Beneficial Management Practices Research Articles

Beneficial Nutrient Management Practice for Improving Maize (<em>Zea mays</em>) Yield in a Tropical Entisol

Beneficial nutrient management practices could increase maize yield via improving soil fertility. A study was conducted in the mid country wet zone of Sri Lanka (WM2b) on Typic Troporthents aiming to formulate a site specific fertilizer (SF) recommendation and to identify beneficial organic soil amendments (OA) to improve the fertility and productivity of soils for maize cultivation. The SF recommendation was developed using modified missing element technique. Incubated mixture of cattle manure and sawdust at 2:1 wet weight basis (CS-i) and biochar (BC) derived from sawdust were selected as OAs. Four treatments, (i) un-amended control (S), (ii) soil amended with SF (SSF), (iii) cattle manure-sawdust CS-i (2.2 Mg ha-1) with SF (CSi+SF) and (iv) biochar (1.1 Mg ha - 1) with SF (BC+SF) were tested in the field for two consecutive growing seasons (Yala 2013 and Maha 2013/14) for maize. According to missing element technique, soil was deficient in K, Mg, P and Zn nutrients and resulted in 38%, 35%, 27% and 24% relative dry-matter reductions, respectively. Addition of OA+SF significantly improved soil organic carbon content compared to SSF. Green cob yield ranged from 7.9 to 16.5 Mg ha-1 in Yala and 5.4 to 12.4 Mg ha -1 in Maha increasing yield significantly in CS-i+SF, BC+SF and SSF over the un-amended control in both seasons. Soil fertility and maize yield were sustained or improved under combined application of site specific fertilizer and organic amendments. Moreover, cut down of K fertilizer is possible with application of BC and CS-i OAs. Hence, SF recommendation along with biochar or cattle manure-sawdust mixture OAs is a beneficial nutrient management practice for cultivating maize.

Modeling the sediment yield and the impact of vegetated filters using an event-based soil erosion model-a case study of a small Canadian watershed

This paper presents the first application of the event-based MHYDAS-Erosion model to a small agricultural watershed under temperate climate conditions (Quebec, Canada). Simulation results based on observed and synthetic rainfall events revealed a bimodal behavior of sediment yield. During high-intensity rainfall events, most of the sediments reaching the watershed outlet originate from cropland. Meanwhile, during low-intensity events, most of the sediments come from the drainage network. Furthermore, simulation results show that implementation of 5-m and 20-m wide vegetated filters throughout the watershed or at the edge of the most problematic fields (4% of the total fields) could reduce soil loss by 52% and 31%, respectively. The modeling framework could be used for the design and location of beneficial management practices such as grass strips and riparian zones.

Beneficial management practices on growth and yield parameters of maize (<em>Zea mays</em>) and soil fertility improvement

Beneficial management practices can be used to improve the crop productivity of tropical Alfisols. This study evaluated beneficial management practices to overcome the soil physical and chemical limitations for growing maize ( Zea mays ). The experiment was conducted in the Low Country Dry Zone (DL1b) on Reddish Brown Earth soil (Typic Rhodustalf). Four treatments; un-amended control (C), site specific fertilizer (SSF), biochar applied at 1 t/ha with SFF (BC+SSF) and rock powder applied at 10 t/ha with SSF (RP+SSF) were tested using maize as the test crop initially in the greenhouse and later in the field at DL1b for two growing seasons (2013 Yala and 2013/2014 Maha ) for their effects on crop growth and soil fertility. Soil was neutral, non-saline, sandy clay loam in texture with comparatively high clay content (27%) and low in organic matter content (1.5%) and deficient in N, P, S, Ca, Zn, and Cu, initially. In the greenhouse, plant dry weight increased significantly with the addition of amendments i.e., fertilizers alone (SSF), or BC+SSF or RP+SSF. In the field study, no significant differences were observed for soil pH with the addition of amendments but biochar application significantly increased cation exchange capacity, organic matter, potentially mineralizable nitrogen and carbon management index. Rock powder+SSF and BC+SSF significantly increased the grain yield over the control in both seasons. Both labile and recalcitrant C were significantly higher in BC+SSF treatment than the others. Further, application of BC and RP had no significant impact on soil textural fractions and bulk density, yet in both seasons, BC+SSF application increased the aggregate stability greater than other treatments. The results of the field experiment suggest that biochar and rock powder with adequate nutrients effectively improved soil fertility and productivity.

