bluuebunny/crossref_metadata_2025 huggingface dataset:
Management practices for control of runoff losses from cotton furrows under storm rainfall. I. Runoff and sediment on a black Vertosol
Authors: Silburn D. M. , Glanville S. F.
Published: September 2002

Improved practices are needed to minimise soil erosion and related
agrochemical transport from cotton fields during rain. We evaluated two
options available to cotton growers, namely retention of surface cover and
controlling wheel traffic, using simulated rain on a hill–furrow system
on a well-aggregated black Vertosol. A companion paper explores effects on
pesticide transport. Increasing cover resulted in an increase in the rain
ultivar by
use the fetus lacks the appropriate enzyme systems, clearance of toxic
substances takes place via the placenta and maternal liver. Thus, a suitable
in vitro system can effectively differentiate between
primary and secondary drug effects. In the present study, 13-day-old fetal
testis, at the stage of incipient differentiation, were cultured for 4 days
in vitro in the presence of graded doses of caffeine,
theophylline or theobromine. It was found that explants exposed to caffeine or
theobromine differentiated normally, developing seminiferous cords made up of
Sertoli and germ cells, soon followed by the differentiation of functionally
active Leydig cells appearing in the newly formed interstitium. However,
explants exposed to theophylline failed to develop seminiferous cords and, as
a consequence, Leydig cells. In conclusion, insights obtained from different
experimental methods, such as organ culture or whole organism studies, are not
always identical. It may be prudent, therefore, to take into account that
certain experimental techniques, despite providing valuable information, may
require confirmation by other
The stability of soils used for cropping in northern Victoria and southern New South Wales
Authors: Vance W. H. , McKenzie B. M. , Tisdall J. M.
Published: September 2002

Three hundred and six soil samples were classified for sodicity on the basis of exchangeable sodium percentage (ESP), and for spontaneous or mechanical dispersion on the basis of a dispersion test (Emerson 1991). Each sample was analysed for pH, electrical conductivity (EC), concentrations of exchangeable and soluble cations (Ca2+, Mg2+, Na+, K+), and concentration of organic carbon (OC). These variables were used to explain the sodicity and dispersive classifications of the 306 samples. Concentrations of exchangeable and soluble Ca2+, Mg2+, and Na+ along with EC and total cation concentration (TCC) significantly affected the sodicity and dispersion classification of the soil. A sodic soil was expected to disperse spontaneously, a non-sodic soil was not expected to disperse spontaneously. From this hypothesis the expected and observed dispersion class was compared with sodicity class. The expected result corresponded to the observed result 77% of the time and the hypothesis was accepted (P < 0.001).
Evaluation of WEPP for runoff and soil loss prediction at Gunnedah, NSW, Australia
Authors: Yu B. , Rosewell C. J.
Published: September 2002

It is important to use historical data to test physically based runoff and
soil erosion prediction models as well as the method to estimate model
parameters. WEPP (Water Erosion Prediction Project) was validated for bare
fallow and annual wheat treatments at Gunnedah, New South Wales, Australia.
Wheat stubble was either burned or mulched. Climate, soil, management, and
runoff and soil loss data were collected for the period 1980–87 for 3
bare fallow plots, and 1950–74 for 10 annual wheat plots. Three slope
lengths from 21 to 62 m were established for the treatment with stubble
burned. Slope steepness varied from 8% to 9% at the site.
Effective saturated hydraulic conductivity and soil erodibility parameters
were estimated from measured soil properties. No further calibration of these
parameters was attempted in order to assess the true potential of the model
for runoff and soil loss predictions. WEPP worked well for the bare fallow
plots with prediction efficiency of 0.97 for event runoff and soil losses.
WEPP generally over-predicted the runoff, and consequently, the soil loss for
annual wheat treatments for the site. WEPP was able to predict the effect of
slope length on sediment concentration and soil loss for the site. CLIGEN,
which provides the continuous climate input to WEPP, was found to produce
adequately the mean daily rainfall, but produced higher than expected peak
rainfall intensity, resulting in higher runoff and soil loss for all
treatments.
Sodic soil reclamation: Modelling and field study
Authors: Suarez Donald L.
Published: September 2002

Reclamation of sodic soils has traditionally been undertaken using calculation
of gypsum or Ca requirement assuming 100% exchange efficiency and
neglect of the contribution of calcium carbonate in the profile. The UNSATCHEM
model is reviewed and then evaluated for its ability to predict field
reclamation of a sodic saline soil. The 40-ha field site was initially at an
electrical conductivity (EC) of 50 dS/m and a sodium absorption ratio
(SAR) of 144 in the top 30 cm. After installation of a drainage system, 24
Mg/ha of gypsum was applied to a depth of 15 cm in the soil. Subsequently,
114 cm of water was applied by almost continuous ponding for 3 months. Model
simulations were made based on infiltration of 70–80 cm of water,
correcting for the estimated evaporation of 41 cm of water. These infiltration
estimates are consistent with the good fit between the measured Cl
concentrations after reclamation and the model predicted values after
70–80 cm of infiltrated water. Model predictions of EC and SAR after
reclamation gave a satisfactory fit to the measured values. The effectiveness
of mixing gypsum to various depths was evaluated in terms of the predicted SAR
profiles. Alternative management practices of green manuring in presence of
calcite were simulated and appeared feasible. In this instance it appears
likely that the field could have been reclaimed either with less water or
without the addition of gypsum.
Sulfur forms in bulk soils and alkaline soil extracts of tropical mountain ecosystems in northern Thailand
Authors: Möller A. , Kaiser K. , Kanchanakool N. , Anecksamphant C. , Jirasuktaveekul W. , Maglinao A. , Niamskul C. , Zech W.
Published: September 2002

