Journal of environmental quality最新文献

Waste tires accumulate in massive quantities worldwide, posing significant environmental challenges. Pyrolysis under high vacuum offers a potential disposal solution, producing recovered carbon black (CB) enriched in zinc (Zn) from zinc oxide used in tire manufacture. Our objective was to evaluate recovered CB from pyrolysis of mining tires (CB4000) as a Zn fertilizer for maize (Zea mays L.) in calcareous soil with low plant-available Zn. This material contained 90 g Zn kg^-1 and increased Zn bioavailability as measured by ion-exchange membranes (plant root simulator [PRS] probes). In 2 years of field and glasshouse trials, CB4000 enhanced Zn uptake and grain and silage yields. The effectiveness of CB4000 to increase stem width, yield and Zn uptake of maize was equal to traditional zinc sulfate (ZnSO₄) fertilizer when applied at double the rate of Zn. Concentrations of toxic organic compounds were below detection or well below regulatory limits for use as a fertilizer and maize tissue concentrations of heavy metals of concern (lead [Pb], chromium [Cr], and nickel [Ni]) were unaffected. These results demonstrate that recovered CB from pyrolyzed mining tires can function as a safe and effective Zn fertilizer, while also offering a sustainable recycling pathway for end-of-life tires.

Rhizosphere bacteria can support crop production by promoting plant health, soil fertility, and resilience to biotic and abiotic stresses. However, the potential role of soil-beneficial bacteria, particularly plant growth-promoting rhizobacteria (PGPR), remains inadequately explored in citrus production grown on pH-stressed soil. This study aimed to evaluate the effect of PGPR on citrus growth and soil health indicators under pH-stressed Florida sandy soil. A greenhouse study was conducted at the University of Florida, Lake Alfred, which followed a 3 × 3 factorial randomized complete block design with three soil pH levels (5.0, 6.5, and 8.0) and three PGPR (P)/fertilizer (F) combinations (P + 75% F, P + 100% F, and 100% F only). Soil pH conditions were adjusted using a soil neutralization curve generated by soil incubation methods. The results showed that the soil pH factor significantly influenced most crop growth parameters, with optimal results at a pH of 6.5. PGPR significantly (p < 0.05) improved the plant height (27.84 cm), root mass density (7.65 mg/cm³), stem diameter (4.89 mm), and aboveground biomass (2.64 g/ plant) compared to without PGPR application. No significant difference between 75% and 100% fertilizer rates were found in crop and soil attributes when PGPR was applied. Soil organic matter and microbial respiration were also significantly improved (p < 0.05) with PGPR inoculation by 1.15 and 1.65 folds, respectively, compared to 100% F-only treatment. The availability of soil nutrients was influenced by PGPR treatments, which likely enhanced nutrient uptake and improved crop growth even with a reduced fertilizer rate. The results suggested that PGPR inoculation combined with partial fertilization can improve soil health indicators and plant growth, even in pH-stressed sandy soils.

In the Canadian prairies, spring snowmelt occurs rapidly and causes flooding in low-lying areas, inducing anaerobic soil conditions and exacerbating phosphorus (P) release to meltwater. Soil amendments can mitigate P loss from flooded soils soon after amendment application; however, their residual benefits are less understood. We examined the initial and residual benefits of alum (Al₂(SO₄)₃·18H₂O), gypsum (CaSO₄·2H₂O), and Epsom salt (MgSO₄·7H₂O) in a simulated snowmelt flooding experiment. Intact soil columns were taken from amended and unamended field plots in the same year and 1 year after the amendment application. The soil columns were flooded and incubated at a cold temperature. Porewater and floodwater samples were analyzed for dissolved reactive P (DRP), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) concentrations, and pH. During the year of application, alum, gypsum, and Epsom salt decreased the mean porewater DRP by 68%, 29%, and 19%, and floodwater DRP by 69%, 51%, and 31%, respectively, relative to unamended treatment, with only alum showing significant differences. One year after applications, alum significantly decreased porewater DRP by 35%, but not floodwater DRP, whereas gypsum or Epsom salt did not decrease porewater or floodwater DRP. Correlation and principal component analysis revealed that porewater and floodwater DRP are positively related to pH and Fe, but only in alum-amended treatment, suggesting the influence of pH and Fe in stabilizing P. While alum was effective in mitigating P loss from flooded soils, its effectiveness decreased over time, with negligible residual benefits a year later.

