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Refereed/Peer-reviewed This study was carried out to determine the carbon (C) allocation of tree components following water stress in radiata pine (Pinus radiata) seedlings. The seedlings were exposed to various water contents (low, moderate and high soil water content) for 30 days and labelled with (CO₂)-C-14 gas for six hours on the 31st day. Biomass in all seedling components (foliage, stems and roots) was significantly higher in the moderate soil water content treatment than in the low soil water content treatment, while seedling biomass did not significantly differ between the moderate soil water and high soil water content treatments. The shoot/root ratio of seedlings decreased when soil water content decreased. The C concentrations of radiata pine seedlings were not affected by the soil water content, whereas the soil water stress-induced difference in the C allocation of seedlings was attributed to differences in seedling biomass. The translocation of pulse-labelled C-14 from the foliage to the roots was enhanced by low soil water content. The distribution of C-14 was highest in foliage, followed by roots, stems and soil. The results indicate that soil water content was one of the primary factors influencing biomass allocation in the early growth of radiata pine seedlings.

Regular application of phosphate (P) fertilisers has been identified as the main source of heavy metal(loid) contamination including cadmium (Cd) in agricultural soils. Some of these P fertilisers that act as a source of Cd contamination of soils have also been found to act as a sink for the immobilisation of this metal(loid). In paddy soils, redox reactions play an important role in the (im)mobilisation of nutrients and heavy metal(loid)s, as a result of flooding of the rice plains. Although a number of studies have examined the potential value of P compounds in the immobilisation of metals in contaminated soils, there has been no comprehensive review on the mechanisms involved in the P-induced (im)mobilisation of Cd in paddy soils. There are a number of factors that influences P induced Cd (im)mobilisation in paddy soils that include pH, redox reactions, liming effect, rhizosphere acidification and root iron plaques. Following a brief overview of the reactions of Cd and common P compounds that are used as fertiliser in soils, the review focuses on the above mentioned mechanisms for the (im)mobilisation of Cd by P compounds in paddy soils. The role of iron plaques on Cd status in soil and rice plants is also discussed followed by a summary and future research needs. Refereed/Peer-reviewed

New Zealand's intensively grazed pastures receive the majority of nitrogen (N) input in the form of urea, which is the major constituent of animal urine and the most common form of mineral N in inorganic N fertilizers. In soil, urea is rapidly hydrolyzed to ammonium (NH4+) ions, a part of which may be lost as ammonia (NH3) and subsequently as nitrous oxide (N2O), which is a greenhouse gas. Two glasshouse experiments were conducted to study the effect of a urease inhibitor (UI), N-(n-butyl) thiophosphoric triamide (NBPT), commercially named Agrotain, applied with urine and urea on urea hydrolysis and NH3 and N2O emissions. Treatments included the commercially available products Sustain Yellow (urea + Agrotain + 4% sulfur coating), Sustain Green (urea + Agrotain) and urea, and cattle urine (476 kg N ha− 1) with and without Agrotain applied to intact soil cores of a fine sandy loam soil. The addition of Agrotain to urine and urea (i.e. Sustain Green) reduced NH3 emission by 22% to 47%, respectively. Agrotain was also effective in reducing N2O emissions from urine and Sustain Green by 62% and 48%, respectively. The reduction in N2O emissions varied with the type and amount of N applied and plant N uptake. Plant N uptake was significantly higher in the soil cores receiving Agrotain with urea than urea alone, but the slight increase in dry matter yield was non-significant. Hence, urease inhibitor reduced N losses through NH3 and N2O emissions, thereby increasing plant uptake of N. Refereed/Peer-reviewed

This study was conducted to evaluate the effects of plantation age on the distribution of carbon (C) and nitrogen (N) in forest floor components in radiata pine (Pinus radiata D. Don) plantations. Forest floor samples from plantations of three age classes (13-year-old; 27-year-old; 41-year-old) with various site qualities (II–VII) were collected from the Kuitpo radiata pine plantations in the Mount Lofty forest region of South Australia. The C concentrations of the forest floor components were significantly higher in the 41-year-old plantation than in the 13-year-old plantation, whereas the N concentrations were significantly lower in the 41-year-old plantation than in the 13-year-old plantation, except for the needle component. The C and N content of needles was significantly larger in the 13-year-old plantation than in the 41-year-old plantation, whereas fine woody materials, such as branches and bark, contributed less to the total C and N contents in the 13-year-old plantation. The total C content of the forest floor did not significantly differ with age, whereas the N content was significantly affected by age in the radiata plantations. The results reflect the existence of considerable variation in the quality and quantity of the C and N in forest floor components associated with different ages of radiata pine growing in sites of various qualities. Refereed/Peer-reviewed

