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The movement of excess phosphorus (P) into streams, rivers and lakes poses a significant threat to water quality and the health of aquatic ecosystems and thus P has been targeted for reduction. In landscapes dominated by agriculture, P is primarily transported through non-point sources which a number of best management practices aim to target. One such practice is vegetated buffer strips (VBS), which are designed to use dense vegetation above the surface and extensive root systems below the surface to reduce runoff velocity, trap sediments, increase infiltration, and increase plant uptake of nutrients. The effectiveness of VBS in reducing P concentrations has been studied and reviewed, but most studies have been undertaken in warm or temperate climates, where runoff is primarily driven through summer rainfall events, and when vegetation is actively growing. In cold climates, the majority of runoff occurs during the snowmelt period when vegetation is not actively taking up nutrients, has been flattened by snow and ice over the winter period, and when soils are frozen. These conditions hinder the ability for VBS to work as designed. Additionally, frozen vegetation can release P after undergoing freeze-thaw cycles (FTCs). Thus, this review aimed to: i) summarize research designed to determine the effectiveness of VBS to reduce P transport undertaken in cold climates; ii) collate research on the potential for vegetation to release P after undergoing FTCs; and iii) identify research gaps to be addressed in determining VBS effectiveness in cold climates. Cold climate VBS implemented in Canada, the northern United States, and northern Europe have shown P removal efficiencies ranging from -36% to +89%, a range that pinpoints the uncertainty surrounding the use of VBS in these landscapes. However, there is consensus in research globally that vegetation does release P after undergoing FTCs, though P concentrations from different species vary across studies. The design and management of VBS in cold climates requires careful consideration and may not always be the best management strategy to reduce P transport. Future research should be undertaken at a larger scale in natural systems and focus on VBS design and management strategies.

Glyphosate is the most commonly-used herbicide in the world. The present review summarizes the discovery, prevalence, chemical and physical properties, mode of action and effects in plants, glyphosate resistance and the environmental fate of glyphosate. Numerous studies are reviewed that demonstrate that glyphosate may run off of fields where it is applied, while other studies provide evidence that plant roots can take up glyphosate. Non-target vegetation may be exposed to glyphosate in the root-zone, where it has the potential to remove aqueous glyphosate from the system. Further study on the effects of root-zone glyphosate on non-target vegetation is required to develop best management practices for land managers seeking to ameliorate the effects of root-zone glyphosate exposure.

Vegetated buffer strips (VBSs) are widely encouraged as a cost-effective strategy to address phosphorus (P) pollution associated with agricultural production. However, there is a lack of evidence in the effectiveness of these measures for tackling diffuse P pollution in cold-climate regions under concentrated runoff flow conditions. This research aimed to investigate the effects of VBSs on reducing P concentrations in surface runoff at three different watersheds in Manitoba, Canada. Surface runoff samples were collected in four sub-catchments from each watershed by installing paired weirs at 0.5-m and at 5-m into the VBSs along the expected runoff flow path. In addition, P concentrations were measured in soil samples collected within and outside of the runoff flow path to gain further insight into P dynamics within VBSs at each study site. The results indicate that VBSs had little or no significant effect on reducing the concentration of P forms in surface runoff in the majority of situations, resulting in reduced runoff losses of total, dissolved and particulate P concentrations in only 23, 12 and 12% of the situations, respectively. In addition, Olsen extractable P concentrations in VBS soils were not significantly different from field soils both within and outside of the flow path. The ineffective P retention by VBSs in this region is likely associated with the fact that the majority of the runoff flow is concentrated through small portions of VBSs and occurs during snowmelt when biogeochemical processes responsible for P retention in VBSs are limited. Further research is needed to develop alternative management practices that enhance P retention during concentrated snowmelt runoff events in such cold-climate regions.

