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Phosphorus (P) limitations to agricultural productivity commonly occur in Australian soils and have largely been overcome by the use of inorganic fertilisers. However, studies have shown that most of the P taken up by plants is from native P pools. The turnover of P and native soil organic matter may be strongly affected by drying and rewetting (DRW). Rewetting dry soil results in a pulse of respiration activity and available nutrients. In Mediterranean-type climates surface soils naturally undergo recurrent DRW cycles. In southern Australia, soils experience DRW due to erratic rainfall within the growing season, and short, high intensity thunderstorms also during summer periods. The principal objective of this thesis was to determine the significance of dry-rewet events, for altering P availability and cycling in agricultural soils in Australia. Soils representing a wide range of soil types and climatic zones of southern Australia, showed large flushes in carbon (C) mineralisation after a single DRW event. For some soils these were comparable with reported values, however large variability in flush size between soils was observed. Soils that commonly experience DRW did not appear to be more resilient to DRW than soils from areas with fewer DRW events. Even when soils had relatively small respiration flushes, as a result of low soil organic matter, a high proportion of the soil C was mineralised after rewetting. Soil physiochemical properties (total C, total N, organic C, humus, microbial biomass P, organic P, sand and silt) were correlated to the size of the flush, hence nutrient availability and soil texture appear to primarily determine flush size. Therefore, the influence of climate on DRW may relate to determining the quantity of organic matter and microbial biomass that is available for turnover. Different size and composition of the microbial biomass within the same soil matrix were achieved by adding three different C substrates (glucose, starch and cellulose at 2.5 g kg-¹) at 5 times over 25 weeks. The treatments showed disparate responses to DRW, due to greater biomass (larger flushes) and effects of community composition, highlighting the central role of the soil microbes in DRW processes. When subjected to multiple DRW events these soils showed smaller rewetting respiration flushes with subsequent rewetting events. In contrast, the amount of P released after rewetting was the same. This study showed that increases in P after rewetting were transient and rapid immobilisation of P by microbes occurred, which may limit the availability to plants. The composition of the microbial community was changed by DRW with a reduction in fungi and gram negative bacteria, showing that certain species are more susceptible to DRW than others. Closer investigation at 2 hourly intervals after rewetting confirmed the transient nature of P flushes. The response in microbial respiration after rewetting was immediate, with the highest activity occurring within the first 2 h. Phosphorus availability was increased by DRW but remained stable over the following 48 h incubation period. The study highlights the rapid nature of changes in available nutrients after rewetting. Furthermore, while potentially only a small component of the P flush that occurred, the DRW soil had higher levels of P than most incubated soil at 48 h, this would be potentially available for plant uptake or movement with the soil solution. Long-term water regimes (continuously moist or air-dry, or DRW occurring at different times during incubation) that were imposed on two soils from different climatic regions over a 14 wk period, did not alter available nutrient (P and C) pools or the size of the microbial biomass. However, these long-term water regimes determined the respiration response of the soils to experimental DRW. The largest flushes occurred in the treatment with the longest dry period, and confirm findings of reported studies that the response of a soil at rewetting is determined by the length of the period that it is dried. Microbial biomass was little affected by experimental DRW, but showed large changes in C:P ratio. Thus, changes in physiological state or community composition may be more affected by DRW than the size of the microbial biomass. Microbial communities were altered by DRW irrespective of climatic history (warm wet summer and temperate Mediterranean), however these changes were not related to specific groups of organisms. In addition, the disparate respiration responses and inhibition of phosphatase by DRW, indicate that functional changes may be induced by DRW but can not be sufficiently explained by quantifying available nutrient pools or the microbial biomass. The use of wheat seedlings bio-indicators of P availability after the long-term water regimes, confirmed that plant available P was altered by DRW, indicated by