Academic literature on the topic 'Red-brown earth'

Samples were collected from unimproved road reserves and adjacent paddocks on a 90 km transect crossing red-brown earth soils in the west and red earth soils in the east. Measurements of pH in water and CaCl2 indicated that the red earths have been acidified by approximately 0.5 pH units over the last 30-40 years. Small increases in CaCl2-extractable A1 were also recorded for the acidified red earths. The red-brown earths do not appear to have been markedly affected by soil acidification to date. Clay mineralogical data and measurements of cation exchange capacity of the <2 �m fraction indicate that red-brown earths are better buffered against acidification than red earths. However, small differences in management practices and rainfall along the transect may also be partially responsible for differences in acidification between soil types.

Crop choice depends on the relative yields of different species, and will vary according to soil type and seasonal conditions. Crop legumes are a relatively new component of agriculture in southern Australia, especially on the drier fringe of the agricultural areas. In this study wheat, barley, field peas and narrow-leafed lupin were compared at Merredin, Western Australia (mean annual rainfall 310 mm) from 1984 to 1986 on a red brown earth, a solonised brown soil, a solodic soil and, in 1984 and 1985, on an acid earthy sand. Oats, cereal rye and triticale were included in 1984, and chickpeas in 1984 and 1986. Highest mean seed yields were produced on the red brown earth and solonised brown soil, although the red brown earth produced very low yields in a dry season. Lowest yields were produced on the earthy sand. Triticale, oats and cereal rye yielded less seed than wheat or barley on all soils except the earthy sand where triticale yielded more than wheat. Legumes yielded less seed than cereals, although the yield for peas was close to that for wheat on the red brown earth. Peas yielded more than lupins or chickpeas on all soils. Lupin yield was closest to pea yield on the solodic soil and earthy sand. A separate series of experiments comparing peas and lupins in different seasonal conditions but on similar soils showed that lupins yielded more than peas when growing season rainfall was high. Peas are the most suitable crop legume for the Merredin area on all fine-textured soils. Lupins remain the choice on coarse-textured soils until pea stubbles can be managed to minimise erosion. In wetter areas lupins are a better choice on coarse-textured soils.

Studies on sodium clay separated from a red-brown earth demonstrated that higher concentrations of magnesium salts than calcium salts were required for flocculation. Statistical analysis of the data from a range of red-brown earths showed that the dispersion of clays from soils with an SAR1:5 >3 increased as the Ca/Mg ratio of 1:5 soil-water extracts decreased below unity. The hydraulic conductivity of columns of <2 mm surface and subsurface samples from one red-brown earth was significantly reduced when Ca/Mg ratios in the percolating solutions were below unity only when the SAR was above 3 and the TCC (total cation concentration) values were less than the predicted flocculation values. When the TCC values of the percolating solution exceeded the flocculation values, hydraulic conductivity was not affected by either SAR or Ca/Mg ratio. If structural problems in sodic soils containing high levels of exchangeable magnesium (e.g. Ca/ Mg < 1) are to be minimized, it is necessary to maintain an electrolyte level above the threshold value for a particular soil. In red-brown earths the specific effect of magnesium is so small that for magnesium-dominant soils an additional gypsum application of 1 t ha-1 for the surface 10 cm of soil should be sufficient.

Latex (natural polymer) and poly-DADMAC (synthetic polymer) were applied to a red brown earth (Alfisol) and a Wiesenboden (Mollisol). Run-off, infiltration, sediment loss and water stable aggregates were measured after subjecting the soils to simulated rainfall. Water retention of latex and poly-DADMAC amended soils was determined. The MED test for hydrophobicity was also carried out for the latex-treated soil. Latex decreased run-off and erosion, and increased infiltration on both soils. Poly-DADMAC minimized run-off and erosion, and increased infiltration on the Wiesenboden. It increased run-off and decreased infiltration on the red-brown earth; however, it still decreased erosion. Latex increased the percentage of water-stable aggregates > 2 mm on the red-brown earth, but it had less effect on the Wiesenboden. Poly-DADMAC decreased the percentage of water-stable aggregates < 0.125 mm on both soils after simulated rainfall. Both latex and poly-DADMAC had little effect on water retention of the red-brown earth and the Wiesenboden. Application of 1.5 g kg-1 of latex increased MED values of both soils, to give values that indicate moderate water-repellence but should not affect plant growth. Generally, latex was more effective on the red-brown earth and poly-DADMAC was more effective on the Wiesenboden. It seems that latex can be effective on all soil types, but poly-DADMAC will have more effect on clay soils.