Sulfur, besides phosphorus, is crucial for the nutrition of plants on tropical
soils. Its availability is closely related to the turnover of soil organic
matter. To get a better insight into transformation of soil S forms during the
decomposition of organic matter, we studied inorganic and organic S pools in
bulk samples and alkaline extracts of soils under different land uses
representative of the tropical highlands of northern Thailand. Samples were
taken from a cabbage cultivation, a Pinus reforestation,
a secondary forest, and a primary forest. Total S ranged from 483 549
mg/kg in the subsoil to 1909 376 mg/kg in the organic layers, which is
relatively high for tropical soils. The major S component in soil was organic
S, comprising 75–99% of total S. Organic S was significantly
correlated with total S, organic C, and total N, indicating that there is a
close relationship between C, N, and S cycling in soil. C-bonded S was the
predominant form in the topsoils (35–99% of total S) but its
presence decreased with soil depth. The maximum concentrations of ester
SO4-S were found in the A horizons (128 49 mg/kg),
whereas the concentrations of inorganic SO4-S were small
in all horizons. Compared with the forest site, the cabbage cultivation site
was strongly depleted in S. C-bonded S was more depleted than ester
SO4-S.
A comparison of the S forms in NaOH extracts with S forms in bulk soil and C
forms as indicated by 13C-NMR spectroscopy showed
(i) that the extracts were very representative of soil
organic S fractions and (ii) that ester
SO4-S was mainly associated with O-substituted aliphatic
C. In contrast, C-bonded S seemed to be connected to more-or-less all C
binding types.
transformation of soil organic matter, sulfate.
The Environmental Mechanic (a tribute to J. R. Philip)
Authors: Bradley Frank , Clothier Brent , Denmead Tom , de Vries Dan , Ford Phillip , Kluitenberg Gerard , Knight John , Raats Pieter , Smiles David , Waechter Trevor , White Ian , Youngs Edward
Published: September 2002

John Philip AO FRS FAA was killed by
accident in Amsterdam in 1999. This
tribute provides a complete bibliography
and brings together perceptions of the work
and of the complex character of the greatest
of Australia�s environmental scientists. It
deals with his contributions in general
applied mathematics, in soil water
movement, in liquid flow in swelling
systems, in coupled heat and mass transfer,
and in micrometeorology and physical
ecology.
Variability of soil water content and bulk density in a sugarcane field
Authors: Tominaga T. T. , Cássaro F. A. M. , Bacchi O. O. S. , Reichardt K. , Oliveira J. C. M. , Timm L. C.
Published: September 2002

The change in management practices of the sugarcane crop in Brazil, from the traditional trash burning before harvest to the new practice that leaves harvest residues on the field after harvest, can lead to alterations in the water regime and also in soil compaction levels. In this study a neutron-gamma surface gauge was used to monitor spatial and temporal variabilities of soil moisture and density in a experimental sugarcane area submitted to 3 harvest management practices: (i) mulched crop with harvest residues, (ii) crop with bare inter-row, and (iii) crop with ash residues from trash burning before harvest. Variability of soil water content and bulk density was studied using geostatistical tools and analysis of variance was used to compare averages. Autocorrelations and semivariograms indicate a spatial dependence of soil water contents, which were higher in the presence of trash residues left on the soil surface after harvest. The average difference between treatments (i) and (ii) was about of 15%, indicating the beneficial mulching effect with respect to soil water retention. Differences between (ii) and (iii) were much smaller.
Wetting rate, sodicity, and soil texture effects on infiltration rate and runoff
Authors: Mamedov A. I. , Levy G. J. , Shainberg I. , Letey J.
Published: September 2002

Surface sealing is determined by aggregate disintegration and clay dispersion,
which in turn depend on aggregate wetting rate, and soil sodicity and texture.
We hypothesised that soil susceptibility to seal formation increases when the
aggregate wetting rate (WR) is increased, and that the effect of WR depends on
soil texture and soil sodicity. The objective of this study was to investigate
the effects of WR on seal formation, by observing infiltration rate (IR) and
runoff, in cultivated soils varying in clay content and exchangeable sodium
percent (ESP). Effects of 3 wetting rates (2, 8, and 64 mm/h) on IR and
runoff from 6 Israeli soils exposed to 60 mm of simulated rain of deionised
water were studied in the laboratory. The soils ranged in clay from 8.8 to
68.3% and ESP levels from 0.9 to 20.4. Effects of WR on soil
infiltration rate and runoff depended on soil texture and soil ESP. In soils
with low clay content (8.8%), the effect of WR on seal formation was
negligible, whereas effect of ESP was significant. Conversely, in clay soils
(>52.1%), WR had a predominant effect on IR and runoff, while the
effect of ESP was notable yet secondary to that of WR. The soils with
intermediate clay content (22.5–40.2% clay) were the soils most
susceptible to seal formation, with WR and ESP having moderate effects on seal
formation. Effects of WR on aggregate disintegration and seal formation
increased with increasing clay content and aggregate stability. Conversely,
the role of ESP in determining sealing decreased with an increase in clay
content and in WR.
Impact of grassland afforestation on soil carbon in New Zealand: a review of paired-site studies
Authors: Davis M. R. , Condron L. M.
Published: September 2002

