The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Manuel Pinto - One of the best experts on this subject based on the ideXlab platform.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
Manuela Inácio - One of the best experts on this subject based on the ideXlab platform.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
R. W. Bell - One of the best experts on this subject based on the ideXlab platform.
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insufficient potassium and sulfur supply threaten the productivity of perennial forage grasses in smallholder farms on tropical Sandy Soils
Plant and Soil, 2021Co-Authors: Joshua Philp, R. W. Bell, Wendy Vance, Peter S. Cornish, Vanndy Lim, Sukanya Kamphayae, Matthew D. DentonAbstract:Perennial forage grass production has the potential to improve smallholder livelihoods in the tropics. However, nutrient management is often challenging, especially on infertile Sandy Soils. This study tested whether typical nutrient management limits the productivity and sustainability of perennial forage grass systems on Sandy Soils. Nutrient balances were estimated for four fields of either Megathyrsus maximus cv. Tanzania or Urochloa hybrid Mulato II. Nutrient limitations were then evaluated in a nutrient omission experiment. All Soils were Sandy (< 10% clay), neutral to acidic (pH (CaCl2) 4.6 to 6.7) and had plant-limiting concentrations of total nitrogen, extractable potassium and extractable sulfur. Nitrogen inputs were typically higher than outputs, with balances ranging from −16 kg ha−1 yr−1 to 293 kg ha−1 yr−1, yet concentrations in forage shoots were low at all sites. Phosphorus balances ranged from −5 kg ha−1 yr−1 to 77 kg ha−1 yr−1 and concentrations in forage shoots were adequate. Potassium inputs were low, resulting in balances from −79 kg ha−1 yr−1 to −138 kg ha−1 yr−1 at locations that did not apply inorganic potassium fertilizer. Potassium concentrations in forage shoots were low and omission of potassium resulted in severely depressed biomass production. Inorganic sulfur fertilizers were not applied to forages and the sulfur balance varied from −1 kg ha−1 yr−1 to −24 kg ha−1 yr−1. Sulfur concentrations in shoots were correspondingly low and production was depressed when sulfur was omitted in the experiment. Balanced nutrition was not achieved, despite substantial fertilizer inputs, resulting in deficiencies of potassium and sulfur, inefficient use of nitrogen and excesses of phosphorus. If current practices continue, potassium and sulfur depletion, phosphorus accumulation and soil acidification can be expected. Recommendations for balanced nutrient management that accounts for high rates of removal in biomass, variable concentrations in organic fertilizers, and leaching potential, are needed to sustain the productivity of perennial forages on tropical Sandy Soils.
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Fertiliser strategies for improved nutrient use efficiency on Sandy Soils in high rainfall regimes
Nutrient Cycling in Agroecosystems, 2009Co-Authors: S. Sitthaphanit, V. Limpinuntana, B. Toomsan, S. Panchaban, R. W. BellAbstract:Fertiliser application strategies for maize ( Zea mays L.) production on Sandy Soils under high rainfall regimes need to be carefully designed to minimise nutrient losses through leaching and maximise crop yield. Experiments were conducted to determine N, P, and K leaching in Sandy Soils with 3–6% clay in surface layers under maize production, and the effectiveness of different N, P, and K fertiliser timing and splitting strategies on leaching of N, P, and K and on maize yield. In a column experiment on an Oxic Paleustult (Korat series) with 3% clay, leaching of N, P, and K from fertiliser (114N-17P-22K in kg ha^−1) was significant under simulated rainfall, but decreased to negligible levels with 3–5 split applications of fertiliser. Maize N and K uptake increased with 3–5 split applications, but not P uptake. Despite continued intense rainfall and further fertilizer additions, leaching was not recorded after day 30, and this was attributed to the effect of plant water uptake on reducing deep drainage. Split applications of fertilizer maintained NP and K in the 0–30 cm layer during 30–60 days when maize nutrient demand was likely to be at its highest, while in the recommended fertilizer regime NPK in the surface layers declined after 30 days. In a field experiment on an Oxic Paleustult (Korat series) with 6% clay, 3–4 splits of fertiliser increased N and K uptake and increased maize yields from 3.3 to 4.5 Mg ha^−1. Postponing basal fertiliser application from pre-planting to 7–15 days after emergence increased uptake of N, P, and K and grain yield emphasising the greater risk of nutrient losses from fertiliser applied at planting than later. Strategies designed to reduce the amount of nutrients applied as fertiliser at planting, such as split application and postponing basal application can decrease the risk of leaching of N, P, and K from fertiliser and improve nutrient use efficiency, and grain yield of maize on Sandy Soils under high growing season rainfall regimes.