A typological characterization of Canadian beef cattle farms based on a producer survey

The diverse nature of beef production was captured by establishing a farm typology based on an extensive survey of 1005 Canadian farms in 2011. The survey provided information on the type of operation, cattle numbers, feed storage and management, manure management, land use, producer demographics and attitudes to risk, and technology adoption. Principal component analysis and cluster analysis were used to understand the relationships among variables and to statistically identify farm types. A total of 41 diagnostic variables from 133 survey questions were used to define 16 principal components explaining 68% of the variation. Cluster analysis yielded eight major clusters as distinct farm types. The largest number of farms (37%) was grouped as small-scale, part-time cow–calf operations. Mixed operations (crop–beef) were next most frequent (22%), followed by large cow–calf backgrounding (18%) and diversified cow–calf operations that included crop–beef mixed operations as well as off-farm activities (11%). Cow–calf operations that finished calves comprised 8% of the total farms surveyed. Extensive cow–calf backgrounding operations, large backgrounding/finishing operations, and large finishing operations represented the remaining 3% of the farms. The typology not only provides a strategy by which the Canadian beef cattle industry can be characterized, but also improves understanding of the diversity of farm management practices to help develop policies and beneficial management practices.

Modeling Impacts of Residential and Agricultural Development and Beneficial Management Practice Scenarios on Phosphorus Dynamics in a Small Watershed

<abstract> <b><sc>Abstract.</sc></b> Both agricultural land uses and residential on-site wastewater systems (OWS) have the potential to be nonpoint sources of phosphorus (P) in rural watersheds. Watershed-scale computer models are a commonly used tool for evaluating the impacts of increased human development on P dynamics and for evaluating how beneficial management practices (BMPs) can reduce P loading. Many agricultural field BMPs have been evaluated using watershed-scale models; however, no studies have compared their efficacy to OWS BMPs in a mixed land use watershed. The objectives of this research were to (1) use the P on-site wastewater simulator (POWSIM) and the Soil and Water Assessment Tool (SWAT) to simulate different agricultural and residential development scenarios in the Thomas Brook watershed in Nova Scotia, Canada, and evaluate their impacts on sediment and total P (TP) loads and TP concentrations and (2) simulate and evaluate different individual and combinations of select agricultural and OWS BMPs. A 50-year simulation period was used for both the development and BMP scenarios. The development scenarios evaluated included increasing the residential population and conversion of hay fields or pastures to corn-based cropping regimes. The agricultural BMPs evaluated were (1) corn and rotational crop replacement with no-till agricultural land uses and (2) no-till corn. Decreased failure rates, increased watercourse setbacks, disposal field replacement, and the use of high P sorption filter media were the OWS BMPs evaluated. The agricultural development scenarios increased cumulative sediment and P loads at the watershed outlet, while the residential scenarios increased the frequency of hyper-eutrophic conditions in the stream during the last 20 simulated years. Agricultural crop replacement BMPs produced the highest reductions in cumulative sediment (13% to 46%) and TP loads (26% to 34%) but had no observable change on the in-stream trophic status. The OWS BMPs produced small reductions in TP loading (2% to 15%), no sediment load reductions, but had a positive effect on the trophic status. The best ranked combination of agricultural and OWS BMPs resulted in a cumulative TP load reduction of 58%, and the dominant trophic state at the end of the 50-year period was mesotrophic, as compared to eutrophic for the reference simulation. The best combination BMP scenario included replacing corn and rotational crops with pastures, using high P sorption filter media (5000 mg P kg^-1 media), and lowering of the OWS failure rate to 5%. The results of these modeling scenarios showed that agricultural BMPs were most effective in reducing cumulative P loads, while OWS BMPs were effective in mitigating in-stream eutrophication impacts. This study highlights the importance of identifying specific water quality issues that need to be targeted prior to implementing a watershed BMP strategy. Further model refinement and testing are required with improved field measurements to improve model confidence before the model should be used for planning and design purposes.

