Agricultural Water Quality Research Articles

The impacts of agricultural land use on nitrogen and phosphorus loads in the Mellupite catchment

Water pollution with nutrients (nitrogen and phosphorus) is nowadays one of the main environmental issues in the Baltic Sea region. The use of fertilizers in agricultural lands is considered as one of the most common source of environmental pollution. This research examines water quality in the Mellupite catchment – a territory with moderate agricultural intensity. It has been determined that hydrological characteristics of the research territory is highly affected by factors such as scale, topography, subsurface drainage intensity and the share of agricultural land in the catchment. This research addresses agricultural land use issue – explores connections between agricultural land use and water quality. Our results suggest that the agricultural land use of the research territory is diverse, but two dominant crop types stands out – grasslands and winter wheat. In general, the summer crops are dominant in the Mellupite catchment, but the distribution of summer and winter crops has become more equal in time from 2005 to 2014 most likely because of increasing demand of rapeseed oil and meal. Connections between crop area and P amount have been observed. Strong correlation between grasslands and phosphorus loads in winter period have been observed, most likely caused by manure as organic fertilizer used late autumn. To confirm causes of crops’ area and nutrient load correlations additional research including detailed fertilizer use should be made.

Tracing social capital: How stakeholder group interactions shape agricultural water quality restoration in the Florida Everglades

Agricultural nonpoint source pollution remains a pressing environmental problem despite decades of policy and environmental initiatives. Cooperative local actions are a crucial element of effective multilevel governance solutions to such problems, but securing farmer participation for water quality protection remains challenging. Social capital—relations of trust, reciprocity, and shared social norms within and between key stakeholder groups—has been found to enable cooperation for environmentally desirable outcomes. However, the downsides of social capital remain under-examined in multilevel governance, where cooperation within one stakeholder group (bonding social capital) may undermine cooperation with other stakeholders (bridging social capital). Given this important gap, researchers need to examine how bonding and bridging social capital may be formed, maintained, or undermined through stakeholder interactions, and the corresponding environmental consequences.In this paper, we address these gaps through a case study of south Florida’s sugar-producing region, whose drainage water flows south into the Florida Everglades. In contrast to persistent water quality impairment elsewhere, Everglades water quality has improved steadily over the past 20 years. These improvements have taken place under a complex set of governance arrangements that established a mandatory long-term numeric water quality target but which relies on shared compliance among farms. These dynamics encouraged interactions among three key groups of stakeholders—farmers, agricultural extension agents, and state regulators—to implement management changes. Drawing on semi-structured interviews, we find that bonding social capital among farmers encourages them to improve their management through a sense of shared responsibility, while also potentially limiting restoration by maintaining perceptions that the regulations are unfair. Bridging social capital helps to legitimize new management efforts, while court-mandated water quality targets incentivize farmers to draw on multiple forms of social capital. We also discuss the relevance of this case for governing agricultural nonpoint source pollution in similar settings elsewhere.

Farmers’ and Consumers’ Preferences for Drinking Water Quality Improvement through Land Management Practices: The Case Study of the Soyang Watershed in South Korea

The drinking water quality along the Soyang watershed has been affected negatively by the intensive agricultural practices in the upstream area. Our study used a choice experiment method in order to estimate the values that the upstream water providers (i.e., farmers) and downstream water users (i.e., consumers) attach to the following attributes, namely, the agricultural profits, water quality, and biodiversity level of the Soyang watershed in South Korea. The preferences of the upstream water providers and downstream water users were presented by a conditional logit model and with interactions. The results from the conditional logit model specifications revealed that water quality is the most important attribute that is preferred by the downstream water users and upstream farmers. Both the upstream farmers and downstream water users have put substantial values on the protection of water bodies in the Soyang watershed, and are concerned about the consequences of water usage on the environment and human health. The respondents in each income group and in different local communities with income levels seemed to have different implicit costs for the water quality improvement in the Soyang watershed. Our study has provided robust results regarding the benefits of water improvement using sustainable land management and can be considered as a fundamental input for aiding the sustainable water–land nexus policies. We suggest that the government carefully designs a policy so as to compensate the highland farmers for their income losses as a result of the changing farming practices.