Chitosan has low uptake for most heavy metals as well as high solubility in monoprotic acids. To address these problems, sulfur-containing functional groups have been introduced to enhance the sorption of heavy metals via formation of strong coordination bonds with heavy metals and also to improve its stability. The approaches to sulfur enrichment to the chitosan structure include grafting of sulfur-containing molecules to C2 amine or C6 hydroxyl groups. Crosslinking and grafting agents such as glutaraldehyde and epichlorohydrin have also been used in chitosan modification. In this review, special emphasis is placed on the synthesis pathways of sulfur-functionalization of chitin and chitosan and their metal uptakes. Generally, the uptake of soft acid metals such as Hg(II) and Cd(II) has been shown to increase with increasing sulfur content of modified chitosan. However, other factors such as the availability of thiol and amine groups as well as surface area of the modified chitosan also influence metal sorption. Refereed/Peer-reviewed

There have been increasing interests in the conversion of organic residues into biochars in order to reduce the rate of decomposition, thereby enhancing carbon (C) sequestration in soils. However energy is required to initiate the pyrolysis process during biochar production which can also lead to the release of greenhouse gasses. Alternative methods can be used to stabilize C in composts and other organic residues without impacting their quality. The objectives of this study include: (i) to compare the rate of decomposition among various organic amendments and (ii) to examine the effect of clay materials on the stabilization of C in organic amendments. The decomposition of a number of organic amendments (composts and biochars) was examined by monitoring the release of carbon-dioxide using respiration experiments. The results indicated that the rate of decomposition as measured by half life (t1/2) varied between the organic amendments and was higher in sandy soil than in clay soil. The half life value ranged from 139 days in the sandy soil and 187 days in the clay soil for poultry manure compost to 9989 days for green waste biochar. Addition of clay materials to compost decreased the rate of decomposition, thereby increasing the stabilization of C. The half life value for poultry manure compost increased from 139 days to 620, 806 and 474 days with the addition of goethite, gibbsite and allophane, respectively. The increase in the stabilization of C with the addition of clay materials may be attributed to the immobilization of C, thereby preventing it from microbial decomposition. Stabilization of C in compost using clay materials did not impact negatively the value of composts in improving soil quality as measured by potentially mineralizable nitrogen and microbial biomass carbon in soil. Refereed/Peer-reviewed

The poultry industry is one of the largest and fastest growing agro-based industries in the world. This can be attributed to an increasing demand for poultry meat and egg products. However, a major problem facing the poultry industry is the large-scale accumulation of wastes including manure and litter which may pose disposal and pollution problems unless environmentally and economically sustainable management technologies are evolved. Most of the litter produced by the poultry industry is currently applied to agricultural land as a source of nutrients and soil amendment. However environmental pollution, resulting from nutrient and contaminant leaching can occur when poultry litter is applied under soil and climatic conditions that do not favour agronomic utilisation of the manure-borne nutrients. This review examines the composition of poultry litter in relation to nutrient content and environmental contaminants, its value as a nutrient source, soil amendment, animal feed and fuel source, and cost-effective innovative technologies for improving its value. Poultry litter provides a major source of nitrogen, phosphorus and trace elements for crop production and is effective in improving physical and biological fertility, indicating that land application remains as the main option for the utilisation of this valuable resource. The alternative use of poultry litter; as an animal feed and fuel source, is limited by contaminants, and high moisture content, respectively. The review proposes best management practices to mitigate environmental consequences associated with air and water quality parameters that are impacted by land application in order to maintain the continued productivity, profitability, and sustainability of the poultry industry. Refereed/Peer-reviewed

