Murray Hannah - Academia.edu (original) (raw)
Papers by Murray Hannah
Environmental Modelling & Software, 2013
ABSTRACT Vegetable farms are one of many nitrogen (N) sources adversely affecting Lake Taihu in e... more ABSTRACT Vegetable farms are one of many nitrogen (N) sources adversely affecting Lake Taihu in eastern China. Given the lack of quantitative “cause and effect” relationships and data relating to these systems, we developed a conceptual Bayesian network to investigate and demonstrate causal relationships and the effects of different mitigation strategies on N exports from vegetable farms in the Lake Taihu region. Structurally, the network comprised one primary transport factor, one primary source factor and three post-mobilisation strategies, and three output factors.In general the network suggests that N exports are more sensitive to transport factors (i.e. runoff volumes) than source factors (i.e. fertiliser application rates) although the cumulative effects of excessive fertiliser were not considered. Post-mobilisation mitigations such as wetlands and ecoditches appear to be particularly effective in decreasing N exports however their implementation on a regional scale may be limited by land availability. While optimising N inputs would be prudent, the network suggests that better irrigation practice, including improved irrigation scheduling, using less imported water and optimising rainfall utilisation would be more effective in achieving environmental goals than simply limiting N supply.
Journal of dairy science, 2014
Late-lactation Holstein cows (n=144) that were offered 15kg dry matter (DM)/cow per day of perenn... more Late-lactation Holstein cows (n=144) that were offered 15kg dry matter (DM)/cow per day of perennial ryegrass to graze were randomized into 24 groups of 6. Each group contained a fistulated cow and groups were allocated to 1 of 3 feeding strategies: (1) control (10 groups): cows were fed crushed wheat grain twice daily in the milking parlor and ryegrass silage at pasture; (2) partial mixed ration (PMR; 10 groups): PMR that was isoenergetic to the control diet and fed twice daily on a feed pad; (3) PMR+canola (4 groups): a proportion of wheat in the PMR was replaced with canola meal to produce more estimated metabolizable protein than other groups. Supplements were fed to the control and PMR cows at 8, 10, 12, 14, or 16kg of DM/d, and to the PMR+canola cows at 14 or 16kg of DM/d. The PMR-fed cows had a lower incidence of ruminal acidosis compared with controls, and ruminal acidosis increased linearly and quadratically with supplement fed. Yield of milk fat was highest in the PMR+cano...
Http Www Publish Csiro Au Act View_File File_Id Ea9950951 Pdf, 1995
Seventy-six years of wheat yield data from a long-term rotation experiment at Dooen in the Victor... more Seventy-six years of wheat yield data from a long-term rotation experiment at Dooen in the Victorian Wimmera were analysed to describe the response of wheat yield to seasonal rainfall, crop sequence, and time. Wheat yields from 7 different 1-to 4-course rotations ...
Australian Journal of Experimental Agriculture, 1997
... Treatment effects on nodulation were determined using ordinal analysis (McCullagh and Nelder ... more ... Treatment effects on nodulation were determined using ordinal analysis (McCullagh and Nelder 1989) with back-transformation of treatment means and uncertainty intervals to the original ordinal scale (Hannah and Quigley 1996). ...
Water pollution is a major environmental problem worldwide. Tracing the source of contaminants in... more Water pollution is a major environmental problem worldwide. Tracing the source of contaminants in our water supplies is often the first step in taking effective remedial action. Organic chemicals can be used to trace the sources of contaminants such as sediments, agrochemicals and nutrients because living organisms, like their wastes and decomposition products, are chemically unique.
Diabetes research (Edinburgh, Scotland)
Analysis of atherogenic risk factors in 493 Maltese-born residents of Melbourne showed that after... more Analysis of atherogenic risk factors in 493 Maltese-born residents of Melbourne showed that after adjustment for the effects of age, fasting plasma insulin was the only factor with a highly significant (p = less than 0.001) association with electrocardiogram abnormalities suggestive of atherosclerotic coronary artery disease. Absence of peripheral arterial pulses was not correlated with abnormal electrocardiogram but was significantly associated with both age and smoking. Elevation of plasma insulin appears to be a significant risk factor for atherosclerotic heart disease.