Irrigation water quality of Al-Gharraf Canal, south of Iraq

To evaluate the water quality of Al-Gharraf Canal south of Iraq for irrigation purpose, analysis of 12 physiochemical parameters of water samples by standard methods was carried out at five stations during the year 2016 (water temperature, pH, electrical conductivity, total dissolved solids, bicarbonate, chloride, calcium, magnesium, sulfate, nitrate, sodium, potassium).Seven irrigation water quality indices were calculated like; sodium percentage (% Na), soluble sodium percentage (SSP), residual sodium bicarbonate (RSBC), Kelly’s ratio (KR), permeability index (PI), magnesium adsorption ratio (MAR), and sodium adsorption ratio (SAR).The results represented as diagrams (Piper, Stiff, Schoeller, Durov, Gibbs, and Wilcox) using AquaChem and RockWork hydro-chemical software.Chemical analysis for canal water demonstrates the calcic chlorinated water type, the dominance of alkalis water, the major cations was in the order of: Na+ > Ca2+ > K+ > Mg2+ and major anions was: Cl- > SO42- > HCO3- > NO3-, the mean values of the irrigation water quality indices were (in meq/l) were; SAR (2.37), % Na (43.4), PI (%) (52.3), SSP (% (38.1), MAR (%) (34.5), KR (0.61), RSBC (-1.78).The results indicate the suitability of canal water for irrigational purposes based on the calculated indices for the majority of crops under special management for salinity and permeability control.The presentation of chemical analysis by diagrams and numbers makes understanding of complex water system too simpler and quicker. This study is a comprehensive assessment towards providing indicators and classification indices on irrigation water quality of the canal ecosystem, which will be the basis for future planning decisions on agricultural demand management measures and water quality monitoring to protect this principal water resource.

Watershed Buffering of Legacy Phosphorus Pressure at a Regional Scale: A Comparison Across Space and Time

Phosphorus (P) plays a crucial role in both agricultural production and water quality. There has been growing recognition of the importance of “legacy” P (surplus P that has accumulated in watersheds over time) for understanding contemporary water quality outcomes; however, little is known about how different watersheds respond to cumulative pressures from surplus P. The “buffering capacity” concept describes the ability of watersheds to attenuate P loading to surface waters by retaining P inputs over time. To explore the role of various watershed characteristics in buffering capacity, we used historic P data to calculate indices describing long- and short-term buffering for 16 large watersheds in southern Quebec, Canada, across a 30-year time span (1981–2011). We examined the correlation between these buffering capacity indicators and a set of key geochemical, hydrological, landscape and socio-ecological variables that we hypothesized could influence P buffering dynamics. Both short- and long-term buffering metrics were most strongly correlated with hydrological characteristics. Riverine TP flux across the watersheds was most strongly correlated with long-term buffering, which could represent a dominant influence of legacy P on contemporary riverine P flux. However, short- and long-term watershed buffering indices were not correlated with each other, suggesting distinctly different timescales and mechanisms of buffering. Combining estimates of long-term P accumulation along with biophysical characteristics of the watershed (including hydrology) explained a much greater share of the variation in riverine TP flux (R2 = 0.69) than biophysical characteristics alone (R2 = 0.36). Our findings reinforce the need to consider P buffering capacity and legacy P accumulation to help guide decision making around regional water quality targets across human-dominated landscapes.

Call for Papers in JEQ: Agricultural Water Quality under Cold Conditions

Call for Papers in JEQ: Agricultural Water Quality under Cold Conditions

Central Coast growers' trust in water quality regulatory process needs rebuilding

Growing evidence of agricultural water pollution in California's Central Coast even after the implementation of tough water quality regulations has increased the pressure on regional stakeholders. Previous research has shown that collaborative relationships between growers and regulators can motivate growers to make management decisions that benefit the environment. However, informal evidence suggested trust might have been eroding between growers and the Central Coast Regional Water Quality Control Board (CCRWQCB, the regulator) since 2004, the year the first legislation went into effect. Using a survey conducted in 2015, interviews and in-depth document review, this study assesses growers' trust of and communication with other agricultural groups and water quality regulatory agencies, specifically CCRWQCB. Survey results were compared to results of the same survey sent out in 2006. Results corroborate other research — growers' trust of most regional agricultural groups was closely correlated with frequency of communication. However, growers' trust of CCRWQCB did not correspond to the relatively high contact frequency and had declined since 2006. The literature on rebuilding trust suggests ways forward for CCRWQCB.