differences in growth, although the large variability in seedling growth made it difficult to quantify these differences. However, the distribution of labile P, available at planting, in soil and plant pools at harvest, showed that long-term water regimes increased P allocation in plant tissue in one soil and decreased it in another. Furthermore, only a small fraction of the labile P present at planting was taken up by plants, which confirms the superior ability of soil microbes to immobilise P that is released by DRW. Nevertheless, since the long-term water regimes increased P availability, this may be transported via surface water or leaching. DRW is important for C and P turnover in soils of southern Australia. However, P flushes occur rapidly after rewetting and are transient. Therefore, DRW appears to have only minor consequences for P availability to plants. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1321018 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

Methods for determining phosphorus in turbid lake and river water using heating with an autoclave or a microwave and employing alkaline peroxodisulphate digestion have been investigated. Suspensions (up to 100 ugP/L) of two standard reference materials (NIES No. 3 Chlorella and NEES No. 2 Pond Sediment) were used to optimised procedures. Quantitative recoveries of phosphorus were achieved when the final solution to be digested contained 0.045 M potassium peroxodisulphate and 0.04 M sodium hydroxide and solutions were autoclaved at 120°C for 60 min. or microwaved at 450 Watts for 5-10 min. Complete recoveries of phosphorus (99- 103%) from 20 ugP/U 50 ugP/L and 100 ugP/L Chlorella suspensions were obtained using autoclave and microwave heating. For the Pond Sediment suspensions complete recoveries of phosphorus (99-104%) from the 20 ugP/L and 50 ugP/L were obtained using both heating methods. Higher recoveries from the 100 u.gP/L Pond Sediment suspensions were obtained using microwave heating (96±1%) than autoclaving (88±5%). Further analysis of Pond Sediment suspensions using the autoclave heating showed that complete recovery of phosphorus (98±l%) from 60 ngP/L suspensions was achieved with incomplete recoveries (92.3±0.7%, 91�2% and 91�1%) from 70 ugP/L, 80 ugP/L and 90 ug P/L suspensions respectively. Recoveries of phosphorus compounds (orthophosphate and phosphonates) added to distilled water and turbid lake water were near quantitative (91-117%) for both digestion methods. A range of turbid lake and river water (TP = 57-106 ugP/L; Turbidity = 16-200 NTU) were analysed for total phosphorus (TP) using the optimised alkaline peroxodisulphate digestion procedures and the APHA AWWA WPCF, sulphuric acid - nitric acid digestion procedure. No difference in total phosphorus measurements were found between the microwave digestion procedure and the APHA AWWA WPCF, nitric acid - sulphuric acid procedure. The autoclave procedure gave significantly lower recoveries of phosphorus (p<0.01), however, differences were only 2-8%. The effect of freezing (-20�C) water samples without or with the addition of 1% hydrochloric acid before determination of total phosphorus (TP) and total dissolved phosphorus (TDP) was also investigated. No significant change in total phosphorus occurred when samples were stored frozen without the addition of 1% hydrochloric acid in high and low density polyethylene bottles for up to 20 weeks and 2 weeks respectively after collection. Significant changes were found in total dissolved phosphorus when samples were stored frozen without the addition of 1% hydrochloric acid in high and low density polyethylene bottles after 1 day and 2 weeks respectively.

Bibliography: leaves 169-193. This study investigated whether both S. Calospora and Glomus sp. "City Beach" WUM 16 both increase the rate of transfer of phosphate (P) to the plant Allium porrum, and whether the addition of P to the soil has any effect on the uptake rates. The main experiment compared the fungi under two P levels in soils. It was found that in soil with no added P, S. calospora depressed plant growth in the early stages, but was increased in later harvests. G. sp. "City Beach" increased plant growth throughout. In soil with added P, both sets of plants produced growth depressions at early stages. The effect on growth due to mycorrhizal symbiosis was greater in plants grown in soil with no phosphate added. There were no significant differences between the two fungi with reflexes of P across the interfaces. There were however temporal differences. The isolate of S. calospora did promote a positive plant growth response in A. porrum and transfer P to the plant. Mycorrhizal arbuscules were examined and visualised using Laser Scanning Confocal Microscope and 3D reconstructions performed. This allowed the surface area and volume of the arbuscules to be quantified in order to investigate differences between the fungi.