Relaxation of the current ICAR limits for variability in milk yield measurements and for accuracy... more Relaxation of the current ICAR limits for variability in milk yield measurements and for accuracy of fat tests would encourage the development of innovative meter and sampler designs. If milk meters with a maximum bias of 2% for milk yield and maximum Coefficient of Variation (CV) of 7.5% were used for daily measurements, the 305-day milk yields per cow could be estimated with about seven times the precision of any ICAR meter currently approved and used for monthly yield measurements. Such meters would be suitable for daily herd management purposes on many farms and, if these installations were ICAR-approved, they would increase the availability of useful data for progeny testing.
Australian Journal of Experimental Agriculture, 2007
Abstract Less than half of Australian dairy farmers undertake production recording that normally ... more Abstract Less than half of Australian dairy farmers undertake production recording that normally requires the collection of milk samples for the measurements of fat, protein and lactose percentages and somatic cell count. Usually the milk samples are collected from ...
Australian Journal of Experimental Agriculture, 2007
... Connect with us. facebook youtube. Citation Clarke T, Hannah MC (2007) A simple statistical m... more ... Connect with us. facebook youtube. Citation Clarke T, Hannah MC (2007) A simple statistical model to estimate precision of 300-day milk and fat production for dairy cows . Australian Journal of Experimental Agriculture 47, 10951099. http://dx.doi.org/10.1071/EA07144. ...
Journal of Dairy Science, 2008
We examined the effects of monensin, provided by controlled-release capsules, on the enteric meth... more We examined the effects of monensin, provided by controlled-release capsules, on the enteric methane emissions and milk production of dairy cows receiving ryegrass pasture and grain. In a grazing experiment, 60 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows in the monensin group received 2 controlled-release capsules, with the second capsule administered 130 d after the first. Milk production was measured for 100 d following insertion of each capsule. The sulfur hexafluoride tracer gas technique was used to measure enteric methane emissions for 4 d starting on d 25 and 81 after insertion of the first capsule, and on d 83 after insertion of the second capsule. All cows grazed together as a single herd on a predominantly ryegrass sward and received 5 kg/d of grain (as-fed basis). In a second experiment, 7 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin controlled-release capsules on methane emissions and dry matter intake. Methane emissions were measured on d 75 after capsule insertion by placing cows in respiration chambers for 3 d. Cows received fresh ryegrass pasture harvested daily and 5 kg/d of grain. The release rate of monensin from the capsules used in both experiments was 240 ± 0.072 mg/d, determined over a 100-d period in ruminally cannulated cows. The monensin dose was calculated to be 12 to 14.5 mg/kg of dry matter intake. There was no effect of monensin on methane production in either the grazing experiment (g/d, g/kg of milk solids) or the chamber experiment (g/d, g/kg of dry matter intake). In the grazing study, there was no effect of
Journal of Dairy Science, 2007
Our study compared methane (CH 4 ) emissions from lactating dairy cows measured using the sulfur ... more Our study compared methane (CH 4 ) emissions from lactating dairy cows measured using the sulfur hexafluoride (SF 6 ) tracer and open-circuit respiration chamber techniques. The study was conducted using 16 lactating Holstein-Friesian cows. In each chamber, the cow was fitted with the SF 6 tracer apparatus to measure total CH 4 emissions, including emissions from the rectum. Fresh ryegrass pasture was harvested daily and fed ad libitum to each cow with a supplement of 5 kg of grain/d. The CH 4 emissions measured using the SF 6 tracer technique were similar to those using the chamber technique: 331 vs. 322 g of CH 4 /d per cow. The accuracy of the SF 6 tracer technique was indicated by considering the ratio of the CH 4 emission measured using the SF 6 tracer to the emission measured using the chamber for each cow on each day. The calculated ratio of 102.3% (SE = 1.51) was not different from 100%. A higher variability within cow between days was found for the SF 6 tracer technique [coefficient of variation (CV) = 6.1%] than for the chamber technique (CV = 4.3%). The variability among cows was substantially higher than within cows, and was higher for the SF 6 technique (CV = 19.6%) than for the chamber technique (CV = 17.8%). Our CH 4 emission data were compared with whole-animal chamber studies conducted in Canada and Ireland. In the Canadian study the SF 6 technique did not measure CH 4 emissions from the rectum and emissions were 8% lower than those measured using the chamber, indicating that emissions from the rectum may be greater than previously measured (1%).
