[Spatial scale effects of landscape patterns on non-point source pollution: A case study of Taizi River Basin in Northeast China]. / éžç‚¹æºæ±¡æŸ“å¯¹æ™¯è§‚æ ¼å±€å“åº”çš„ç©ºé—´å°ºåº¦æ•ˆåº”­­ä»¥ä¸œåŒ—太子河流域为例.

River water quality is influenced by natural processes and human activities. Multi-scale landscape patterns can affect river water quality by altering the generation and transport processes of pollutants at different spatial scales. Taking Taizi River Basin in Northeast China as an example, we analyzed the relationship between landscape patterns and non-point source pollution in rivers based on water quality monitoring data and land use data by using correlation analysis and redundancy analysis methods. We aimed to determine the key spatial scales for the responses of landscape patterns to non-point source pollution and identify the key landscape indices influencing river non-point source pollution. The results showed that water quality of Taizi River Basin had seasonal differences, with better water quality during the flood season than non-flood season. Spatially, total nitrogen (TN) and total phosphorus (TP) were higher at the confluence points of tributaries and downstream areas. The impact of landscape patterns on non-point source pollution was stronger during the non-flood season than the flood season, while the influence on TN was stronger than on TP. At the spatial scale of within 500 m buffer zone during the flood season and at the sub-watershed scale during the non-flood season, landscape patterns showed the highest explanatory power for the variations of TN and TP. At the type level, built-up land, cropland, and bare land were positively correlated with TN and TP, while forest was negatively correlated with TN and TP, which were the key types influencing non-point source pollution. At the landscape level, patch density, percentage of like adjacencies, and contagion index were key indicators affecting watershed water quality. Lower patch density was associated with better connectivity and aggregation of "sink" landscapes, leading to better purification effects on TN, but more pronounced retention effects on TP. Conversely, higher landscape diversity and denser pattern of multiple types would cause the deterioration of water quality. Our results suggested that rational allocation of landscape types within the watershed and riparian buffer zones, appropriately enriching landscape diversity, and optimizing landscape aggregation and connectivity would be effective measures for improving water quality and achieving sustainable ecological management.

Simulating the land use change effects on non-point source pollution in the Duliujian River Basin.

The uncertainty in the generation and formation of non-point source pollution makes it challenging to monitor and control this type of pollution. The SWAT model is frequently used to simulate non-point source pollution in watersheds and is mainly applied to natural watersheds that are less affected by human activities. This study focuses on the Duliujian River Basin (Xiqing section), which is characterized by a dense population and rapid urbanization. Based on the calibrated SWAT model, this study analyzed the effects of land use change on non-point source pollution both temporally and spatially. It was found that nitrogen and phosphorus non-point source pollution load losses were closely related to land use type, with agricultural land and high-density urban land (including rural settlements) being the main contributors to riverine nitrogen and phosphorus pollution. This indicates the necessity of analyzing the impact of land use changes on non-point source pollution loads by identifying critical source areas and altering the land use types that contribute heavily to pollution in these areas. The simulation results of land use type changes in these critical source areas showed that the reduction effect on non-point source pollution load is in the order of forest land > grassland > low-density residential area. To effectively curb surface source pollution in the study area, strategies such as modifying urban land use types, increasing vegetation cover and ground infiltration rate, and strictly controlling the discharge of domestic waste and sewage from urban areas can be implemented.

Preventing Agricultural Non-Point Source Pollution in China: The Effect of Environmental Regulation with Digitization.

Environmental regulation (ER) is essential to preventing agricultural non-point source pollution (ANSP). Prior research has focused on the effect of ER on agricultural pollution (AP), but little is known about the impact of ER following digitization on preventing AP, particularly ANSP. Based on the spatial heterogeneity, the effect of ER was examined using a geographic detector tool with provincial panel data from 2010 to 2020 in rural China. The results show that ER is a driver in preventing ANSP, primarily because of the constraint on farmers' behavior. Digitization positively affects the prevention of ANSP, as the new impetus for the infrastructure, technology, and capital is supported. The interaction between ER and digitalization forms a driving effect on the prevention of ANSP, indicating that digitalization constitutes the path dependence of farmers' rule acquisition and perception and addresses the "free riding" dilemma of farmers' participation, thereby enabling the incentive of ER to make agricultural production green and efficient. These findings indicate that the endogenous factor of digitization allowing ER is essential to preventing ANSP.