The total amount of nitrogen and phosphorus in animal manures, and the proportion of this amount that becomes available as dissolved inorganic nitrogen and phosphorus within a month after manures are added to water were examined in the context of fertilization guidelines for pond aquaculture. A literature study was conducted to synthesize information on the dry matter, total nitrogen and total phosphorus contents, and the biochemical oxygen demands of different manures. This information was used to compile a fertilizer database and to examine dry matter-nutrient relationships for different manures. Significantly high correlations between dry matter and total nitrogen, and between dry matter and total phosphorus were observed for poultry manure, and different forms of beef and dairy cattle manures. These relationships can be used to estimate the nutrient contents of manures if the dry matter contents are measured. A laboratory experiment was conducted to determine the amount of nitrogen and phosphorus that becomes available as dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) over a five week period when poultry, swine and dairy manures are added to water. Mean DIN and DIP concentrations reached highest levels on the 5th day after manure addition for all the manures. These concentrations corresponded to 60.5, 49.5 and 30.1% of the total nitrogen and 78.4, 77.4 and 58% of the total phosphorus supplied by poultry, swine and dairy manures respectively. DIN and DIP concentrations were significantly different among the three manures on all sampling days. Poultry manure supplied the highest amount of nitrogen and phosphorus, followed by swine and dairy manures. Pond fertilization guidelines based on the nitrogen and phosphorus requirements for algae should consider the available portion and not the total nitrogen and phosphorus contents of manures to calculate fertilizer requirements. Another study was conducted to examine the effects of temperature and repeated manure addition on nutrient release patterns from poultry manure. Different temperatures over a three week period did not have a pronounced impact on DIN and DIP levels. Two phases of DIN build-up were observed, whereas DIP levels showed an increasing pattern throughout the temperature experiment. The overall proportion of the total nitrogen and phosphorus supplied by poultry manure that became available as DIN and DIP for all the experimental units considered together amounted to about 64 and 70% respectively, which is consistent with the earlier study. Repeated manure addition resulted in significantly lower DIN and higher DIP concentrations in the interval following the second manure addition compared to the first interval, although nutrient release patterns appeared to be similar. / Graduation date: 1993

L'orientation du choix des agriculteurs vers des variétés efficientes dans l'utilisation du P est une issue économique pour améliorer leur productivité. Dans cette optique, la variation génétique de l'efficience d'utilisation du phosphore (EUP) chez la fève a été étudiée au champ (sous conditions pluviales) et en pots sous conditions semi-contrôlées. Dans les essais au champ sur deux années et dans deux situations de disponibilité du P dans le sol (faible/optimale) la variation génétique de l'EUP a été significative. La première année, avec une teneur en P du sol de 11,35 mg P(Olsen)/kg sol (niveau optimal), la variété Defès à petites graines, produisant peu de paille, s'est révélée la plus efficiente dans l'utilisation de P. Alors que la seconde année, avec une teneur en P du sol de 5 mg P(Olsen) /kg sol) (niveau faible) la variété Karabiga à grosses graines a été la plus efficiente dans l'utilisation du P. L'EUP a été positivement corrélée à l'indice de récolte (IR) et à l'indice de récolte relatif au P (IRP). La réserve totale du P dans le grain a été positivement corrélée au poids moyen du grain à l'inverse de sa concentration en P. Dans les essais en pots on a trouvé que la grosseur du grain par son influence positive sur la biomasse (MSR) et le volume (VR) racinaires détermine la variation génétique de l'EUP. Les génotypes à grosses graines se sont révélés les plus efficients que ce soit dans l'utilisation du P du sol ou de celui apporté. L'EUP calculée sur la base de la biomasse à la floraison a été positivement corrélée au VR et à la MSR mais elle a été négativement corrélée au rapport matière sèche racinaire à la matière