Catalytic hydrotreatment is a key strategy for improving the quality of biomass-derived pyrolysis oil by reducing oxygen content, enhancing stability, and increasing energy density. In this study, one-step upgrading was conducted using noble metal mono- and bi-metallic catalysts (nickel-Ni, nickel molybdenum-NiMo, and cobalt molybdenum-CoMo) in the presence of hydrogen at 350 degrees C. Catalyst screening revealed that CoMo catalysts were ineffective, resulting primarily in coke due to uncontrolled polymerization. By contrast, Ni- and NiMo-based catalysts produced upgraded oils with distinct differences in yield, composition, and hydrogen utilization. Nickel supported on silica-alumina (Ni/SiO2-Al2O3) achieved the highest energy recovery (80.1%) due to lower hydrogen consumption, while retaining a higher oxygen content. NiMo catalysts, supported on zirconia, provided superior deoxygenation (oxygen removal >84.9%) and the highest higher heating value (34.6 MJ/kg), while suppressing coke. Extending reaction time from 2 to 3 h enhanced oxygen removal and shifted product distribution toward cycloketones and heavier distillate fractions at the cost of lower liquid yield and increased gas formation. Gas analysis, thermogravimetric analysis, Van Krevelen trends, and simulation distillation profiles highlight the mechanistic balance between hydrogenation, cracking, and condensation over NiMo-based catalysts.

Plant growth-promoting rhizobacteria (PGPR) offer a sustainable strategy to minimize dependence on conventional inorganic and organic fertilizers. The objective of this study was to determine the effects of a multi-strain Bacillus PGPR mixture and poultry litter (PL) on the early growth of annual ryegrass (Lolium multiflorum Lam.) and tall fescue (Lolium arundinaceum Schreb.). Six treatments were evaluated: 0%, 50%, 75%, and 100% PL (equivalent to 269 kg N ha(-1)) combined with PGPR; 100% PL alone; and a control without inputs. PGPR inoculation did not affect seedling emergence (p > 0.05) in either species after 7 days. However, in annual ryegrass, PGPR markedly increased shoot and root biomass compared to the control (p < 0.05). Notably, the combination of 75% PL with PGPR produced annual ryegrass plants with height, number of tillers, shoot, and root biomass, root morphological traits, crude protein (CP), and nutrient concentrations comparable to 100% PL alone. No significant increases in these parameters were observed with PGPR inoculation at the 100% PL rate. In tall fescue, PGPR alone produced shoot biomass similar to all PL treatments, regardless of PGPR. Root biomass and morphological traits declined as PL rates increased. While all PL treatments resulted in significantly (p < 0.05) higher CP and nutrient concentrations compared to the control and PGPR-only treatments, no significant differences were observed among PL rates. These results indicate that integrating 75% PL + PGPR maintains early forage growth equivalent to 100% PL, offering a sustainable approach to reducing fertilizer inputs in forage production systems.

This meta-analysis quantifies the impact of plant growth promoting rhizobacteria (PGPR) on the growth and nutrient status of maize (Zea mays L.), wheat (Triticum aestivum L.), soybean (Glycine max [L.] Merr.), and chickpea (Cicer arietinum L.) under drought stress, while identifying key moderators of these microbial effects. Drought treatments in the studies ranged from mild [≈70–80% field capacity (FC)/water holding capacity (WHC)] to moderate (≈40–69% FC/WHC or 50% ETc) and severe (<40% FC/WHC or prolonged water withholding). Across studies, PGPR inoculation significantly improved shoot dry weight (SDW), root dry weight (RDW), and yield by 38%, 52%, and 38%, respectively, while simultaneously increasing nitrogen, phosphorus, and potassium concentrations by 24%, 44%, and 28%. Crop type significantly moderated responses, as legumes generally exhibited stronger benefits than cereals, with SDW increasing by 79% and 30%, respectively. Drought severity strongly influenced PGPR effectiveness, with the largest improvements occurring under moderate drought, with RDW increasing by 61% and yield by 56%. Moderator analysis revealed that the variability in PGPR effectiveness was driven by experimental conditions (field vs. controlled), soil texture, and soil pH. Inoculation strategy also played a critical role with multi-strain consortia outperforming single-strain inoculants, increasing SDW by 70% compared to 28%. Furthermore, consortia combining taxonomically distinct phyla (Firmicutes and Proteobacteria) were more effective than those comprising closely related taxa. These findings provide valuable insight into agronomic and environmental moderators influencing PGPR effectiveness and support the targeted deployment of phylogenetically diverse microbial consortia to enhance drought resilience in major cropping systems.