Lime requirement curves based on relative yield and pH data for 4 soil types were derived to estimate the amount of lime required to reach maximum yield for wheat, triticale, barley, and canola. Simple equations expressing lime requirement as a function of soil pH accounted for >90% of the variation in applied lime on 3 soil types (red brown earth, red podsolic, podsolised red earth). When aluminium and manganese (0.01 mol CaCl2/L extracted) were included in these equations, either individually or together, they did not improve the relationship significantly for these 3 sites; however, manganese significantly improved the predictability of lime for solodic soil. A comparison of this model with a laboratory-based model showed good correlation for 3 soils (red brown earth, red podsolic, podsolised red earth), but the laboratory method underestimated the field lime requirement of solodic soil.

A high NIR reflectance ceramic pigments palette based on rare earths except black (La,Li-SrCuSi4O10 blue wesselsite, Pr-CeO2 red-brown cerianite, Mo-Y2Ce2O7 yellow cerate, Sr4Mn2CuO9 black hexagonal perovskite) was compared with the coolest traditional pigments palette prepared by dry powder coating (DPC) to obtain “core-shell” pigments (Co-willemite blue, Cr-franklinite brown, Ni,Sb-rutile yellow, Co,Cr-spinel black). Adding CaCO3 as a binder, normalized NIR reflectance at L* = 85, 55 and 30 was compared for yellow, brown and blue-black powders, respectively. Rare earths lack intense absorption bands in the NIR range and therefore its pigments show higher NIR reflectance, but normalized measurements show smaller differences and even have an inverse result for blue pigments. The pigmenting capacity and stability study in different media show that the stability of cool rare earth pigments is lower than that of DPC classical pigments, except in the case of the red-brown Pr-cerianite pigment.

Five field trials to screen a range of barley germplasm for tolerance to saline soil conditions were conducted on irrigation farms in southern New South Wales, in areas affected by secondary salinisation from shallow watertables. Three trials were located on heavy grey clay soils and 2 on red-brown earth soils. An electromagnetic soil conductivity meter (EM-38) was used to quantify the salinity of individual field plots. Cultivars were compared in terms of their grain yield response to soil salinity. Yields were significantly reduced by soil salinity at all sites except 1 on red-brown earth. Both genetic and site differences in salinity response were identified. The reduction in yield per unit increase in electrical conductivity of the saturated paste (EC,), averaged across sites, varied from 4.7% for Forrest to 6.6% for Schooner. However, the yield reduction per unit increase in EC,, averaged across cultivars, varied from 4.1% in a red-brown earth to 6.4% in heavy clays.