Science-based Trials of Rowcrops Integrated with Prairie Strips (STRIPS) can improve water quality and reduce antimicrobial resistance genes (ARGs) from manured field runoff. Prior studies showed significant reductions in ARG abundances with prairie strips, but no enrichment was detected in surface soil layers, prompting further investigation into transport pathways. We hypothesized that ARGs may move vertically through strip soils. In an 8-week soil column experiment, we characterized the vertical transport of manure-amendment ARGs in prairie strip soils and leachate, comparing columns amended with anaerobically digested swine manure (ADM) and undigested swine manure (UDM) to a mineral-based control (mineral solution amendment [MIN]). In amendment manures, the ARG concentrations in ADM and UDM were similar, and ADM had increased antibiotic residual concentrations. ADM and UDM amendments resulted in elevated ARG abundances in soil and leachate compared to MIN. After manure amendment, ARGs were transported up to 52.5 cm from the soil surface after rainfall events. Tetracycline resistance genes were persistently detected in amended subsurface soils, with tetM detectable until week 8 in both ADM and UDM amended soils, and tetO persisting to week 3 in ADM and week 8 in UDM amended soils. Generally, ADM amendments had lower ARG persistence than UDM, highlighting different transport dynamics depending on manure treatment. Most manure-derived ARGs appeared to be retained or degraded within the strip soil profiles, with only 9.6 and 6.1 percent of UDM and ADM amendment ARGs recovered, respectively. Our results support that prairie strips can mitigate ARGs from manured field stormwater runoff and that ARGs are transported vertically through the soils and mostly retained at surface depths.

Aluminum (Al³⁺) toxicity is a major constraint to wheat (Triticum aestivum L.) productivity in acidic soils, where it restricts root growth and impairs nutrient and water uptake. Characterizing root system architecture (RSA) offers an effective approach for early screening of genotypes capable of maintaining growth under Al³⁺ stress. This work aimed (i) to evaluate the effects of increasing Al³⁺ concentrations on shoot development and RSA in wheat cultivars and (ii) to identify root traits that serve as reliable indicators of Al³⁺ tolerance. Four cultivars, Anahuac, IAC-5, Onix, and Quartzo, were grown in a greenhouse for 15 days under increasing concentrations of Al³⁺ (0, 37.5, 75, and 150 µM). The cv. IAC-5 presented the highest tolerance to Al³⁺, verified by the maintenance of shoot dry weight and foliar area, nearly twice the average of the other cultivars and reductions of only 1.4% and 13.9%, respectively, at 150 µM Al³⁺ compared to 0 µM Al³⁺. Anahuac and Quartzo showed pronounced reductions in shoot and root growth (approximately 50%), with Anahuac being the most sensitive. Increasing Al³⁺ concentrations reduced total root length, number of forks, and the proportion of thin roots while increasing average root diameter; root thickening was particularly evident in Al-sensitive cultivars and in first- and second-order lateral roots. Al³⁺ tolerance was associated with sustained root emission and elongation, especially lateral roots during early vegetative state. Overall, RSA characterization, particularly root length, diameter, and branching traits, provides an efficient and rapid phenotyping strategy for selecting Al³⁺-tolerant wheat genotypes.

Phosphorus (P) is essential for crop growth but leaches through subsurface drainage discharge, impacting water quality. This study's objectives are to (1) apply hybrid statistical-machine learning to quantify the contributions of incidental (new) and legacy (old) P in drainage discharge from organic site and inorganic site and (2) evaluate the effect of manure application timing on P loss. We collected data from two on-farm sites in southeast Michigan, USA. A linear regression equation was used to analyze P load based on drainage discharge and fertilizer application timing. The data were split into calibration and validation sets, and machine learning was used for training. The results showed strong model prediction performance. Organic fertilizers contributed approximately twice the observed total phosphorus (TP) loss (7.54 kg ha⁻¹ vs. 3.73 kg ha⁻¹) and nearly four times the dissolved reactive phosphorus (DRP) loss (4.90 kg ha⁻¹ vs. 1.05 kg ha⁻¹) compared to inorganic P loss, mainly due to the greater P application rate and higher soil test P. When applied during winter months (December–January), organic fertilizer contributed to greater new P loss, whereas early fall applications (October–November) resulted in lower new P loss, showing the importance of application timing. At the organic site, legacy P was the dominant contributor to TP and DRP losses, accounting for 84% and 79% of losses, respectively. At the inorganic site, legacy P was responsible for 97% of TP loss and the entirety (100%) of DRP loss. In conclusion, legacy P was the dominant source of P loss through drainage discharge, and winter organic fertilizer application significantly increased new P loss.

The Annual Phosphorus Loss Estimator (APLE) model is a commonly used annual time-step model for predicting annual field-scale surface runoff and erosion losses of dissolved and particulate P as well as annual changes in total and Mehlich-3 extractable soil P. APLE was developed and coded as an Microsoft Excel workbook to provide a modeling option for users with limited modeling experience and lack of access to expensive software packages. The advantage of using Excel is that most users have both access and familiarity with Excel. However, the calculations within Excel require numerous calls to multiple cells, making it a challenge to modify and update the model. Moreover, the graphics are limited, and the current version does not have the ability to compare model predictions with observations. This limits the model's use and functionality. To address this, we have developed a Graphical User Interface application of APLE (APLE2026) to provide a cleaner and more intuitive user interface, improved graphics, and enhanced data analysis. This novel software package of APLE provides a more seamless way to run the model and view model output enhancing the functionality of APLE.