Assessing cost‐effectiveness when environmental benefits are bundled: agricultural water management in Great Barrier Reef catchments

Using economic analysis to prioritise improvements in environmental conditions is particularly difficult when multiple benefits are involved. This includes ‘bundling’ issues in agricultural pollution management, where a change in management action or farming systems generates multiple improvements, such as reductions in more than one pollutant. In this study, we conceptualise and compare two different approaches to analysing cost‐effectiveness when varying bundles of benefits are generated for a single project investment. Each approach requires data to be transformed in some way to allow the analysis to proceed. The index approach requires the transformation on the benefits side so that the effects of multiple pollutant changes can be combined into a measure for each project which can then be compared to costs. By comparison, the disaggregation approach requires the transformation on the costs side where costs for each project have to be apportioned across the different pollutants involved. The paper provides novel insights with an application to agricultural water quality improvements into the Great Barrier Reef in Australia, demonstrating that while both approaches are effective in prioritising projects by cost‐effectiveness, the disaggregation approach provides more insightful results and values that may be relevant for use as upper value guidelines in future project selection.

Environmental Indicator Principium with Case References to Agricultural Soil, Water, and Air Quality and Model-Derived Indicators.

Environmental indicators are powerful tools for tracking environmental changes, measuring environmental performance, and informing policymakers. Many diverse environmental indicators, including agricultural environmental indicators, are currently in use or being developed. This special collection of technical papers expands on the peer-reviewed literature on environmental indicators and their application to important current issues in the following areas: (i) model-derived indicators to indicate phosphorus losses from arable land to surface runoff and subsurface drainage, (ii) glutathione-ascorbate cycle-related antioxidants as early-warning bioindicators of polybrominated diphenyl ether toxicity in mangroves, and (iii) assessing the effectiveness of using organic matrix biobeds to limit herbicide dissipation from agricultural fields, thereby controlling on-farm point-source pollution. This introductory review also provides an overview of environmental indicators, mainly for agriculture, with examples related to the quality of the agricultural soil-water-air continuum and the application of model-derived indicators. Current knowledge gaps and future lines of investigation are also discussed. It appears that environmental indicators, particularly those for agriculture, work efficiently at the field, catchment, and local scales and serve as valuable metrics of system functioning and response; however, these indicators need to be refined or further developed to comprehensively meet community expectations in terms of providing a consistent picture of relevant issues and/or allowing comparisons to be made nationally or internationally.

Detecting seasonal and cyclical trends in agricultural runoff water quality-hypothesis tests and block bootstrap power analysis.

Seasonal and cyclic trends in nutrient concentrations at four agricultural drainage ditches were assessed using a dataset generated from a multivariate, multiscale, multiyear water quality monitoring effort in the agriculturally dominant Lower Rio Grande Valley (LRGV) River Watershed in South Texas. An innovative bootstrap sampling-based power analysis procedure was developed to evaluate the ability of Mann-Whitney and Noether tests to discern trends and to guide future monitoring efforts. The Mann-Whitney U test was able to detect significant changes between summer and winter nutrient concentrations at sites with lower depths and unimpeded flows. Pollutant dilution, non-agricultural loadings, and in-channel flow structures (weirs) masked the effects of seasonality. The detection of cyclical trends using the Noether test was highest in the presence of vegetation mainly for total phosphorus and oxidized nitrogen (nitrite + nitrate) compared to dissolved phosphorus and reduced nitrogen (total Kjeldahl nitrogen-TKN). Prospective power analysis indicated that while increased monitoring can lead to higher statistical power, the effect size (i.e., the total number of trend sequences within a time-series) had a greater influence on the Noether test. Both Mann-Whitney and Noether tests provide complementary information on seasonal and cyclic behavior of pollutant concentrations and are affected by different processes. The results from these statistical tests when evaluated in the context of flow, vegetation, and in-channel hydraulic alterations can help guide future data collection and monitoring efforts. The study highlights the need for long-term monitoring of agricultural drainage ditches to properly discern seasonal and cyclical trends.