Purpose Nitrous oxide (N2O) and methane (CH4) are some of the most important greenhouse gases in the atmosphere of the 21st century. Vegetated riparian bufers are primarily implemented for their water quality functions in agroecosystems. Their location in agricultural landscapes allows them to intercept and process pollutants from adjacent agricultural land. They recycle organic matter, which increases soil carbon (C), intercept nitrogen (N)-rich runof from adjacent croplands, and are seasonally anoxic. Thus processes producing environmentally harmful gases including N2O and CH4 are promoted. Against this context, the study quantifed atmospheric losses between a cropland and vegetated riparian bufers that serve it. Methods Environmental variables and simultaneous N2O and CH4 emissions were measured for a 6-month period in a replicated plot-scale facility comprising maize (Zea mays L.). A static chamber was used to measure gas emissions. The cropping was served by three vegetated riparian bufers, namely: (i) grass riparian bufer; (ii) willow riparian bufer and; (iii) woodland riparian bufer, which were compared with a no-bufer control. Results The no-bufer control generated the largest cumulative N2O emissions of 18.9 kg ha−1 (95% confdence interval: 0.5–63.6) whilst the maize crop upslope generated the largest cumulative CH4 emissions (5.1±0.88 kg ha−1 ). Soil N2O and CH4-based global warming potential (GWP) were lower in the willow (1223.5±362.0 and 134.7±74.0 kg CO2-eq. ha−1 year−1 , respectively) and woodland (1771.3±800.5 and 3.4±35.9 kg CO2-eq. ha−1 year−1 , respectively) riparian bufers. Conclusions Our results suggest that in maize production and where no riparian bufer vegetation is introduced for water quality purposes (no bufer control), atmospheric CH4 and N2O concerns may result.

Agriculture is often responsible for the eutrophication of surface waters due to the loss of phosphorus—a normally limiting nutrient in freshwater ecosystems. Tile-drained agricultural catchments tend to increase this problem by accelerating the transport of phosphorus through subsurface drains both in dissolved (reactive and organic phosphorus) and particulate (particle-bound phosphorus) forms. The reduction of excess phosphorus loads from agricultural catchments prior to reaching downstream surface waters is therefore necessary. Edge-of-field technologies have been investigated, developed and implemented in areas with excess phosphorus losses to receive and treat the drainage discharge, when measures at the farm-scale are not able to sufficiently reduce the loads. The implementation of these technologies shall base on the phosphorus dynamics of specific catchments (e.g., phosphorus load and dominant phosphorus form) in order to ensure that local retention goals are met. Widely accepted technologies include constructed wetlands, restored wetlands, vegetated buffer strips and filter materials. These have demonstrated a large variability in the retention of phosphorus, and results from the literature can help targeting specific catchment conditions with suitable technologies. This review provides a comprehensive analysis of the currently used edge-of-field technologies for phosphorus retention in tile-drained catchments, with great focus on performance, application and limitations.

1. In Europe and North America, there is growing concern that biodiversity declines associated with agricultural intensification will adversely impact the functioning and sustainability of agricultural ecosystems. Enhancing habitat heterogeneity in agricultural landscapes promotes biodiversity and, whilst erecting fences adjacent to watercourses is widely advocated as a means of mitigating diffuse pollution, associated biodiversity benefits have been largely overlooked. 2. A range of riparian margins and their adjacent grassland fields were investigated to determine the effects of riparian management on the diversity and functional structure of carabid assemblages. Carabid assemblages of fields and open margins (i.e. unfenced watercourses) were more diverse and species rich than those of fenced margins. 3. The functional structure of carabid assemblages in fenced margins differed from grassland fields and open margins. This disparity was greater in wide margins (i.e. fences erected over 5·4 m from watercourses) than narrow margins (i.e. fences erected within 2·6 m of watercourses). Wide margins had the highest relative proportions of carabids which had pushing body forms, were flightless, very small in size and Collembola specialists. During early summer, wide margins also had the highest proportion of carabids that overwinter as adults. 4. The taxonomic and functional structure of carabid assemblages was more sensitive for detecting impacts of agricultural management than measurements of diversity. It is likely that this also applies to other taxa, thus emphasising the need to consider a wide range of assemblage attributes when investigating agricultural impacts on biodiversity. 5. Synthesis and applications. Fenced riparian margins, particularly those over 5·4 m wide, harbour carabids with poor dispersal ability which are vulnerable to habitat fragmentation. While lack of management benefits sedentary species, a wider range of taxa (e.g. pollinators, foraging birds and flowering plants) are enhanced by management to obtain a more open vegetation structure (e.g. restricted grazing or mowing). It is important that management practices are implemented at a sufficiently fine spatial scale to allow recolonisation of species with restricted dispersal from adjacent undisturbed habitats. Wide riparian margins have the potential to enhance taxonomic and functional diversity at the landscape scale. Management actions must, however, be carefully balanced to ensure that they promote a wide range of taxa without unduly interfering with the margin's ability to mitigate diffuse pollution.