Gypsum requirements of a Red-Brown Earth used for dryland cropping were determined by 2 methods: those of the State Chemistry Laboratory (SCL) and of the Institute for Sustainable Irrigated Agriculture (ISIA). These are based, respectively, on exchangeable cations of soil by the Tucker method, and on water-soluble cations in a 1:5 water extract of soil. Information was also gained on longevity of gypsum effects on soil. Gypsum was applied to plots at rates 0·5, 1, and 2 times that predicted by ISIA, whereas the SCL method predicted that no gypsum was required. After 2 years, plots were split and the 3 rates of gypsum were either applied to soil previously untreated with gypsum, or re-applied to the soil treated 2 years before. According to the SCL test, the 0–10 cm soil depth of the Red-Brown Earth was not sodic (ESP <6), it was slightly magnesic (EMgP >25), and required no gypsum. However, it was found that gypsum lowered ESP, EMgP, and clay dispersion, with some effects extending into the 10–20 cm soil depth. With the ISIA method, the 0–10 cm soil depth was classed as low-sodic, but potentially dispersive; it required 2·5 t/ha of gypsum if soil was cultivated, but no gypsum if it was direct-drilled or was under pasture. One year after application, only the highest rate of gypsum (5 t/ha) significantly (P < 0·001) raised the electrolyte concentration of the soil suspension, although all rates reduced (P < 0·001) SAR, and the 2 higher rates reduced (P < 0·01) clay dispersion. However, these effects had disappeared after Year 3. There were significant increases in crop yields due to gypsum treatment in Year 1 (0·5–0·9 t/ha, P < 0·01) and Year 2 (0·3 t/ha, P < 0·001), but no response in Year 3. Fungal diseases seemed to reduce wheat responses, and the highest rate of gypsum caused chlorosis of lupins. Judging by crop performance, the ISIA method predicted an optimal rate of gypsum for the 0–10 cm layer of this soil type. The SCL prediction was also only for the 0–10 cm layer, but had it been used for deeper layers in the profile (the original intention for the technique), it would have given a recommendation not very different from the ISIA method.

Understanding the dispersivity and migration of cellulose nanocrystals (CNCs) in porous media is important for exploring their potential for soil and water remediation. In this study, a series of saturated column experiments were conducted to investigate the coupled effects of ionic strength, iron oxides (hematite), and soil colloids on the transport of CNCs through quartz sand and natural soils (red earth and brown earth). Results showed that CNCs had high mobility in oxide-free sand and that iron oxide coating reduced the mobility of CNCs. An analysis of Derjaguin-Landau-Verwey-Overbeek interactions indicated that CNCs exhibited a deep primary minimum, nonexistent maximum repulsion and secondary minimum on hematite-coated sand, favorable for the attachment of CNCs. The maximum effluent percentage of CNCs was 96% in natural soils at 5 mM, but this value decreased to 4% at 50 mM. Soil colloids facilitated the transport of CNCs in brown earth with larger effect at higher ionic strength. The ionic strength effect was larger in natural soils than sand and in red earth than brown earth. The study showed that CNCs can travel 0.2 m to 72 m in porous media, depending on soil properties, solution chemistry, and soil colloids.

The kinetics of organic C loss were studied in six southern Queensland soils subjected to different periods (0-70 years) of cultivation and cereal cropping. The equation: Ct = Ce + (C0 - Ce)exp(- kt), where C0, Ce and C, are organic C contents initially, at equilibrium and at time k respectively, and k is the rate of loss of organic C from soil, was employed in the study. The parameter k was calculated both for %C (kc) and for weight of organic C/volume of soil (k,), determined by correcting for differences in sampling depth due to changes in bulk density upon cultivation. Mean annual rainfall largely determined both C, and Ce, presumably by influencing the amount of dry matter produced. Values of kc and kw varied greatly among the soils studied. For the 0-0.1 m depth, kw was 0.065, 0.080, 0.180, 0.259, 0.069 and 1.224 year-1 respectively for Waco (black earth - initially grassland), Langland-Logie (grey brown and red clays - brigalow), Cecilvale (grey, brown and red clays - poplar box), Billa Billa (grey, brown and red clays - belah), Thallon (grey, brown and red clays - coolibah) and Riverview (red earths - silver-leaved ironbark). The k values were significantly correlated with organic Chrease activity ratio (r = 0.99***) and reciprocal of clay content (r = 0.97**) of the virgin soils. In stepwise multiple regression analysis, aggregation index (for kc values) or exchangeable sodium percentage (for kw) and organic C/urease activity ratio of soils were significantly associated with the overall rate of loss of organic C. It was inferred, therefore, that the relative inaccessibility and protection of organic matter against microbial and enzymic attack resulted in reduced organic C loss. Losses of organic C from the deeper layers (0-0.2 m, 0-0.3 m) were observed in Waco, Langlands-Logie, Cecilvale and Riverview soils, although generally rate of loss decreased with depth.

