystalline aluminosilicates and quartz, and these were associated with minor amounts of Fe oxides, lesser amounts of Ca, Mg, Na, K, Ti and P oxides, and variable levels of incompletely combusted C. The ashes consisted of particles predominantly in the silt plus fine sand fraction (67-98%), and electron microscopy revealed that ash matrices consisted of glassy spherical particles and less regularly shaped spongy particles. The available water capacity was high and varied from 27 to 105% with 11 of the 13 samples having values > 40%. Twelve of the 13 ashes were alkaline to strongly alkaline (pH range 8.0-12.8). Soluble salt levels were related to the coal source, and electrical conductivity of the saturation extracts (ECse) varied from 0.63 to 7.0 mS cm -1 for 11 of the samples; two ashes produced from brown coal had ECse values of 46.0 and 55.0 mS cm-1. The nutritional status of the ashes was assessed on samples leached with water to reduce the soluble salts to equilibrium levels. The ashes contained negligible amounts of N, but their P status was variable. The amounts of NH4OAc-extractable Ca and Mg were generally high in most samples and were considered more than adequate for most plant species; however, NH4OAc-extractable K values were generally low. Adequate levels of sulfate-S existed in 12 of the 13 samples, and levels of DTPAextractable Cu, Zn, Mn and Fe were high when compared with published critical values. Most of the unleached samples contained potentially toxic levels of B. The results are discussed with reference to the establishment of vegetation on ash dumps and to the use of fly ash in ameliorating the properties of soils.
Changes in the abundance and activity of certain soil and litter fauna in the jarrah forest of Western Australia after a moderate intensity fire
Authors: Abbott I
Published: April 2005

Soil coring and pitfall trapping in high quality jarrah forest from December 1979 until November 1982 evaluated the effect of a moderate intensity fire on the abundance and activity of the larger invertebrates inhabiting soil and litter. A burnt plot subject to a moderate intensity fire (780 kW m-1) in January 1980 was compared with an adjacent unburned control plot. Differences between the plots in the invertebrate fauna collected on 17 sampling dates after the fire were assessed by the Wilcoxon non-parametric test. Ten taxa in the soil cores showed no significant difference in density between plots from February 1980 to November 1982: Megascolecidae (earthworms), Araneae (spiders), Isopoda (daters), Isoptera (termites), Dermaptera (earwigs), Orthoptera part (crickets), Coleoptera (beetle) larvae, Coleoptera adults, Diptera (fly) larvae and Formicidae (ants). Diplopoda (millipedes) occurred at significantly greater densities in the burnt plot, and Chilopoda (centipedes), Thysanura (silverfish) and Blattodea (cockroaches) at significantly lower densities in the burnt plot. The total number of taxa and the density and biomass of that part of the invertebrate fauna studied did not differ significantly between plots. Similar numbers of 12 taxa were captured in pitfall traps in both plots: earthworms, spiders, Pseudoscorpionida (pseudoscorpions), centipedes, termites, cockroaches, earwigs, adult beetles, fly larvae, Hemiptera (bugs), Lepidoptera larvae (caterpillars) and Orthoptera part (grasshoppers). Crickets, beetle larvae and ants were captured in greater numbers in the unburnt plot. Similar numbers of taxa and of individuals (of all taxa combined) were captured in the plots. Therefore, all but three taxa recovered in density within three years of a moderate intensity fire in the jarrah forest. The relative abundance and/or activity of three other taxa remained depressed on the burned plot during the same period.
Hydrologic effects of crop residue management practices
Authors: Freebairn DM , Boughton WC
Published: April 2005

A daily water balance model of catchment behaviour was used with rainfall and runoff data from three 1 ha catchments over the period 1976-1981 inclusive to study the effects of different practices of crop residue management on volumes and peak rates of runoff. The practices studied were stubble burning, stubble incorporation, and stubble mulching. Rainfall and runoff data from the six-year study period were used to calibrate the catchment model to each of the management practices in turn. A 64-year record of daily rainfalls from a nearby meteorological station was used to estimate the long-term effects of the practices on the frequency distributions of runoff. An empirical relationship between peak rates of runoff and daily amounts of runoff was used with the daily water balance model to estimate the effects of the practices on peak rates of runoff. Burning of stubble produced the highest peak rates and amounts of runoff and mulching the lowest.
Mellowing and anisotropy induced by wetting of moulded soil samples
Authors: Mckenzie BM , Dexter AR
Published: April 2005