Excessive poultry litter (PL) application in forage systems poses environmental risks. This study evaluated the potential of plant growth-promoting rhizobacteria (PGPR) to reduce PL dependence in annual ryegrass (Lolium multiflorum) and tall fescue (Lolium arundinaceum) production. Four PL rates (0

Phosphorus (P) loading from farmland to water bodies through surface runoff is a major water quality concern. Soil test P (STP) methods developed for fertilizer recommendations are commonly used for estimating environmental P loss. This research evaluated the relationship between P concentration in runoff and STP concentrations determined by different methods (water‐soluble P, Mehlich‐1 [M1], and Mehlich‐3 [M3]) and quantified the differences in P loads in runoff from soils having distinct STP levels. Artificial rainfall simulations (RS) were conducted at four sites (1, 2, 3, and 4), having mean M1‐P values of 143, 236, 28, and 5 mg kg −1 , respectively. Runoff samples were analyzed for dissolved reactive P (DRP) and total P (TP). The correlation between DRP and TP concentrations with M1 and M3 was similar in direction, but M3 had a greater correlation coefficient and was reliable for estimating environmental P loss from Coastal Plain soils. Among the four sites, cumulative DRP and TP loadings (118.4 and 232.3 g ha −1 ) from the first RS at site 2 with the highest M1 values were significantly higher than the other three sites (range: 3.48–37.5 g ha −1 for DRP and 6.03–83.1 g ha −1 for TP). Similarly, site 2 had the highest loading for both DRP and TP (123.5 and 194.8 g ha −1 ) during the second RS. No statistical differences were found between the first and second RS for both DRP and TP loads, indicating rainfall events of similar intensity occurring 24 h apart produced the same amount of P loss in runoff.

Gypsum use in agriculture has a longstanding history, yet there remains a critical need for research to understand better its impact on plant development and plant nutrient availability. This study evaluated the impact of flue gas desulfurization gypsum (FGDG) amendments on the physical and chemical properties of pine bark substrates and the growth and nutrient uptake of chrysanthemum ‘Wanda Red’. Pine bark was incorporated with controlled-release fertilizer, micronutrient fertilizer, dolomitic limestone, and varying FGDG rates (0%, 2.5%, 5%, and 10% v:v). Plant growth metrics, including dry weight, canopy volume, and foliar nutrient concentrations, were recorded at bud initiation and peak bloom. Flue gas desulfurization gypsum amendments did not significantly affect plant dry weight at bud initiation, although plants without FGDG had greater canopy volumes. By peak bloom, plants without FGDG exhibited greater dry weights, but no difference in growth indices was observed (P = 0.8648). Although the 0% gypsum plants recorded a larger size at bud initiation, there were no differences by full bloom. Foliar nutrient analyses revealed that FGDG amendments influenced nutrient uptake, with notable reductions in nitrogen (P = 0.0035) and potassium (P < 0.0001) at bud initiation but no significant differences at peak bloom. Conversely, phosphorus and calcium concentrations increased with FGDG amendments, suggesting improved retention and availability. Overall, although FGDG amendments led to reduced uptake of some nutrients and minor delays in bloom, all treatments produced marketable chrysanthemums, indicating that FGDG can be integrated into production practices without compromising plant quality. Further studies are recommended to explore lower gypsum rates and their interactions with nutrient retention and crop demand.