Australian Journal of Experimental Agriculture, 2007
Introduction In Victoria, the prevalence of the cattle disease enzootic bovine leucosis (EBL) is ... more Introduction In Victoria, the prevalence of the cattle disease enzootic bovine leucosis (EBL) is very low. The Victorian EBL Eradication Program commenced in 1994 and aims to eradicate EBL from the states' dairy herd (Ridge and Galvin 2005). Samples of milk are collected ...
Weed Research, 1996
logistic curve-fitting procedure, in each case, Rv alues were >0.90 and lack-of-fit tests were cl... more logistic curve-fitting procedure, in each case, Rv alues were >0.90 and lack-of-fit tests were clearly non-significant at the 0.05 level. Chisquare tests were used to measure differences between ED.SD'S. The method does not require the pre-germination and selection of seedlings, daily watering or root-washing and results are obtained 7 days from sowing, providing favourable use for routine analyses and large-scale trials.
Soil Use and Management, 2006
Twenty-five pasture soils were sampled from high-rainfall zones of southeastern Australia to exam... more Twenty-five pasture soils were sampled from high-rainfall zones of southeastern Australia to examine relationships between soil properties, and between soil properties and P buffering capacity (PBC) measures. Correlations between PBC values and soil properties were generally poor, with the exception of oxalate-extractable Al (Al ox ) (r ‡ 0.97). Predictions of PBC were further improved when clay, as well as Al ox , was included in a linear regression model (r 2 ‡ 0.98). When Al ox and oxalate-extractable Fe were excluded from the modelling exercise, a more complex three-term linear regression model, including pH H 2 O , exchangeable H and cation exchange capacity, adequately fitted both PBC values of the 25 soils examined in this study (r 2 ‡ 0.76). However, the Al ox , Al ox plus clay and the three-term models gave poor predictions of the PBC values when the models were validated using 28 independent soils. These results emphasize the importance of model validation, because predictive models based on soil properties were not robust when tested across a broader range of soil types. In comparison, direct measures of PBC, such as single-point P sorption measures, are more practical and robust methods of estimating PBC for Australian soils.
Australian Journal of Soil Research, 2002
Soil phosphorus (P) buffering capacity (PBC) is an important soil property that influences the am... more Soil phosphorus (P) buffering capacity (PBC) is an important soil property that influences the amount of P fertiliser available for plant uptake. However, current methods of determining PBC are time-consuming and uneconomic in most commercial soil testing programs. The current study examined simpler methods of measuring the PBC of a wide range of Australian soils. Phosphorus sorption and extractable P data from 290 soils (initial data set) were collated to define the range of PBC values of Australian agricultural soils. Independently, detailed chemical and physical analyses were undertaken on a second set of 90 agricultural soils (principal data set), which were selected to represent the range of soil properties measured on the initial data set.
Soil Biology and Biochemistry, 2009
... Granular inoculants are soil-applied, usually in the seeding furrow at the same depth as the ... more ... Granular inoculants are soil-applied, usually in the seeding furrow at the same depth as the seed or just below it. Soil placement confers a range of advantages, as the inoculant is physically separated from the seed, in contrast to peat slurry inoculants. ...
Journal of Hydrology, 2013
ABSTRACT Agriculture, particularly pastoral based dairying, has intensified significantly in the ... more ABSTRACT Agriculture, particularly pastoral based dairying, has intensified significantly in the past two decades. There are mounting concerns that this intensification could be linked to declining environmental quality. This paper analyses changes in water quality in three catchments in south-west Victoria, Australia, where the dominant land use has been dairying for the past 21 years and where the intensity of milk production has increased, driven by changes in farming systems and imports of nitrogen (N) and phosphorus (P) in various forms. We aimed to investigate if water quality has changed over that period and if such changes were related to the intensity of land use at the catchment scale. Three adjoining catchments were investigated which are different in terms of hydrology, biochemistry and land use proportions. Statistical analysis of continuous datasets showed that concentrations of N and P changed over the 21 year period. There were notable links between the intensification of milk production and increasing concentrations of N and P in streams from 1990 to 2000. The influence varied between catchments possibly due to hydrological differences that in turn influence biogeochemistry. From 2000 to 2011, there is some evidence this link may be starting to become decoupled due to various changes in farming systems, although it is difficult to specify which changes have had the greatest effect. The outcome of the close links between production intensification and water quality is that without fundamental changes to the farming systems, or without physical changes implemented in the catchment such as more effective riparian buffers or treatment wetlands, increases in agricultural intensity may lead to further degradation of water quality. Through this study the importance of investigating multiple water quality parameters and land use datasets to understand catchment functioning has been highlighted. Crown Copyright
Journal of Environment Quality, 2008
This book presents and discusses some mainstream and moderately recent parametric inference techn... more This book presents and discusses some mainstream and moderately recent parametric inference techniques that the author has found to be useful in the course of his career as a statistical consultant in the environmental sciences. In the words of the author,“This book ...
