Paul Milham

Western Sydney University · Hawkesbury Institute for the Environment

Many plants of commercial interest are propagated in tissue culture, with some presenting difficulties in their mineral balance. Historically, this issue has been addressed by varying the mineral composition of the media hoping to find a satisfactory combination. However, a potentially more efficient approach has been successful for several species...

Biochar is a soil amendment that can change soil's physical and hydraulic properties. However, biochar application is far from being a 'one size fits-all' approach. The impact of the management practices is dependent on biochar type (feedstock and production conditions), application depth and method, climate and site characteristics. Hence, this st...

The long‑term application of organic amendments like manure, biochar and biogas slurry can increase phosphorus (P) levels in agricultural soils; however, at present, it’s not clear how this affects the P association with different mobile water‑dispersible colloidal particles (Pcoll). Thus, this study aimed to assess the effects of the long‑term app...

Rice (Oryza sativa L.) has inherently low concentrations of nitrogen (N) and zinc (Zn), and those concentrations are falling as the atmospheric concentration of carbon dioxide ([CO2]) increases, threatening the quality of human diets. We investigated the effect of two levels of Zn supply (marginal and luxury), on Zn and N concentrations in whole gr...

Excessively high concentrations of selenium (Se) in soil are toxic to crop plants, and inoculation with arbuscular mycorrhizal fungi (AMF) can reverse Se stress in maize (Zea mays L.). To investigate the underlying mechanisms, maize seedlings were treated with sodium selenate (5 mg Se[VI] kg⁻¹) and/or AMF (Funneliformis mosseae and Claroideoglomus...

Mobile colloids impact phosphorus (P) binding and transport in agroecosystems. However, their relationship to P lability and their relative importance to P bioavailability is unclear. In soils amended with organic fertilisers, we investigated the effects of nano (NC, 1–20 nm), fine (FC, 20–220 nm), and medium (MC; 220–450 nm) colloids suspended in...

The manure fertilizer increases the phosphorus (P) saturation of soils and the colloidal P release to water bodies. Manure of different particle-sizes may have different effects on colloidal P release by soil, and to date there is limited knowledge on colloidal P release from soils amended with different size manures. We produced sheep micro- (SMic...

Tobacco (Nicotiana tabacum) waste is produced in many countries and is phytotoxic due to the alkaloid content; in Vietnam the waste is usually burned causing air pollution. We composted tobacco waste with chicken manure in different proportions—1 t of waste ± accelerant (C1 and C2); 0.8 t of waste + 0.2 t of chicken manure ± accelerant (C3 and C4);...

Phosphorus (P) is limiting nutrient in many soils, and P availability may often depend on iron (Fe) speciation. Colloidal iron phosphate (FePO4coll) is potentially present in soils, and we tested the hypothesis that phytate exudation by Pteris vittata might dissolve FePO4coll by growing the plant in nutrient solution to which FePO4coll was added. T...

The agricultural use of manure fertilizer increases the phosphorus (P) saturation of soils and the risk of colloidal P (P coll) release to aquatic ecosystems. Two experiments were conducted to identify whether Pteris vittata plantation can decrease P coll contents in two soils (Cambisol and Anthrosol) amended with various manure P rates (0, 10, 25,...

Zinc (Zn) is an important micronutrient in the human body, and health complications associated with insufficient dietary intake of Zn can be overcome by increasing the bioavailable concentrations in edible parts of crops (biofortification). Wheat (Triticum aestivum L) is the most consumed cereal crop in the world; therefore, it is an excellent targ...

Photosynthesis in wheat (Triticum aestivum L.) pericarps may contribute appreciably to wheat grain yield. Consequently, we investigated the temporal variation of traits related to photosynthesis and sucrose metabolism in the pericarps and flag leaves of three wheat genotypes, Huandoy, Amurskaja 75 and Greece 25, which are reported to differ in expr...

Context. Shifting agricultural operations to more sustainable management practices is needed in the face of a changing climate. Aims. In this study, the short-term effects of three tillage systems (no tillage, minimum tillage and conventional tillage) on a wide selection of soil properties in a semiarid agrosystem of eastern Tunisia were assessed....

Phosphorus (P) is limiting nutrient in soil system. The P availability in soil strongly depend on Iron (Fe) speciation. Colloidal iron phosphate (FePO 4coll ) is an important phosphorus (P) fraction in soil solution that carry P from soil to water bodies. This study tested the hypothesis that phytate exudation by Pteris vittata (P. vittata) can dis...