Improvement of Supplementary Irrigation Water Quality for Rain-Fed Agriculture in the Semi-Arid Region Using Magnetization Techniques

Rain-fed agriculture depends on the groundwater as a supplementary source of irrigation. The poor quality of water from the hard rock area is applied to the crops to save the crop. Continuous irrigation leads to degradation of soil, drip irrigation system as well plants. This study assessed the damages on the drip irrigation system and soil, inflicted by the use of low-quality irrigation water. The quality of water was improved with reference to raw water in terms of pH (1.57% - 5.88%), EC (3.08% - 10.08%), ions (0.96% - 46%) by using magnetization method, without disrupting the existing irrigation system in the basaltic aquifer in semi-arid to the arid condition. This was demonstrated before the farmers in central India.

Suitability of Groundwater Quality for Irrigational use between Silkanth and Kundgaon, North of River Narmada in the Upper Alluvial Plains of Narmada Valley, District Sehore and Dewas, M.P., India

Groundwater is one of the earth’s most widely distributed resources and is consistently catering to the requirement of the agricultural irrigation. In the present study, an attempt has been made to understand the hydrochemistry and its agricultural water quality of groundwater between Silkhanth and Kundgaon, North of river Narmada, Madhya Pradesh. During the course of water quality studies of the area, 17 groundwater samples were collected and chemically analysed. Results obtained from water chemistry were used in the determination of different irrigational specifications to appraise the agricultural quality of groundwater. Important specifications like Sodium Adsorption Ratio (SAR) Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP) and Kelly’s Ratio (KR) are used for decisive the appropriateness of groundwater for the agricultural purposes. Result shows that the majority of groundwater belongs to Medium to - High Saline and Low sodium water. As per the magnesium ratio classification, the groundwaters of the study area has no magnesium hazards. Kelly’s ratio shows that majority of groundwater belongs to suitable class. As per the classification based on RSC the groundwater belongs to Safe class. As per the guidelines of Ayers and Westcot, majority of water have slight to moderate toxicity with respect to Nitrate and their use is restricted for semitolerant crops.

Beyond the nutrient strategies: Common ground to accelerate agricultural water quality improvement in the upper Midwest

Nutrients in drainage waters from the Upper Mississippi River Basin states have been a well-documented contributor to the Gulf of Mexico hypoxic zone for decades, and in response, twelve states have developed strategies to address this issue, with Iowa, Minnesota, and Illinois performing rigorous science assessments which estimated nitrogen and phosphorus reduction effectiveness for numerous agricultural non-point source conservation practices. The practices identified in these strategies were compared to identify areas of consensus and discord on nutrient load reduction potentials. Additionally, each practice was assessed for (1) the suitability to stack or be layered with other practices (stackability), (2) the ability to track implementation within a state or regionally (trackability), and (3) the level of production system change required to implement the practice. Overall, there was general consensus among the state strategies in the nutrient load reduction effectiveness of most practices with the exception of cover crops (10%–31% nitrogen reduction) and bioreactors (13%–43% nitrogen reduction). The most effective water quality-improvement practices (i.e., land-use change practices) required relatively more production system changes to agronomic management and were the most trackable (scores: 5, 1–5 scale), although they were also less stackable with other practices (scores: 1 to 1.8; 1–5 scale) and were the least cost effective on a unit area basis (generally $15 to $964 per ha). The most cost effective practices tended to be highly stackable (e.g., nitrogen management: (−)$49 per ha and stackability of 4.7), which indicated that stacking a variety of practices may be the most cost effective use of conservation dollars. The practices that were most difficult to track had relatively lower nitrogen loss reduction effectiveness, but these practices were less costly to implement and required relatively less production system change to agronomic management, two factors of importance to many producers.