Journal of Dairy Research, 1999
Applied dairy research is characterized by experiments for which financial and physical constrain... more Applied dairy research is characterized by experiments for which financial and physical constraints permit only a small number of experimental units. With few units it is difficult to replicate treatments, and without replication experimental error cannot be estimated. The statistical analysis and interpretation of such experiments is problematic. However, if there have been several such experiments it may be possible to perform a combined analysis. Nine unreplicated experiments comparing effects of diet on the composition of cows' milk and on cheese characteristics were jointly analysed as an incomplete block design. This analysis method was contrasted with analyses of individual experiments. For cheese moisture, the key outcome measurement, the assessment of statistical significance concurred for the two methods in 13 out of 21 comparisons of treatments with the control. Sources of error variation allowed for under the two methods were delineated. The combined analysis paradigm provided stronger inference and a wider interpretation of results than could be achieved using analyses for individual experiments. Unequal replication of treatments and unequal concurrence of treatments within experiments over the series gave rise to a wide range of SED. The challenge of presenting results with unequal SED was addressed graphically using error bars. Attention to series design, in particular the apportioning of replication and treatment concurrence across the series of experiments, was shown to ameliorate presentation difficulties and, more importantly, to yield higher precision at no extra cost.
Environmental Modelling & Software, 2013
ABSTRACT Vegetable farms are one of many nitrogen (N) sources adversely affecting Lake Taihu in e... more ABSTRACT Vegetable farms are one of many nitrogen (N) sources adversely affecting Lake Taihu in eastern China. Given the lack of quantitative “cause and effect” relationships and data relating to these systems, we developed a conceptual Bayesian network to investigate and demonstrate causal relationships and the effects of different mitigation strategies on N exports from vegetable farms in the Lake Taihu region. Structurally, the network comprised one primary transport factor, one primary source factor and three post-mobilisation strategies, and three output factors.In general the network suggests that N exports are more sensitive to transport factors (i.e. runoff volumes) than source factors (i.e. fertiliser application rates) although the cumulative effects of excessive fertiliser were not considered. Post-mobilisation mitigations such as wetlands and ecoditches appear to be particularly effective in decreasing N exports however their implementation on a regional scale may be limited by land availability. While optimising N inputs would be prudent, the network suggests that better irrigation practice, including improved irrigation scheduling, using less imported water and optimising rainfall utilisation would be more effective in achieving environmental goals than simply limiting N supply.
Journal of dairy science, 2014
Late-lactation Holstein cows (n=144) that were offered 15kg dry matter (DM)/cow per day of perenn... more Late-lactation Holstein cows (n=144) that were offered 15kg dry matter (DM)/cow per day of perennial ryegrass to graze were randomized into 24 groups of 6. Each group contained a fistulated cow and groups were allocated to 1 of 3 feeding strategies: (1) control (10 groups): cows were fed crushed wheat grain twice daily in the milking parlor and ryegrass silage at pasture; (2) partial mixed ration (PMR; 10 groups): PMR that was isoenergetic to the control diet and fed twice daily on a feed pad; (3) PMR+canola (4 groups): a proportion of wheat in the PMR was replaced with canola meal to produce more estimated metabolizable protein than other groups. Supplements were fed to the control and PMR cows at 8, 10, 12, 14, or 16kg of DM/d, and to the PMR+canola cows at 14 or 16kg of DM/d. The PMR-fed cows had a lower incidence of ruminal acidosis compared with controls, and ruminal acidosis increased linearly and quadratically with supplement fed. Yield of milk fat was highest in the PMR+cano...