Globally, around 0.4×106 km2 area of land is estimated to be disturbed by mining activities, thereby contributing to severe environmental consequences including the generation of large amounts of mine spoils. The shortfall in topsoil due to poor striping practices and low levels of organic matter have been identified as common problems in rehabilitation of mining spoil. High heavy metal concentrations in mine spoil can adversely impact microbial activity and subsequent revegetation succession. The release of acids associated with mine spoils (ie, acid mine drainage through oxidation of pyrite) can also create adverse effects on the surrounding vegetation.Large quantities of biowaste, such as manure compost, biosolids, and municipal solid waste (MSW) that are low in contaminants [including metal(loid)s] can be used to rehabilitate mine spoils. These biowastes provide a source of nutrients and improve the fertility of spoils. These biowastes also act as a sink for metal(loid)s in mine tailings reducing their bioavailability through adsorption, complexation, reduction, and volatilization of metal(loid)s.This review provides an overview of the sources of biowastes and the current regulations for utilization; describes their benefits in terms of improving the physical, chemical, and biological properties of mine spoils; and elaborates on the role of the utilization of biowastes on mine spoil rehabilitation through several case studies. Finally, future research needs and strategies are identified in terms of sustainable biowaste utilization in mine spoil rehabilitation. Refereed/Peer-reviewed

Biochar has created a lot of interest because of its unique properties of sustainable agricultural production and environmental protection. Biochar is known to reduce nitrogen loss from soil in terms of nitrous oxide emission and ammonia volatilization, improve the nutrient retention capacity and structural and chemical properties of soil, and increase plant growth and productivity. Biowaste materials such as biosolids, municipal waste, and paper mill sludge are effective raw materials for biochar production. These materials are rich in nutrient content, and biochar produced using these waste products is highly effective for agricultural production and environmental remediation.

Globally, around 10 × 107 tons year−1 of biosolids is generated from wastewater treatment facilities. Biosolids contain significant amounts of organic matters and nutrients. Therefore, biosolids can be used to improve infertile and degraded soils in certain mine sites. Shortfalls in topsoil, heavy metal–rich tailings and drainage, residual soils with poor physical properties, and low–organic matter soils are common consequences of degraded mine soils. These issues adversely affect soil health including microbial activity, flora, and fauna, thereby hindering reestablishment of the lost ecological integrity. Rehabilitation has been achieved in a number of mine sites by incorporating biosolids, which demonstrated sustainable remediation of these sites. Improvements in the biological, chemical, and physical properties of degraded lands are associated with these rehabilitation cases. Furthermore, these improvements enhance the nutrient cycling, water purification, and restoration of plants and increase the recreational value of the land, thereby helping in the emergence of novel ecosystems. This chapter describes the composition of different types of biosolids and their generation, benefits, and current regulations for use, particularly regarding mine site rehabilitation and environmental contamination issues including human health concerns. Finally, challenges and future research needs are identified in terms of the minimization of environmental complications and sustainable use of biosolids.

Many countries including New Zealand, Australia, and South Korea discharge of farm effluents containing large reserves of plant nutrients into surface waters. Such discharge is currently considered a discretionary activity and requires legal consent that demands the effluent nutrient concentration to be minimized before entering surface waters. This can be achieved by land disposal or nutrient stripping of the effluent by tertiary treatment. Although the pond system (ie, biological treatment) is effective in removing suspended solids and carbon, there has been some debate about its efficiency in removing nutrients. Porous materials such as zeolite, a naturally occurring and electrically charged aluminosilicate material, can be used to adsorb nutrients from effluents. Then the nutrient-enriched material can be recycled as a soil conditioner or nutrient source. This chapter examines the potential of zeolite in nutrient stripping from wastewater streams and its value as a nutrient source. Refereed/Peer-reviewed

While landfilling provides a simple and economic means of waste disposal, it causes environmental impacts including leachate generation and greenhouse gas emissions. Increasingly, revegetation is practiced on traditionally managed landfill sites to mitigate environmental degradation. It also provides a source of biomass for energy production. Biomass from landfill sites can be converted to bioenergy through biochemical and thermochemical processes. Selection of suitable biomass-producing plants (high-yielding crops), pretreatments (e.g., removal of lignin) and providing ideal conditions for the conversion processes (e.g., temperature and pressure) influence the quantity and quality of energy generated. This chapter provides an overview of the potential volumes of biomass produced from landfills and the various methods of biomass energy conversion.

