Journal of environmental quality最新文献

In Germany during several decades, emissions and thus the chemical climate affecting forests have changed significantly. The effects of these changes on the element balance of forests can be documented only by long-term observations, as has been done at the Höglwald site (Southern Bavaria) since 1985. Since then, structural changes in agriculture have led to a reduction in emissions of reduced nitrogen (NH₃). There was also a slight decrease in emissions of oxidized nitrogen (NO_x). Air pollution control measures, especially in the 1980s, led to a particularly drastic reduction of sulfur emissions (SO₂). Consequently, inputs to the ecosystem decreased by almost 95% between 1985 and 2020. Dry deposition nowadays plays practically no role for this element. High nitrogen inputs, dominated by reduced nitrogen, have led to a high proton production through N transformations. This has gradually reduced the buffering capacity of the topsoil. Comparing measured fluxes shows that with decreasing sulfur inputs, the sulfur stored in the topsoil from times of high deposition was remobilized. At the Höglwald, this process occurred rather clearly over a period of about 28 years and has resulted in only about 11% of the initial amount of sulfur being still present in the topsoil (humus layer + mineral soil down to 40 cm) in 2020. Forestry should take the changed chemical conditions into account in its nutrient management.

Agricultural runoff accounts for >40% of Chesapeake Bay's nonpoint source nitrogen (N) pollution, representing a complex problem requiring systems-level management approaches. Traditional nitrogen management strategies, focused primarily on field-level best management practices, have proven insufficient to achieve watershed restoration goals, underscoring the need for systems-level management approaches that account for interactions across the entire food production chain. In this study, we investigate the effects of simulated future agricultural changes and management scenarios on agricultural N loss in the Chesapeake Bay Watershed using a systems approach production chain analysis that tracks nitrogen flows through seven distinct stages of food production, processing, and consumption chains. We developed scenarios including future agricultural intensification, efficiency improvement management strategies, and combined scenarios to evaluate system-wide responses. Our results show that a combination of interconnected factors is the most influential in controlling total nitrogen loss, including expected factors like the production amounts of crops and animals and fertilizer application rates, as well as several less widely discussed factors, including live animal weight gained and feed conversion ratios. Although live animal weight gain and feed conversion ratio were previously identified as sensitive variables in earlier applications of the nitrogen flow model, our study advances this work by quantifying their relative importance to total nitrogen loss. In addition, the present analysis extends these insights to future climate-impacted scenarios by incorporating climate-driven changes in crop yields and projected growth in animal production. This combined approach clarifies not only which factors matter most but also how their influence evolves under changing environmental and production conditions, thereby identifying the most consequential leverage points for future nitrogen management. These findings demonstrate that systems-level perspectives across interconnected food production chains can provide viable information for identifying pathways to meet watershed quality objectives while accommodating projected agricultural intensification under changing climate conditions.

Vanadium (V) is a potentially toxic metal widely distributed in the environment. This study investigates temperature effects on V adsorption and speciation in biochar (BC) and BC–metal oxide composites under conditions relevant to contaminated soils in temperate climates. While BC and metal oxide nanoparticles can individually immobilize V, limited information exists on temperature effects. This study investigates V adsorption and surface characteristics of BC alone and BC combined with iron (Fe), aluminum (Al), and titanium (Ti) oxide nanoparticles (BC: oxides at 5:1 ratio) at warm (22°C) and cold (4°C) temperatures. V adsorption was conducted at pH 7.5 using concentrations from 0 to 40 mg L⁻¹. Visual MINTEQ modeling software was used to predict dissolved V species at experimental conditions. Surface characteristics were examined using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier transform infrared spectroscopy. Adsorption data were fitted to the Freundlich (r² ∼0.99) and Langmuir (r² = 0.66–0.96) isotherms. Maximum adsorption capacity followed the order: BCAl-cold = BCAl-warm > BCTi-cold > BCTi-warm = BC-cold = BC-warm > BCFe-warm = BCFe-cold. Predicted orthovanadate (%) was higher at warm temperatures. H₂VO₄⁻ was the dominant species at pH 7.5 under both temperatures. Microaggregates were observed in BCAl and BCTi, indicating greater surface area than BC or BCFe. SEM-EDS showed V and Al enrichment on BCAl surfaces suggesting the inner-sphere complexes between Al–oxygen (O) and H₂VO₄⁻. These results offer mechanistic insight into V adsorption on BC–nano-oxide composites under varying climatic conditions and support their potential use in remediating V-contaminated soils.