Over the years, cultivation using sustainable tillage practices has gained significant importance, but the impact of tillage on soil water infiltration is still a concern for landowners due to the possible effects on crop yield. This study investigates the impact of different tillage managements on the infiltration rate of sandy clay loam soil unde...

Wild rice Oryza rufipogon, a progenitor of cultivated rice Oryza sativa L., possesses superior salinity tolerance and is a potential donor for breeding salinity tolerance traits in rice. However, a mechanistic basis of salinity tolerance in this donor species has not been established. Here, we examined salinity tolerance from the early vegetative s...

Cabbage (Brassica oleracea var. capitata L.) is widely grown in the highlands of North Western Vietnam, and foliar analysis of 18 crops in the Bac Ha district, and 9 in the Sa Pa district of the Lao Cai Province, revealed low mean concentrations of boron (B, 15.6 mg kg⁻¹), and copper (Cu, 4.8 mg kg⁻¹). In three following field experiments, B treatm...

Eucalypts are likely to play a critical role in the response of Australian forests to rising atmospheric CO2 concentration ([CO2]) and temperature. Although eucalypts are frequently phosphorus (P) limited in native soils, few studies have examined the main and interactive effects of P availability, [CO2] and temperature on eucalypt morphology, phys...

Main conclusion Site-specific changes of photosynthesis, a relatively new concept, can be used to improve the productivity of critical food crops to mitigate the foreseen food crisis. Abstract Global food security is threatened by an increasing population and the effects of climate change. Large yield improvements were achieved in major cereal cro...

Acid-soluble soil phosphorus (P) is a potential resource in P-limited agricultural systems that may become critical as global P sources decrease in the future. The fate of P in three alkaline Vertisols, a major agricultural soil type, after acidic incubation was investigated using synchrotron-based K-edge X-ray absorption near-edge structure (XANES...

Aims: Cadmium (Cd) is a toxic metal in soils and its accumulation in plants poses severe problems to agricultural production and human health. Most of research has focused on the Cd toxicity to plants, but reports on Cd co-transport and regulation by the major counter ion Chloride (Cl) is limited. This study aims to understand the mechanisms of the...

Soil microorganisms are essential to the functioning of soil ecosystems, and this study aimed to examine the effects of additions of carbon and nitrogen (N) to the soil on soil microflora, and whether these amendments could be used to both increase and reduce plant N concentrations in an orchard crop, thereby facilitating studies on the multitrophi...

Inductively coupled plasma-mass spectroscopic (ICP-MS) analysis of leaves from 22 cabbage crops in the Sa Pả and Bắc Hà districts of Láo Cai Province, North-Western Việt Nam, revealed unexpectedly high concentrations of chromium (Cr) and nickel (Ni). The concentrations were strongly linearly related (r² = 0.94), indicating sample contamination duri...

Elevated concentrations of carbon dioxide (e[CO2]) affect plant growth and physiological characteristics, including metal accumulation, and the activity of anti-oxidant enzymes. These effects were investigated in cadmium (Cd) tolerant wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor (L.) Moench.) cultivars. Plants were grown at the ambient...

Cadmium (Cd) in the soil solution is in dynamic equilibrium with the reservoir of bioavailable Cd attached to the solid phase, i.e. the labile pool (CdE). Traditionally, CdE is estimated using the radioisotope ¹⁰⁹Cd, which has severely restricted access to estimates of CdE. Using stable isotope dilution and isotope ratio measurement by inductive co...

To elucidate the mechanism of plant growth we investigated chromosome region affecting traits (CRATs) using the chromosome segment substitution lines derived from a cross between japonica ‘Koshihikari’ and indica ‘Kasalath’ using rice (Oryza sativa L.). Four CRATs associated with increased plant growth rate were identified which were derived from ‘...

Though rice is the predominant source of energy and micronutrients for more than half of the world population, it does not provide enough zinc (Zn) to match human nutritional requirements. Moreover, climate change, particularly rising atmospheric carbon dioxide concentration, reduces the grain Zn concentration. Therefore, rice biofortification has...

Calcium phosphate (CaP) minerals may comprise the main phosphorus (P) reserve in alkaline soils, with solubility dependent on pH and the concentration of Ca and/or P in solution. Combining several techniques in a novel way, we studied these phenomena by progressively depleting P from suspensions of two soils (low P) using an anion exchange membrane...

Cadmium is a cumulative, chronic toxicant in humans for which the main exposure pathway is via plant foods. Cadmium-tolerant plants may be used to create healthier food products, provided that the tolerance is associated with the exclusion of Cd from the edible portion of the plant. An earlier study identified the cabbage (Brassica oleracea L.) var...