Phosphorus index (P-index) was developed to assess field vulnerability to phosphorus (P) loss and guide P management decisions. The original structure of the P-index was additive, and with continued refinement, multiplicative and component-based indices were developed. Alabama adopted the additive version in early 2000; however, the tool was never tested for its performance. The objectives of this study were to (i) evaluate the Alabama P-index using edge-of-field P loss data, (ii) test if multiplicative (Tennessee) and component-based (Georgia) P-indices perform better, and (iii) improve and test the performance of a modified Alabama P-index. We evaluated the performance by examining the strength and directional relationship between P-index scores and annual P loads. The Alabama P-index showed weak correlations (r < 0.50) between risk scores and measured dissolved reactive phosphorus (DRP), total particulate phosphorus (TPP), and total phosphorus (TP) loads. Additionally, directional inaccuracies were observed, indicating that the index misclassified the relative risk of P loss. Further, we evaluated multiplicative and component-based indices but found similar discrepancies between predicted risk scores and actual P loading. Subsequently, we modified the Alabama P-index by replacing soil test P with the phosphorus saturation ratio and substituting the underground outlet system factor with the timing of P application. Minor adjustments to weighting factors were made. The modified P-index demonstrated statistically significant correlations (r > 0.51) and directional alignment with DRP, TPP, and TP loads, suggesting it can serve as a reliable interim tool for assessing P losses. Future research should focus on restructuring and validating a component-based P-index tailored to Alabama's agricultural systems.

Edge-of-field (EoF) water sampling methods play a crucial role in understanding non-point source nutrient fate and its environmental impacts, yet accurately interpreting water quality studies, remains challenging. This study evaluates and compares four EoF runoff water sampling techniques: (1) a commercial automated sampler (ISCO) with hourly sampling, (2) a low-cost internet of things sampler low-cost sampler with hourly sampling, (3) hourly hand sampling (grab hourly sampling), and (4) intermittent grab sampling (GB) in 2023 and 2024 at a surface irrigated agricultural site in Fort Collins, Colorado involving three levels of tillage intensity. Nine water quality parameters (nitrate-N, nitrite-N, total Kjeldahl nitrogen, orthophosphate-P, total phosphorus (TP), total suspended solids (TSS), total dissolved solids, pH, and specific conductivity) were measured over nine irrigation-driven and two rainfall storm runoff events. Resulting concentration values were modeled simultaneously using a Bayesian hierarchical generalized linear mixed model, enabling causal inference with uncertainty quantification while accommodating for missing data. Results show strong alignment across samplers for most analytes, confirming the validity of integrating diverse methods in long-term and widespread monitoring. However, ISCO samples exhibited consistently elevated TSS and TP due to a purge-induced sediment plume from the flume's stainless-steel bottom intake; excluding the first ISCO sample of each pair of sample draws restored agreement with other methods. These findings show the importance of flume morphology, intake placement, purge protocol, and selective data exclusion (if necessary) to ensure comparability across sampling methods.

The phosphorus (P) availability's role in carbon (C) and nitrogen (N) accumulation in long-term systems remains unclear. This study evaluated the P fertilization's influence on C and N storage, C:N ratio, humic matter, and the C:clay ratio in two long-term corn (Zea mays L.)/soybean [Glycine max (L.) Merr.] rotation trials under conservation tillage in North Carolina. Soil samples were collected at 0–5, 5–10, 10–20, and 20–30 cm. A linear-plateau model evaluated the effect of soil test phosphorus (STP), from long-term fertilization, on C and N stocks at 0–10, 0–20, and 0–30 cm. Both sites exhibited depth-based STP gradients, although P rates significantly affected C stocks only in the 0–10 cm layer at Tidewater. P availability influenced C stocks at both sites, with greater P content and a higher critical soil test phosphorus value (CSTV) in Tidewater. CSTVs derived from C and N stocks were strongly correlated with those based on relative crop yield (R² = 0.99). On average, the sandy soil at Tidewater accumulated more C than the clayey soil at Piedmont, reflecting differences in C stabilization. Maintaining soil test phosphorus near the CSTV increased C stocks by 2.1–2.7 Mg ha⁻¹ and N stocks by 0.2–0.3 Mg ha⁻¹ across the evaluated depths, contributing to improved soil fertility and agroecosystem resilience. Piedmont soils, despite lower total C stocks, showed greater C storage potential due to higher clay content, reinforcing the need for site-specific P management adapted to soil texture and C stabilization capacity.