Urbanization generates significant amounts of sewage sludge (SS), with relatively high concentrations of plant nutrients such as phosphorus (P). When biochemically stabilized by composting, SS (composted sewage sludge [CSW]) can serve as a sustainable P source in agriculture, supporting a circular economy and reducing agriculture's dependence on finite phosphate rock. The objective of this study was to assess the ability of CSW to supply P to plants grown on calcareous and noncalcareous soils of contrasting properties. Compost quality was assessed to support the scaling up of this study for agronomic application. Durum wheat (Triticum durum L.) was grown under controlled conditions, and three treatments were applied to the soils: (1) control without P (CON), (2) diammonium phosphate (DAP)—a common synthetic P fertilizer, and (3) CSW, the last two to supply 50 mg kg⁻¹ of P. The P content was 46% higher in CSW than before composting (24.0 vs. 16.4 g kg⁻¹). In the pot experiments, total soil P concentrations increased by 11% with DAP and CSW relative to CON. The highest P internal utilization efficiency was obtained with CON and CSW in the Entisol and CON in the Vertisol, while wheat grain yields were highest with DAP and CSW across soils. CSW increased harvest index and one-grain weight in the calcareous soil relative to CON. Moreover, CSW and DAP led to similar P uptake in wheat, significantly higher than CON. Our results highlight the potential of CSW as an effective P source for wheat in soils of southern Europe and others with similar properties.

Microplastics derived from agricultural plastic films accumulate in soils, potentially impacting ecosystem functions such as soil organic carbon (SOC) storage. Microbial degradation of biodegradable plastics, which are intentionally tilled into soil, may accelerate or inhibit the mineralization of native SOC, known as priming effects. Moreover, the interaction between microplastics and nitrogen (N) on SOC dynamics remains poorly understood, despite their concurrent presence in agroecosystems. We used a 193-day incubation experiment to investigate the degradation and priming effects of three biodegradable microplastics (polybutylene succinate [PBS], polylactic acid [PLA], and a PLA-polyhydroxyalkanoate blend [PLA/PHA]) compared to a conventional microplastic (low-density polyethylene [LDPE]) in agricultural soil under low and high N conditions. Isotope (¹³C) tracing allowed us to determine the cumulative loss of plastic- versus SOC-derived C as CO₂-C. Biodegradable microplastics varied in biodegradation rates and priming effects, with PLA/PHA losing the most plastic-C (17.88%) and inducing the greatest positive priming effects (371 µg C g dry soil⁻¹). In contrast, PLA, PBS, and LDPE showed <1% plastic-C loss and weaker priming effects ranging from positive to negative (73.1, 8.81, and −45.4 µg C g dry soil⁻¹, respectively). Although N addition decreased total C loss from both native SOC and microplastics, it did not alter priming effects. Priming effects were positively associated with dissolved organic and microbial biomass C, enzyme activities, and pH. We conclude that biodegradable microplastics may threaten native SOC pools, and higher N availability may promote persistence of biodegradable plastics in soils.