sèche aérienne (MSRMSA). Les génotypes à petites graines montrent une meilleure réponse à l'apport de P. L'apport du phosphore a amélioré la surface foliaire (SF), la production en biomasse à la floraison et à la maturité, la rétention des organes reproducteurs et le rendement grain. La SF et le rapport MSRMSA différencient entre génotypes tolérants/sensibles à la déficience phosphatée. Les génotypes sensibles ont une SF moins importante et un MSRMSA élevé comparativement aux génotypes tolérants. Sur cette base, l'évaluation d'un plus grand nombre de génotypes pour l'EUP est réalisable économiquement en pots mais devrait être complétée par des essais au champ sur un nombre restreint de génotypes. Selon la conduite culturale (pluviale ou irriguée) et l'utilisation du produit final, les agriculteurs peuvent se baser sur le choix du calibre de la semence de fève pour une meilleure EUP. Pour les améliorateurs, l'EUP chez la fève pourrait être augmentée par l'amélioration des indices IR et IRP / To improve productivity in an economical way, farmers need to choose varieties with a high Phosphorus (P) use efficiency. This study focuses on genetic variation of P use efficiency (PUE) on Vicia faba L, both in field (pluvial conditions) and in pots (semi-controlled conditions). Trials in field were occurred during two years and in two different situations of P availability in soil (low/optimal). The genetic variation of PUE was significant. The first year, in soil with optimal phosphorus content (11.35 mg P(Olsen)/kg soil) the variety Defès, with small seeds and producing few straw, was the more efficient in P use. Harvest index (HI) and phosphorus harvest index (PHI) were positively correlated with PUE. The second year, in soil with low phosphorus content (5 mg P(Olsen)/kg soil), the variety Karabiga, large seeds one, was the most efficient in P use. The total storage of P in seed is positively correlated with seed dry weight, even if its concentration decreases with seed dry weight. Pots trials showed the positive influence of seed size on dry matter (RDM) and volume (RV) of roots. By that way, seed size determines genetic variation of PUE. Large seeds genotypes are the most efficient, both in use of soil P and fertilizer P. There is a positive correlation between PUE based on above ground biomass production at flowering and root's characteristics (RDM, RV). Inversely, PUE is negatively correlated with root to shoot ratio (RDSDM). The P supply improved leaf area (LA), dry matter production at flowering and at maturity, retention of flowers, and seed yield. Genotypes tolerant/sensitive to P deficiency can be differentiated thanks to LA and RDSDM. Sensitive genotypes have a smaller LA and a higher RDSDM than tolerant ones. According to farmer's practices (pluvial or irrigated) and the use of the final product, farmers' choice can be based on the seed size of faba bean to achieve the best PUE. For breeders, improvement of HI and PHI indices would increase PUE on faba bean

Concerns over water quality have led to required removal of 50 % of dairy manure phosphorus (P) from the impaired Bosque River Watershed. Application of composted dairy manure (CDM) to sod and moving P off the watershed with sod has prompted a study using box lysimeters to determine NO3--N and P leaching from transplanted sod grown with CDM and inorganic fertilizer as well as sprigs top-dressed with CDM. Treatments were applied to lysimeters filled with a silica sand medium. Three leaching events were imposed, leaching 0.07 to 0.09 % of the total P applied and 0.09 to 1.43 % of total N applied. Concentrations of P in leachate averaged 0.04 to 0.25 mg L-1. Top-dressed CDM on sprigs leached statistically greater amounts of NO3--N than both transplanted sod treatments and greater P than the fertilizer grown sod. After the third leaching event, all treatments received an additional application of P, 100 kg ha-1 as CDM for manure-grown sod and sprigs, 50 kg ha-1 as triple superphosphate for fertilizer-grown sod. An additional three leachings were imposed. Top-dressed sprigs and transplanted sod leached similar amounts of P following the additional P application. Applied nutrients appeared to stay mainly in the sod layer and in the sand medium just below the sod layer. Top-dressed CDM appears to exhibit greater leaching losses of NO3--N than transplanted manure-grown sod and greater N and P losses than transplanted fertilizer grown sod.

