Reducing phosphorus losses from agricultural land to surface water.

Phosphorus (P) enrichment of water impairs its quality by stimulating algal growth and eutrophication, affecting an estimated 1.7 billion people. Remediation costs are substantial, estimated at $1 billion annually in Europe and $2.

Difficulties in using land use pressure and soil quality indicators to predict water quality.

Intensive agriculture can impair river water quality. Soil quality monitoring has been used to measure the effect of land use intensification on water quality at a point and field scales but not at the catchment scale. Other farm scale land use pressures, like stocking rate and the value of land, which relate to land use intensity are now publicly available, nationally.

A global dataset on phosphorus in agricultural soils.

Numerous drivers such as farming practices, erosion, land-use change, and soil biogeochemical background, determine the global spatial distribution of phosphorus (P) in agricultural soils. Here, we revised an approach published earlier (called here GPASOIL-v0), in which several global datasets describing these drivers were combined with a process model for soil P dynamics to reconstruct the past and current distribution of P in cropland and grassland soils. The objective of the present update, called GPASOIL-v1, is to incorporate recent advances in process understanding about soil inorganic P dynamics, in datasets to describe the different drivers, and in regional soil P measurements for benchmarking.

Reference conditions and threshold values for nitrate-nitrogen in New Zealand groundwaters.

Management of groundwater quality is assisted by an understanding of reference conditions, which describe the concentration ranges expected for key substances in the absence of human impact. This study evaluates reference conditions for NO-N in New Zealand groundwater based on three complementary methods: hierarchical cluster analysis, relationships to groundwater age, and regression against a measure of land-use impact. The three methods result in very similar national-scale estimates of reference conditions for NO-N concentration in oxic, minimally impacted groundwater, with the 80th, 90th and 95th percentiles found to be 1.

Factors controlling shallow subsurface dissolved reactive phosphorus concentration and loss kinetics from poorly drained saturated grassland soils.

Shallow subsurface pathways dominate dissolved reactive phosphorus (DRP) losses in grassland soils that are: poorly drained, shallow, or have a perched water table in wetter months causing saturation-excess runoff. Saturated conditions can lead to anoxia, which can accelerate phosphorus (P) loss. Two scales of investigation were utilized in this study.

Growing for good: producing a healthy, low greenhouse gas and water quality footprint diet in Aotearoa, New Zealand.

Food production plays a central role in the health of humanity and our environment. New Zealand produces a large amount of food, but it is unknown if it can produce enough of the right crops in the places to better the health of New Zealanders, profitably, while maintaining New Zealand's primary production exports and meeting ambitions to lower greenhouse gas (GHGs) emissions and nutrient losses to water. We tested two scenarios that aimed at delivering a healthy diet while maximising profit and minimising GHGs (climate-focused scenario) or losses of nitrogen (N) and phosphorus (P) to water (freshwater-focused scenario).

Reductive dissolution of phosphorus associated with iron-oxides during saturation in agricultural soil profiles.

In soils with a fragipan or poor permeability, water may remain in a soil profile long enough to make it anoxic and reductive. The reductive dissolution of iron (Fe)- and manganese (Mn)-oxides can release associated phosphorus (P). Therefore, the dissolved P would be vulnerable to subsurface flow and could contaminate nearby streams.

Sediment phosphorus buffering in streams at baseflow: A meta-analysis.

Phosphorus (P) pollution of surface waters remains a challenge for protecting and improving water quality. Central to the challenge is understanding what regulates P concentrations in streams. This quantitative review synthesizes the literature on a major control of P concentrations in streams at baseflow-the sediment P buffer-to better understand streamwater-sediment P interactions.

Changes in soil cadmium concentrations with time following cessation of phosphorus fertilizer inputs.

Cadmium (Cd) can accumulate in soil from the application of phosphorus fertilizer. However, there is little information on what happens to soil Cd concentrations when Cd inputs stop. This study used soil and pasture samples collected from a long-term field trial to measure changes in Cd concentrations in soil for 22 yr after Cd inputs from fertilizer had stopped and assessed whether the application of nitrogen (N) (50 kg ha  yr ) could increase plant uptake of Cd and reduce soil Cd concentrations.

Role of Organic Anions and Phosphatase Enzymes in Phosphorus Acquisition in the Rhizospheres of Legumes and Grasses Grown in a Low Phosphorus Pasture Soil.

Rhizosphere processes play a critical role in phosphorus (P) acquisition by plants and microbes, especially under P-limited conditions. Here, we investigated the impacts of nutrient addition and plant species on plant growth, rhizosphere processes, and soil P dynamics. In a glasshouse experiment, blue lupin (), white clover ( L.

Quantifying the Extent of Anthropogenic Eutrophication of Lakes at a National Scale in New Zealand.

Quantifying environmental changes relative to ecosystem reference conditions (baseline or natural states) can inform assessment of anthropogenic impacts and the development of restoration objectives and targets. We developed statistical models to predict current and reference concentrations of total nitrogen (TN) and total phosphorus (TP) in surface waters for a nationally representative sample of ≥1033 New Zealand lakes. The lake-specific nutrient concentrations reflected variation in factors including anthropogenic nutrient loads, hydrology, geology, elevation, climate, and lake and catchment morphology.

