Assessment of environmental and farm business impacts of phosphorus policies in two European regions

This paper presents analyses of the economic and environmental impact of relevant phosphorus management policy scenarios, using representative pig and poultry farms in the Emilia-Romagna region (Po River basin, Italy) and Niedersachsen region (Ems River basin, Germany) as case studies. The analysis was done by using a farm-level linear programming bioeconomic model developed for different farm and animal types-sows, fattening pigs, laying hens and broilers. The baseline for the assessed scenarios involved farms situated within the Nitrate Vulnerable Zones (NVZs) and therefore, were subject to indirect phosphorus fertilization limitations via the Nitrates Directive (ND). The analyzed phosphorus management policy scenarios included the implementation of two different balances of 8.7 kg and 4.35 kg of P per ha per year, inspired by the German Fertilizer Ordinance for phosphorus fertilization implemented in 2007 and later updated from 2017 up to 2023, respectively. We also included a more rigorous zero P balance scenario. The results of the scenario simulations, based on model assumptions, reveal that the introduction of direct phosphorus management policies for pig and poultry farms situated in high livestock dense regions can be done without causing any significant impact on farm gross margin (around 2% of reduction) for both regions and all four animal types, except for sows and broiler production in the Ems River Basin (up to 12% of reduction). Selected technologies and methods, inspired by current practices, have been analyzed for their cost efficiency to achieve the target P balance of the individual scenarios, including export of slurry out of the farm or export of separation solids. Results also highlight that the Nitrates Directive alone is not enough to handle the P issue in monogastric livestock farms

Impact of sediment type, light and nutrient availability on benthic diatom communities of a large estuarine bay: Moreton Bay, Australia

Shifts in diatom species composition may be used to infer past changes in environmental conditions in fresh, estuarine and marine systems. Establishing the primary drivers of present day diatom community composition is a vital step in their use as a proxy for past conditions. Moreton Bay, Australia, has experienced extensive modification of its catchments and western and southern shorelines. Regional weather patterns and terrestrial runoff have created a gradient in water quality from relatively degraded western and southern areas to relatively pristine northern and eastern areas. The aim of this study was to examine the relative impact of short term changes to light and/or nutrient availability and long term changes in sediment type, light and nutrient availability to subtidal benthic community composition. Short term changes were imposed using a manipulative field experiment whilst long term changes were obtained from a field survey of sites across the gradient of water quality. Diatoms were found to be the dominant microalgal group at all studied sites. The diatom communities were comprised primarily of small benthic epipsammic species and community composition was primarily driven by changes in sediment silt content. Short term changes in light and/or nutrient availability had little impact on community composition. In this open estuarine system the use of diatom indices to infer past water quality must take into account the sediment silt content in their interpretations