The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
M.d.a. Bolland - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of Dicalcium Phosphate Compared with Superphosphate for Wheat Grown on Acidic Sandy Soils
Journal of Plant Nutrition, 2005Co-Authors: Rf Brennan, M.d.a. BollandAbstract:The effectiveness of dicalcium phosphate (DCP) was compared with the effectiveness of Superphosphate in a greenhouse experiment using two sandy acidic soils from southwestern Australia. Fertilizer effectiveness was determined using yield of dried shoots of 46-day-old spring wheat ( Triticum aestivum L.) plants.The DCP was about one-third as effective as Superphosphate for yellow sand and one-fifth as effective for red sand; thus, about three to five times the amount of phosphorus (P) as DCP was required to produce the same yield as P added as Superphosphate. Per unit of applied P, the P concentration in dried shoots was larger for soil treated with Superphosphate than for soil treated with DCP. Critical P, the P concentration that was related to 90% of the maximum shoot yield, was about 0.70% (dry weight basis) for both sources of P and both soils.
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Incubating Superphosphate in ‘dry’soil can reduce its effectiveness
Fertilizer Research, 1995Co-Authors: M.d.a. Bolland, N. J. BarrowAbstract:Single Superphosphate was incubated for six months at 25°C in soil which had been subject to one of three moisture treatments. These were: dried in a glasshouse, dried at a constant temperature of 25°C, or moist soil. Phosphorus (P) effectiveness was then compared with effectiveness of P from freshly-applied Superphosphate using yields of wheat (Triticum aestivum) and triticale (×Triticosecale) tops in pot experiments.
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Effectiveness of Ecophos compared with single and coastal Superphosphates
Fertilizer Research, 1995Co-Authors: M.d.a. BollandAbstract:Ecophos is a possible alternative phosphorus (P) fertilizer to single and coastal Superphosphate for clover pasture (Trifolium subterraneum) on P leaching, sandy, humic podzols in the > 800 mm annual average rainfall areas of south-western Australia. Ecophos and coastal Superphosphate are partially acidulated rock phosphates (PARP) fertilizers. Ecophos is made from calcium iron aluminium (crandallite millisite) rock phosphate. Coastal Superphosphate is made from apatite. The sandy humic podzols are known to promote extensive dissolution of rock phosphates, including the untreated rock phosphate present in PARP fertilizers. In this field study (early April 1992 to end of October 1994), the effectiveness of the PARP fertilizers was calculated relative to the effectiveness of single Superphosphate (relative effectiveness or RE), using yield and P content of dry clover herbage. The RE of the PARP fertilizers varied markedly between assessments, both within and between years, from being much less effective than single Superphosphate, to equally or much more efective. This great diversity in RE is attributed to the different extents P can be leached in the soil, depending on seasonal conditions. It is concluded that Ecophos is a suitable alternative P fertilizer for the soil and environment studied.
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Long-term residual value of North Carolina and Queensland rock phosphates compared with triple Superphosphate
Fertilizer Research, 1995Co-Authors: M.d.a. Bolland, R. J. GilkesAbstract:The effectiveness of large single applications of North Carolina reactive rock phosphate, Queensland non-reactive rock phosphate, and Calciphos, were compared to the effectiveness of Superphosphate in field experiments in south-western Australia for up to 11 years after application. As measured using plant yield, Superphosphate was the most effective fertilizer in the year of application, and relative to freshly-applied Superphosphate, the effectiveness of the Superphosphate residues declined to be about 15 to 65% as effective in the year after application, and 5 to 20% as effective 9 to 10 years after application. Relative to freshly-applied Superphosphate, all the rock phosphates were 10 to 30% as effective in the year of application, and the residues remained 2 to 20% as effective in the 10 years after application. The bicarbonate soil test reagent predicted a more gradual decrease in effectiveness of Superphosphate of up to 70% 10 years after application. For rock phosphate, the reagent predicted effectiveness to be always lower than for Superphosphate, being initially 2 to 11% as effective in the year after application, and from 10% to equally as effective 10 years later. Therefore rock phosphates are unlikely to be economic alternatives to Superphosphate in the short or long term on most lateritic soils in south-western Australia.
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Comparison of single and coastal Superphosphate for subterranean clover on phosphorus leaching soils
Fertilizer Research, 1995Co-Authors: M.d.a. Bolland, M. F. Clarke, F. C. BoetelAbstract:“Coastal Superphosphate”, a partially acidulated rock phosphate (PARP), is being considered as an alternative fertilizer to single Superphosphate for pastures in high rainfall (> 800 mm annual average) areas of south-western Australia. The effectiveness of single and coastal Superphosphate, as P fertilizers, was measured in two field experiments using dry herbage yield of subterranean clover (Trifolium subterraneum). The experiments were started in April 1990 and were terminated at the end of 1993. In the years after P applications, soil samples were collected each January to measure Colwell soil-test P, which was related to plant yields measured later on that year, to provide soil P test calibrations.