Afforestation of grassland provides an opportunity for partial mitigation of increasing carbon dioxide (CO2) levels in the atmosphere through carbon (C) fixation in biomass, but little is known of the impact of afforestation on soil C. To determine the impact of afforestation on soil C levels, data from published papers, theses, and unpublished studies of paired adjoining grassland and afforested sites in New Zealand were assembled and compared. The forest sites within each pair were planted into grassland rather than some other land use, and were a minimum of 10 years old. A total of 28 paired sites had information on both mineral soil C concentration and bulk density, 17 with the forest part of the pair aged 10-20 years, and 11 with the forest aged more than 20 years. Forest floor C information was available for 9 sites. Only 3 of the forest stands had been harvested. Results indicated that afforestation of grassland soils reduces upper mineral soil (mainly 0-10 cm layer) C levels by about 4.5 t/ha or 9.5% in the short-term; however, beyond forest age 20 years there was no difference mineral in soil C between the two systems. Soil bulk density in the 0-10 cm layer was unaffected by afforestation during the first rotation. This allowed comparison of a larger number of sites (27 with forest aged 10-20 years, 18 with forest aged >20 years) that had C concentration data only. Analysis of this larger data set confirmed results obtained from the C mass data alone. Effects of afforestation on mineral soil C were most pronounced in the upper soil and declined rapidly with depth to the extent that at most sites there was no influence of afforestation on soil C below the 0-10 cm layer. At some sites, however, the impact of afforestation proceeded to greater depths, and further study is required to determine reasons for differences between sites in this regard. The impacts of afforestation on soil C observed from the paired-site studies agree well with those of recent analyses for the upper soil layer using New Zealand national soils databases. At greater depths, however, analyses using the databases appear to greatly overestimate the influence of afforestation on soil C. The available data indicate that C accumulating in the forest floor is likely to exceed any short-term reduction in mineral soil C arising from grassland afforestation.
The potential impact of long-term copper fungicide usage on soil microbial biomass and microbial activity in an avocado orchard
Authors: Merrington G. , Rogers S. L. , Zwieten L. Van
Published: September 2002

The impact of copper-based fungicides on soil microbial function in an avocado orchard was assessed. Copper (Cu) residues (280 and 340 mg/kg, respectively) in surface soils (0-2 cm) of an established avocado orchard were shown to be significantly (n = 6, P ≤ 0.05) greater than a nearby reference site under natural vegetation (13 mg/kg). The bioavailable fraction of Cu in these soils was also shown to be significantly greater (2.15 and 1.29 mg/kg, c. pCu2+ 8.64) than in the reference site (0.71 mg/kg, c. pCu2+ 9.2), as measured by ion-selective electrode in CaCl2 extraction. Similar trends were observed for the 2-10 cm soil profile. Data suggest that the Cu residues are responsible for significant reductions in biomass carbon (Cmic) even though the orchard soils had similar or elevated levels of total organic carbon (Corg). The Cmic : Corg ratio was significantly lower in all of the Cu contaminated soils, and a significant correlation was observed between CaCl2-extractable Cu in the surface soils and Cmic (n = 16, r2 = 0.68, P b 0.01). Soil respiration in surface soils from the orchard were elevated (6.04 and 5.57 mg CO2-C/kg.day) compared with the reference soil (3.04 mg CO2-C/kg.day), and the metabolic quotient (qCO2) was also significantly greater.
Studies of soil water drawdowns by single radish roots at decreasing soil water content using computer-assisted tomography
Authors: Hamza M. A. , Anderson S. H. , Aylmore L. A. G.
Published: September 2002

Application of computer-assisted tomography to the attenuation of X-rays has
been used to compare the drawdowns in soil water content associated with
radish roots at starting soil water contents (θv)
of 0.3 cm3/cm3 and 0.1
cm3/cm3, respectively.
Decreasing soil water content results in an increase in the appearance of
‘beam hardening’. Decreasing soil water content from 0.3 to 0.1
cm3/cm3 caused the
transpiration rate to decrease by 6–10 times. This was presumably due to
a reduction in the water potential gradient across the root membrane. The
transpiration rate decreased less rapidly than did the water content at the
soil–root interface, suggesting some osmotic adjustment by the leaves.
This osmotic adjustment would allow the plant to maintain transpiration rate
even at relatively low soil water content. The drawdown distances associated
with roots growing at the lower soil water content were 8 times smaller than
those at the high soil water content and the value of
θv at the soil–root interface at the end of
the transpiration period was 2.5 times lower. The radish roots exhibited a
temporary slight decrease in diameter after the transpiration commenced
followed by a significant temporary increase. However, root diameter
stabilised around its original value when the plant attained an almost steady
water uptake rate. Despite the complexity arising from ‘beam
hardening’, CAT scanning can provide valuable information on processes
at the root–soil interface.
Estimation of erosion model erodibility parameters from media properties
Authors: Sheridan G. J. , So H. B. , Loch R. J. , Walker C. M.
Published: September 2002