China's agricultural non-point source pollution and green growth: interaction and spatial spillover.

Based on the panel data of 31 provinces in China from 2000 to 2019, a spatial simultaneous equation model is used to study the two-way interaction and spatial spillover between non-point source pollution and agricultural green development. The results show that (1) non-point source pollution is the most significant hindering factor for agricultural green development, agricultural green development can reduce non-point source pollution, and non-point source pollution and agricultural green development have significant spatial spillover effects respectively. (2) Yield development target is an important internal factor influencing the relationship between agricultural green development transition and non-point source pollution. Environmental regulation and agricultural R&D stock promote agricultural green development but also aggravate non-point source pollution. Production scale cannot promote agricultural green development but can help reduce non-point source pollution. (3) Urbanization and agricultural trade dependence both promote the green development of agriculture, while farmers' income and agricultural machinery strength increase and reduce non-point source pollution respectively. To promote the agricultural non-point source pollution treatment and green development, we should strengthen the protection of agricultural resources and the monitoring of agricultural environment and change the production relations of small farmers.

Spatial variability of soil nutrients in seasonal rivers: A case study from the Guo River Basin, China.

Agricultural non-point source pollution refers that substance such as nitrogen and phosphorus cause water environment pollution through surface runoff and underground leakage in agricultural production activities. Water environment pollution related to agricultural non-point source pollution in the Huaihe River Basin is becoming more and more prominent. Therefore, it is necessary to analyze the characteristic of soil nutrient in cultivated land and explore the spatial variation and influencing factors of soil nutrients at the watershed scale. A total of 239 topsoil samples were collected from the Guo river basin, and the related factors of soil organic matter (SOM), total carbon (TC), total nitrogen (TN), total phosphorous (TP), total potassium (TK) and potential of hydrogen (PH) were studied by using descriptive statistics and geostatistical methods. The results showed that TK and PH were weak variation, while SOM, TC, TN and TP were medium variation. Soil pH, TP, TK, TC and SOM had moderate spatial variability, which was caused by both random factors and structural factors such as soil texture, soil type, fertilization and local ecological restoration management. Soil TN showed a strong spatial correlation, mainly due to soil texture and soil type. If the recommended fertilization amount is still given based on the average value of soil nutrients ignoring the spatial heterogeneity, it will not only affect crop production efficiency and fertilizer utilization, but may also cause greater environmental pollution. This study can provide a theoretical basis for the management of agro-ecological environments throughout the basin area.

An Evolutionary Game Model for the Multi-agent Co-Governance of Agricultural Non-Point Source Pollution Control under Intensive Management Pattern in China.

This paper focuses on the sustainable development dilemma of agricultural production in China under the pattern of intensive management, which is seriously challenged by agricultural non-point source pollution. The key to effectively break through the dilemma is to promote the co-governance of agricultural non-point source pollution control by stakeholders including local governments, new agricultural operators and traditional farmers. Accordingly, this paper discusses the interactive decision-making relationships between new agricultural operators and traditional farmers under the guidance of local governments, by constructing a trilateral evolutionary game model, as well as analyzing evolutionary cooperative stability strategies and realizing the simulation of evolution processes in different scenarios by MATLAB. The results show that new agricultural operators play a leading role in agricultural non-point source pollution control, whose strategies have effects such as technology spillover. The rewards from the superior government will support local governments in taking proactive action in the co-governance of agricultural non-point source pollution control, and then local governments can offer technical support and subsidies to new agricultural operators and traditional farmers for reducing their costs. Furthermore, this paper also finds that there are green synergy effects among the groups, where the variations of parameters and strategies by one group would affect the two others. Additionally, agricultural land operation rights transfers would cause traditional farmers to take more time to cooperate in the co-governance of agricultural non-point source pollution control. In order to promote the multi-agent co-governance of agricultural non-point source pollution control under intensive management pattern, this paper suggests that it should be necessary to reduce their costs and improve incentives, as well as to increase the common interests among groups and enhance their green synergy effects.