Geogenic arsenic (As) contamination in groundwater causes serious health and environmental concerns. Anthropogenic actions also contaminate natural ecosystems, including groundwater aquifer systems, with As severely impacting human health and ecosystems. Considering practical feasibility and sustainable water management, this research work aims to determine the adsorptive properties of pine wood raw biochar (PWBC) and engineered iron-modified biochar (Fe-PWBC) in As(V) removal. Co-transport and deposition of As(V) with PWBC and Fe-PWBC were investigated in saturated columns, and experimental data were modeled using HYDRUS-1D to determine effective As removal in the managed aquifer recharge technique. Sand-packed saturated columns lead to high As(V) deposition at an ionic strength (IS) of 0 mM, whereas an IS of 10 mM mobilizes As(V) at pH 6.7 +/- 0.1. Considering co-transport, the adsorptive behavior of PWBC and Fe-PWBC were analyzed for 5-10 mg/L As(V) under varying pH (5.5 +/- 0.1 to 10.5 +/- 0.1), IS (0-10 mM), As(V) concentrations (5-10 mg/L), and biochar dosages (50-100 mg/L). Significantly, increased biochar deposition was observed with increased IS due to aggregation and ionic effects, and Fe-PWBC showed higher potential As(V) adsorption compared to PWBC. Understanding the fate and remediation of As in saturated porous media is crucial for developing effective remediation techniques. Overall, Fe-PWBC acts as a better carrier for As(V) in saturated porous media and facilitates adsorption onto its active sites than PWBC during co-transport and deposition governed by solution chemistry. Lastly, this work concludes with implications of biochar use in aquifer recharging and biochar-sand-packed fitting in hand pumps for groundwater recharge and safe drinking water supply.

Anthropogenic activities contribute to excessive nitrate (NO3−) concentrations in water and soil ecosystems and negatively impact the environment and human health. The current debate and major challenges associated with biochar application are aimed to minimize the negative impacts of NO3−, and advance agricultural and environmental sustainability. Critical discussion on practical applicability for NO3− removal from contaminated soil–water and cost–benefit analysis for scaling up biochar applications are yet to be discussed. Therefore, this review emphasizes the practical applications and feasibility of biochar in NO3− removal via treating naturally contaminated soil and water environments. Naturally contaminated groundwater and stormwater have been treated with different filter materials to achieve NO3− removal up to 70–100

Effective control of harmful algal blooms (HABs) is critical for improving and maintaining water quality. Common treatment strategies, such as copper sulfate pentahydrate with alkalinity-based dosing, often prescribe higher doses (>250 μg/L Cu) than may be necessary to achieve HAB control in many systems. The present study evaluated the performance of a previously developed multiple linear regression (MLR) based copper dosing method when compared to alkalinity-based doses after three repeated copper treatments spaced every two weeks. A 42-day field based mesocosm experiment was conducted in a hypereutrophic aquaculture pond where the alkalinity-based dose (350 μg/L Cu), full MLR based dose (80 μg/L Cu), and half of the MLR dose (40 μg/L Cu) were applied every 14 days (3x across the experiment) to mimic common application practices in aquaculture, recreational pond, and drinking water management. Initially, all copper treatments saw an identical ∼95% reduction in cyanobacteria, indicating that smaller doses are as effective as the larger alkalinity-based doses for HAB control. Moreover, the comparatively smaller, MLR-based doses caused less harm to beneficial green algae (chlorophytes) and zooplankton (important phytoplankton grazers) over the course of the experiment. Notably, it was observed that the alkalinity-based dose showed decreasing efficacy with each subsequent treatment, indicating that lower doses offer better control of harmful phytoplankton genera over time. Overall, the results of the present study demonstrate that repeated low MLR-based Cu dosing strategy offers superior long-term control of HABs with less ecological impact than higher, alkalinity-based Cu dosing.

Copper sulfate pentahydrate has been extensively used to control the growth of nuisance phytoplankton, including toxigenic cyanobacteria, in freshwater systems for more than 100 years. While the use of copper is well-studied, the dosing methodologies employed are less understood and lack a rigorous scientific basis. The present study aimed to develop a predictive multiple linear regression (MLR) model based on basic water quality parameters that can be used to determine an optimal algicidal dose that minimizes non-target effects on the overall aquatic ecosystem. This model was developed from a series of comprehensive controlled laboratory bioassays relating key water quality parameters, such as pH, hardness, alkalinity, and dissolved organic carbon (DOC), to algal copper toxicity. These bioassays demonstrated that DOC and pH were the most important predictors of copper toxicity to phytoplankton (r(2) = 0.813, p < 0.0001). Subsequently, a rigorous field-based test of the novel MLR-derived dose was conducted using a replicated, 28-day experiment in an active aquaculture pond. The MLR-based dose, which contained 60% less copper than the standard dose, resulted in equivalent control of harmful algae (95% reduction) to the higher standard dose. Furthermore, the MLR dose caused less harm to the overall beneficial phytoplankton and zooplankton communities than the alkalinity-based dose. These results show that MLR can be used for the development of more ecologically sound methods of controlling harmful algal blooms.