Soil acidification can be accelerated by intensive farming or prevented by sustainable management practices. Soil acidification in a managed agricultural production system is caused by the transformation of carbon (C), nitrogen (N), and sulfur (S), which releases protons (H+) to soil solution. Soil acidification decreases soil pH, causing adverse effects on plants and soil microorganisms. Acidification, coupled with aluminum, manganese, and iron toxicities, and phosphorus, calcium, magnesium, and potassium deficiencies, can lead to low soil fertility. Soil acidity influences soil C and N cycles by controlling activities of microorganisms involved in the transformations of these two elements. Traditionally, lime materials are added to neutralize acidic soils and to overcome the problems associated with soil acidification, but they also influence C and N cycles, thereby affecting greenhouse gas (GHG) flux in soils. For example, liming has been shown to decrease nitrification-induced nitrous oxide (N2O) emission from many agricultural lands. However, there are concerns that liming increases the availability of soil nitrate ( N O 3 − ), which is a substrate for N2O emission through denitrification. The dissolution of liming materials can act as either a net source or sink for carbon dioxide (CO2). Lime-derived CO2 reacts with microbial respiration-derived carbonic acid in soils to yield carbonate material, serving as a sink of CO2 in soil. In calcareous soils with high pH, agricultural lime (CaCO3) serves as a net sink for CO2 whereas in acid soils it serves as a net source of CO2. In acid soils, increased availability of aluminum (Al3+) ions inhibits activity of methane (CH4) oxidizers. Adding lime to soils has shown to increase CH4 oxidation and reduce GHG emission. The present review brings together basic concepts of soil acidification and recent developments on the implications of liming in relation to C and N transformations and cycling, particularly GHG emissions from soils. Given the major influence of lime addition on soil microorganisms relating to C and N cycles, future research should focus on the role of liming on soil microbial communities to provide insight into combined mitigation of N2O, CO2, and CH4 gases from agricultural soils.

Soil is the sink and source of heavy metals (both geogenic and anthropogenic) and plants are the ecosystem regulators, balancing the chemistry of life on earth. However, roots are the only connection between soil and plants, which are the real engineers of ecosystem dynamics responsible for environmental balance and stability. The plant-soil interface termed as ‘rhizosphere’ is a typical zone of soil where the physical, chemical and biological characteristics are different from bulk soil (outside the rhizosphere region). This is mainly controlled by physiological response from plants to the environmental changes through exudation of chemicals from root region and the cascade of chemical (changes in pH and redox potential, release of anions and nutrient transformation) and biological (microbial association) events that follow. The other adaptive mechanisms include root length and area as affected by temperature, moisture and nutrient content of the soil. In the recent years, advanced technologies have lead to significant findings at the micro-level in rhizosphere research, targeting the role of root-soil interface towards nutrient availability and agricultural productivity. However, with increasing human activities (including agriculture), undesirable quantites of heavy metals are being added to the environment thereby resulting in soil contamination. This review will discuss in detail on the processes involved in the (im) mobilisation of heavy metals in and around the root region as affected by chemical (pH and root exudates) and biological (microorganisms) components. Refereed/Peer-reviewed

Biosolid samples from the Bolivar Wastewater Treatment Plant (South Australia) were mixed with lime (1, 3 and 5%; w/w basis), red mud (Comalco Alumina Refinery, Queensland, Australia), fly ash (Alinta Energy, South Australia, Australia) and bentonite (IPOH Pacific Ltd., Queensland, Australia) (5, 10 and 20%; w/w basis). They were incubated under aerobic conditions at room temperature for seven months so that the effects of various additives on transformation of heavy metals in biosolids could be examined. The specific objectives were to study, (i) the redistribution of metals in the biosolids; and (ii) the mobilization of metals and their subsequent release to pore water. Both the NH4NO3 extractable concentration of Cd (CdNN), Cu (CuNN) and Pb (PbNN) from biosolids and the concentration of these metals in pore water were investigated. Co-composting biosolids using alkaline materials and clay mineral have been shown to immobilize metals. The pH of both biosolids and pore water increased while dissolved organic carbon (DOC) decreased on co-composting biosolids with inorganic amendments. The addition of red mud and lime resulted in the highest pH increase, and red mud proved to be most efficient in the sorption of DOC, Cd, Cu and Pb in comparison to lime, coal fly ash, and bentonite. The NH4NO3 extractable Cd (CdNN), Pb (PbNN) and Cu (CuNN) from biosolids and these metals' total concentration in pore water were lower in all amendments than biosolids alone. The effect of amendments on immobilizing biosolids-derived Cd, Pb and Cu varied according to both the nature and level of amendments being added. While red mud and lime were most effective in the immobilization of Cd and Pb in the biosolids and their subsequent release to pore water, bentonite was most effective in immobilizing Cu in the biosolids. Refereed/Peer-reviewed