'Get a Fish' vs. 'Get a Fishing Skill': Farmers' Preferred Compensation Methods to Control Agricultural Nonpoint Source Pollution.

Ecological compensation is an important means for controlling agricultural nonpoint source pollution, and compensation methods comprise an essential part of the compensation policy for mitigating this form of pollution. Farmers' choice of compensation methods affects their response to compensation policies as well as the effects of pollution control and ecological compensation efficiency. This study divides ecological compensation methods into two distinct philosophies-the "get a fish" method (GFM) and "get a fishing skill" method (GFSM)-based on policy objectives, to determine farmers' choice between the two methods and the factors influencing this choice. Furthermore, by analyzing survey data of 632 farmers in the Ankang and Hanzhong cities in China and using the multivariate probit model, the study determines farmers' preferred option among four specific compensation modes of GFM and GFSM. The three main results are as follows. (1) The probability of farmers choosing GFM is 82%, while that of choosing GFSM is 51%. Therefore, GFM should receive more attention in compensation policies relating to agricultural nonpoint source pollution control. (2) Of the four compensation modes, the study finds a substitution effect between farmers' choice of capital and technology compensations, capital and project compensations, material and project compensations, while there is a complementary relationship between the choice of material and technology compensations. Therefore, when constructing the compensation policy basket, attention should be given to achieving an organic combination of different compensation methods. (3) Highly educated, young, and male farmers with lower part-time employment, large cultivated land, and a high level of eco-friendly technology adoption and policy understanding are more likely to choose GFSM. Hence, the government should prioritize promoting GFSM for farmers with these characteristics, thereby creating a demonstration effect to encourage transition from GFM to GFSM.

Can FinTech Development Curb Agricultural Nonpoint Source Pollution?

The green development of FinTech empowerment has become a compelling theme in economic development. In this study, based on the weighted least squares (WLS) and threshold regression methods of cross-sectional data, we empirically examine the impact of FinTech development on agricultural nonpoint source (NPS) pollution, a major cause of impaired surface water quality. Our results show that there is an inverted "U" shape relationship between the development of FinTech and agricultural NPS pollution. That is, after crossing a "threshold value", the level of FinTech development can curb agricultural NPS pollution. At the structural level, the availability of FinTech services, the FinTech infrastructure, and the agricultural NPS pollution also have an inverted "U" shape relationship. At the threshold effect, in the developing stage of an agricultural economy, the overall level of FinTech development, the use of FinTech services, the availability of FinTech services, and the FinTech infrastructure have an inverted "U" shape relationship with agricultural NPS pollution. On the other hand, in the developed stage of an agricultural economy, the impact of FinTech development and its structure on agricultural NPS pollution is insignificant. Hence, we can conclude that FinTech development can help reduce agricultural NPS pollution in under-developed regions. However, due to the fact that a "U" shape relationship always exists between FinTech service quality and agricultural NPS pollution, the quality of FinTech service should be the main focus to reduce agricultural NPS pollution more effectively.

Buffer Strips on the Low-Lying Plain of Veneto Region (Italy): Environmental Benefits and Efficient Use of Wood as an Energy Resource.