Dual permeability modeling of tile drain management influences on hydrologic and nutrient transport characteristics in macroporous soil

Summary Tile drainage management is considered a beneficial management practice (BMP) for reducing nutrient loads in surface water. In this study, 2-dimensional dual permeability models were developed to simulate flow and transport following liquid swine manure and rhodamine WT (strongly sorbing) tracer application on macroporous clay loam soils under controlled (CD) and free drainage (FD) tile management. Dominant flow and transport characteristics were successfully replicated, including higher and more continuous tile discharge and lower peak rhodamine WT concentrations in FD tile effluent; in relation to CD, where discharge was intermittent, peak rhodamine concentrations higher, and mass exchange from macropores into the soil matrix greater. Explicit representation of preferential flow was essential, as macropores transmitted >98% of surface infiltration, tile flow, and tile solute loads for both FD and CD. Incorporating an active 3rd type lower boundary condition that facilitated groundwater interaction was imperative for simulating CD, as the higher (relative to FD) water table enhanced water and soluble nutrient movement from the soil profile into deeper groundwater. Scenario analysis revealed that in conditions where slight upwards hydraulic gradients exist beneath tiles, groundwater upwelling can influence the concentration of surface derived solutes in tile effluent under FD conditions; whereas the higher and flatter CD water table can restrict groundwater upwelling. Results show that while CD can reduce tile discharge, it can also lead to an increase in surface-application derived nutrient concentrations in tile effluent and hence surface water receptors, and it can promote NO 3 loading into groundwater. This study demonstrates dual permeability modeling as a tool for increasing the conceptual understanding of tile drainage BMPs.

Exploring agricultural advice networks, beneficial management practices and water quality on the landscape: A geospatial social-ecological systems analysis

Agricultural practices have been linked to detrimental effects on ecosystems, with water quality of particular concern. Research has been devoted to understanding uptake of beneficial, or best, management practices (BMPs) in agriculture; however, sources of advice and subsequent effects on the landscape have not been elucidated. This study set out to understand (1) what sources of information agricultural producers rely on when making land-management decisions; (2) the characteristics of their advice networks; and (3) how the advice network linked spatially to water quality on the landscape. A watershed in Alberta was used as a case study and respondents identified that regional advisors were relied upon most often for advice and these advisors had the most influence on the adoption of BMPs. Results indicate that respondents with connections to regional actors implemented more BMPs that those without. Regional government actors had a greater effect than regional non-governmental actors. Local actors played a lesser role in advice networks related to BMP adoption. A 3D geovisualization was used to explore linkages among advisors, BMPs, and water quality. This technique may be useful for other scenarios and can contribute to policy development and enhanced practices.

Environmental Stewardship and Technical Efficiency in Canadian Prairie Canola Production

This study examines beneficial management practice (BMP) adoption and technical efficiency for canola producers in the Canadian Prairie Provinces. A Just‐Pope stochastic frontier production function is estimated using data from a survey of canola producers. Yield is modeled as a function of nutrients and precipitation. A linear inefficiency function includes farm specific variables and a set of binary variables representing BMP adoption. BMP variables for nutrient management planning and precision farming are positively related to technical efficiency while results for the other BMP indicators are mixed. Model estimates appear to be significantly influenced by moisture problems that occurred through the Prairie region during the 2011 cropping year. The study results suggest that for Western Canadian canola producers, there is potential complementarity for some BMPs in terms of improving technical efficiency while simultaneously advancing environmental stewardship.