Alkaline Vertisols contain calcium phosphate (CaP) minerals that dissolve in response to both acidification and the depletion of concentration of phosphorus (P) or calcium (Ca) in the soil solution, conditions commonly observed within the rhizosphere. In these soils, reserve-P is defined as the difference between the concentrations of P extracted b...

Phosphorus (P) available to plants in alkaline, vertic soils is thought to be buffered by the dissolution of various calcium phosphate minerals (CaP), driven by pH and the concentration of Ca and/or P in solution. To investigate this hypothesis we incrementally acidified 6 alkaline vertic soils of CaP 300–6000 mg kg− 1 in the presence or absence of...

Cadmium (Cd) is a toxic heavy metal whose concentration in soils is rising. This study investigated the effect of transpiration on Cd uptake by plants using soil conditions akin to those experienced by field crops. Two experiments were performed using baby leaf spinach (Spinacia oleracea L.) grown in soil containing Chloride (Cl) at a typical conce...

Background and aims Rice (Oryza sativa L.) and pearl millet (Pennisetum glaucum L.) biofortification breeding programs require accurate and convenient methods to identify nutrient dense genotypes. The aim of this study was to investigate energy-dispersive X-ray fluorescence spectrometry (EDXRF) for the measurement of zinc (Zn) and iron (Fe) concent...

Background and aims Crop biofortification programs require fast, accurate and inexpensive methods of identifying nutrient dense genotypes. This study investigated energy-dispersive X-ray fluorescence spectrometry (EDXRF) for the measurement of zinc (Zn), iron (Fe) and selenium (Se) concentrations in whole grain wheat. Methods Grain samples were ob...

To investigate O exchange during the reaction of POCl3 and water, natural abundance POCl3 was reacted with water highly enriched in 18O, and the resulting H3PO4 was isolated as KH2PO4. This reaction was conducted with and without tetrahydrofuran (THF) as a solvent, and was controlled in THF and violent in its absence. Approximately 5 × 10–4 M aqueo...

There is a need to be able to identify soils with the potential to generate high concentrations of phosphorus (P) in runoff, and a need to predict these concentrations for modelling and risk-assessment purposes. Attempts to use agronomic soil tests such as Colwell P for such purposes have met with limited success. In this research, we examined the...

The mineral constituents of soils were analysed for their agricultural potential by the Soils and Fertilizers Research Institute (SFRI). Until recently the laboratories had no reference materials to validate the tests. This deficit was overcome by creating a reference soil sample. The first step was to collect about 100 kg of surface soil from an u...

Molybdate-reactive phosphorus (MRP) in soil-free 0.5 M sodium bicarbonate (NaHCO3) extracts of 20 soils held at 22 °C increased 0–25% (median 11%) after 24 h and by 5–120% (median 43%) after 72 h. Addition of 2.5 mL L−1 of chloroform (1) or 0.25–1 g L−1 of thymol (2), phenyl mercury acetate (3), sodium cyanide (4), or sodium azide (5) showed that o...

Nitrogen supply to crops impacts on the synthesis of the green photosynthetic pigment, chlorophyll, and on plant nitrate concentration. Insufficient N supply decreases nitrate concentrations, chlorophyll synthesis and plant productivity. Excess N supply causes undesirably high nitrate concentrations in leafy vegetables and does not increase chlorop...

Fertilizer phosphorus (P) and grazing-related factors can influence runoff P concentrations from grazed pastures. To investigate these effects, we monitored the concentrations of P in surface runoff from grazed dairy pasture plots (50 x 25 m) treated with four fertilizer P rates (0, 20, 40, and 80 kg ha(-1) yr(-1)) for 3.5 yr at Camden, New South W...

Acid tolerance of Austrodanthonia accessions was evaluated in two experiments. In the first, seeds of the 183 Austrodanthonia accessions from 15 species, two Austrodanthonia cultivars (Taranna and Bunderra) and three exotic grasses, were sown in pots containing a sandy loam soil at pHCa 3.9, 4.4 and 5.3. Seedling emergence and survival were recorde...

A survey of 34 farms covering the major soil types used for growing vegetables within the greater Sydney metropolitan region ( New South Wales, Australia) was undertaken to determine the effect of vegetable production on soil chemical and physical properties. Comparison of farmed 'vegetable' v. unfarmed 'reference' sites revealed that the soils use...

Plants take up cadmium (Cd) from the soil, and the concentration of Cd in some plant products is a health concern. Plant uptake of Cd is poorly predicted by its concentration in soils; consequently, there is interest in the binding and distribution of Cd in soil. Synchrotron micro-X-ray fluorescence spectroscopy (micro-XRFS) is the most sensitive m...