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Fertiliser strategies for improved nutrient use efficiency on Sandy Soils in high rainfall regimes
Nutrient Cycling in Agroecosystems, 2009Co-Authors: S. Sitthaphanit, V. Limpinuntana, B. Toomsan, S. Panchaban, R. W. BellAbstract:Fertiliser application strategies for maize ( Zea mays L.) production on Sandy Soils under high rainfall regimes need to be carefully designed to minimise nutrient losses through leaching and maximise crop yield. Experiments were conducted to determine N, P, and K leaching in Sandy Soils with 3–6% clay in surface layers under maize production, and the effectiveness of different N, P, and K fertiliser timing and splitting strategies on leaching of N, P, and K and on maize yield. In a column experiment on an Oxic Paleustult (Korat series) with 3% clay, leaching of N, P, and K from fertiliser (114N-17P-22K in kg ha^−1) was significant under simulated rainfall, but decreased to negligible levels with 3–5 split applications of fertiliser. Maize N and K uptake increased with 3–5 split applications, but not P uptake. Despite continued intense rainfall and further fertilizer additions, leaching was not recorded after day 30, and this was attributed to the effect of plant water uptake on reducing deep drainage. Split applications of fertilizer maintained NP and K in the 0–30 cm layer during 30–60 days when maize nutrient demand was likely to be at its highest, while in the recommended fertilizer regime NPK in the surface layers declined after 30 days. In a field experiment on an Oxic Paleustult (Korat series) with 6% clay, 3–4 splits of fertiliser increased N and K uptake and increased maize yields from 3.3 to 4.5 Mg ha^−1. Postponing basal fertiliser application from pre-planting to 7–15 days after emergence increased uptake of N, P, and K and grain yield emphasising the greater risk of nutrient losses from fertiliser applied at planting than later. Strategies designed to reduce the amount of nutrients applied as fertiliser at planting, such as split application and postponing basal application can decrease the risk of leaching of N, P, and K from fertiliser and improve nutrient use efficiency, and grain yield of maize on Sandy Soils under high growing season rainfall regimes.
Virgínia Pereira - One of the best experts on this subject based on the ideXlab platform.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
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Mercury contamination in Sandy Soils surrounding an industrial emission source (Estarreja, Portugal)
Geoderma, 1998Co-Authors: Manuela Inácio, Virgínia Pereira, Manuel PintoAbstract:Abstract This study reports the degree and the extent of mercury contamination in Sandy Soils surrounding a chloralkali plant at Estarreja, Portugal. Total mercury concentration in the Soils studied is at a maximum in the upper 5 cm, ranging from 117 to 49,233 μ g kg −1 . The profile distribution pattern for total mercury together with the results of a sequential extraction suggest that the element is strongly retained by the soil components. An upper limit of acceptable levels of mercury for this area is proposed based both on statistics and regulatory guidelines from other countries. Taking that limit, geostatistical methods were used to delimit a zone of heavy contamination. Atmospheric fall-out seems to be the main source of contamination of the Soils studied.
Matthew D. Denton - One of the best experts on this subject based on the ideXlab platform.