Effects of Weather and Land Management on the Western Prairie Fringed-orchid (Platanthera praeclara) at the Northern Limit of its Range in Manitoba, Canada

Abstract The western prairie fringed-orchid is a rare North American orchid restricted to a few remnants of wet to mesic tallgrass prairie. It is federally listed in both Canada and the United States and both countries have developed a recovery plan for the species. Two key management objectives are to monitor population trends and identify beneficial management practices. We used 21 y of data from the Manitoba metapopulation to assess effects of weather and land management on this species. Our results suggest the metapopulation in Manitoba is relatively stable. Western prairie fringed-orchids appear to benefit most from a combination of warm temperatures in the previous growing season followed by cool snowy but short winters and wet springs. Periodic burning (e.g., every 2–3 y) may benefit fringed-orchids, whereas grazing may be detrimental. This was not a controlled experiment, however, and gaps in the data may have influenced our results. Prescribed burning is a viable management tool for curtailing wo...

Watershed derived nutrients for Lake Ontario inflows: Model calibration considering typical land operations in Southern Ontario

Abstract Continuous daily simulation of watershed-derived nutrient and sediment loads is required to estimate nearshore water quality in Lake Ontario and the impact of watershed beneficial management practices on lake water quality. In this study, the Soil and Water Assessment Tool (SWAT) is used to build watershed models that incorporate detailed information about representative land operation activities applicable to agricultural watersheds in Southern Ontario. SWAT is calibrated in a multi-objective simulation–optimization framework for the Rouge River watershed with a relatively high spatial resolution monitoring network. These parameters were directly applied to the model for an adjacent watershed, Duffins Creek. The model performed satisfactorily in both watersheds in terms of water balance and temporal, vertical, and spatial redistribution of water. Assessment of the model performance metrics shows a good agreement in the frequency distribution of measured and simulated water quality constituents. Both watersheds are experiencing rapid urbanization, so decision makers in the region may find the developed model useful to analyze the impact of future landuse and operation changes on watershed-derived sediment and nutrients to be delivered into Lake Ontario.

Evaluation of greenhouse gas emissions from hog manure application in a Canadian cow–calf production system using whole-farm models

The development of beneficial management practices is a key strategy to reduce greenhouse gas (GHG) emissions from animal agriculture. The objective of the present study was to evaluate the impact of time and amount of hog manure application on farm productivity and GHG emissions from a cow–calf production system using two whole-farm models. Detailed model inputs (climate, soil and manure properties, farm operation data) were collected from a 3-year field study that evaluated the following three treatments: no application of hog manure on grassland (baseline); a single application of hog manure on grassland in spring (single); and two applications of hog manure as fall and spring (split). All three treatments were simulated in a representative cow–calf production system at the farm-gate using the following whole-farm models: a Coupled Components Model (CCM) that used existing farm component models and the Integrated Farm System Model (IFSM). Annual GHG intensities for the baseline scenario were 17.7 kg CO2-eq/kg liveweight for CCM and 18.1 kg CO2-eq/kg liveweight for IFSM. Of the total farm GHG emissions, 73–77% were from enteric methane production. The application of hog manure on grassland showed a mean emission increase of 7.8 and 8.4 kg CO2-eq/kg liveweight above the baseline for the single and split scenarios, respectively. For the manured scenarios, farm GHG emissions were mainly from enteric methane (47–54%) and soil nitrous oxide (33–41%). Emission estimates from the different GHG sources in the farm varied between models for the single and split application scenarios. Although farm productivity was 3–4% higher in the split than in single application (0.14 t liveweight/ha), the environmental advantage of applying manure in a single or split application was not consistent between models for farm emission intensity. Further component and whole-farm assessments are required to fully understand the impact of timing and the amount of livestock manure application on GHG emissions from beef production systems.