The aim of this research was to enable erodibility values for hillslope-scale
erosion prediction models to be determined from easily measured media
properties. Simulated rainfall and overland flow experiments were carried out
on 34 soils and overburdens from 15 Queensland open-cut coal mines at The
University of Queensland Erosion Processes Laboratory. Properties of the 34
media determined included aggregate stability, Atterberg limits, bulk density,
cation exchange capacity, dispersion ratios, electrical conductivity,
exchangeable sodium percentage, organic carbon content, pH, texture, and water
content at field capacity and wilting point. Correlation and stepwise multiple
regression procedures were used to determine those media properties that could
best be used to predict rill and interill erodibility. Correlations between
media properties and sediment delivery at each of 5, 10, 15, 20, and
30% slope revealed that different media properties were correlated with
erosion rates at different slopes. A media property could show a strong
correlation with erodibility at 30% slope, and a low correlation at
5% slope. Splitting the data set into soils only, and overburdens only,
showed that properties that were positively correlated with erosion rates for
one group could be negatively correlated for the other group. Therefore, in
this study, erodibility could not be explicitly linked to one set of media
properties for all medium types and erosive conditions. It was concluded that
a single regression equation could not be used to predict erodibility under
all conditions. Instead, 4 equations were developed to predict rill and
interill erodibility, for soils and overburdens separately. The need for
separate regression equations was attributed to the presence of different
erosive sub-processes for specific combinations of medium type and slope
gradient.
The long-term effects of lime (CaCO3), gypsum (CaSO4.2H2O), and tillage on the physical and chemical properties of a sodic red-brown earth
Authors: Valzano F. P. , Murphy B. W. , Greene R. S. B.
Published: September 2002

In 1994 a long-term field trial with 9 lime–gypsum combinations and 2
tillage treatments (reduced tillage and direct drill) was established on a
sodic red-brown earth soil [surface pH(water) 6.5] at a property
near Peak Hill, NSW, Australia. The lime-gypsum treatments were: L0G0 (lime 0
t/ha, gypsum 0 t/ha), L0G1, L0G2.5, L0G5, L1G0, L2.5G0, L5G0, L1G1,
and L2.5G1.
After 3 years, higher rates of lime and gypsum or their combinations
significantly (P < 0.01) increased exchangeable and
soluble calcium and decreased exchangeable and soluble sodium in the
0–100 mm layer of the soil. Gypsum was found to decrease the total
soluble cation concentration (TCC) in some instances, while lime maintained
TCC at 1995 levels. Soil pH was significantly higher on all lime plots and
electrical conductivity was slightly higher on plots treated with lime than on
control plots. Organic carbon levels were significantly higher in plots with
gypsum and high levels of the lime–gypsum combination (L2.5G1). The
effectiveness of the lime treatments was influenced by the initial soil pH (as
suggested by the findings of other studies).
The lime, and to a lesser extent the gypsum treatments, improved the physical
properties of the soil as measured by the Emerson aggregate test, penetrometer
resistance, infiltration, and water availability. A tillage effect was also
present resulting in less dispersion, decreased penetrometer resistance, and
higher infiltration rates in plots prepared with reduced tillage practices
than direct drill plots. Plant-available water content (AWC) was significantly
higher in the surface soil of plots treated with L2.5G1 than control
treatments. The L5G0 and L0G5 treatments did not significantly improve the
AWC. Crop yields were increased by some of the lime–gypsum treatments in
both 1995 and 1996. Corresponding with the increased AWC, the L2.5G1 treatment
produced the highest crop yields. Plots with reduced tillage had consistently
higher yields than those with direct drill treatment.
Understanding subsoil acidification: effect of nitrogen transformation and nitrate leaching
Authors: Rengel Z. , Tang C. , Raphael C. , Bowden J. W.
Published: September 2002

Nitrification and nitrate leaching have been suggested to be major causes of
soil acidification. However, it is unknown whether these processes cause
subsoil acidification. Soil column experiments examined the effect of the
addition of Ca(NO3)2 or
(NH4)2SO4 to
the topsoil horizon on subsoil acidification under nodulated lupins
(Lupinus angustifolius L.) and subterranean clover
(Trifolium subterraneum L.). Nitrate leaching was
achieved by adding excess water to the surface of the columns.
Where basal nutrients were applied only to the top 10-cm layer, about
60–70% of the total root length of lupin and over 50% of
subterranean clover were distributed in that layer. Plants grown without added
nitrate for 105 days decreased soil pH at all layers but more significantly in
the top 20 cm (by up to 0.7 units); the decrease in pH correlated well with
increased root length density of both species (r
2 = 0 .9 8 , n = 9).
The addition of Ca(NO3)2 to the
top 10-cm layer caused less acidification by about 0.1 pH units at all depths
than the treatment without
Ca(NO3)2 .
Where basal nutrients were applied uniformly throughout the column, root
length density of lupin and subterranean clover tended to increase with depth.
The addition of
(NH4)2SO4 in
the top 10 cm significantly increased
NO3– concentration in all
layers but NH4+ was mainly
retained in the top 30-cm layer. Lupin and subterranean clover grown without
added NH4+ for 82 days
decreased soil pH by 0.3 units at all depths. Compared with the plants
receiving no (NH4)2SO
4 , lupin grown with
(NH4)2SO4 at
0–10 cm depth in the column caused more acidification by 0.05–0.2
pH units in the top 10 cm but less acidification by 0.15–0.17 units at
10–40 cm depth in the column; subterranean clover grown with
(NH4)2SO4
caused more acidification by 0.35–0.46 units in the top 10 cm and less
acidification by 0.14–0.19 units in the 20–50 cm layer.
The results suggest that the leaching of nitrate from topsoil is unlikely to
cause subsoil acidification. In contrast, the uptake of nitrate by the roots
reduces net acid production in subsoil layers.
Rapid assessment of soil compaction damage II. Relationships between the SOILpak score, strength and aeration measurements, clod shrinkage parameters, and image analysis data on a Vertisol
Authors: McKenzie D. C.
Published: September 2002