In rural areas, unpaved roads can drive water quality degradation via sediment inputs. Excess sediment loss from poorly maintained unpaved roads to adjacent waterways blocks sunlight, decreasing primary productivity and increasing nutrient concentrations. This is particularly relevant to Arkansas, where 85% of county roads are unpaved; however, few studies have explored the impacts of unpaved roads in rural watersheds dominated by pasture. We sampled Brush Creek (Arkansas) to understand local (i.e., road crossing type) and watershed-scale (e.g., land cover/use) controls on sediment loss. We collected monthly baseflow and four opportunistic storm flow samples for total suspended solids (TSS) upstream and downstream at bridge, culvert, and direct stream crossings. Mean TSS yields downstream versus upstream of road crossings were comparable, especially at bridge and culvert sites, indicating these road crossings may not be critical TSS sources. At the watershed scale, TSS load showed increasing trends as both total length of unpaved roads and area of pastureland in a subwatershed increased (linear mixed effects; β = 0.03, R² = 0.41, p > 0.1; β = 0.67, R² = 0.42, p = 0.07, respectively). Moreover, TSS yields were higher during stormflow than baseflow (26.87 ± 6.82 vs. 0.38 ± 0.04 kg km⁻² day⁻¹; unpaired t-test, p < 0.01). Finally, seasonality influenced local and watershed patterns of TSS loss via variation in transport controls, including wet season conditions, discharge rates, and overland flow. Our findings indicate watershed-scale characteristics are key contributors to sediment loss in rural watersheds. Targeted best management practice implementation should focus on unpaved roads and pasturelands during key transport periods to effectively protect downstream water quality.

Saturated buffers are important edge-of-field conservation practices to reduce nitrate-nitrogen (NO₃-N) loading from subsurface (tile) drainage systems to downstream waters. The impact of seasonal management of weir elevations in the water control structure on NO₃-N removal has not been well studied. This study evaluated the effect of control box weir elevation management on nitrate removal and compared in situ flow treatment with design predictions from the USDA Natural Resources Conservation Service conservation practice standard 604. A 253 m long saturated buffer draining approximately 6 ha was monitored for flow and NO₃-N load from 2022 to 2024. The weir elevation was adjusted to “full drainage” (no treatment), “growing season” (reduced treatment capacity), and “fallow season” (full treatment capacity) settings according to weather conditions and field operations. During a 29-day full drainage period in 2022, the saturated buffer bypassed 25% of the annual drainage flow and 28% of the annual NO₃-N load. However, the fraction of flow treated and NO₃-N load removal efficiency was greater in 2022 than 2023 and 2024. Treated flow within the saturated buffer was greater than predicted, while peak drainage system flow was less, resulting in a greater percentage of drainage system capacity treated by the saturated buffer than designed. These discrepancies suggest that alternative design methods should be explored. While the saturated buffer removed substantial NO₃-N in the year with alternative weir management, careful consideration should be given for potential sites that may require extended full drainage periods, as large NO₃-N losses can bypass during such conditions.

This study evaluates the fate and variability of soil organic carbon (SOC) stocks and nitrogen species using the latest version of the Soil and Water Assessment Tool–Carbon (SWAT-C) and assesses how conservation practices influence their dynamics in the Raccoon River Watershed (RRW). Dominated by intensive agricultural production, the RRW is a significant contributor of sediment and nutrient loads to local rivers and the Mississippi River. This SWAT-C model simulates the export of SOC and nitrogen species and evaluates their responses under varying management scenarios. Model calibration was performed for streamflow, sediment, nitrate, total nitrogen, and organic carbon with monitoring data at both a sub-basin and the watershed outlet. The SWAT-C model achieved satisfactory to very good performance, with Nash–Sutcliffe efficiency values of 0.76–0.80, coefficients of determination (R²) of 0.78–0.86, and percent bias ranging from –18% to 12%. We assessed the effects of three conservation practices on SOC and nitrogen fate and transport: no-till, residue harvest with cover crop implementation, and residue harvest without cover crops. The SWAT-C results were compared with a historical baseline to quantify changes in the carbon and nitrogen loadings associated with each practice. This study highlights the role of conservation management and provides valuable insights for improving water quality and carbon sustainability in intensively farmed regions.