Sarath B Tennakoon - One of the best experts on this subject based on the ideXlab platform.
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An economic analysis of the field performance of North Carolina reactive phosphate rock compared with single Superphosphate for selected sites from the National Reactive Phosphate Rock Project
Australian Journal of Experimental Agriculture, 1997Co-Authors: P. G. Simpson, Peter W. G. Sale, Sarath B TennakoonAbstract:Summary. An economic analysis was undertaken using pasture yield data from 8 selected sites from the National Reactive Phosphate Rock Project, that encompassed 7 different performance scenarios for North Carolina phosphate rock. The aims were to determine whether the use of North Carolina phosphate rock in place of single Superphosphate might result in a positive financial benefit in the 4th year, and after 4 years of annual applications of fertiliser. The analysis was carried out using annual P applications of North Carolina phosphate rock and single Superphosphate, that resulted in pasture yields equivalent to 50, 70 or 90% of the maximum yield response of single Superphosphate in the 4th year. Annual pasture dry matter yields, produced by these fertiliser applications, were converted to stocking rates, and dollar incomes were derived by applying appropriate gross margins. The analysis was also undertaken to determine the financial benefit from large, year-1 applications of North Carolina phosphate rock. Single Superphosphate was priced at $168/t while North Carolina phosphate rock plus sulfur was priced at $180/t. The economic analysis found that a positive financial benefit with North Carolina phosphate rock occurred for only one scenario where the agronomic performance of North Carolina phosphate rock and single Superphosphate were equivalent in the 4th year of annual fertiliser application. For 3 other scenarios where the performance of North Carolina phosphate rock and single Superphosphate were also equivalent in the 4th year, the economic performance of North Carolina phosphate rock was poor due to (i) a ‘lag’ effect where pasture yield with North Carolina phosphate rock was generally less than that with single Superphosphate in years 1–3, and/or to (ii) a seasonal effect where the autumn–early winter pasture responses with North Carolina phosphate rock were less than those with single Superphosphate, necessitating a reduction in annual stocking rates on the North Carolina phosphate rock-fertilised pasture. A key finding was that large, single, year-1 applications of North Carolina phosphate rock generally overcame these seasonal and/or yearly lag effects, and led to positive financial benefits from North Carolina phosphate rock applied in this way. Annual applications of North Carolina phosphate rock were economically viable at sandy, high rainfall sites where water-soluble P from single Superphosphate would be readily leached from the root zone, provided that the soil P status was adequate and conditions were conducive to reactive phosphate rock dissolution. However, North Carolina phosphate rock was not an economically viable fertiliser to apply annually at (i) non-leaching sites where the soil P status was low and marked yield penalties occurred in the first few years of North Carolina phosphate rock use, (ii) where the soil had a very high P-sorption capacity, and (iii) where North Carolina phosphate rock dissolution was restricted by low rainfall or high pH. The inclusion of estimated residual P value had only a small impact on the economic outcome for scenarios which had not already performed poorly due to seasonal or lag effects.
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Building an expert system to advise on the use of reactive phosphate rock on Australian pastures
Australian Journal of Experimental Agriculture, 1997Co-Authors: Pieter Gillard, Peter W. G. Sale, Sarath B TennakoonAbstract:Summary. An expert system has been developed, using the results from the National Reactive Phosphate Rock Project, to determine whether reactive phosphate rock is likely to be an effective substitute for water-soluble Superphosphate fertiliser for a given pasture environment. The evaluation is made from site information [annual rainfall, pasture composition and the likelihood of phosphorus (P) leaching], and soil information (pH, Colwell P, soil colour and field texture). The expert system can determine the effectiveness of both highly reactive and moderately reactive phosphate rocks. Observed substitution values of triple Superphosphate for the highly reactive North Carolina phosphate rock (ratio of the respective P levels required to produce 50% of the maximum observed yield response to triple Superphosphate) were closely related to values predicted by the expert system (r = 0.92); the relationship between observed and predicted substitution values of single Superphosphate for the moderately reactive Hemrawein phosphate rock was also close (r= 0.86). The expert system gives one of 4 different recommendations for reactive phosphate rock based on the magnitude of the predicted substitution values. These are ‘immediately effective’, ‘effective in the medium term’, ‘marginally effective’, and ‘not effective’. The system was validated using the results from independent field experiments that provided measures of the effectiveness of reactive phosphate rock at different pasture sites.
Rf Brennan - One of the best experts on this subject based on the ideXlab platform.