Vegetated buffer strips (VBS) are recognized as a cost-effective way to reduce agricultural nonpoint-source pollution. In agroecosystems with high field fragmentation, only narrow VBS that partially compromise farmers' revenue are accepted. This study aimed to identify some ecosystem services as provided by VBS in terms of soil and water quality, and VBS performance in terms of wood for energy purposes. Buffer strip design (3 vs. 6 m wide) and composition were considered to define best practices for wood use at the farm level and for the local firewood market. Results showed that yearly wood pole production was 0.5 t 100 m, on average, ranging between a minimum of 0.22 t 100 m and a maximum of 0.72 t 100 m per row. Wood production had negligible effects on farmers' revenue. By contrast, water quality was enhanced, especially with 6-m-wide VBS. Specific subsidies for the maintenance of VBS increased total income despite a reduction in crop production (-17.5% in 6-m VBS with two rows). Subsidies might be better quantified at a site-specific level by taking into account all ecosystem services that are provided by VBS. Promising solutions to increase farmers' income are related to the wood seasoning process for firewood production; reducing the moisture content to <25% before the start of the winter season increases its market value.

Effectiveness of Vegetated Buffer Strips in Controlling Legacy Phosphorus Exports from Agricultural Land.

The continued phosphorus (P) impairment of freshwaters and the associated risk of eutrophication raise questions regarding the efficiency of current beneficial management practices (BMPs) for improving water quality. Vegetated buffer strips (VBSs) are widely encouraged BMPs for reducing P export from agricultural land. However, there is a lack of evidence regarding the long-term efficiency of VBSs for reducing legacy P losses. This research used soil analyses to investigate the P removal efficiency of an unmanaged VBS for controlling P loss from agricultural land in Manitoba, Canada, between 1954 and 2011. The results showed statistically significant retention of total P, Olsen extractable P, and 0.01 M CaCl extractable P by a 5-m wide VBS compared with field soils. We found that surface soils at 5-m into the VBS had a significantly greater P sorption capacity and a smaller degree of P saturation (DPS) than adjacent field soils. The elevated DPS in field soils is likely associated with gradual P enrichment as a result of manure or fertilizer application over time and the strong affinity of P compounds for soil. Although P stratification in the VBS over 57 yr resulted in a significant increase (∼11%) in DPS of VBS topsoil compared with VBS subsoil, our findings do not support the saturation of VBS soils with P. However, cutting and removal of vegetation from VBS could be a useful strategy to remove P from VBS and minimize possible P remobilization associated with vegetation senescence, especially where the climate is cold and runoff is dominated by snowmelt.

Channelizing Streams for Agricultural Drainage Impairs their Nutrient Removal Capacity.

In agricultural basins, fluvial ecosystems can work as filters when retaining the nutrient excess from agricultural activities, mitigating the impacts downstream. In frequently flooded areas, like the Pampas Region of Argentina, natural streams are being channelized to reduce flood frequency and intensity, thus increasing land suitability for crop production, but the impact of these interventions on nutrient removal capacity by streams is unknown. To evaluate the effects of channelizing streams on the assimilation rate of nitrate, ammonia, and phosphorus, nutrient addition experiments were performed in streams of the southern Pampas under three different conditions: (i) channelized reaches without (C.A. Mey.) Palla (reeds), (ii) unchannelized reaches without reeds, and (iii) unchannelized reaches with reeds. Assimilation rates were estimated by applying the one-dimensional transport with inflow and storage (OTIS) model, which considers the solute transport with lateral flow and storage. Nitrate and ammonia uptake rates were higher in unchannelized than in channelized stream reaches, and a higher nitrate assimilation rate was found in the presence of reeds, indicating an important role of this macrophyte in the nitrate uptake. In the case of phosphorous, uptake rates were higher in unchannelized reaches with reeds than in the channelized reaches. These results suggest that channelizing first-order streams in agricultural landscapes of the Argentine Pampas may significantly reduce the ability of streams to mitigate nutrients loss to continental and marine water sinks.

Passive Dosing of Organic Substrates for Nitrate-Removing Bioreactors Applied in Field Margins.