Includes bibliographical references. The beneficial effects of tillage are often negated in Australian soils by poor aggregate structural stability. If irrigation or rain falls on exposed freshly tilled soil, crusting or harsetting often develops on drying. Rainfall intensity, kinetic energy, rate of wetting, antecedent water content and soil management history have been implicated in aggregate breakdown.

Irrigation water of poor quality can have deleterious effects on soils. However, the effect of drip irrigation on seasonal and long term (e.g. over 50 years) changes in soil chemical properties is poorly understood, complicated by the two-dimensional water flow patterns beneath drippers. Field and laboratory experiments were conducted, along with computer modelling, to evaluate morphological and physio-chemical changes in a typical Barossa Valley Red Brown Earth (Palexeralf, Chromosol or Lixisol) when drip irrigated under various changing management practices. This work focused on the following two management changes : (i) switching from long-term irrigation with a saline source to less saline water and (ii) gypsum (CaSO₄) application. A literature review (Chapter 1) focuses on the distribution, features, properties and management of Red Brown Earths in the premium viticultural regions of the Barossa Valley and McLaren Vale, South Australia. The effects of irrigation method and water quality on the rate and extent of soil deterioration are emphasised. The review also discusses the irrigation of grapes (Vitis vinifera) and summarises previous research into the effect of sodicity and salinity on grape and wine characteristics. This chapter shows the importance of Red Brown Earths to Australian viticulture, but highlights their susceptibility to chemical and physical degradation. Degradation may be prevented or remediated by increasing organic matter levels, applying gypsum, modifying cropping and through tillage practices such as deep ripping. Chapter 2 provides general information on the two study sites investigated, one in the Barossa Valley and the other at McLaren Vale. Local climate, geology, geomorphology and soils are described. Chapter 3 details laboratory, field and sampling methods used to elucidate changes in soil chemical and physical properties following irrigation. The genesis of the non-irrigated Red Brown Earth in the Barossa Valley is described in Chapter 4, and is inferred from geochemical, soil chemical, layer silicate and carbonate mineralogical data. Elemental gain and loss calculations showed 42% of original parent material mass was lost during the formation of A and A2 horizons, while the Bt1 and Bt2 horizons gained 50% of original parent material mass. This is consistent with substrate weathering and illuviation of clay from surface to lower horizons. The depth distributions of all major elements were similar ; the A horizon contained lower amounts of major elements than the remainder of the profile, indicating this region was intensely weathered. This chapter also compares the non-irrigated site to the adjacent irrigated site (separated by 10 m) to determine if the sites are pedogenically identical and geochemical changes from irrigation. Many of the differences between the non-irrigated and irrigated sites appear to be correlated with variations in quartz, clay, Fe oxide and carbonate contents, with little geological variation between the sample sites. In Chapter 5 morphological, chemical and physical properties of a non-irrigated and irrigated Red Brown Earth in the Barossa Valley are compared. Alternating applications of saline irrigation water (in summer) and non-saline rain water (in winter) have caused an increase in electrical conductivity (EC [subscript se]), sodium adsorption ratio (SAR), bulk density (ρ b) and pH. This has resulted in enhanced clay dispersion and migration. Impacts on SAR and ρ b are more pronounced at points away from the dripper due to the presence of an argillic horizon, which has greatly influenced the variations in these soil properties with depth and distance from the dripper. Dispersion and migration of clay were promoted by alternating levels of EC, while SAR remained relatively constant, resulting in the formation of a less permeable layer in the Bt1 horizon. Clay dispersion (breakdown of micro-aggregate structure) was inferred from reduced numbers of pores and voids, alterations in colouring (an indication that iron has changed oxidation state) and increased bulk density (up to 30 %). Eleven years of irrigation changed the soil from a Calcic Palexeralf (non-irrigated) to an Aquic Natrixeralf (irrigated) (Soil Survey Staff, 1999). These results, combined with data from Chapter 4, were used to develop a mechanistic model of soil changes with irrigation. Chapters 6, 7 and 8 describe field experiments conducted in the Barossa Valley and McLaren Vale regions. This data shows seasonal and spatial variations in soil saturation extract properties ( EC [subscript se], SAR [subscript se], Na [subscipt se] and Ca [subscript se] ). At the Barossa Valley site (Chapter 6) non-irrigated soils had low EC [subscript se], SAR [subscript se], Na [subscript se] and Ca [subscript se] values throughout the sampling period. The irrigated treatments included eleven years of drip irrigation with saline water (2.5 dS / m) and also gypsum application at 0, 4 or 8 tonnes/hectare in 2001 and 2002. Salts in the profile increased with gypsum application rate, with high levels occurring midwinter 2002 prior to rainfall leaching salts. SAR has declined with gypsum application, particularly in the A horizon and at 100 cm from the dripper in the Bt1 horizon ; this has the potential