Applying organic amendments including biosolids and composts to agricultural land could increase carbon (C) storage in soils and contribute significantly to the reduction of greenhouse gas emissions. Although a number of studies have examined the potential value of biosolids as a soil conditioner and nutrient source, there has been only limited work on the impact of biosolid application on C sequestration in soils. The objective of this study was to examine the potential value of biosolids in C sequestration in soils. Two types of experiments were conducted to examine the effect of biosolid application on C sequestration. In the first laboratory incubation experiment, the rate of decomposition of a range of biosolid samples was compared with other organic amendments including composts and biochars. In the second field experiment, the effect of biosolids on the growth of two bioenergy crops, Brassica juncea (Indian mustard) and Helianthus annuus (sunflower) on a landfill site was examined in relation to biomass production and C sequestration. The rate of decomposition varied amongst the organic amendments, and followed: composts > biosolids > biochar. There was a hundred fold difference in the rate of decomposition between biochar and other organic amendments. The rate of decomposition of biosolids decreased with increasing iron (Fe) and aluminum (Al) contents of biosolids. Biosolid application increased the dry matter yield of both plant species (by 2-2.5 fold), thereby increasing the biomass C input to soils. The rate of net C sequestration resulting from biosolid application (Mg C ha−1 yr−1 Mg−1 biosolids) was higher for mustard (0.103) than sunflower (0.087). Biosolid application is likely to result in a higher level of C sequestration when compared to other management strategies including fertilizer application and conservation tillage, which is attributed to increased microbial biomass, and Fe and Al oxide-induced immobilization of C. Refereed/Peer-reviewed

Volcanic ash soils display distinctive morphological, physical and chemical properties and they contain several times more organic matter than non-volcanic soils. So far, there are few studies of soil organic matter (SOM) distribution in different chemically and physically protected carbon pools of soil horizons of volcanic soils. The aim of this study was to determine the SOM distribution (and its δ13C and δ15N composition) in different chemical and physical fractions at various depth horizons of two Andisols under pasture or rain forest in southern Chile. We used the amount of humus-complexes (Cp) extracted with Na pyrophosphate as a measure of C stabilized by aluminum (Alp) and iron (Fep) in combination with density fractionation to separate particulate organic matter as free (fPOM), occluded (oPOM) and organic matter associated with the mineral fraction (MF). The results showed that soil SOM stock (0–40 cm) in the pasture soil was 166 Mg C ha−1 (11.7 Mg N ha−1) and in the forest soil 100 Mg C ha−1 (4.1 Mg N ha−1). The SOM variation was explained largely by the differences in Cp, Alp and Fep. About 34% of total soil C was found as Cp in both oPOM and MF in the topsoil, whereas 33–53% was found in the subsoil horizons. The oPOM fraction was more important in the forest soil and generally decreased in the subsoil where these fractions were enriched with δ13C and δ15N. Our results emphasize the importance of the humus complex and oPOM formation as the SOM stabilization mechanism in the forest Andisol, whereas under pasture organo-mineral interaction, including the formation of humic-metal complexes, is the most important stabilization mechanism. A conceptual model is lacking to demonstrate the major areas of uncertainty within known mechanisms and factors that explain the distribution of SOM through soil profiles in Andisols. Refereed/Peer-reviewed