Compacted and well-structured sites, on a Vertisol used for irrigated cotton
production, were compared using a range of procedures for assessing soil
structural form. The techniques considered were: visual/ tactile
assessment using the SOILpak score, shear strength, penetration resistance,
core bulk density and air-filled porosity, clod shrinkage analysis, and image
analysis. All of the methods under consideration distinguished compacted soil
from well-structured soil, including core bulk density, which had previously
been thought of as a poor measure of soil structure in Vertisols. The simple
SOILpak scoring procedure was shown to have great potential as a tool for land
managers. Soil factors known to directly affect root growth, mechanical
impedance and aeration, correlated well with the indirect procedures. The
cheaper methods (SOILpak score and core bulk density determination) related
most strongly to shear strength at the reference water content (plastic
limit). The SOILpak score was more strongly related to air-filled porosity
than clod shrinkage analysis or image analysis; shear strength had the same
predictive power as the SOILpak score for estimating air-filled porosity.
However, an advantage of using resin-impregnated soil monoliths and the
SOLICON image analysis system is that the samples are big enough to represent
a large proportion of the root-zone. Staining of the soil with a Rhodamine dye
solution provided images that were too coarse for the routine determination of
SOLICON parameters, but it is a useful and rapid procedure for highlighting
those macropores that are connected with the soil surface. Clod shrinkage
parameters underestimated soil air-filled porosity where compacted aggregates
were interspersed with finely aggregated soil.
Cotton root growth in a compacted Vertisol (Grey Vertosol). II. Correlation with image analysis parameters
Authors: McKenzie D. C. , Greenhalgh S. E. , Koppi A. J. , MacLeod D. A. , McBratney A. B.
Published: September 2002

A differential staining procedure was developed to study the degree of
association between soil structural form parameters, derived using the SOLICON
image analysis system, and the root growth of cotton plants. Under the
climatic conditions that prevailed during the experimental period, severe
impedance of taproots was associated with a clod width in the range 28 mm to
≥30 mm and a macroporosity value in the range 0.00–0.04
m3/m3. The new root assessment
procedure detected soil structural features, for example, well-aerated zones
adjacent to near-surface roots in degraded soil not shown by other methods and
allowed direct measurement of the proportion of a root’s surface in
contact with the soil atmosphere. However, the assessment method should be
complemented by direct measurement of the morphology of nearby cotton taproots
that have been pulled from the soil. Features that can be assessed include
root flatness, the number of lateral roots, root obliquity, and the degree of
tapering. In this experiment the lack of flattening in roots pulled from the
compacted soil suggested that poor aeration was a bigger problem for the
cotton plants than mechanical impedance. Root deformation was not associated
with a large decline in lint yield at this site because the crop was irrigated
frequently and did not suffer any nutritional stress, and the relatively steep
field slope permitted rapid surface drainage.
Effect of regular irrigation with dairy farm effluent on soil organic matter and soil microbial biomass
Authors: Barkle G. F. , Stenger R. , Singleton P. L. , Painter D. J.
Published: September 2002

Over recent years regulatory authorities in New Zealand have promoted
irrigation of dairy farm effluent (DFE) onto the land, to protect surface
water quality. The rate at which the resistant organic matter from DFE
accumulates in the soil and the effect of any accumulation on other soil
organic matter (SOM) related pools, such as microbial biomass, are, however,
unknown. This information is necessary to determine the long-term impact and
sustainability of land-applied DFE.
In this paper we report on changes over 4 years in organic carbon (C
org) and total nitrogen (N t )
from a soil receiving a high application rate of DFE. Soil microbial biomass
(C mic ) measurements were also included to test the hypothesis that C
mic or the C mic /C
org ratio can be used as an early indicator of changes
in SOM.
The regular irrigation with DFE at the high rates used in this study increased
the C mic , pH, C org , and N
t of the soil receiving the effluent. The time series of
C mic showed that this measurement is suitable as an
early indicator of changes in C org and N
t , whereas a single determination of the C
mic /C org ratio was not.
The sustainability of DFE application onto land in terms of N leaching can be
maintained only when the supply of inorganic N is continually matched by the
demand of the pasture. This means that inorganic N fertilisation has to be
reduced concurrently with the gradually increasing N mineralisation from the
accumulating organic matter.
Review: A bioavailability-based rationale for controlling metal and metalloid contamination of agricultural land in Australia and New Zealand
Authors: McLaughlin M. J. , Hamon R. E. , McLaren R. G. , Speir T. W. , Rogers S. L.
Published: September 2002

