Добірка наукової літератури з теми "Phosphorus addition and soil water content on phosphorus pools in acid sulfate soils"

Acid sulfate soils (ASS) are common in wetlands and important for crop production. However, little is known about P availability in ASS which is constrained due to high Fe content and changing redox potential. This thesis aimed to investigate the effect of P addition, pH and soil water content on P pools in ASS. A sandy sulfuric ASS (pH 3.2) was used in the experiments. In the first experiment, the ASS was amended with NaOH or Ca(OH)2) to achieve soil pH 4 or 5.5, without or with addition of inorganic P equivalent to 20 kg ha−1. Soils were incubated in either submerged or moist conditions (100% of maximum water holding capacity). After two weeks, P pools and Fe /Al oxides were determined. P pools were higher with P addition than without. The increase in pH enhanced Fe oxides but had little effect on labile P. Added soluble P was available after two weeks of addition under submerged conditions. In Experiment 2, the ASS (pH adjusted to 5.5) was amended with phosphate at 0, 96, 385, 578 and 770 mg P kg−1 and incubated under submerged conditions. P pools were measured after two and four weeks. Sorption and release of P were determined in incubated soils and jarosite, separately. The maximum sorption capacity of the soil was 350 mg P kg-1. Jarosite had a high capacity to bind P and contributed about 50% to P binding in this soil. Labile P represented more than 50% of added P at P rates above 350 mg P kg-1. The third chapter included two experiments. In the first experiment, the ASS (pH adjusted to 5.5) was amended with 400 mg P kg-1 as inorganic P, manure or combinations of inorganic P/manure and was incubated submerged. After two and four weeks, labile P was measured. Labile P in treatments with 50% of P added as manure was about half of that in treatments with a greater proportion of inorganic P. In the second experiment, treatments (inorganic P alone: 100F, manure alone: 100M, combination of manure and inorganic P: 50M/50F and unamended control) were kept submerged, then moist, followed by resubmergence. At the end of first submergence, labile P was two-fold higher in 100F than in manure treatments. But in the moist period and after resubmergence, labile P did not differ between 100F and 100M. Oxalate extractable Fe was higher in 100M than 100F and remained unchanged until the end of the experiment. In experiment 4, the ASS (without or with pH increase to 5.5) was amended with mangrove roots to achieve an organic carbon (OC) addition of 50% or 150% of native soil OC and incubated under submerged, moist and then resubmerged conditions. At the end of each four-week period, P pools, amorphous Fe/Al and potential P sorption were measured. Mangrove roots addition decreased the redox potential and increased labile P under submerged conditions, but only at pH 5.5. P binding was enhanced by root addition during the first 8 weeks, but not after re-submergence.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2020

Soil Chemical Methods – Australasia describes over 200 laboratory and field chemical tests relevant to Australasia and beyond. The information and methodology provided across 20 chapters is comprehensive, systematic, uniquely coded, up-to-date and designed to promote chemical measurement quality. There is guidance on the choice and application of analytical methods from soil sampling through to the reporting of results. In many cases, optional analytical ‘finishes’ are provided, such as flow-injection analysis, electro-chemistry, multiple flame technologies, and alternatives to chemical testing offered by near-range and mid-range infrared diffuse reflectance spectroscopy. The book supersedes and updates the soil chemical testing section of the 1992 Australian Laboratory Handbook of Soil and Water Chemical Methods of Rayment and Higginson, while retaining method codes and other strengths of that Handbook. Chapters cover soil sampling, sample preparation and moisture content; electrical conductivity and redox potential; soil pH; chloride; carbon; nitrogen; phosphorus; sulphur; gypsum; micronutrients; extractable iron, aluminium and silicon; saturation extracts; ion-exchange properties; lime requirements; total miscellaneous elements; miscellaneous extractable elements; alkaline earth carbonates and acid sulfate soils. In addition, there are informative Appendices, including information on the accuracy and precision of selected methods. This book targets practising analysts, laboratory managers, students, academics, researchers, consultants and advisors involved in the analysis, use and management of soils for fertility assessments, land use surveys, environmental studies and for natural resource management.

Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.