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Insufficient potassium and sulfur supply threaten the productivity of perennial forage grasses in smallholder farms on tropical Sandy Soils
Plant and Soil, 2021Co-Authors: Joshua Neil Monty Philp, Wendy Vance, Richard W. Bell, Peter S. Cornish, Vanndy Lim, Sukanya Kamphayae, Matthew D. DentonAbstract:Aims Perennial forage grass production has the potential to improve smallholder livelihoods in the tropics. However, nutrient management is often challenging, especially on infertile Sandy Soils. This study tested whether typical nutrient management limits the productivity and sustainability of perennial forage grass systems on Sandy Soils. Methods Nutrient balances were estimated for four fields of either Megathyrsus maximus cv. Tanzania or Urochloa hybrid Mulato II. Nutrient limitations were then evaluated in a nutrient omission experiment. Results All Soils were Sandy (< 10% clay), neutral to acidic (pH (CaCl_2) 4.6 to 6.7) and had plant-limiting concentrations of total nitrogen, extractable potassium and extractable sulfur. Nitrogen inputs were typically higher than outputs, with balances ranging from −16 kg ha^−1 yr^−1 to 293 kg ha^−1 yr^−1, yet concentrations in forage shoots were low at all sites. Phosphorus balances ranged from −5 kg ha^−1 yr^−1 to 77 kg ha^−1 yr^−1 and concentrations in forage shoots were adequate. Potassium inputs were low, resulting in balances from −79 kg ha^−1 yr^−1 to −138 kg ha^−1 yr^−1 at locations that did not apply inorganic potassium fertilizer. Potassium concentrations in forage shoots were low and omission of potassium resulted in severely depressed biomass production. Inorganic sulfur fertilizers were not applied to forages and the sulfur balance varied from −1 kg ha^−1 yr^−1 to −24 kg ha^−1 yr^−1. Sulfur concentrations in shoots were correspondingly low and production was depressed when sulfur was omitted in the experiment. Conclusion Balanced nutrition was not achieved, despite substantial fertilizer inputs, resulting in deficiencies of potassium and sulfur, inefficient use of nitrogen and excesses of phosphorus. If current practices continue, potassium and sulfur depletion, phosphorus accumulation and soil acidification can be expected. Recommendations for balanced nutrient management that accounts for high rates of removal in biomass, variable concentrations in organic fertilizers, and leaching potential, are needed to sustain the productivity of perennial forages on tropical Sandy Soils.
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insufficient potassium and sulfur supply threaten the productivity of perennial forage grasses in smallholder farms on tropical Sandy Soils
Plant and Soil, 2021Co-Authors: Joshua Philp, R. W. Bell, Wendy Vance, Peter S. Cornish, Vanndy Lim, Sukanya Kamphayae, Matthew D. DentonAbstract:Perennial forage grass production has the potential to improve smallholder livelihoods in the tropics. However, nutrient management is often challenging, especially on infertile Sandy Soils. This study tested whether typical nutrient management limits the productivity and sustainability of perennial forage grass systems on Sandy Soils. Nutrient balances were estimated for four fields of either Megathyrsus maximus cv. Tanzania or Urochloa hybrid Mulato II. Nutrient limitations were then evaluated in a nutrient omission experiment. All Soils were Sandy (< 10% clay), neutral to acidic (pH (CaCl2) 4.6 to 6.7) and had plant-limiting concentrations of total nitrogen, extractable potassium and extractable sulfur. Nitrogen inputs were typically higher than outputs, with balances ranging from −16 kg ha−1 yr−1 to 293 kg ha−1 yr−1, yet concentrations in forage shoots were low at all sites. Phosphorus balances ranged from −5 kg ha−1 yr−1 to 77 kg ha−1 yr−1 and concentrations in forage shoots were adequate. Potassium inputs were low, resulting in balances from −79 kg ha−1 yr−1 to −138 kg ha−1 yr−1 at locations that did not apply inorganic potassium fertilizer. Potassium concentrations in forage shoots were low and omission of potassium resulted in severely depressed biomass production. Inorganic sulfur fertilizers were not applied to forages and the sulfur balance varied from −1 kg ha−1 yr−1 to −24 kg ha−1 yr−1. Sulfur concentrations in shoots were correspondingly low and production was depressed when sulfur was omitted in the experiment. Balanced nutrition was not achieved, despite substantial fertilizer inputs, resulting in deficiencies of potassium and sulfur, inefficient use of nitrogen and excesses of phosphorus. If current practices continue, potassium and sulfur depletion, phosphorus accumulation and soil acidification can be expected. Recommendations for balanced nutrient management that accounts for high rates of removal in biomass, variable concentrations in organic fertilizers, and leaching potential, are needed to sustain the productivity of perennial forages on tropical Sandy Soils.