Metal pollution of agricultural land in Australia and New Zealand is less
severe than that documented in many European countries, due to the lower
density of urban developments and a lower level of industrialisation. However,
Australia and New Zealand are highly dependent on plant production systems
based on plant-microbial symbioses (e.g. Rhizobium,
mycorrhizae) and other natural biogeochemical processes for maintaining
nutrient status in soils that are generally low in nutrients and, in
Australia, also low in organic matter. Data linking metal concentrations in
soil to agricultural and ecological effects are sparse for Australia and New
Zealand, and regulatory frameworks and guidelines to control metal
contamination of soils rely heavily on data generated in countries of the
northern hemisphere. Adoption of benchmark concentrations for metal
contaminants from these countries has led to inappropriate levels being chosen
for several elements. These problems could be avoided and metal contamination
of soils could be more effectively controlled if instead of relying on total
concentrations of metals in soil and soil amendments, regulations and
guidelines considered the biologically active fractions. This review considers
the advantages and disadvantages of a bioavailability-based approach to the
control of metal contamination of soils and suggests improvements needed to
avoid both over- and under-protective measures.
A response-surface calibration model for rapid and versatile site-specific lime-requirement predictions in south-eastern Australia
Authors: Rossel R. A. Viscarra , McBratney A. B.
Published: September 2002

The development of response-surface calibration models that may be used in
conjunction with the lime requirement buffer methods is described. The buffer
methods tested were the Woodruff, New Wooruff, Mehlich, and Shoemaker, McLean
and Pratt lime-requirement buffers. Model predictions were compared with those
obtained from multivariate models and buffer methods calibrated using
conventional linear regressions. The multivariate models described lime
requirement as a function of a number of soil variables. All of the models
were validated against soil : CaCO 3 incubations using a
statistical jackknifing procedure for error and bias estimations. The
advantages of the derived response-surface models were their improved
prediction accuracy and flexibility, with a choice of any target pH
CaCl 2 value between 5.5 and 7 without need for
individual calibrations. The response-surface model for the Woodruff buffer
method produced the most accurate predictions of lime requirement. The
uncertainty of its lime requirement predictions for acid soil in an
agricultural field at Kelso, New South Wales, Australia, measured by
95% confidence intervals, was 0.22 Mg/ha. A spatial analysis of
lime requirement for the field showed a range of 4–11 Mg/ha. This
range provides a reason for site-specific lime applications. Under- and
over-applications resulting from a ‘blanket’ 7.13 Mg/ha
single-rate application of lime over the field were estimated to range from
–4 to 2.9 Mg/ha.
Field shrinkage curves of a swelling clay soil: analysis of multiple structural swelling and shrinkage phases in the prisms of a Vertisol
Authors: Cabidoche Y-M. , Ruy S.
Published: September 2002

The variations in the layer thickness of a Vertisol cropped with sugarcane
were recorded under natural conditions for several months. Drainage pipes were
installed at 1.10 m depth to drain water quickly from macro-cracks. The soil
gravimetric water content was measured from the surface to 1.10 m depth at
weekly intervals. The relation between soil water content and soil bulk
specific volume (shrinkage curve) is not unique. A significant structural
swelling or shrinkage can occur at any water content of the clay matrix while
the macro-cracks remain air-filled. The variations in structural water content
account for >60% and 80% of the total water content
variations, respectively, in topsoil and subsoil. In the latter, the
intra-prism structural porosity is filled and then emptied prior to matric
porosity. This explains the disappearance of the water stress in such dry soil
after any rainfall event. A more detailed description of the intra-prism
structural porosity is required for a better understanding of the processes.
Our work suggests that this porosity is mainly formed by planar
inter-aggregate voids in the tilled layers, whereas its shape is tubular in
the deeper layers. The results already provide guidelines concerning the
modelling of water flow in such Vertisol, i.e. water flow in structural pores
is quite independent of matric and crack flows.
Changes in chemical nature of soil organic carbon in Vertisols under wheat in south-eastern Queensland
Authors: Skjemstad J. O. , Dalal R. C. , Janik L. J. , McGowan J. A.
Published: September 2002

The impact of cropping and cultivation (up to 50 years) on the nature and pool
structure of organic C in two different soil types was investigated using a
combination of physical and chemical fractionations and solid-state
13 C NMR spectroscopy. NMR spectroscopy revealed that
aryl C contributed significantly to the organic C in the Waco soil
(Pellustert) but not in the Langlands-Logie soil (Chromustert). The aryl C
content of both soils was largely preserved despite the significant decrease
in total organic C, following cultivation, although other organic forms
appeared to rapidly decline at similar rates to one another. High energy UV
photo-oxidation along with solid-state 13 C NMR
spectroscopy demonstrated that the aryl C was mainly charcoal (char) in the
<53 mm fraction of the soils which appeared to be highly resistant to
microbial decomposition. Char C content of the Waco soil remained near 6.0 g
C/kg soil and near 2.0 g C/kg soil for the Langlands-Logie soil. This
char was evident to a depth of at least 30 cm in both soils.
Fractionation yielded 4 organic C fractions: particulate organic C, humic C,
char C, and physically protected C. By equating these fractions to the
resistant plant material (particulate organic C), humic pool (humic C), and
inert pool (char C) of the RothC soil C turnover model and comparing a number
of simulations with measured fractions, we showed that the inert pool equated
well with the measured char C. The measured particulate organic C fraction was
of an appropriate size to represent the resistant plant material pool of the
model but appeared to have a much slower turnover rate. Similarly, the
measured humic pool was of a similar size to that required by the model but
was more labile (faster turnover rate) than that used in the RothC model. This
may be due to a combination of the labile proteinaceous nature of this pool
and its lower than expected protection by physical association with the
smectitic clay matrix.
Flame residence times and rates of weight loss of eucalypt forest fuel particles
Authors: Burrows N. D.
Published: September 2002