Http Www Publish Csiro Au Act View_File File_Id Ea9950951 Pdf, 1995
Seventy-six years of wheat yield data from a long-term rotation experiment at Dooen in the Victor... more Seventy-six years of wheat yield data from a long-term rotation experiment at Dooen in the Victorian Wimmera were analysed to describe the response of wheat yield to seasonal rainfall, crop sequence, and time. Wheat yields from 7 different 1-to 4-course rotations ...
Australian Journal of Experimental Agriculture, 1997
... Treatment effects on nodulation were determined using ordinal analysis (McCullagh and Nelder ... more ... Treatment effects on nodulation were determined using ordinal analysis (McCullagh and Nelder 1989) with back-transformation of treatment means and uncertainty intervals to the original ordinal scale (Hannah and Quigley 1996). ...
Water pollution is a major environmental problem worldwide. Tracing the source of contaminants in... more Water pollution is a major environmental problem worldwide. Tracing the source of contaminants in our water supplies is often the first step in taking effective remedial action. Organic chemicals can be used to trace the sources of contaminants such as sediments, agrochemicals and nutrients because living organisms, like their wastes and decomposition products, are chemically unique.
Diabetes research (Edinburgh, Scotland)
Analysis of atherogenic risk factors in 493 Maltese-born residents of Melbourne showed that after... more Analysis of atherogenic risk factors in 493 Maltese-born residents of Melbourne showed that after adjustment for the effects of age, fasting plasma insulin was the only factor with a highly significant (p = less than 0.001) association with electrocardiogram abnormalities suggestive of atherosclerotic coronary artery disease. Absence of peripheral arterial pulses was not correlated with abnormal electrocardiogram but was significantly associated with both age and smoking. Elevation of plasma insulin appears to be a significant risk factor for atherosclerotic heart disease.
Relaxation of the current ICAR limits for variability in milk yield measurements and for accuracy... more Relaxation of the current ICAR limits for variability in milk yield measurements and for accuracy of fat tests would encourage the development of innovative meter and sampler designs. If milk meters with a maximum bias of 2% for milk yield and maximum Coefficient of Variation (CV) of 7.5% were used for daily measurements, the 305-day milk yields per cow could be estimated with about seven times the precision of any ICAR meter currently approved and used for monthly yield measurements. Such meters would be suitable for daily herd management purposes on many farms and, if these installations were ICAR-approved, they would increase the availability of useful data for progeny testing.
Australian Journal of Experimental Agriculture, 2007
Abstract Less than half of Australian dairy farmers undertake production recording that normally ... more Abstract Less than half of Australian dairy farmers undertake production recording that normally requires the collection of milk samples for the measurements of fat, protein and lactose percentages and somatic cell count. Usually the milk samples are collected from ...
Australian Journal of Experimental Agriculture, 2007
... Connect with us. facebook youtube. Citation Clarke T, Hannah MC (2007) A simple statistical m... more ... Connect with us. facebook youtube. Citation Clarke T, Hannah MC (2007) A simple statistical model to estimate precision of 300-day milk and fat production for dairy cows . Australian Journal of Experimental Agriculture 47, 10951099. http://dx.doi.org/10.1071/EA07144. ...