Transforming phosphorus use on the island of Ireland: A model for a sustainable system.

Phosphorus is an essential part of the world food web and a non-substitutable nutrient in all biological systems. Losses of phosphorus occur along the food-supply chain and cause environmental degradation and eutrophication. A key global challenge is to meet rising worldwide food demand while protecting water and environmental quality, and seeking to manage uncertainty around potential future phosphorus price or supply shocks.

Managing Diffuse Phosphorus at the Source versus at the Sink.

Judicious phosphorus (P) management is a global grand challenge and critical to achieving and maintaining water quality objectives while maintaining food production. The management of point sources has been successful in lowering P inputs to aquatic environments, but more difficult is reducing P discharges associated with diffuse sources, such as nonpoint runoff from agriculture and urban landscapes, as well as P accumulated in soils and sediments. Strategies for effective diffuse-P management are imperative.

Transforming soil phosphorus fertility management strategies to support the delivery of multiple ecosystem services from agricultural systems.

Despite greater emphasis on holistic phosphorus (P) management, current nutrient advice delivered at farm-scale still focuses almost exclusively on agricultural production. This limits our ability to address national and international strategies for the delivery of multiple ecosystem services (ES). Currently there is no operational framework in place to manage P fertility for multiple ES delivery and to identify the costs of potentially sacrificing crop yield and/or quality.

A review of regulations and guidelines related to winter manure application.

Winter manure application elevates nutrient losses and impairment of water quality as compared to manure applications in other seasons. In conjunction with reviewing global distribution of animal densities, we reviewed worldwide mandatory regulations and voluntary guidelines on efforts to reduce off-site nutrient losses associated with winter manure applications. Most of the developed countries implement regulations or guidelines to restrict winter manure application, which range from a regulative ban to guidelines based upon weather and field management conditions.

Temperature and Nitrogen Effects on Phosphorus Uptake by Agricultural Stream-Bed Sediments.

Climate change will likely increase the growing season, temperatures, and ratio of nitrogen (N) to phosphorus (P) loss from land to water. However, it is unknown how these factors influence P concentrations in streams. We sought to evaluate differences in biotic and abiotic processes affecting stream sediment P dynamics under different temperature and N-enrichment regimes.

Extreme phosphorus losses in drainage from grazed dairy pastures on marginal land.

With the installation of artificial drainage and large inputs of lime and fertilizer, dairy farming can be profitable on marginal land. We hypothesized that this will lead to large phosphorus (P) losses and potential surface water impairment if the soil has little capacity to sorb added P. Phosphorous was measured in drainage from three "marginal" soils used for dairying: an Organic soil that had been developed out of scrub for 2 yr and used for winter forage cropping, a Podzol that had been developed into pasture for 10 yr, and an intergrade soil that had been in pasture for 2 yr.

The use of alum to decrease phosphorus losses in runoff from grassland soils.

Phosphorus (P) loss from land can impair surface water quality. Aluminum sulfate (alum)-treated, compared with untreated, manure or slurry decreases P loss when applied to land; our hypothesis was that alum may also decrease P loss when directly applied to grassland grazed by dairy cows. A rainfall simulation showed that alum decreased mean concentrations of filterable reactive P (FRP) by 25 to 70% and total P (TP) by 20 to 40%, depending on soil P, Al, and Fe concentration and alum application rate.

Bayesian network for point and diffuse source phosphorus transfer from dairy pastures in South otago, new zealand.

Many factors affect the magnitude of nutrient losses from dairy farm systems. Bayesian Networks (BNs) are an alternative to conventional modeling that can evaluate complex multifactor problems using forward and backward reasoning. A BN of annual total phosphorus (TP) exports was developed for a hypothetical dairy farm in the south Otago region of New Zealand and was used to investigate and integrate the effects of different management options under contrasting rainfall and drainage regimes.

A review of the cost-effectiveness and suitability of mitigation strategies to prevent phosphorus loss from dairy farms in New Zealand and Australia.

The loss of phosphorus (P) from land to water is detrimental to surface water quality in many parts of New Zealand and Australia. Farming, especially pasture-based dairying, can be a source of P loss, but preventing it requires a range of fully costed strategies because little or no subsidies are available and the effectiveness of mitigation strategies varies with different farm management systems, topography, stream density, and climate. This paper reviews the cost-effectiveness of mitigation strategies for New Zealand and Australian dairy farms, grouping strategies into (i) management (e.

Minimising phosphorus losses from the soil matrix.

Phosphorus loss from land, due to agricultural intensification, can impair water quality. The quantity lost is a function of runoff and availability, which is affected by inputs and the ability of the soil to retain P. Losses are exacerbated if surface runoff or drainage occurs soon after P inputs (e.

Approaches for quantifying and managing diffuse phosphorus exports at the farm/small catchment scale.

Quantifying and managing diffuse P losses from small catchments or at the farm scale requires detailed knowledge of farming practices and their interaction with catchment processes. However, detailed knowledge may not be available and hence modeling is required. This paper demonstrates two approaches to developing tools that assist P losses from New Zealand or Australian dairy farms.