Evaluating the U.S. Food Safety Modernization Act Produce Safety Rule Standard for Microbial Quality of Agricultural Water for Growing Produce

The U.S. Food and Drug Administration (FDA) has defined standards for the microbial quality of agricultural surface water used for irrigation. According to the FDA produce safety rule (PSR), a microbial water quality profile requires analysis of a minimum of 20 samples for Escherichia coli over 2 to 4 years. The geometric mean (GM) level of E. coli should not exceed 126 CFU/100 mL, and the statistical threshold value (STV) should not exceed 410 CFU/100 mL. The water quality profile should be updated by analysis of a minimum of five samples per year. We used an extensive set of data on levels of E. coli and other fecal indicator organisms, the presence or absence of Salmonella, and physicochemical parameters in six agricultural irrigation ponds in West Central Florida to evaluate the empirical and theoretical basis of this PSR. We found highly variable log-transformed E. coli levels, with standard deviations exceeding those assumed in the PSR by up to threefold. Lognormal distributions provided an acceptable fit to the data in most cases but may underestimate extreme levels. Replacing censored data with the detection limit of the microbial tests underestimated the true variability, leading to biased estimates of GM and STV. Maximum likelihood estimation using truncated lognormal distributions is recommended. Twenty samples are not sufficient to characterize the bacteriological quality of irrigation ponds, and a rolling data set of five samples per year used to update GM and STV values results in highly uncertain results and delays in detecting a shift in water quality. In these ponds, E. coli was an adequate predictor of the presence of Salmonella in 150-mL samples, and turbidity was a second significant variable. The variability in levels of E. coli in agricultural water was higher than that anticipated when the PSR was finalized, and more detailed information based on mechanistic modeling is necessary to develop targeted risk management strategies.

Specification Scheme of Pig Liquid Manure as Organic Agricultural Substances Used for Organic Farming

A more efficient use of nutrients from organic sources can benefit both farmers and water quality in agriculture. In this paper we reviewed information related to the regulations and guidelines of a swine liquid fertilizer to propose an establishment scheme for the official standards of swine manure slurry as a liquid fertilizer for organic farming. According to the law of establishment and designation of official standard of fertilizers, the liquid fertilizer made with pig liquid manure belongs to the byproduct fertilizer as of one of organic fertilizer. However, the official standards for byproduct fertilizers including the liquid fertilizer set by the Rural Development Administration (RDA), especially for a liquid swine manure fertilizer, should be revised to meet the goals of laws pursuing the environmentally sound agriculture, especially for organic farming because the terms and relevant standards need additional specific standards alike the standards such as impurities and parameter for declaration in EU. Therefore, it is suggested that official standards for byproduct fertilizers should be revised with respect to nutrient, salt content as of SAR and Na content instead of NaCl. Also we need to develop the maximum limit of heavy metals in soil to which the liquid fertilizer can be applied, as well as application rate depending on EC of the liquid fertilizer. Proposed standard for the quality of a pig slurry manure fertilizer.

Evaluation of Water Quality for Sustainable Agriculture in Bangladesh

Sustainable groundwater quality has become a major concern for the agro-based country like Bangladesh. Integrated approaches of various irrigation water quality indices and geostatistical modeling were applied to evaluate the suitability and for spatial mapping of groundwater quality of Faridpur District in central Bangladesh. The irrigation water quality index (IWQI) revealed that majority of the samples were suitable for irrigation. Similar outcomes were recorded from other indices including Na%, sodium adsorption ratio (SAR), residual sodium bicarbonate (RSBC), total hardness (TH), Kelley’s ratio (KR), and magnesium adsorption ratio (MAR). Classifications based on Wilcox diagram and permeability index (PI) plot indicated a similar conclusion wherein almost all the samples were safe for agricultural uses without posing considerable effect on the soil fertility and overall crop yield. Principal component analysis (PCA) grouped the major cations and anions into three principal components including dissolution of calcite minerals, leaching of silicate sediments, and ion exchange process. Spatial mapping of IWQI identified that groundwater in the northern side of Faridpur region were more suitable for irrigational uses relative to central and southern side, possibly due to gradients of domestic discharges and agricultural activates from north to south side. These findings would provide useful information to water distributors, managers, and decision makers for taking adaptive measures in irrigation water quality management systems.

Comparison of yield components and quality factors of sweet corn under different irrigation scheduling strategies

Rising energy costs, declining groundwater supplies, increasing competition for water resources between agricultural, industrial and domestic users and irrigation-induced water quality problems are providing considerable impetus to improving efficiency in irrigated agriculture. Much of the groundwater used for irrigation is found in closed underground basins. Water percolation is the only source of water available for recharge. In some basins, the pumping rate is much greater than the recharge from percolation and ‘water mining’ occurs. The aim of this study was to compare the yield components and quality factors of sweet corn grown under different irrigation scheduling strategies. The treatment with 426 mm of seasonal irrigation offered the largest commercial yields, with an appropriate quality production, good irrigation efficiency, the highest gross margin and the best break-even point irrigation strategy. Treatments with higher application produced lower irrigation efficiencies.