Denitrifying bioreactors are dependent on organic matter supply as a substrate for effective NO removal. In this study, the difference in removal efficiency and side effects when using different organic matter sources and dosing strategies was tested in two field experiments. The organic matter sources tested were woodchips and ethanol. The effect of woodchips was tested using woodchip-enveloped drains. Ethanol was supplied to a flow-through reactor by passive dosing by diffusion through silicone tubing. The woodchip-enveloped drains showed a removal efficiency of 80% during the first year of application, but this rate decreased during the second and third years of application, coinciding with a decrease in dissolved organic C and an increase in redox potential. The removal efficiency was higher and remained higher over a longer period of time when the drains were installed more deeply. The flow-through reactor with ethanol could lead to a higher removal efficiency (up to 95%) at higher hydraulic retention time (HRT, 0.1 d) than the woodchip-enveloped drains (HRT = 5 d). Passive dosing of organic substrates is simple, needs little maintenance and no energy, and can be performed independent of electricity. A denitrifying bioreactor with a controlled drainage inlet and outlet is a promising setup for optimizing N removal and minimizing side effects.

Management Options to Reduce Phosphorus Leaching from Vegetated Buffer Strips.

Vegetated buffer strips (VBS) between agricultural areas and surface waters are important retention areas for eroded particulate P through which they may obtain critically high degrees of P saturation imposing high risk of soluble P leaching. We tested topsoil removal and three harvesting frequencies (once, twice, or four times per year) of natural buffer vegetation to reduce P leaching with the aim to offset erosional P accumulation and high degrees of P saturation. We used a simple numerical time-step model to estimate changes in VBS soil P levels with and without harvest. Harvesting offset erosional deposition as it resulted in an annual ammonium oxalate-extractable P reduction of 0.3 to 2.8% (25-cm topsoil content) in soils of the VBS and thus, with time, reduced potential P leaching below a baseline of 50 µg L. Topsoil removal only marginally reduced potential leaching at two sites and not anywhere near this baseline. The harvest frequency only marginally affected the annual P removal, making single annual harvests the most economical. We estimate 50 to 300 yr to reach the P leaching baseline, due to substantial amounts of P accumulated in the soils. Even in high-erosion-risk situations in our study, harvesting reduced soil P content and the P leaching risk. We suggest harvesting as a practical and efficient management to combat P leaching from agricultural VBS, not just for short-term reductions of dissolved P, but also for reductions of the total soil P pool and for possible multiple benefits for VBS.

Giant Cane Vegetative Buffer for Improving Soil and Surface Water Quality.

Over the past four decades, riparian buffers have proven effective in retaining nutrients and sediment from agricultural runoff. Many grass species have been used with variable success in riparian buffers to improve the water quality of runoff. However, limited information is available on the effectiveness of giant cane [ (Walt.) Muhl] in improving surface water quality compared with grass species such as Kentucky bluegrass ( L.) and orchardgrass ( L.). Therefore, the objective of our study was to determine the quality of runoff leaving vegetative buffer plots planted with giant cane, Kentucky bluegrass, and orchardgrass. Additionally, a bare-ground control and continuous corn ( L.) was also monitored for comparison of runoff with vegetative buffers. The giant cane treatment had significantly greater infiltration rates (38.18 mm h, < 0.05) than bare ground (1.61 mm h), corn (5.75 mm h), Kentucky bluegrass (12.30 mm h), and orchardgrass (4.21 mm h) treatments. Dissolved reactive P in runoff was ranked as follows: corn > giant cane = Kentucky bluegrass = orchardgrass > bare ground. The total P from the corn treatment (1.70 mg L, < 0.05) was significantly higher than for bare ground (1.22 mg L), giant cane (0.69 mg L), Kentucky bluegrass (0.86 mg L), and orchardgrass (0.54 mg L). Giant cane, Kentucky bluegrass, and orchardgrass significantly reduced the total P concentration more than bare ground and corn. Results from this study demonstrate the utility of giant cane as a vegetated buffer to reduce nutrient and sediment concentrations in agricultural runoff.

Duckweed as an Agricultural Amendment: Nitrogen Mineralization, Leaching, and Sorghum Uptake.