to reflocculate clay particles and improve soil hydraulic conductivity. Chapter 7 presents further results from the Barossa Valley site, this treatment had been irrigated for 9 years with saline water (2.5 dS / m) prior to switching to a less saline water source (0.5 dS / m). The soil also received gypsum at 0, 4 or 8 tonnes / hectare in 2001 and 2002. It was found that the first few years are critical when switching to a less saline water source. EC declines rapidly, but SAR requires a number of years, depending on conditions, to decline, resulting in a period during which the Bt1 horizon may become dispersed. Gypsum application increased the EC [subscipt se] but not to the EC [subscript se] levels of soil irrigated with saline water. Chapter 8 examines soil chemical properties of a McLaren Vale vineyard, irrigated with moderately saline water (1.2 dS / m) since 1987 and treated with gypsum every second year since establishment. This practice prevented the SAR (< 8) rising and a large zone of the soil profile (20 to 100 cm from dripper) has a high calcium level (> 5 mmol / L). However, irrigation caused the leaching of calcium beneath the dripper in both the A and B horizons (0 to 20 cm from dripper) (< 4 mmol / L). Chapters 9 and 10 interpret and discuss results from continuous monitoring of redox potential (Eh) and soil solution composition in the Barossa Valley vineyard, irrigated with saline or non-saline water, and gypsum-treated at 0 and 4 tonnes / hectare. Soil pore water solution (Chapter 9) collected by suction cups is compared to results obtained in chapters 6 and 7. The soil has extended zones and times of high SAR and low EC. This was particularly evident in the upper B horizon, where the SAR of the soil remained stable throughout the year while the EC was more seasonally variable with EC declining during the winter months. The A horizon does not appear to be as susceptible to clay dispersion (compared to the B horizon) because during periods of low EC the SAR also declines, which may be due to the low CEC (low clay and organic matter content) of this horizon. Chapter 10 presents redox potentials (Eh) measured using platinum redox electrodes installed in the A, A2 and Bt1 horizons to examine whether Eh of the profile varies with irrigation water quality and gypsum application. Saline irrigation water caused the B horizon to become waterlogged in winter months, while less saline irrigation water caused a perched watertable to develop, due to a dispersed Bt1 horizon. Application of gypsum reduced the soil Eh particularly in the A2 horizon (+ 500 to + 50 mV) during winter. Thus redox potential can be influenced by irrigation water quality and gypsum applications. Chapter 11 incorporated site data from the Barossa Valley non-irrigated site into a predictive mathematical model, TRANSMIT, a 2D version of LEACHM. This model was used to predict zones of gypsum accumulation during long-term irrigation (67 years). When applied over the entire soil surface, gypsum accumulated at 60 to 90 cm from the dripper in the B horizon; higher application rates caused increased accumulation. When applied immediately beneath the irrigation dripper, gypsum accumulated in a 'column' under the dripper (at 0 to 35 cm radius from the dripper), with very little movement away from the dripper. Also, the zone of accumulation of salts from high and low salinity irrigation water was investigated. These regions were found to be similar, although concentrations were significantly lower with low salinity water. In low rainfall years salts accumulated throughout the B horizon (35 - 150 cm), while in periods of high rainfall (and leaching) the A, A2 and Bt1 horizons (0 - 60 cm) were leached, although at greater depths (80 - 150 cm) salt concentrations remained high. Chapter 12 summarises results and provides an understanding of soil processes in drip irrigated soils to underpin improved management options for viticulture. This study combines results from redox and soil solution monitoring, mineralogy, elemental gains and losses, and seasonal soil sampling to develop a mechanistic model of soil processes, which was combined with computer modelling to predict future properties of the soil. Major conclusions and recommendations of this study include : - Application of saline irrigation water to soil then ameliorated with gypsum - The first application of gypsum was leached by the subsequent irrigation from extended regions of the soil. As Na continues to enter the system via irrigation water, gypsum needs to be regularly applied. Otherwise calcium will be leached through the soil and SAR increases. - Application of non-saline irrigation water to soil then ameliorated with gypsum - The soil was found to only require one application at 8 tons / ha as this reduced SAR sufficiently. As less salt is entering the soil, subsequent gypsum applications can be at a lower rate or less frequently than required for saline irrigation water. - Gypsum applied directly beneath the dripper systems distributes calcium to a narrow region of the soil, while large regions of the soil require amelioration (high SAR) and are not receiving calcium. Therefore, gypsum application through the drip system or only beneath the dripper should be combined with broad acre application. - A range of methods to sample vineyards is recommended for duplex soils, including the use of saturation extracts, sampling time, sampling location (distance from dripper) and depth of sampling. This work is critical for vineyard management and may be applicable to other Australian viticulture regions with Red Brown Earths.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004.