All currently applied methods for soil moisture measurement and mapping in agricultural fields are laborintensive and time-consuming. The Pulsed Fast Thermal Neutron Analysis (PFTNA) method, described in this article, can provide in situ soil moisture distribution data across agricultural fields by field scanning with a mobile PFTNA system in a reasonably short time. This method is based on acquiring soil gamma ray responses when irradiated by fast neutrons. The response gamma spectra [thermal neutron capture (TNC) gamma spectra] contain the gamma ray peak related to hydrogen present in soil. Since the majority of hydrogen is contained in soil water, soil moisture can be determined from the value of the hydrogen peak area in TNC spectra. A power dependency with a non-zero constant term was used to convert the hydrogen peak area to soil moisture content. To create this dependency, the hydrogen peak area in the TNC spectra was plotted against moisture data obtained using other methods (gravimetric, time domain reflectometry, nuclear radiation transmission) in the same agricultural fields. Developed methods for PFTNA field scanning and data processing provided data for moisture mapping; this scanning method involved moving at 5 km h- 1, simultaneously recording GPS coordinates and TNC gamma spectra every 30 s, and scanning paths that uniformly covered surveyed fields. Comparison of these maps with those created using data from traditional soil moisture measurement methods (gravimetric, time domain reflectometry, nuclear radiation transmission) demonstrated good agreement. Note that PFTNA scanning of a 20-hectare field can acquire the data needed for mapping in approximately one hour. Thus, PFTNA scanning can be recommended as a more efficient method for measuring and mapping soil moisture in agricultural fields.

Poultry litter (PL) can be used as a viable alternative to phosphate fertilizers. However, there is a lack of information about phosphorus (P) distribution in inorganic (Pi) and organic (Po) forms and its transformation in soils amended with PL of varying age (based on litter clean-out frequency) and application rate. This study aimed to determine the effect of PL age and application rate on soil P forms and their bioavailability. Soils were amended with 5 and 10 Mg ha-1 PL using 6-, 18-, and 30-month-old litter and incubated for 6 months. Soil P fractionation was performed following the Hedley protocol. Soil P availability and soil P storage capacity (SPSC) were determined using Mehlich 3 (M3) extraction. Results indicated that P transformation from labile to stable P forms occurred over 150-day incubation. Litter age had no significant effect on the distribution of soil P forms. However, the highly reactive Pi (HRPi) form was higher for treatments with 10 Mg ha-1 PL on Day 0, indicating a risk for P loss, which was also revealed by negative SPSC for those treatments. At Day 0, M3-P was positively correlated to HRPi. However, from Day 30 to 150, M3-P was strongly correlated to both HRPi and moderately reactive Pi (MRPi) forms, indicating MRPi contribution to soil P availability. The negative relationship between HRPi and SPSC further confirms that high HRPi on Day 0 may be an environmental concern.

Effects of rising atmospheric CO2 concentration [CO2] on pastures and grazing lands are beginning to be researched, but these important systems remain understudied compared to other agronomic and forest ecosystems. Therefore, we conducted a long-term (2005–2015) study of bahiagrass (Paspalum notatum Flüggé) response to elevated [CO2] and fertility management. The study was conducted at the USDA-ARS, National Soil Dynamics Laboratory open-top field chamber facility, Auburn, AL. A newly established bahiagrass pasture was exposed to either ambient or elevated (ambient + 200 µmol mol−1) [CO2]. Following one year of pasture establishment, half the plots received a fertilizer treatment [N at 90 kg ha−1 three times yearly plus P, K, and lime as recommended by soil testing]; the remaining plots received no fertilization. These treatments were implemented to represent managed (M) and unmanaged (U) pastures; both are common in the southeastern US. Root cores (0–60 cm depth) were collected annually in October and processed using standard procedures. Fertility additions consistently increased both root length density (53.8%) and root dry weight density (68.2%) compared to unmanaged plots, but these root variables were generally unaffected by either [CO2] or its interaction with management. The results suggest that southern bahiagrass pastures could benefit greatly from fertilizer additions. However, bahiagrass pasture root growth is unlikely to be greatly affected by rising atmospheric [CO2], at least by those levels expected during this century.