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Effectiveness of Dicalcium Phosphate Compared with Superphosphate for Wheat Grown on Acidic Sandy Soils
Journal of Plant Nutrition, 2005Co-Authors: Rf Brennan, M.d.a. BollandAbstract:The effectiveness of dicalcium phosphate (DCP) was compared with the effectiveness of Superphosphate in a greenhouse experiment using two sandy acidic soils from southwestern Australia. Fertilizer effectiveness was determined using yield of dried shoots of 46-day-old spring wheat ( Triticum aestivum L.) plants.The DCP was about one-third as effective as Superphosphate for yellow sand and one-fifth as effective for red sand; thus, about three to five times the amount of phosphorus (P) as DCP was required to produce the same yield as P added as Superphosphate. Per unit of applied P, the P concentration in dried shoots was larger for soil treated with Superphosphate than for soil treated with DCP. Critical P, the P concentration that was related to 90% of the maximum shoot yield, was about 0.70% (dry weight basis) for both sources of P and both soils.
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Effect of Superphosphate and nitrogen on yield and take-all of wheat
Fertilizer Research, 1992Co-Authors: Rf BrennanAbstract:Wheat was grown continuously in soil amended with 5 levels of Superphosphate and with 4 levels of urea at 3 sites. The incidence and severity of take-all, caused byGaeumannomyces graminis var.tritici, declined with increasing rates of application of both Superphosphate and urea.
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Effect of aphids and mites on herbage and seed production of subterranean clover (cv. Daliak) in response to Superphosphate and potash
Australian Journal of Experimental Agriculture, 1992Co-Authors: Rf Brennan, M GrimmAbstract:Summary. The dry matter production (DM) and seed yield of subterranean clover (Trifolium subterraneum L. cv. Daliak) were reduced by infestations of redlegged earth mite (Halotydeus destructor Tucker) and blue-green aphid (Acyrthosiphon kondoi Shinji) during spring growth, flowering and burr burial. The dominance of these pests varied with season. The effects of spraying with insecticides on the DM and seed yield responses to Superphosphate and potassium chloride fertilisers were measured. Responses to Superphosphate were described by Mitscherlich functions for each of 3 levels of potassium chloride, except for seed yields with pest sprays. At optimum levels of Superphosphate and potassium chloride, controlling pests increased DM by up to 150% (from 4.37 to 6.52 t/ha). For all levels of Superphosphate, spraying to control pests where no potassium chloride was applied significantly increased DM over that on unsprayed plots that were fertilised with potassium chloride. The maximum DM response to Superphosphate application was achieved at 15-20 kg Piha. With optimum Superphosphate, the value for DM depended on the combination of spraying for pests and amount of potassium chloride applied, generating a series of Mitscherlich response curves for Superphosphate application with differing maximum yields. With optimum Superphosphate applied, the least DM recorded within a season was 3.47 t/ha (pests not sprayed, nil potassium chloride), and the most was 6.52 t/ha (pests sprayed, 120 kg potassium chloridefha), an increase of about 180%. At optimum levels of Superphosphate and potassium chloride, controlling pests increased seed yield by up to 380% (from 290 to 1100 kglha). With optimum Superphosphate, seed yield within a season ranged from 210 (pests not sprayed, nil potassium chloride) to 1100 kg/ha (pests sprayed, 120 kg potassium chlorideha), an increase of 524%. With pests sprayed, seed yield declined with Superphosphate applications >20 kg Pha; the relationship was best described by a quadratic function. With pests not sprayed, seed yield did not decline with increasing amounts of Superphosphate, and the relationship fitted a Mitscherlich function.
D. J. Reuter - One of the best experts on this subject based on the ideXlab platform.
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An appraisal of the National Reactive Phosphate Rock Project
Australian Journal of Experimental Agriculture, 1997Co-Authors: D. J. ReuterAbstract:Summary. An expert system has been developed, using the results from the National Reactive Phosphate Rock Project, to determine whether reactive phosphate rock is likely to be an effective substitute for water-soluble Superphosphate fertiliser for a given pasture environment. The evaluation is made from site information [annual rainfall, pasture composition and the likelihood of phosphorus (P) leaching], and soil information (pH, Colwell P, soil colour and field texture). The expert system can determine the effectiveness of both highly reactive and moderately reactive phosphate rocks. Observed substitution values of triple Superphosphate for the highly reactive North Carolina phosphate rock (ratio of the respective P levels required to produce 50% of the maximum observed yield response to triple Superphosphate) were closely related to values predicted by the expert system (r = 0.92); the relationship between observed and predicted substitution values of single Superphosphate for the moderately reactive Hemrawein phosphate rock was also close (r= 0.86). The expert system gives one of 4 different recommendations for reactive phosphate rock based on the magnitude of the predicted substitution values. These are ‘immediately effective’, ‘effective in the medium term’, ‘marginally effective’, and ‘not effective’. The system was validated using the results from independent field experiments that provided measures of the effectiveness of reactive phosphate rock at different pasture sites.