Some Australian native perennial grasses that evolved on acidic soils are useful pasture species such as the 25 species of Austrodanthonia. We evaluated the range of acidity tolerance and growth potential in the field of 9 species of Austrodanthonia, comprising 18 accessions collected from southern temperate New South Wales (NSW) as well as the com...

The vegetative growth of Japanese millet ( Echinochloa utilis Ohwi et Yabuno) was much lens reduced by pre‐emergent treatments of thiobencarb ( S ‐eithyl hexahydro‐1,4‐azepine‐l‐thiolcarbamate) and molinate (S‐(4‐chlorobenzyl)‐ N.N ‐diethylithiolcarbamate] when the herbicides were applied at <4 l a.i. ha ⁻¹ over rice stubble ash. The effcct was cau...

Résumé: Zusammenfassung: Summary Carbon produced by burning paspalum ( Paspalum dilatatum L.) under a wide range of conditions (ash‐C) adsorbed appreciable quantities of diuron from aqueous solution. However, commercially activated‐C was a more efficient adsorbent than any of the ash‐C products whose activity was related to their conditions of form...

The response of Eucalyptus grandis seedlings to elevated atmospheric CO2 concentrations was examined by growing seedlings at either 340 or 660 n mol CO2 mol-1 for 6 weeks. Graded increments of phosphorus and nitrogen fertilizers were added to a soil deficient in these nutrients to establish if the growth response to increasing nutrient availability...

Abstract Advanced selections (families 20010 and 20062) of P. radiata D. Don were exposed to either 340 or 660 μmol CO2 mol 1 for 2 years to establish if growth responses to high CO2 would persist during the development of woody tissues. The experiment was carried out in glasshouses and some of the trees at each CO2 concentration were subjected to...

Liming is an effective method of correcting soil acidity, but the cost and other factors, such as sub-soil acidity, topography, and nutrient availability may limit its benefits. An alternative option is to grow acid tolerant plants. Pot experiments are an effective way of identifying plants with the genetic potential to grow in acidic soils. These...

Soil organic acids such as humic and fulvic acids can play an important role in influencing inorganic phosphate availability in P-fertilized soils by inhibiting formation of thermodynamically stable calcium phosphates. Calcium phosphate phases which are important in these systems may include amorphous calcium phosphate (Ca9(PO4)6·nH2O; ACP), dicalc...

Undisturbed surface soils on the peri-urban fringe of the Sydney Basin are mostly acidic, with low concentrations of total cadmium (Cd-t) and a wide range of other properties. In taxonomically similar soils on vegetable farms, Cd-t is typically about 20-fold greater and undesirably large concentrations of Cd occur in some of the vegetables. We used...

The study compares the effects of biosolids compost (BC) and inorganic fertiliser (IF) on the nutrient status of a clay loam at Rydalmere in Western Sydney, and an earthy sand at Somersby, 85 km north of Sydney. The soils represent the textural range used for vegetable production in the Sydney Basin of New South Wales. The soils had been under perm...

Despite the importance of mineral nutrition for plantlet growth in vitro, there have been few studies on mineral uptake from growth media or on optimising the media used in tissue culture. As plants in vitro experience abnormal growth conditions and may not possess roots, they may use different mechanisms of mineral uptake than plants growing ex vi...

Australia's tropical grasslands are dominated by C4grasses, characterized by their unique biochemistry and anatomy. Two naturalized C4grasses (Panicum coloratum and Cenchrus ciliaris) were used to investigate whether high CO2partial pressure [ p(CO2)] influences photosynthetic nitrogen use efficiency and plant nitrogen use efficiency (PNUE and NUE...

Isotope distributions in phosphate are useful measurements in geochemical systems since they give information on origin and environmental oxygen exchange processes. It is often necessary to perform measurements rapidly at the parts per million level on milligram quantities of sample. However, current methodologies require conversion to gas and/or t...

________________________________________________________________________________________________ Phosphorus, an essential macronutrient for plant growth, plays an integral role in cell division, growth, energy metabolism and transfer reactions within the plant. We conducted a pot experiment under controlled conditions to examine how P supply (0, 10...

Wheat ( Triticum aestivum) cv. Hartog and Rosella were grown at CO 2 concentrations of 280 l litre -1 (representing the pre-industrial CO 2 concentration), 350 l litre -1 (ambient) or 900 l litre -1 (an extreme projection of atmospheric CO 2 concentration). The plants were grown in naturally lit glasshouses in 7 litre pots containing soil to which...