Agricultural Cost Sharing and Water Quality in the Chesapeake Bay: Estimating Indirect Effects of Environmental Payments

AbstractThis article analyzes the effect of agricultural cost sharing for cover crops on the acres of three conservation practices. A survey of farmers from Maryland is used to estimate the direct effect of cover crop cost sharing on the acres of cover crops, and the indirect effect of cover crop cost sharing on the acres of two other practices: conservation tillage and contour/strip cropping. A two‐stage simultaneous equation approach is used to correct for voluntary self‐selection into cost‐sharing programs, and to account for substitution effects among conservation practices. Using model parameters from the U.S. Environmental Protection Agency's Chesapeake Bay Program, the estimated effects of cost sharing are then translated to pollution reduction in order to quantify water quality benefits. The results indicate that the large cover crop cost sharing effort in Maryland had considerable effects on cover crop acreage, substantially reducing nitrogen and phosphorus runoff. Moreover, after accounting for the indirect effects on conservation tillage, the cost per pound of phosphorus abatement in the Chesapeake Bay decreased by between 60–67%.

An inexact log-normal distribution-based stochastic chance-constrained model for agricultural water quality management

ABSTRACTIn this study, an inexact log-normal-based stochastic chance-constrained programming model was developed for solving the non-point source pollution issues caused by agricultural activities. Compared to the general stochastic chance-constrained programming model, the main advantage of the proposed model is that it allows random variables to be expressed as a log-normal distribution, rather than a general normal distribution. Possible deviations in solutions caused by irrational parameter assumptions were avoided. The agricultural system management in the Erhai Lake watershed was used as a case study, where critical system factors, including rainfall and runoff amounts, show characteristics of a log-normal distribution. Several interval solutions were obtained under different constraint-satisfaction levels, which were useful in evaluating the trade-off between system economy and reliability. The applied results show that the proposed model could help decision makers to design optimal production patterns under complex uncertainties. The successful application of this model is expected to provide a good example for agricultural management in many other watersheds.

Intercropping with Switchgrass Improves Net Greenhouse Gas Balance in Hybrid Poplar Plantations on a Sand Soil

Core Ideas A critical issue in the production of biofuels has been the competition with food crops Intercropping switchgrass and hybrid poplar was found to be a viable bioenergy production strategy Intercropped biomass production offset increases in GHGs and GWP N2O emissions factors averaged 1% of the applied N over the study In the Pacific Northwest, commercial hybrid poplar (Populus generosa Henry × Populus canadensis Moench.) is managed at low stocking densities under irrigation for high-value timber production. The objectives of this study were to measure greenhouse gas emissions (CH4, CO2, and N2O) during intercropping of switchgrass (Panicum virgatum L.) with hybrid poplar; estimate losses of fertilizer-N as N2O, and estimate global warming potentials (GWP) of the intercrop. Cumulative above-ground biomass-C of the poplar monoculture (PM) closely matched the four year growing season (GS) soil CO2–C emissions, where aboveground biomass of the switchgrass monoculture (SM) and intercrop (IC) exceeded GS CO2–C emissions by 14.1 Mg C ha-1. Soil CH4–C uptake was not significantly different between treatments, while GS N2O-N emissions for PM were ∼80% lower than both IC and SM. N2O emissions factors averaged 0.7% of the applied N-fertilizer. Cumulative contributions of CO2 emissions to GWP were offset by biomass-C resulting in a near zero balance (−5.1 Mg CO2eq ha -1) for the PM, where, IC and SM sequestered significantly more CO2 resulting in a net GWP of −42.5 and –32.2 Mg CO2eq ha-1, respectively. Intercropping with switchgrass can improve the net greenhouse gas balance of hybrid poplar. Continued research is needed on the effects of irrigated bioenergy production on GHG emissions in intercropped systems as they will become increasingly important as agricultural water use, water availability and quality are challenged by climate change.