Journal of Dairy Science, 2008
We examined the effects of monensin, provided by controlled-release capsules, on the enteric meth... more We examined the effects of monensin, provided by controlled-release capsules, on the enteric methane emissions and milk production of dairy cows receiving ryegrass pasture and grain. In a grazing experiment, 60 Holstein-Friesian cows were assigned randomly to 1 of 2 groups (control or monensin). Cows in the monensin group received 2 controlled-release capsules, with the second capsule administered 130 d after the first. Milk production was measured for 100 d following insertion of each capsule. The sulfur hexafluoride tracer gas technique was used to measure enteric methane emissions for 4 d starting on d 25 and 81 after insertion of the first capsule, and on d 83 after insertion of the second capsule. All cows grazed together as a single herd on a predominantly ryegrass sward and received 5 kg/d of grain (as-fed basis). In a second experiment, 7 pairs of lactating dairy cows (control and monensin) were used to determine the effects of monensin controlled-release capsules on methane emissions and dry matter intake. Methane emissions were measured on d 75 after capsule insertion by placing cows in respiration chambers for 3 d. Cows received fresh ryegrass pasture harvested daily and 5 kg/d of grain. The release rate of monensin from the capsules used in both experiments was 240 ± 0.072 mg/d, determined over a 100-d period in ruminally cannulated cows. The monensin dose was calculated to be 12 to 14.5 mg/kg of dry matter intake. There was no effect of monensin on methane production in either the grazing experiment (g/d, g/kg of milk solids) or the chamber experiment (g/d, g/kg of dry matter intake). In the grazing study, there was no effect of
Journal of Dairy Science, 2007
Our study compared methane (CH 4 ) emissions from lactating dairy cows measured using the sulfur ... more Our study compared methane (CH 4 ) emissions from lactating dairy cows measured using the sulfur hexafluoride (SF 6 ) tracer and open-circuit respiration chamber techniques. The study was conducted using 16 lactating Holstein-Friesian cows. In each chamber, the cow was fitted with the SF 6 tracer apparatus to measure total CH 4 emissions, including emissions from the rectum. Fresh ryegrass pasture was harvested daily and fed ad libitum to each cow with a supplement of 5 kg of grain/d. The CH 4 emissions measured using the SF 6 tracer technique were similar to those using the chamber technique: 331 vs. 322 g of CH 4 /d per cow. The accuracy of the SF 6 tracer technique was indicated by considering the ratio of the CH 4 emission measured using the SF 6 tracer to the emission measured using the chamber for each cow on each day. The calculated ratio of 102.3% (SE = 1.51) was not different from 100%. A higher variability within cow between days was found for the SF 6 tracer technique [coefficient of variation (CV) = 6.1%] than for the chamber technique (CV = 4.3%). The variability among cows was substantially higher than within cows, and was higher for the SF 6 technique (CV = 19.6%) than for the chamber technique (CV = 17.8%). Our CH 4 emission data were compared with whole-animal chamber studies conducted in Canada and Ireland. In the Canadian study the SF 6 technique did not measure CH 4 emissions from the rectum and emissions were 8% lower than those measured using the chamber, indicating that emissions from the rectum may be greater than previously measured (1%).
Australian Journal of Experimental Agriculture, 2007
Introduction In Victoria, the prevalence of the cattle disease enzootic bovine leucosis (EBL) is ... more Introduction In Victoria, the prevalence of the cattle disease enzootic bovine leucosis (EBL) is very low. The Victorian EBL Eradication Program commenced in 1994 and aims to eradicate EBL from the states' dairy herd (Ridge and Galvin 2005). Samples of milk are collected ...
Weed Research, 1996
logistic curve-fitting procedure, in each case, Rv alues were >0.90 and lack-of-fit tests were cl... more logistic curve-fitting procedure, in each case, Rv alues were >0.90 and lack-of-fit tests were clearly non-significant at the 0.05 level. Chisquare tests were used to measure differences between ED.SD'S. The method does not require the pre-germination and selection of seedlings, daily watering or root-washing and results are obtained 7 days from sowing, providing favourable use for routine analyses and large-scale trials.
Soil Use and Management, 2006
Twenty-five pasture soils were sampled from high-rainfall zones of southeastern Australia to exam... more Twenty-five pasture soils were sampled from high-rainfall zones of southeastern Australia to examine relationships between soil properties, and between soil properties and P buffering capacity (PBC) measures. Correlations between PBC values and soil properties were generally poor, with the exception of oxalate-extractable Al (Al ox ) (r ‡ 0.97). Predictions of PBC were further improved when clay, as well as Al ox , was included in a linear regression model (r 2 ‡ 0.98). When Al ox and oxalate-extractable Fe were excluded from the modelling exercise, a more complex three-term linear regression model, including pH H 2 O , exchangeable H and cation exchange capacity, adequately fitted both PBC values of the 25 soils examined in this study (r 2 ‡ 0.76). However, the Al ox , Al ox plus clay and the three-term models gave poor predictions of the PBC values when the models were validated using 28 independent soils. These results emphasize the importance of model validation, because predictive models based on soil properties were not robust when tested across a broader range of soil types. In comparison, direct measures of PBC, such as single-point P sorption measures, are more practical and robust methods of estimating PBC for Australian soils.