The membrane bioreactor (MBR) is becoming increasingly popular for wastewater treatment, mainly due to its capability of producing high quality effluent with a relatively small footprint. However, high plant maintenance and operating costs due to membrane fouling limit the wide spread application of MBRs. Membrane fouling generally depends on the interactions between the membrane and, the activated sludge mixed liquor, which in turn, are affected by the chosen operating conditions. The present research study aimed to explore the process performance and membrane fouling in the membrane enhanced biological phosphorus removal (MEBPR) process under different operating conditions by, (1) comparing two MEBPRs operated in parallel, one with constant inflow and another with a variable inflow, and by, (2) operating the MEBPRs with different solids retention times (SRT). On-line filtration experiments were conducted simultaneously in both MEBPR systems by using test membrane modules. From the transmembrane pressure (TMP) data of the test membrane modules, it was revealed that fouling propensities of the MEBPR mixed liquors were similar in both parallel reactors under the operating conditions applied, although the fouling propensity of the aerobic mixed liquors of both reactors increased when the SRT of the reactors was reduced. Routinely monitored reactor performance data suggest that an MEBPR process with a varying inflow (dynamic operating condition) performs similarly to an MEBPR process with steady operating conditions at SRTs of 10 days and 20 days. Mixed liquor characterization tests were conducted, including critical flux, capillary suction time (CST), time to filter (TTF) and, bound and soluble extracellular polymeric substances (EPS) were quantified, to evaluate their role on membrane fouling. The tests results suggest that the inflow variation in an MEBPR process did not make a significant difference in any of the measured parameters. With decreased SRT, an increase in the concentrations of EPS was observed, especially the bound protein, and the bound and soluble humic-like substances. This suggests that these components of activated sludge mixed liquors may be related to membrane fouling. No clear relationship was observed between membrane fouling and other measured parameters, including critical flux, normalized CST and normalized TTF.

Graduation date: 1992

Three experiments were conducted to determine the efficacy of an <i>Escherichia coli</i> 6-phytase (Quantum phytase) in laying hens fed corn-soybean meal based diets. In experiment 1, the Escherichia coli 6-phytase (Quantum) was evaluated for its efficacy in a 40-wk laying hen production trial. A total of 1080 White Leghorn hens were fed mash corn-soybean meal (CSM) based diets containing 0.35%, 0.25% or 0.15% of non-phytate phosphorus (NPP) with the 0.25% and 0.15% diets containing 200, 400 and 600 U/kg of exogenous phytase. Only minor differences in production characteristics were found between the 0.35% and 0.25% treatments regardless of phytase addition, indicating that 0.25% NPP resulted in P intake that was at or above the hens requirement. In contrast, the hens fed the 0.15% NPP diet without phytase supplementation had significantly reduced production performance in comparison to the 0.35% treatment. The addition of phytase to the 0.15% diet improved these production characteristics to levels equal to or better than the 0.35% diet. The results indicated that Quantum phytase was efficacious in CSM-based diets fed to White Leghorn laying hens and can be used to reduce the need for diet supplementation with inorganic phosphorus. In experiment 2, the effect of Quantum phytase on nutrient digestibility and bone ash in laying hens fed CSM-based diets was investigated. A total of 108 White Leghorn hens were fed CSM-based diets containing 0.35%, 0.25% or 0.15% NPP with the 0.25% and 0.15% diets containing 200, 400 or 600 U/kg of exogenous phytase. A linear reduction in phytate digestibility, ileal protein digestibility and soluble P was reported with increasing levels of exogenous phytase in the 0.25% diet. Tibial bone ash percentage was higher in 61-wk-old hens fed 0.25% diets supplemented with 200 or 400 U/kg phytase. Overall, the Quantum phytase was not efficacious in improving nutrient digestibility in laying hens fed CSM-based diets deficient in NPP. In experiment 3, the impact of dietary Ca and P level on the efficacy of an E. coli-derived 6-phytase and the apparent digestibility of various nutrients was investigated in White Leghorn laying hens fed CSM-based diets. A total of 384 White Leghorn hens were fed CSM-based diets containing four levels of Ca (2.5, 3.5, 4.5 or 5.5%), two levels of NPP (0.15 or 0.30%), and two levels of phytase (300 or 600 U/kg feed). Increasing dietary Ca caused a decrease in AMEn, duodenal protein digestibility, Ca and phytate digestibility, percentage soluble P in feces and the percentage of poor quality eggs, while significantly increasing bone ash and hen-housed and hen-day egg production. The higher level of NPP (0.30%) decreased AMEn, fecal protein, Ca and P digestibility, and hen-housed and hen-day egg production, while increasing fecal soluble P and egg specific gravity in comparison to the lower NPP level. The higher level of dietary phytase (600 U/kg feed) significantly increased AMEn, phytate and P digestibility, soluble P in feces, and hen-day and hen-housed egg production, while significantly reducing the percentage of soft shelled, cracked and broken eggs. Overall, dietary phytase, Ca and NPP levels, either as main effects or in an interactive manner, can affect apparent nutrient digestibility and production traits in laying hens fed CSM-based diets.