Peter W. G. Sale - One of the best experts on this subject based on the ideXlab platform.
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An economic analysis of the field performance of North Carolina reactive phosphate rock compared with single Superphosphate for selected sites from the National Reactive Phosphate Rock Project
Australian Journal of Experimental Agriculture, 1997Co-Authors: P. G. Simpson, Peter W. G. Sale, Sarath B TennakoonAbstract:Summary. An economic analysis was undertaken using pasture yield data from 8 selected sites from the National Reactive Phosphate Rock Project, that encompassed 7 different performance scenarios for North Carolina phosphate rock. The aims were to determine whether the use of North Carolina phosphate rock in place of single Superphosphate might result in a positive financial benefit in the 4th year, and after 4 years of annual applications of fertiliser. The analysis was carried out using annual P applications of North Carolina phosphate rock and single Superphosphate, that resulted in pasture yields equivalent to 50, 70 or 90% of the maximum yield response of single Superphosphate in the 4th year. Annual pasture dry matter yields, produced by these fertiliser applications, were converted to stocking rates, and dollar incomes were derived by applying appropriate gross margins. The analysis was also undertaken to determine the financial benefit from large, year-1 applications of North Carolina phosphate rock. Single Superphosphate was priced at $168/t while North Carolina phosphate rock plus sulfur was priced at $180/t. The economic analysis found that a positive financial benefit with North Carolina phosphate rock occurred for only one scenario where the agronomic performance of North Carolina phosphate rock and single Superphosphate were equivalent in the 4th year of annual fertiliser application. For 3 other scenarios where the performance of North Carolina phosphate rock and single Superphosphate were also equivalent in the 4th year, the economic performance of North Carolina phosphate rock was poor due to (i) a ‘lag’ effect where pasture yield with North Carolina phosphate rock was generally less than that with single Superphosphate in years 1–3, and/or to (ii) a seasonal effect where the autumn–early winter pasture responses with North Carolina phosphate rock were less than those with single Superphosphate, necessitating a reduction in annual stocking rates on the North Carolina phosphate rock-fertilised pasture. A key finding was that large, single, year-1 applications of North Carolina phosphate rock generally overcame these seasonal and/or yearly lag effects, and led to positive financial benefits from North Carolina phosphate rock applied in this way. Annual applications of North Carolina phosphate rock were economically viable at sandy, high rainfall sites where water-soluble P from single Superphosphate would be readily leached from the root zone, provided that the soil P status was adequate and conditions were conducive to reactive phosphate rock dissolution. However, North Carolina phosphate rock was not an economically viable fertiliser to apply annually at (i) non-leaching sites where the soil P status was low and marked yield penalties occurred in the first few years of North Carolina phosphate rock use, (ii) where the soil had a very high P-sorption capacity, and (iii) where North Carolina phosphate rock dissolution was restricted by low rainfall or high pH. The inclusion of estimated residual P value had only a small impact on the economic outcome for scenarios which had not already performed poorly due to seasonal or lag effects.
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Building an expert system to advise on the use of reactive phosphate rock on Australian pastures
Australian Journal of Experimental Agriculture, 1997Co-Authors: Pieter Gillard, Peter W. G. Sale, Sarath B TennakoonAbstract:Summary. An expert system has been developed, using the results from the National Reactive Phosphate Rock Project, to determine whether reactive phosphate rock is likely to be an effective substitute for water-soluble Superphosphate fertiliser for a given pasture environment. The evaluation is made from site information [annual rainfall, pasture composition and the likelihood of phosphorus (P) leaching], and soil information (pH, Colwell P, soil colour and field texture). The expert system can determine the effectiveness of both highly reactive and moderately reactive phosphate rocks. Observed substitution values of triple Superphosphate for the highly reactive North Carolina phosphate rock (ratio of the respective P levels required to produce 50% of the maximum observed yield response to triple Superphosphate) were closely related to values predicted by the expert system (r = 0.92); the relationship between observed and predicted substitution values of single Superphosphate for the moderately reactive Hemrawein phosphate rock was also close (r= 0.86). The expert system gives one of 4 different recommendations for reactive phosphate rock based on the magnitude of the predicted substitution values. These are ‘immediately effective’, ‘effective in the medium term’, ‘marginally effective’, and ‘not effective’. The system was validated using the results from independent field experiments that provided measures of the effectiveness of reactive phosphate rock at different pasture sites.