Disks of seven soils were prepared by moulding the soils at water contents in excess of their plastic limits and by drying. The disks were placed on edge on sintered glass funnels, were wetted from an arbitrary point on their circumference and were then dried isotropically. Disks that had been wetted were weaker than control disks that had not been wetted. For some soils there is a water potential, termed the critical mellowing potential, in excess of which little or no mellowing occurs. For three of the soils studied the mellowing occurred to different extents in different directions. Anisotropic mellowing was investigated as a function of the potential of the source of water causing wetting. Results from multiple wettings of disks indicate that anisotropic mellowing may lead to equilibrium states for a number of soil physical properties including structure and strength.
Effects of lime on yields and phosphate uptake by clover in relation to changes in soil phosphate and related characteristics
Authors: Holford ICR
Published: April 2005

In a glasshouse experiment on 15 acid soils from north-eastern New South Wales, lime was applied in factorial combination with phosphate to determine their effects and interactions on the yield and phosphorus uptake of white clover. Phosphate caused significant yield responses on all but one soil. The higher rate of lime increased the uptake of soil phosphate, but decreased the apparent uptake of fertilizer phosphate from most soils. These effects were generally consistent with lime-induced increases in phosphate concentration in the soil solution, exchangeable phosphate and buffer capacity. The effects of lime on yields and phosphorus uptake by clover on the 14 phosphate-deficient soils suggest that responses to lime will depend on whether the soils are high in manganese or toxic in aluminium. Where clover contained > 110 ppm manganese, lime increased yields only in the absence of applied phosphate (negative interactions). Where clover contained toxic levels of aluminium, lime increased yields only in the presence of phosphate (positive interaction). In the former soils, lime increased the levels of exchangeable phosphate, phosphate concentration in solution, and uptake of soil phosphate, but generally depressed the uptake of fertilizer phosphate. In the aluminium toxic soil, lime greatly decreased the levels of exchangeable phosphate and buffer capacity, and increased the uptake of fertilizer phosphate but not of soil phosphate.
The effects of landforming on crop production on a red-brown earth
Authors: Jessop RS , Macleod DA , Hulme PJ , Mckenzie DC
Published: April 2005

Crop growth on the exposed subsoils of Macquarie Valley red-brown earths, which have been levelled for flood irrigation development, is much less than on undisturbed and fill areas. A project was carried out to quantify the differences in properties between topsoil and exposed subsoil and to relate these differences to observed crop performance. Cotton growth was measured on cut (surface soil removed) and fill (additional surface soil added from cut areas) sites. Soil samples were collected from both sites for chemical and physical analysis. To supplement these measurements pot experiments were conducted using cut and fill soils, a mixture of the two to simulate mixing in the field, all with or without gypsum. In the field, cotton growth on the cut soil was less than half that on the fill due to lower emergence and slower subsequent growth. Pot experiments confirmed these differences, although the surface structural problems were exacerbated by the rapid wetting of soil in pots. Differences between the surface of the cut and fill soils were attributed to the poorer development and lower stability of structure in the exposed subsoil. Below 30 cm, ESP, EMgP and Dispersion Index were higher in the cut than in the fill sites; ECaP and pH were lower. The pot experiments indicated that mixing of topsoil and subsoil improved emergence and subsequent growth, compared with the exposed subsoil, but gypsum had no significant ameliorative effect.
The Levenshtein metric, a new means for soil classification tested by data from a sand-podzol chronosequence and evaluated by discriminant function analysis
Authors: Little IP , Ross DR
Published: April 2005

Soil profiles are difficult to compare by statistical methods because sampling depths and intervals and the number of samples per profile may vary. This paper discusses a novel method for handling the problem. Chemical data from 52 soil profiles, which formed a chronosequence of podzols from Fraser Island, south-eastern Queensland, was classified using the Levenshtein metric. The soils varied from undifferentiated sands to deeply weathered podzols with many metres of bleached A, horizon. The data used were the proportions by weight in the soil samples of Na, K, Ca, Mg, Fe and Al extracted by mild acid digests. A polythetic divisive program was used to form seven groups from a matrix of six attributes and 573 samples. These groups were used to code profiles into strings of digits whose length equalled the number of samples in a profile. The Levenshtein metric then formed these strings into a dissimilarity matrix, which in turn was used to produce groups by an agglomerative hierarchical procedure. The groups produced by this procedure were checked using discriminant function analysis applied to depth function parameters derived from the original data set used in the pattern analysis procedures. These parameters were derived from a model which is consistent with ideas of soil genesis, hence their use should favour a classification related to soil development. The classificatory procedure could also be weighted for the depth to the B horizon, a procedure that was considered to be a direct weighting for the degree of soil development. Discriminant function analysis showed that the groups produced could be discriminated on the basis of depth function parameters regardless of any depth weighting. The groups were consistent with the known geochronology, but contained an important component due to other factors such as parent material and surface accumulation due to plant activity. Classification involving the Levenshtein metric proved to be a sound means of taking adequate account of the variation present in the data. Supplementary procedures provided by TAXON enable fresh insights into the nature of the individuals and their interrelationships to be obtained.
Nitrogen sorption isotherms and the microstructure of vertisols
Authors: Murray RS , Coughton KJ , Quirk JP
Published: April 2005