Floods and water quality in Canada: A review of the interactions with urbanization, agriculture and forestry

Water quality remains a major issue in Canada. This paper reviews recent research on the impacts of urbanization, agriculture and forestry on water quality in Canada. Specific water quality issues such as mining, sewage treatment and waste treatment are not included in this paper. For each land use, a brief summary of the dominant processes linking runoff to water quality is provided and recent findings are summarized. With respect to urbanized watersheds, the relatively large proportion of impervious areas, lower vegetation cover and the presence of high-density drainage systems alter surface water routing and timing of peak flows. High concentrations of heavy metals are considered to be the most important water quality problem in urban runoff, but nutrients, pathogens, concentration of pharmaceuticals and water temperature also often contribute. In watersheds dominated by agricultural activities, overland flow is an important vector of pollutants, but subsurface flow such as macropore and tile-drain flows also play a role in the alteration of water quality during or after high runoff events. Nutrients, pesticides, pathogens and sediments remain important topics of research in agricultural watersheds, and the modelling effort has significantly increased in the last few decades. Beneficial management practices (BMPs) are being tested and applied at a local scale, mostly on experimental watersheds. Forestry-related activities also affect water quality. In forested watersheds, studies have been ongoing for many decades, but have decreased in intensity in the last 15 years. Sediment delivery and water temperature can be strongly affected in watersheds with significant clear-cut logging and riparian buffer strips and sylviculture remain the main mitigation BMPs. There is a need for an increase in the monitoring effort for most water quality variables in Canada. The authors recommend that flow-dependent monitoring frameworks should be further developed and implemented in the future.

Groundwater Monitoring to Support Development of BMPs for Groundwater Protection: The Abbotsford‐Sumas Aquifer Case Study

AbstractThe Abbotsford‐Sumas Aquifer is arguably the most studied case in Canada of groundwater nitrate contamination associated with agricultural production. Underlying some of the most productive agricultural land in Canada, this highly vulnerable trans‐boundary aquifer provides a unique case study on the opportunities and challenges of addressing water quality issues. A groundwater monitoring program initiated in the early 1990s has been important in tracking spatial and temporal variation in groundwater nitrate concentration. However, small land parcels with spatially and temporally variable land use and management practices and sub‐horizontal flow in this highly permeable sand and gravel aquifer make it difficult to relate groundwater monitoring results to specific agricultural practices. Other approaches pointed to the historical over‐application of N relative to crop requirement (primarily as manure used to increase soil organic matter during replanting but also as a nutrient source during production). Despite changes in agricultural practices, and programs aimed at raising grower awareness, no appreciable change in average groundwater nitrate concentration has occurred over the monitoring period. On individual land parcels, nitrate contamination may be reduced through development and adoption of an integrated suite of beneficial management practices (BMPs) to improve N fertilization, irrigation and alley vegetation management, and in particular to eliminate application of any organic soil amendment such as untreated manure in which the N has not been stabilized (e.g., by composting). However, the substantial N imbalance on a regional scale, and the lack of an effective on‐going consultative process among stakeholders, remain major barriers to the development, demonstration and adoption of BMPs.

Controls on Nitrate Loading and Implications for BMPs Under Intensive Potato Production Systems in Prince Edward Island, Canada