Shape, size, composition and arrangement of fuel particles within a fuel array
significantly affect the way in which wildland fires behave. Australian
eucalypt forest fire behaviour models characterise fine fuels according to the
quantity burnt in the flaming zone, and the upper size limit for fine fuel
particles is somewhat arbitrarily set at 6 mm for the McArthur Forest Fire
Danger Meter and 10 mm for the Forest Fire Behaviour Tables for Western
Australia.
Flame residence time and rate of weight loss during combustion of dry eucalypt
leaves and different dimensions of round wood were measured to provide a
scientific basis for standardising litter fuel sampling in dry eucalypt
forests. Eucalypt leaves burnt at a rate equivalent to a piece of 4 mm
diameter round wood, with smaller diameter round wood being the most flammable
component of the fuel array. Based on flame residence times of individual fuel
particles measured in the laboratory, and eucalypt surface fuel arrays
observed in the field, fine litter fuel sampling should be standardised to
leaves and round wood less than 6 mm in diameter. This study also enables the
determination of the contribution of larger fuel particles to flaming zone
combustion and intensity.
Fire impacts and crowning in the boreal forest: study of a large wildfire in western Quebec
Authors: Kafka Victor , Gauthier Sylvie , Bergeron Yves
Published: September 2002

Within the context of studying the ecological impacts of wildland fires in the
boreal forest, a spatial analysis of a major wildfire was conducted. The fire
covered nearly 500 km 2 in the north-western part of
Quebec’s boreal forest in the summer of 1995. The spatial distribution
of different fire impacts on the forest canopy was obtained using timber
damage assessment maps. Fire impacts varied throughout the burned area,
ranging from areas where trees had completely burned crowns (43%) to
remaining patches of trees with green foliage (3%). The effects of
local stand and site factors on crown fire, as assessed by the fire impacts,
were evaluated using geographic information systems. Despite the large extent
and high intensity of the wildfire created by extreme fire weather conditions,
stepwise logistic regression and analysis by log–linear models indicated
that variations in surface material, stand composition, and estimated stand
age played a role in the presence or absence of crowning at the stand level.
However, it appears that height and density of stand, as well as topography,
did not have a significant influence. Our study presents the variability of
fire impacts and its implications, and it provides a better understanding of
the relationships between landscape components and fire crowning.
Résumé.Dans le cadre de
l’étude de la dynamique de la forêumflex;t
boréale, une analyse d’un grand incendie a
été réalisée. À la fin
de l’été 1995, cet incendie a couvert un
territoire de près de 500 km 2 dans la partie
nord-ouest de la forêumflex;t boréale
québécoise. La distribution spatiale des impacts du feu
sur la voute forestière a été obtenue
à partir de cartes d’évaluation des dommages aux
forêumflex;ts causés par le feu. Dans la zone
brûumflex;lée, la gamme des impacts de l’incendie
varie d’étendues où les arbres
présentent des cimes complètement
brûumflex;lées (43%) à des secteurs
où le feuillage des arbres est demeuré vert (3%).
L’effet de facteurs biotiques et abiotiques sur l’occurrence
d’un feu de cime a été établi
à l’aide d’un système d’information
géographique. Une régression logistique pas à
pas et une analyse de modèles log-linéaires ont
révélé que certaines modalités des
dépôts de surface, de la composition et de l’âge
du peuplement ont joué un rôle important dans
l’occurrence d’un feu de cime au niveau du peuplement. Par contre,
il semble que la hauteur et la densité du peuplement, ainsi que la
topographie, n’aient pas eu d’effets significatifs. Notre
étude met en lumière la variabilité et
l’importance des impacts d’un incendie, tout en permettant de
mieux comprendre la relation entre les composantes du territoire et le
comportement des incendies.
Effects of exotic grasses on potential fine fuel loads in the groundcover of south Florida slash pine savannas
Authors: Platt William J. , Gottschalk Robert M.
Published: September 2002

Invasive exotic grasses have been hypothesized to increase fine fuel loads,
thereby increasing the frequency and intensity of fires. Most studies,
however, have been conducted in habitats in which natural fires do not occur
frequently. We investigated the effects of two invasive grass species,
Imperata cylindrica and
Neyraudia reynaudiana, on potential fine fuel loads of
south Florida slash pine savannas, which naturally experience frequent fires
during the lightning season. Total above-ground biomass of fine fuels and
litter biomass were greater in areas where exotic grasses were present than in
nearby areas not containing these grasses. In addition, less above-ground
biomass of native species was present in areas where
N. reynaudiana was present. The increases in both
potential total fine fuels and litter suggest that exotic grass invasions can
change fire characteristics, even in ecosystems where fires occur very
frequently.
Modeling fire effects
Authors: Reinhardt Elizabeth D. , Keane Robert E. , Brown James K.
Published: September 2002