The microstructure of 12 Queensland cracking clay soils has been examined using low temperature nitrogen sorption. The adsorption isotherms are satisfactorily described, below about P/Po = 0.8, by the general BET equation with n values in the range 2-4; this is consistent with the presence of pores of width 1.4-2.8 nm. Increased values of n, obtained after critical point drying or addition of kaolinite to the clay fraction of one soil, support the physical significance of this parameter as a measure of pore size. The desorption isotherms all exhibit pronounced steps at about P/Po = 0.5, which is near the widely accepted lower limit of applicability of the Kelvin equation, but which is also consistent with the presence of pores with widths of 2.7 nm. The consistency of these two sorption branches is such that the desorption isotherms have been interpreted as arising from the drainage of independent assemblies of slits and wedge-shaped voids, with widths concentrated in the range 0-3 nm, probably generated by the extended interleaving of smectite lamellae. The validity of this interpretation of the data, and the origin and significance of this microstructure in relation to clay particle shape and size, are discussed.
Yield responsiveness and response curvature as essential criteria for the evaluation and calibration of soil phosphate tests for wheat
Authors: Holford ICR , Morgan JM , Bradley J , Cullis BR
Published: April 2005

In a study using data from 57 wheat field experiments on the central-western slopes of New South Wales, eight soil phosphate tests (Bray,, Bray,, alkaline fluoride, Mehlich, Truog, lactate, Olsen and Colwell) were evaluated and calibrated in terms of responsiveness (�) and response curvature (C) parameters derived from the Mitscherlich equation. The results showed that, regardless of how well correlated a soil test is with yield responsiveness, it cannot give a satisfactory estimate of fertilizer requirement unless yield response curvature is also taken into account. The tendency of soil test values, especially of the Colwell test, to be negatively related to response curvature, and hence inversely related to fertilizer effectiveness, compounded the problem of directly relating soil test values to fertilizer requirement. The best test (lactate) accounted for only 28% of the variance in fertilizer requirement, compared with 50% of the variance in responsiveness, and the worst test (Colwell) was completely unrelated to fertilizer requirements. When fertilizer requirement was estimated from the lactate test value and the actual response curvature for each experiment, 68% of the variance (from the actual fertilizer requirement) was accounted for. Thirteen experiments were subject to drier conditions than the others, and these were less responsive and had lower fertilizer requirements relative to soil test values. In relation to yield responsiveness, the Colwell test was most sensitive (P < 0.001) to dry conditions, while the two best tests (lactate and Bray,) were the least sensitive (P > 0.05). The results demonstrated the superiority of acidic anionic extractants over alkaline bicarbonate extractants on moderately acid to alkaline wheat-growing soils.
Temporal fluctuations in soil test values under permanent pasture in New England, N.S.W
Authors: Friesen DK , Blair GJ , Duncan M
Published: April 2005

Soil test P, K and pH were monitored on a monthly basis for two years in two P-rate grazing experiments on permanent pastures near Armidale, N.S.W. Highly significant fluctuations in time were observed for all soil tests at both sites. Components of variance derived from variance analyses indicated that temporal variation formed from 45-98% of the total random variance, depending on the soil test and site concerned. The relative magnitude of the temporal component did not vary substantially between fertilized and unfertilized plots. Correlation analyses did not establish any consistent association between soil test values and soil moisture index (SMI) or soil temperature, except for soil pH where positive and negative correlations, respectively, were found. Sampling efficiency analysis indicated that more than one sampling time would be required annually (or even bi-annually) to determine soil test means within acceptable confidence limits. Observation that the spatial component of variation was reduced in smaller plots suggests the use of small plots to monitor changes in soil fertility in large paddocks.
The residual effectiveness of phosphorus for stylosanthes pastures on red and yellow earths in the semi-arid tropics
Authors: Probert ME , Williams J
Published: April 2005

A mathematical description is presented of the effects through time of phosphorus fertilizer application on the growth of Stylosanthes hamata cv. Verano and on changes in extractable soil phosphorus on a red and a yellow earth in the semi-arid tropics. For the five years of observations, the models used provided reasonable descriptions of both aspects. It was not possible, however, to clearly demonstrate which of two functions tested better described the decreasing effectiveness of phosphorus with time. The simpler exponential function provided as good a fit to the yield data as did the function proposed by Barrow, whilst for the extractable phosphorus data the latter did explain a significantly higher proportion of the variance, but its coefficients could not be estimated with great precision. The results show that the phosphorus requirements of such pastures on these soils are modest. Extractable soil phosporus levels of approximately 12 �g g-1 in either 0.005 M H2SO4 or 0.5 M NaHCO3 are indicated as being adequate to ensure near-maximum yields of the legume. Long-term maintenance fertilizer needs as predicted by the models are discussed.