AbstractPotato production is critical to economy of Prince Edward Island (PEI), but has been linked to increasing groundwater nitrate contamination and anoxic events in estuaries. Given that PEI is entirely groundwater‐dependent for potable water, this has resulted in considerable pressure to find solutions to protect water quality. However, our understanding of the controls on nitrate loading to groundwater, and the consequent potential to mitigate nitrate loading through beneficial management practices (BMPs), is limited. In PEI, flow and nitrate transport in the vadose zone are controlled by the matrix porosity of the till and sandstone, while flow and transport in the saturated zone are controlled by a conductive fracture network with limited storage capacity. Diffusion of nitrate stored in the matrix may introduce a significant time lag between reduced nitrate loading from implementation of BMPs and measureable improvement in groundwater quality. BMPs with potential to mitigate nitrate loading to groundwater through improved nitrogen fertilizer practices in producing potato crops have been identified, but implementation of these practices alone is not sufficient to control nitrate loading due to the economic context of potato production. Additional BMPs for improved potato cropping systems have also been identified; however, reducing the intensity of agricultural production, including the proportion of land in potato production, at the watershed level may be required to meet the drinking water guideline for nitrate in PEI. Given the important role of market forces in determining profitability of crop production, it becomes challenging to modify crop production practices to meet an environmental goal without some additional external incentive or public pressure.

Increasing Stocking Density Reduces Emissions of Fugitive Dust from Cattle Feedyards

<abstract><title><italic>Abstract. </italic></title> The moisture and compaction dynamics of an open-lot corral surface in a cattle feedyard depend strongly on the spatial density at which the animals are stocked. Because the moisture content and bulk density of the corral surface directly influence its intrinsic dust susceptibility, emission of fugitive dust from a feedyard surface should be sensitive to changes in stocking density. In the summer of 2012 we measured airborne dust concentrations upwind and downwind of feedyard pens stocked at two different densities, 718 (control) and 1,435 hd ha^-1, over a 160-d feeding period. Doubled stocking density was achieved in two different ways, by (A) confining cattle to half the pen area using electric cross-fencing and (B) doubling the number of cattle in the pens. Path-averaged dust concentrations were measured upwind and downwind of feedyard pens using an optical particle sizer (OPS model 3330, TSI Inc., Shoreview, Minn.) and an earlier-model optical sensor (model DUSTTRAK II 8530, TSI Inc., Shoreview, Minn.) mounted on mobile monitoring platforms. Because the monitoring platforms used different instruments, during the data analysis phase DUSTTRAK data were compared only to DUSTTRAK data, and OPS data were compared only to OPS data. Downwind 1-min concentrations of dust varied from 1 to 4,478 μg m^-3 for the control pens, 1 to 2,431 μg m^-3 for the pens with cross-fencing (treatment A), and 1 to 2,872 μg m^-3 for the pens with twice as many cattle as the control pens (treatment B). Dispersion modeling using AERMOD revealed that the apparent dust-emission fluxes from treatments A and B were 79.4% and 80.6% lower, respectively, than the apparent emission flux from the control pens (23.45 μg m^-2 s^-1). We conclude that stocking-density manipulation is likely to be a viable Beneficial Management Practice (BMP) for controlling fugitive dust from open-lot cattle feedyards but that improved, path-averaged monitoring techniques appropriate to the feedyard source geometry are needed.

Economics of riparian beneficial management practices for improved water quality: A representative farm analysis in the Canadian Prairie region