We have examined the effects of both pH and phosphate concentrations on molybdate sorption by four Chilean Andisols with varying chemical properties. For both anions adsorption decreased with an increase in soil pH and also with organic matter content in the soils. In general, more phosphate than molybdate was sorbed by the soils. The Freundlich equation adequately described adsorption of both anions. Differences in the extent of sorption of molybdate and phosphate and in isotherm shape between soils were ascribed to variations in soil properties. The competitive sorp-tion data were adequately described by the multicomponent Freundlich equations. Phosphate strongly competed with molybdate for sorption sites on the Andisols, causing molybdate sorption to decrease by 10-27%. The competition coefficients for phosphate and molybdate sorption were variable, indicating that competition between the two anions was not symmetrical. The present results provide further evidence to indicate that the surfaces of Andisols are rich in reactive Al-OH and Fe-OH groups, exposed at colloidal particle surfaces. Molybdate sorption appeared to be mainly associated with free Al- and Fe-oxides, while phosphate sorption was primarily regulated by Al- and Fe-humus complexes. Refereed/Peer-reviewed

Municipal and winery wastewater can provide a valuable irrigation source in regions where water accessibility is problematic or sustainable disposal of waste is essential. It is imperative, however, that when used for irrigation, water conservation benefits are not compromised by a decline in soil and plant health. To date, published literature investigating the use of wastewaters for grapevine production is restricted to a limited set of studies. Globally, wastewater usage within the horticultural sector, including winegrape production, is increasing. It is necessary, therefore, to better understand the short- and long-term implications of such practice. Although wastewaters may contain a range of organic and inorganic pollutants, this review focuses primarily on specific issues associated with high salt loading that is typical under wastewater irrigation. Managing salt, in particular sodium (Na+) and potassium (K+), in wastewater will be necessary in order to maintain the soil physical, chemical and biological health in the long term. Soil structural degradation resulting from a high concentration of exchangeable monovalent cations is of major concern where wastewater is being used for irrigation. This review will address (i) the effect of wastewater irrigation on vine performance and grape quality; (ii) chemical and physical changes in soils irrigated with municipal and winery wastewater; and (iii) management practices that may assist in ameliorating vineyard soils abundant in monovalent cations as a result of wastewater irrigation. Refereed/Peer-reviewed

In Australia, application of winery wastewater to land is increasingly being viewed as the most environmentally sound and cost-effective means of disposal. This wastewater contains high concentrations of both sodium (Na+) and potassium (K+), which have the potential to accumulate in the profile of irrigated soils and adversely alter physical properties such as aggregate stability and hydraulic conductivity. Cation exchange equilibria in soil of mixed illite and kaolinite mineralogy have been investigated in binary Ca–Na and Ca–K systems and in a ternary Ca–Na–K system. In the respective binary systems, resulting exchangeable potassium percentage was nearly twice the corresponding exchangeable sodium percentage (ESP), indicating a high binding affinity of K+ in this soil. In a ternary system, soils were equilibrated with solutions of differing sodium adsorption ratio (SAR) and potassium adsorption ratio (PAR) within ranges typical of winery wastewater. The presence of K+ had a significant effect on the relationship between SAR and ESP, whereby ESP decreased with increasing PAR. Resulting ESP in the ternary system was consistently lower than in the binary system. Cation selectivity between solid and solution phases in the ternary system was calculated from the Vanselow and K-selectivity coefficients and showed a decreasing selectivity for Na+ with increasing K+ in solution. It is expected that, due to the high K+ content of winery wastewater (i.e. >400 mg/L), adsorption of Na+, and subsequent ESP, will be less than in wastewaters of comparable Na+ concentration yet absent K+.

Coal provides the primary source of energy for many countries including Asia, South America, North America and Europe, and large quantities of waste products are produced during the combustion of coal in coal-fired power stations. This review paper gives an overview of the various types of coal combustion products (CCPs) and their utilization in various sectors, with a particular emphasis on the role of CCPs in managing the bioavailability of nutrients and heavy metals in relation to enhancing soil chemical fertility and mitigating metal contaminated soils. Currently, CCPs are used extensively in agricultural and construction industries. In agricultural industries, they are used primarily as an amendment to improve the physical and chemical properties of soil, as a source of liming material to ameliorate soil acidity and as a nutrient source to supply calcium and sulphur. In the construction industry, they are used mainly as a source of concrete, roofing material and road surface sealing. Increasingly, CCPs are used in the remediation of contaminated environments including control of acid mine drainage, mitigating phosphorus leaching in farm lands and immobilization of toxic metals in mine sites and agricultural soils.