Amorim, H. C. S., Ashworth, A. J., Ducey, T. F., Brewer-Gunsaulis, V. B., Drescher, G. L., Owens, P. R., Patterson, A. H., DeBlasis, G., & van Straaten, I. (2025). Recycling waste via insect agriculture: Frass impacts on soil and plant health. Journal of Environmental Quality, 54, 1457–1469. https://doi.org/10.1002/jeq2.70089

A reader identified an inaccurate statement in the first sentence of the Conclusions section. The current text reads: “Insect manure or ‘frass’ is a promising amendment for organic and conventional systems, with 12 times greater concentrations of heavy metals and potentially toxic elements than poultry litter.” It should instead read: “Insect manure or ‘frass’ is a promising amendment for organic and conventional systems. Poultry litter had up to 12 times greater concentrations of heavy metals and potentially toxic elements than frass.”

We apologize for this error.

Upscaling crop yield and nitrate-N leaching loss from experimental sites to large areas under alternative crop rotations is crucial for assessing strategies and setting goals to protect groundwater quality at a regional scale. Nitrogen (N) rate field trials were used to calibrate the Environmental Policy Integrated Climate (EPIC) model for continuous-corn (Zea mays L.) (C-C), corn-soybean (Glycine max L.) (C-Sb), and alfalfa (Medicago sativa L.)-corn (A-C), with or without rye (Secale cereale L.) cover crop. Satellite estimates of crop evapotranspiration (ET_c) were used to upscale the EPIC model for crop yield and nitrate-N leaching, using the irrigation-water permitting data from 2010 to 2017 for 13,375 ha of sandy soils in Bonanza Valley, central Minnesota. Four alternative management scenarios were evaluated with EPIC: (1) reducing N fertilizer rate from the maximum return to N value (MRTN) (of 0.05 to a value of 0.1 (for the N price/crop value ratio), (2) adding rye cover crop at MRTN of 0.1, (3) irrigating with EPIC auto-trigger in scenario 2, and (4) converting 50% of C-C acreage in scenario 3 to A-C. Nash-Sutcliffe coefficients, normalized root-mean-square error, and R² values based on ET_c/crop yield for calibration and validation of the EPIC model ranged 0.95–0.54, 4.67–19.4, and 0.96–0.74; and 0.74–0.41, 7.99–23.4, and 0.88–0.55, respectively. Results indicate that corn yield at MRTN of 0.05 averaged 12.5, 13.2, and 13.4 t ha⁻¹ under C-C, C-Sb, and A-C rotations, while yields at MRTN of 0.1 were reduced by 4.1%, 3.5%, and 3.3%, respectively. The baseline scenario of C-C, C-Sb, and A-C rotations at MRTN of 0.05 had annual nitrate-N leaching losses of 51.8, 45.5, and 31.4 kg ha⁻¹, while MRTN of 0.1 reduced these losses by 9.1%, 5.0%, and 3.8%, respectively. Rye after corn and soybean reduced nitrate-N leaching losses in the MRTN of 0.1 scenario by 5.8% and 13.6%, respectively. EPIC auto-irrigation of corn, soybean, and alfalfa at MRTN of 0.1 reduced nitrate-N leaching losses with rye (relative to conventional irrigation) by 9.6%, 9.1%, and 8.5%, respectively. Further, replacing half of the C-C acreage with A-C rotation would provide a 6.1% reduction, resulting in a total reduction of 27.4% in nitrate-N leaching to groundwater when all alternative practices are combined. Overall, augmenting EPIC model with field-observed ancillary data and remote sensing successfully predicted the yield and NO₃-N leaching losses under different crop rotations, indicating opportunities to upscale field-scale agroecosystem simulations, particularly if used to calculate NO₃-N leaching on a long-term basis at the regional scales.