Australian Journal of Soil Research, 2002
Soil phosphorus (P) buffering capacity (PBC) is an important soil property that influences the am... more Soil phosphorus (P) buffering capacity (PBC) is an important soil property that influences the amount of P fertiliser available for plant uptake. However, current methods of determining PBC are time-consuming and uneconomic in most commercial soil testing programs. The current study examined simpler methods of measuring the PBC of a wide range of Australian soils. Phosphorus sorption and extractable P data from 290 soils (initial data set) were collated to define the range of PBC values of Australian agricultural soils. Independently, detailed chemical and physical analyses were undertaken on a second set of 90 agricultural soils (principal data set), which were selected to represent the range of soil properties measured on the initial data set.
Soil Biology and Biochemistry, 2009
... Granular inoculants are soil-applied, usually in the seeding furrow at the same depth as the ... more ... Granular inoculants are soil-applied, usually in the seeding furrow at the same depth as the seed or just below it. Soil placement confers a range of advantages, as the inoculant is physically separated from the seed, in contrast to peat slurry inoculants. ...
Journal of Hydrology, 2013
ABSTRACT Agriculture, particularly pastoral based dairying, has intensified significantly in the ... more ABSTRACT Agriculture, particularly pastoral based dairying, has intensified significantly in the past two decades. There are mounting concerns that this intensification could be linked to declining environmental quality. This paper analyses changes in water quality in three catchments in south-west Victoria, Australia, where the dominant land use has been dairying for the past 21 years and where the intensity of milk production has increased, driven by changes in farming systems and imports of nitrogen (N) and phosphorus (P) in various forms. We aimed to investigate if water quality has changed over that period and if such changes were related to the intensity of land use at the catchment scale. Three adjoining catchments were investigated which are different in terms of hydrology, biochemistry and land use proportions. Statistical analysis of continuous datasets showed that concentrations of N and P changed over the 21 year period. There were notable links between the intensification of milk production and increasing concentrations of N and P in streams from 1990 to 2000. The influence varied between catchments possibly due to hydrological differences that in turn influence biogeochemistry. From 2000 to 2011, there is some evidence this link may be starting to become decoupled due to various changes in farming systems, although it is difficult to specify which changes have had the greatest effect. The outcome of the close links between production intensification and water quality is that without fundamental changes to the farming systems, or without physical changes implemented in the catchment such as more effective riparian buffers or treatment wetlands, increases in agricultural intensity may lead to further degradation of water quality. Through this study the importance of investigating multiple water quality parameters and land use datasets to understand catchment functioning has been highlighted. Crown Copyright
Journal of Environment Quality, 2008
This book presents and discusses some mainstream and moderately recent parametric inference techn... more This book presents and discusses some mainstream and moderately recent parametric inference techniques that the author has found to be useful in the course of his career as a statistical consultant in the environmental sciences. In the words of the author,“This book ...
Journal of Dairy Research, 1999
Applied dairy research is characterized by experiments for which financial and physical constrain... more Applied dairy research is characterized by experiments for which financial and physical constraints permit only a small number of experimental units. With few units it is difficult to replicate treatments, and without replication experimental error cannot be estimated. The statistical analysis and interpretation of such experiments is problematic. However, if there have been several such experiments it may be possible to perform a combined analysis. Nine unreplicated experiments comparing effects of diet on the composition of cows' milk and on cheese characteristics were jointly analysed as an incomplete block design. This analysis method was contrasted with analyses of individual experiments. For cheese moisture, the key outcome measurement, the assessment of statistical significance concurred for the two methods in 13 out of 21 comparisons of treatments with the control. Sources of error variation allowed for under the two methods were delineated. The combined analysis paradigm provided stronger inference and a wider interpretation of results than could be achieved using analyses for individual experiments. Unequal replication of treatments and unequal concurrence of treatments within experiments over the series gave rise to a wide range of SED. The challenge of presenting results with unequal SED was addressed graphically using error bars. Attention to series design, in particular the apportioning of replication and treatment concurrence across the series of experiments, was shown to ameliorate presentation difficulties and, more importantly, to yield higher precision at no extra cost.