This paper examines the economics of adopting agricultural beneficial management practices (BMPs) to protect riparian areas in the Canadian Prairies. Monte Carlo simulation methods and cost/benefit analysis (net present value) are used to evaluate BMP adoption for a set of representative cropping and mixed farm operations in Alberta and Saskatchewan. BMPs considered in the analysis involve restoration, maintenance and/or protection of riparian areas and associated wetlands. Implementation of these BMPs by the representative farms is generally costly, resulting in negative net benefits. This is primarily due to opportunity costs from forgone returns and BMP establishment costs. The farm level results are combined with estimates of public values for riparian ecosystem services using the Pannell land use policy framework. Results indicate that in many cases, positive incentives, such as subsidies or conservation auctions, are appropriate policy responses to encourage increased production of riparian/wetland ecosystem services. Given the uncertainty in public and private benefit estimates, it may also be the case that no intervention is the optimal policy response in some instances. There is significant scope for further research in order to obtain better estimates of benefits and costs associated with riparian area management.Ce travail étudie les gains économiques obtenus en adoptant de meilleures pratiques agricoles de management (MPAMs) pour protéger les zones riparienne des Rocheuses Canadiennes. Nous combinons les méthodes statistiques de Monte Carlo et une analyse coût/bénéfice (valeur présente nette) pour évaluer l’adoption de meilleure pratiques pour un échantillon représentatif de fermes céréalières dans l’Alberta et la Saskatchewan. Les MPAMs considérées dans notre analyse impliquent la restauration, le maintien et/ou la protection des zones riparienne et des marais qui leur sont associés. La mise en place d’une MPAM est en général couteuse et réduit les bénéfices nets. Cette réduction est en grande partie due aux coûts de mise en œuvre de la MPAM et à la perte nette d’exploitation qui résulte de la MPAM. En nous aidant du cadre règlementaire de l’utilisation des terres développé par Pannell, les résultats obtenus à l’échelle de la ferme sont combinés avec les estimations des valeurs publiques pour des services des écosystèmes riparien. Nos résultats montrent que dans de nombreux cas des incitations positives telles que des subventions ou des enchères de conservation sont nécessaires pour encourager la production de services obtenus grâce aux écosystèmes riparien. Dans certains cas, étant donnée l’incertitude, il est possible qu’il soit optimal de ne pas intervenir du tout. Notre étude montre aussi l’importance de continuer les travaux de recherche dans le management des zones ripariennes.

Land use change impacts on water quality in three lake winnipeg watersheds.

Lake Winnipeg eutrophication results from excess nutrient loading due to agricultural activities across the watershed. Estimating nonpoint-source pollution and the mitigation effects of beneficial management practices (BMPs) is an important step in protecting the water quality of streams and receiving waters. The use of computer models to systematically compare different landscapes and agricultural systems across the Red-Assiniboine basin has not been attempted at watersheds of this size in Manitoba. In this study, the Soil and Water Assessment Tool was applied and calibrated for three pilot watersheds of the Lake Winnipeg basin. Monthly flow calibration yielded overall satisfactory Nash-Sutcliffe efficiency (NSE), with values above 0.7 for all simulations. Total phosphorus (TP) calibration NSE ranged from 0.64 to 0.76, total N (TN) ranged from 0.22 to 0.75, and total suspended solids (TSS) ranged from 0.29 to 0.68. Based on the assessment of the TP exceedance levels from 1993 to 2007, annual loads were above proposed objectives for the three watersheds more than half of the time. Four BMP scenarios based on land use changes were studied in the watersheds: annual cropland to hay land (ACHL), wetland restoration (WR), marginal annual cropland conversion to hay land (MACHL), and wetland restoration on marginal cropland (WRMAC). Of these land use change scenarios, ACHL had the greatest impact: TSS loads were reduced by 33 to 65%, TN by 58 to 82%, and TP by 38 to 72% over the simulation period. By analyzing unit area and percentage of load reduction, the results indicate that the WR and WRMAC scenarios had a significant impact on water quality in high loading zones in the three watersheds. Such reductions of sediment, N, and P are possible through land use change scenarios, suggesting that land conservation should be a key component of any Lake Winnipeg restoration strategy.

Soil Testing to Predict Dissolved Reactive Phosphorus Loss in Surface Runoff from Organic Soils