Excessive N and P in surface waters can promote eutrophication (algae-dominated, low-O waters), which decreases water quality and aquatic life. Duckweed (Lemnaceae), a floating aquatic plant, rapidly absorbs N and P from water and its composition shows strong potential as a soil amendment. Therefore, it may be used to transfer N and P from eutrophic water bodies to agricultural fields. In this work, dried duckweed was incorporated into agricultural soil in microcosm, column, and field tests to evaluate biological N cycling, nutrient retention, and crop yield compared with compost, diammonium phosphate (DAP), and an amendment-free control. In microcosm tests, 25 ± 13% of duckweed N was mineralized, providing on average less mineral N than DAP (107 ± 21%), but more than compost (11 ± 12%). In columns, duckweed treatments leached only 2% of the N added, significantly less than DAP, which leached 60% of its N. Compared with the control, DAP leached significantly more phosphate (78%), whereas duckweed and compost treatments leached less (56 and 27%, respectively). Crop yield, as well as runoff N and P, were measured in field tests growing forage sorghum [ (L.) Moench.]. Although less total N was applied to duckweed plots than to DAP plots (75 vs. 130 kg ha, respectively), duckweed was found to retain 30% more total mineral N in a tilled agricultural field than DAP, while supporting a comparable yield. These tests indicate that duckweed may provide a sustainable source of N and P for agriculture.

Varying Influence of Dairy Manure Injection on Phosphorus Loss in Runoff over Four Years.

Surface application of manure on no-till farms can exacerbate P losses in runoff, contributing to the eutrophication of surface waters. We monitored 12 400-m field plots over 4 yr to compare P losses in surface runoff and lateral subsurface flow with shallow disk injection and broadcast application of dairy manure. Given the substantial variability in annual P losses, as well as a gradual, annual buildup of residual soil test P, significant differences in runoff P losses were detected in only 1 of 4 yr: in 2014, total P losses in runoff were 68% greater from broadcast manure plots than injected manure plots. Dissolved and particulate P were roughly even in their contribution to runoff. Even so, there were significant relationships between annual dissolved P losses and P in the soil surface, which pointed to soils as a regular source of P in runoff. Overall, results confirm the potential for injection to reduce P loss in runoff relative to broadcast application, but because in a few sampling dates injection resulted in greater losses, this study also highlights the importance of assessing mitigation benefits of manure application practices over longer timeframes.

Dedicated Bioenergy Crops and Water Erosion.

Information on the water quality impact of perennial warm-season grasses (WSGs) when grown in marginal lands as dedicated energy crops is limited. We studied how WSGs affected runoff, sediment, and nutrient losses and related near-surface soil properties to those of no-till corn ( L.) on an eroded soil in southwestern Iowa and a center pivot corner in east-central Nebraska. The experiment at the eroded soil was established in 2012, and treatments included 'Liberty' switchgrass ( L.) and no-till continuous corn. The experiment at the pivot corner was established in 2013 with 'Liberty' switchgrass, 'Shawnee' switchgrass, low-diversity grass mixture, and corn. We simulated rainfall at 63.5 ± 2.8 mm h for 1 h to portray 5-yr return periods and measured water erosion in spring 2017. Time to runoff start and runoff depth did not differ between WSGs and corn. On the eroded soil, sediment and nutrient losses did not differ between treatments. At the pivot corner, sediment (0.71 vs. 0.15 Mg ha) and PO-P (0.037 vs. 0.006 kg ha) losses were five times higher in corn than in WSGs. Near-surface soil properties did not differ on the eroded soil, but at the pivot corner, wet aggregate stability was four times higher and residue cover was 34% higher in WSGs than in corn. Water-stable aggregates were negatively correlated with NO-N and PO-P losses. Overall, WSGs can improve water quality in marginally productive croplands, but their effectiveness appears to be site specific.

Nutrient, Metal, and Organics Removal from Stormwater Using a Range of Bioretention Soil Mixtures.