This study tests the hypothesis that microbial biomass phosphorus (P) makes a significant contribution to P solubility in riparian buffer strip soils. In 36 soils collected from buffer strips within three UK soil associations, water-extractable inorganic P solubility was most strongly related to NaHCO 3 extractable inorganic P. However, within individual soil associations where soil pedological properties and management were similar, water-extractable inorganic P was most strongly related to microbial biomass P. These results highlight the difficulty in predicting dissolved P leaching risk based on agronomic soil P tests alone and the dissolved P leaching risk presented by having soils high in organic matter and microbial biomass P in close proximity to surface waters.

An experimental study was conducted in Tillamook, Oregon, USA, to quantify the effectiveness of edge-of-field vegetated buffers for reducing transport of fecal coliform bacteria (FCB) from agricultural fields amended with dairy cow manure. Installation of vegetated buffers on loamy soils dramatically reduced the bacterial contamination of runoff water from manure-treated pasturelands, but the size of the vegetated buffer was not an important determinant of bacterial removal efficiency. Only 10% of the runoff samples collected from treatment cells having vegetated buffers exhibited FCB concentrations >200 colony forming units (cfu)/100 mL (a common water quality standard value), and the median concentration for all cells containing vegetated buffers was only 6 cfu/100 mL. The presence of a vegetated buffer of any size, from 1 to 25 m, generally reduced the median FCB concentration in runoff by more than 99%. Results for FCB load calculations were similar. Our results suggest that where substantial FCB contamination of runoff occurs from manure-treated pasturelands, it might be disproportionately associated with specific field or management conditions, such as the presence of soils that exhibit low water infiltration and generate larger volumes of runoff or the absence of a vegetated buffer. Buffer size regulations that do not consider such differences might not be efficient or effective in reducing bacterial contamination of runoff.

The implementation of nature-based solutions (NBSs) can be a suitable and sustainable approach to coping with environmental issues related to diffuse water pollution from agriculture. NBSs exploit natural mitigation processes that can promote the removal of different contaminants from agricultural wastewater, and they can also enable the recovery of otherwise lost resources (i.e., nutrients). Among these, nitrogen impacts different ecosystems, resulting in serious environmental and human health issues. Recent research activities have investigated the capability of NBS to remove nitrogen from polluted water. However, the regulating mechanisms for nitrogen removal can be complex, since a wide range of decontamination pathways, such as plant uptake, microbial degradation, substrate adsorption and filtration, precipitation, sedimentation, and volatilization, can be involved. Investigating these processes is beneficial for the enhancement of the performance of NBSs. The present study provides a comprehensive review of factors that can influence nitrogen removal in different types of NBSs, and the possible strategies for nitrogen recovery that have been reported in the literature.

Soil erosion from agricultural fields is a persistent ecological problem, potentially leading to eutrophication of aquatic habitats in the catchment area. Often used and recommended mitigation measures are vegetated filter strips (VFS) as buffer zones between arable land and water bodies. However, if they are designed and managed poorly, nutrients — especially phosphorus (P) — may accumulate in the soil. Ultimately, VFS can switch from being a nutrient sink to a source. This problem is further aggravated if the field runoff does not occur as uniform sheet flow, but rather in concentrated form, as is usually the case. To assess the impact of concentrated flow on VFS performance, we have taken soil core samples from field-VFS transition zones at six sites in Lower Austria. We determined a multitude of physical and chemical soil parameters, focusing on P fractions and indices. Our results revealed that concentrated flow can lead to an accumulation of P in the VFS. P levels in the VFS inside the area of concentrated runoff can be equal to or higher than in the field, even though they receive no direct fertilization. However, the concentration and distribution of nutrients in the fields and VFSs were also site-specific and affected by local factors such as the age of the VFS, cropping, and fertilization. Accordingly, there is a need for more sophisticated, bespoke VFS designs that can cope with site-specific runoff volumes and movements of nutrients that occur.