Includes bibliographical references.
xxiv, 177 p. : ill. ; 30 cm.
The beneficial effects of tillage are often negated in Australian soils by poor aggregate structural stability. If irrigation or rain falls on exposed freshly tilled soil, crusting or hardsetting often develops on drying. Rainfall intensity, kinetic energy, rate of wetting, anticedent water contentand soil management history have been implicated in aggregate breakdown.
Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1995

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A soil profile exhibiting strong textural differentiation between surface and subsurface horizons at Keyneton, South Australia, was sampled for quantitative and qualitative analyses of the processes responsible for development. From constant resistant mineral ratios throughout the profile it was concluded that the soil had formed from uniform parent material, suggesting that pedological processes had heavily influenced formation. Particle size distribution, clay mineralogy determined by XRD, and microstructural features indicated that clay accumulation in the subsurface was accompanied by a greater intensity of weathering in the surface horizons. The presence of void argillans in the B horizon provided strong evidence for the translocation of clay. Mass balance calculations showed significant volumetric expansion and mass gain throughout the entire profile, but greatest in the B horizons. Al, Fe, Na and Si were all gained in large quantities. The results indicate that clay translocation by illuviation is a dominant process in the development of textural differentiation, with some clay likely to have formed in situ.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical cinches, 2012

For many of us who studied and came of age in the last two decades of the twentieth century, there was nothing more prosaic, lacking in romance, and less worthy of our scientific curiosity than petroleum. The basic questions about its composition and origin had been answered, and it was no longer one of Nature’s secrets luring us to discovery, but rather the dull stuff of industry and business, money and technology. Some of us even imagined, naively, that we would witness the end of the age of fossil fuels: they were the bane of modern man, the source of pollution, environmental disaster, and climate change that threatened to disrupt ecosystems and civilizations around the entire globe. Finding new reserves, we reasoned, would only forestall the inevitable, or exacerbate the havoc. But when Jürgen joined Germany’s government-funded Institute of Petroleum and Organic Geochemistry in 1975, there was still a sense of mission in finding new reserves. The energy crisis of the early 1970s had created a heightened awareness of the value of fossil fuels and the need for conservation, but the accepted wisdom remained that oil was the key to the future and well-being of civilization. And the chemistry, it seems, was anything but banal—it was, in fact, leading not just to a better success rate in finding new reserves of oil, but also to a new understanding of life that no one had foreseen. Certainly for Geoff and the generations of organic chemists that came before him, the oils that occasionally seeped out of a crack in a rock, or came spouting out of the earth if one drilled a hole in the right place, were as intriguing as the life some said they came from. Liquid from a solid, organic from mineral, black or brown or dark red, it was as if blood were oozing from stone, an enigma that inspired inquiry from scientists long before it found its place among man’s most coveted commodities.