A column study was conducted to test the ability of bioretention soil mixtures (BSMs) to remove nutrients, metals, and polyaromatic hydrocarbons (PAHs) from stormwater collected from an urban highway. Infiltration rate, plant growth response, and turbidity of the effluent were also measured. The BSMs were made from a range of types and rates of composts and additional materials such as water treatment residuals, sawdust, and oyster shells. Sand was used as a control. Total N and P in stormwater measured 1.8 ± 1 and 0.08 ± 0.03 mg L. All treatments were a source of these nutrients. Metal concentrations in the stormwater were low, with mean Cu and Zn concentrations of 39.8 ± 19.1 and 173 ± 113 µg L, and Cd and Pb close to detection limits. All treatments absorbed Cu and Zn from stormwater with varying levels of removal efficiency. The three treatments tested removed 84 to 100% of the PAHs from the stormwater. In general, contaminant removal (N, P, and Zn) efficiency was not related to infiltration rate, with a slight decrease in Cu removal efficiency observed with increased infiltration rate ( = 0.32). These results indicate that the BSMs tested were a source of nutrients but were generally effective at removing metals and PAHs from stormwater.

Potential Efficiency of Grassy or Shrub Willow Buffer Strips against Nutrient Runoff from Soybean and Corn Fields in Southern Quebec, Canada.

Riparian buffer strips (RBS) are encouraged to control agricultural diffuse pollution. In Quebec Province, Canada, a policy promotes 3-m-wide RBS. Abiding farmers minimally maintain herbaceous vegetation, but nutrient retention efficiency could be improved with woody biomass. This work aimed to assess if fast-growing willows ( Seemen 'SX64') could reduce nutrient loads to a stream, in addition to yielding biomass. Triplicate treatments of two stem densities and a herbaceous control plot were monitored from 2011 to 2013 in a randomized block design on agricultural fields of the St. Lawrence Lowlands with sandy loam (Saint-Roch-de-l'Achigan [SR]) and organic-rich (Boisbriand [BB]) soils. Runoff, interstitial water, and water from the saturated zone were sampled 16 (SR) and 14 (BB) times to quantify nutrient buffering (NO, NH, P, and K). Sampling campaigns followed (i) snowmelt or ≥15-mm natural precipitation events after (ii) fertilization and (iii) glyphosate-based herbicide applications. Concentration reduction before and after the RBS was highest for nitrates (77-81% in runoff at BB, 92-98% at 35- to 70-cm depth at SR) just after fertilization, when edge-of-field concentrations peaked. Total P removal was observed in runoff after fertilization at SR, and K removal was punctually witnessed at BB. Riparian buffer strips were inefficient for NH and dissolved P removal, and RBS effluents exceeded aquatic life protection standards. plantations, irrespective of stem density, were not more efficient than herbaceous RBS. This shows that without fertilizer input reductions, narrow RBS are insufficient to protect streams from excess nutrients in corn ( L.) and soybean [ (L.) Merr.] crops.

An Assessment of the Multifunctionality of Integrated Buffer Zones in Northwestern Europe.

Integrated buffer zones (IBZs) have recently been introduced in the Northwestern Europe temperate zone to improve delivery of ecosystem services compared with the services associated with long-established vegetated buffer zones. A common feature of all the studied IBZ sites is that tile drainage, which previously discharged directly into the streams, is now intercepted within the IBZ. Specifically, the design of IBZs combines a pond, where soil particles present in drain water or surface runoff can be deposited, and a planted subsurface flow infiltration zone. Together, these two components should provide an optimum environment for microbial processes and plant uptake of nutrients. Nutrient reduction capacities, biodiversity enhancement, and biomass production functions were assessed with different emphasis across 11 IBZ sites located in Denmark, Great Britain, and Sweden. Despite the small size of the buffer zones (250-800 m) and thus the small proportion of the drained catchment (mostly <1%), these studies cumulatively suggest that IBZs are effective enhancements to traditional buffer zones, as they (i) reduce total N and P loads to small streams and rivers, (ii) act as valuable improved habitats for aquatic and amphibian species, and (iii) offer economic benefits by producing fast-growing wetland plant biomass. Based on our assessment of the pilot sites, guidance is provided on the implementation and management of IBZs within agricultural landscapes.