Phosphorus loss from surface runoff contributes to eutrophication of surface water, a problem that is often severe from polders with organic soils where agricultural production is intensive. A soil P test is essential to predict the potential for P losses to precisely conduct environmental risk assessment and to efficiently develop and evaluate beneficial management practices. This study evaluated the possibility of using the environmental and agronomic soil P tests, soil P sorption index (PSI), and degree of soil P saturation (DPS), which are used for mineral soils, to predict surface runoff dissolved reactive P (DRP) from organic soils. Forty‐four soils from eight subgroups representative of organic lands across Ontario were selected to provide a wide range of soil test P (STP) within each category. A surface runoff study was conducted following the U.S. National Phosphorus Research Project protocol. Flow‐weighted mean runoff DRP concentration (DRP30) was linearly related to soil water‐ and CaCl2–extractable P concentrations but with data distribution patterns that inefficiently represented the soil variability in P release potentials. The runoff DRP30 was significantly related to Bray‐1 P and FeO‐extractable P concentrations in split‐line models, each with a change point, but not to Mehlich‐3 P and Olsen P. All DPS values calculated based on STP and their derived PSIs were closely related to runoff DRP30 in either a linear or a split‐line model. The DPS values expressed as Bray‐1 P/(PSI + Bray‐1 P) and FeO P/(PSI + FeO P) showed the highest correlation with runoff DRP30 and thus can be recommended as environmental risk indicators of surface runoff DRP from organic soils.

Determining water and nitrogen balances for beneficial management practices using lysimeters at Wagna test site (Austria)

The shallow Murtal aquifer south of Graz, Austria, provides easily withdrawable groundwater, which is supplied as drinking water without any chemical treatment. The aquifer is also used intensively by agriculture. Common agricultural management practices are the main source for diffuse nitrogen leaching and high groundwater nitrate concentrations. To safeguard the coexisting use of these two important resources, lysimeters are operated at the agricultural test site Wagna, Austria, and the influence of two beneficial management practices – low nitrogen input and organic farming – on nitrogen leaching towards groundwater is investigated. The technical lysimeter design as presented here consists of: (1) high-resolution weighing cells, (2) a suction controlled lower boundary condition for sucking off seepage water, thus emulating undisturbed field conditions, (3) comparative soil temperature, water content and matrix potential measurements inside and outside the lysimeter at different depths, (4) an installation of the lysimeters directly into test plots and (5) a removable upper lysimeter ring enabling machinery soil tillage. Our results indicate that oasis effects or fringe effects of the lysimeter cylinder on unsaturated water flow did not occur. Another lysimeter cultivated with lawn is operated for observing grass-reference evapotranspiration, which resulted in good agreement with calculated grass-reference evapotranspiration according to the FAO-Penman–Monteith method. We conclude that lysimeters installed at Wagna test site did not show any fringe effects and, thus, are appropriate tools for measuring water balance elements and nitrogen leaching of arable and grass land at point scale. Furthermore, our results for the period of 2005 to 2011 show that beneficial management practices reduced nitrate leaching and, hence, may allow for a sustainable coexistence of drinking water supply and agriculture in the Murtal aquifer.

Insights gained from geochemical studies in the Waterloo Moraine: Indications and implications for anthropogenic loading

The Waterloo Moraine is a historic and continuing groundwater resource for the growing Region of Waterloo in southern Ontario, Canada, providing hundreds of thousands of litres of fresh water daily to the regional water supply. The complex stratigraphy of the Moraine is characterized by a system of multiple aquifers separated by regionally discontinuous aquitards, complicating resource assessments. The Region’s extensive monitoring and production well network has been sampled repeatedly over the last four decades, providing insights into how long-term pumping and urban development have affected aquifer geochemistry. Various environmental tracers were used to identify groundwater residence time and mixing including 3H, 3H/3He, CFCs, SF6, 14C, and 4He. Studies on the Waterloo Moraine provided important contributions to the application of these environmental tracers by validating unsaturated zone transport theory and documenting the effects of localized atmospheric CFC contamination. These studies have also provided important information about groundwater flow and mixing in the Moraine. Both historical and recent hydrogeological studies identified urban applications of road deicers (salt) and rural agricultural practices (nitrate loadings) as potential problems for future use of groundwater as a domestic water supply for the region, with Cl and NO3-N concentrations in some areas approaching 900 and 17 mg/L, respectively. The effects of these urban and rural contaminant issues are explored, and efforts to mitigate and reduce the impact, including the effects of best (beneficial) management practices, are discussed. The potential impacts of these non-point source contaminants on the public water supply should be considered when planning new residential developments.