In South Australia, 95,000 megalitres (ML) of municipal wastewater is collected and treated in metropolitan Adelaide. Approximately 50 % of this volume is treated at the Bolivar wastewater treatment plant (WWTP) to produce a high quality wastewater suitable for irrigation without health related restriction to vegetable and salad crops. Following treatment wastewater is piped to horticultural growers on the Northern Adelaide Plains through Virginia Pipeline Scheme (VPS). The establishment of the VPS is not only effective in reducing the amount of wastewater entering the Gulf St Vincent but also facilitates the recycling of otherwise waste water for irrigation purposes. The VPS is the largest recycled water scheme in Australia serving around 250 horticultural growers. This paper provides an overview of the scheme focusing on the level of wastewater treatment at Bolivar WWTP, the value of the treated water as a source of irrigation water, carbon and nutrients for crop growth, and the socio-economic and environmental implications of its use for irrigation. Refereed/Peer-reviewed

Maintaining growth through intensification in the New Zealand dairy industry is a challenge for various reasons, in particular sustainably managing the large volumes of effluent. Dairy farm effluents have traditionally been treated using two-pond systems that are effective in the removal of carbon and suspended solids, however limited in their ability to remove nutrients. In the past these nutrient-rich two-pond treated effluents were disposed of in surface waters. Current environmental concerns associated with the direct discharge of these effluents to surface waters has prompted in developing technologies to either minimise the nutrient content of the effluent or apply effluents to land. Here, we discuss various approaches and methods of treatment that enable producers to sustainably manage farm effluents, including advanced pond treatment systems, stripping techniques to reduce nutrient concentration,land application strategies involving nutrient budgeting models to minimise environmental degradation and enhance fodder quality. We also discuss alternative uses of farm effluents to produce energy and animal feed Refereed/Peer-reviewed

This chapter discusses some basic concepts related to chemical bioavailability in terrestrial environments. Bioavailability refers to how much of a chemical is available to a living biota. The bioavailability of a chemical defines the relationship between the concentration of the chemical in the terrestrial environment and the level of the chemical that actually enters the receptor causing either positive or negative effect on the organism. Bioavailability is species-specific because the dose which reaches an organism's target organs or tissues, and results in a biological response, may vary among receptors. Chemical bioavailability is considered an important consideration in the environment because the availability of chemicals may be mitigated once the chemical comes in contact with the soil and sediment. For this reason, both fertility status of soils as well as risk assessment of contaminated sites requires quantification of chemical bioavailability much like any other parameter in a risk calculation. Concepts related to physicochemical factors influencing dissolution and precipitation into the mineral phase are introduced in this chapter. Precipitation is discussed as a commonly occurring process that controls the solubility of many elements including aluminum, iron, manganese, magnesium, and calcium. The sorption of a chemical onto soil that plays an important role in determining its bioaccessibility and subsequent bioavailability is also elaborated. usc

In New Zealand, urine deposited by grazing animals represents the largest source of nitrogen (N) losses, as gaseous emissions of ammonia (NH₃) and nitrous oxide (N₂O), and leaching of nitrate (NO₃⁻).We determined the effect of dicyandiamide (DCD) on gaseous emissions from pasture with increasing rates of urine-N application, mineral N transformations and potential leaching of N using undisturbed soil cores of Manawatu sandy loam at field capacity. The treatments included four levels of urine-N applied at 0 (control), 14.4, 29.0 and 57.0 g N/m² with and without DCD at 2.5 g/m². Results showed a significant (P < 0.05) increase in NH₃ and N₂O-N emissions as urine application was increased. The addition of DCD to corresponding urine treatments reduced N₂O emissions by 33, 56 and 80%, respectively. The addition of DCD with urine to the intact soil cores at field capacity moisture content resulted in a significant increase in the soil ammonium-N (NH₄⁺-N) concentration but little change in NH₃ emissions. Addition of DCD to urine reduced potential NO₃⁻-N leaching by 60–65% but potential NH₄⁺-N leaching increased by 2–3.5 times. There was no difference in pasture dry matter production with and without DCD treatments. Refereed/Peer-reviewed