This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999
Fire effects are modeled for a variety of reasons including: to evaluate risk,
to develop treatment prescriptions, to compare management options, and to
understand ecosystems. Fire effects modeling may be conducted at a range of
temporal and spatial scales. First-order fire effects are those that are the
direct result of the combustion process such as plant injury and death, fuel
consumption and smoke production. Modeling these effects provides an important
cornerstone for models that operate at larger spatial and temporal scales.
Detailed physical models of heat transfer and the combustion process under
development should provide a vehicle for quantifying fire treatment and
predicting fire effects. Second-order fire effects are indirect consequences
of fire and other post-fire interactions such as weather. They may take place
a few hours to many decades after a fire. Some important second-order fire
effects are smoke dispersion, erosion, and vegetation succession. Many
approaches have been used to model fire effects including empirical,
mechanistic, stochastic, and combinations of all three. Selection of the
appropriate model approach and scale depends on the objectives of the modeler,
as well as the quality and quantity of available data. This paper is not meant
to provide an exhaustive review of fire effects models. Instead, it presents a
background in approaches to modeling fire effects to provide managers a basis
for selecting and interpreting simulation tools.
Characterizing fuels in the 21st Century
Authors: Sandberg David V. , Ottmar Roger D. , Cushon Geoffrey H.
Published: September 2002

This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999
The ongoing development of sophisticated fire behavior and effects models has
demonstrated the need for a comprehensive system of fuel classification that
more accurately captures the structural complexity and geographic diversity of
fuelbeds. The Fire and Environmental Research Applications Team (FERA) of the
USDA Forest Service, Pacific Northwest Research Station, is developing a
national system of fuel characteristic classification (FCC). The system is
designed to accommodate researchers and managers operating at a variety of
scales, and who have access to a variety of kinds of input data. Users can
generate fuel characteristics by accessing existing fuelbed descriptions
(fuelbed prototypes) using generic information such as cover type or
vegetation form. Fuelbed prototypes will provide the best available
predictions of the kind, quality and abundance of fuels. Users can accept
these default settings or modify some or all of them using more detailed
information about vegetation structure and fuel biomass. When the user has
completed editing the fuelbed data, the FCC system calculates or infers
quantitative fuel characteristics (physical, chemical, and structural
properties) and probable fire parameters specific to that fuelbed. Each
user-described fuelbed is also assigned to one of approximately 192 stylized
fuel characteristic classes.
How effective is spotlighting for detecting the greater glider (Petauroides volans)?
Authors: Lindenmayer D. B. , Cunningham R. B. , Donnelly C. F. , Incoll R. D. , Pope M. L. , Tribolet C. R. , Viggers K. L. , Welsh A. H.
Published: September 2002

The efficacy of spotlighting as a field survey technique for detecting the
greater glider (Petauroides volans) was assessed by
comparing the precise location of radio-tracked animals with locations
determined simultaneously from spotlighting searches. Radio-collars were
fitted to 20 greater gliders in three eucalypt patches embedded within an
extensive radiata pine (Pinus radiata) plantation near
Tumut in south-eastern New South Wales. Our success rate for detecting
collared animals was low, even when survey effort was increased. These
findings suggest that spotlighting underestimates actual population size. A
further, properly designed study, in different forest types is needed to
provide precise estimates of the magnitude of the bias in counts of
P. volans obtained by spotlighting.
Seasonal variation in the reproductive activity of the wild rabbit (Oryctolagus cuniculus algirus) in a Mediterranean ecosystem
Authors: Gonçalves H. , Alves P. C. , Rocha A.
Published: September 2002

To establish a successful strategy for managing wild rabbit (Oryctolagus cuniculus algirus) populations it is essential to have a clear understanding of reproductive biology. In Portugal, previous work suggested a seasonal pattern of reproductive activity for this species. In this study we present additional information on the seasonal reproductive activity of the wild rabbit as well as data on the influence that environmental factors have on the onset and length of the breeding season.

The study was carried out in Pancas, southern Portugal, from October 1997 to September 1998. Rabbits were collected every two months and post mortem analyses were performed. In the males, circulating concentration of testosterone, gonadal weight, daily sperm production, diameter of the seminiferous tubules and the thickness of epithelial cells were measured. The numbers of corpora lutea, embryos and placental scars were recorded in the females. To assess abundance and quality of food, samples of herbaceous vegetation were collected and analysed for water, fibre and crude protein content.

The reproductive season extended from November to June with a peak in March/April, with both sexes showing an annual cycle of gonadal development and subsequent regression. All analysed females were pregnant and/or lactating between March and June. The mean litter size estimated by counting the embryos in the uteri was 3.90 ± 0.50. Daily sperm production was highest between November and April. Testicular function was strongly correlated with environmental temperature and the water content of the vegetation, and both testicular and ovarian development were correlated with vegetation biomass.