Flue Gas Desulfurization (FGD) gypsum is a byproduct of the coal-fired power plant process commonly used to remove sulfur dioxide emissions from the flue gas. FGD gypsum has numerous industrial, agricultural, and environmental applications. This study aimed to explore a novel approach involving the use of FGD gypsum combined with different litter treatments as bedding for broiler production. It focused on performance metrics, including adjusted feed conversion ratio (AFCR) and average body weight (BW), foot pad dermatitis (FPD), and fear response over 5 consecutive flocks. A total of 1,800 one-day-old Ross 708 chicks were randomly assigned to 24 pens (75 birds/pen), divided into 6 treatment groups (4 pens/treatment), with 5 replications and raised until 42 d old (d). Treatments were gypsum that was decaked (D), rotovated (E), and rotovated then windrowed (F) between flocks. Control treatments using pine shavings were decaked (A), rotovated (B), and windrowed postrotovating (C). AFCR, average BW, and mortality were used as a measure of production. Foot pad dermatitis scores were taken on d42 using a scale of 0 (absence), 1 (mild), and 2 (severe). Response to observer and human approach test were used to measure fear response. Data were analyzed as a 2-way ANOVA (Proc Glimmix) for the main effects of bedding type and litter treatment. Means were identified using Tukey's HSD. No effect of bedding type or litter treatment was found for AFCR, BW, or mortality. FPD scores 2 and 1, were higher with pine shavings than gypsum (P = 0.01 and P = 0.01, respectively). While FPD scores 0 were higher for gypsum than the pine shaving (P = 0.01). No difference in fear response was found among birds raised on any of the gypsum litter treatments and any of the pine shaving litter treatments. Overall, the use of gypsum as bedding results in equivalent production and fear response to pine shavings, while increasing FPD quality when compared to pine shaving.

Non-destructive methodology for determining carbon content in large or semi-infinite (soil) samples is discussed. This methodology is based on deconvoluting the sample’s gamma spectra (received by tagged neutron method) on the sample component's spectra by accounting for neutron and gamma radiation attenuations. This algorithm was tested with both Monte-Carlo simulations and experimental gamma spectra. Good agreement was found between defined and actual sample component content. Application of this method for soil carbon determinations in agricultural fields is discussed.

Interest in improving the long-term sustainability of agricultural production systems has focused on identifying management practices that promote soil health. No tillage, cover cropping, and amending soils with broiler (Gallus gallus domesticus L.) litter are commonly adopted conservation practices that have been shown to improve soil fertility and crop yield. However, the overall influence of these conservation practices on soil health in the southeastern US are not well understood. Thus, a study was conducted to evaluate the influence of tillage, broiler litter (BL) applications, and cropping systems on soil biochemical properties. Soils were collected from field research plots under long-term management (>than 25 years of tillage, 15 years of broiler litter application, and 15 years of cropping system). Soil microbial biomass, C, N, and P, amidohydrolases, and dissolved organic matter (DOM) were evaluated as indicators of soil health. Adopting tillage and BL into the agricultural management system modified the biochemical parameters of the soils evaluated. Most of these modifications occurred in the 0–5 cm depth. Higher microbial biomass carbon (MBC; 85%) and nitrogen (MBN; 10%) and enzyme activities of asparaginase (65%) and glutaminase (70%) were observed in the 0–5 cm depth under no tillage (NT) compared to conventional tillage (CT), indicating greater biological activities were established in these soil ecosystems. Broiler litter applications increased microbial biomass N and activities of asparaginase and glutaminase in both soil depths. In addition, microbial biomass phosphorus (MBP) was increased following BL application in the 0–5 cm depth. The results suggest that long-term management of NT and BL additions can improve the health of eroded southeastern US soils by altering the soil biochemical parameters.

Catfish aquaculture ponds are at high risk of experiencing excessive algal growth, especially cyanobacteria, that can lead to negative water quality issues due to their consistent input through regular feedings and internal cycling of nutrients. Conventional algaecides used in aquaculture, such as copper sulfate, may be effective in the short-term but can potentially lead to developed resistance in phytoplankton over time or harmful effects on non-target species. An alternative nutrient management strategy, which has traditionally been used in land-based agriculture, is via flue gas desulfurization (FGD) gypsum, a form of calcium sulfate that is created as a by-product of carbon-based energy sources. A six-month field experiment was conducted on active catfish aquaculture ponds at a farm in west Alabama to test the effects of FGD gypsum on water quality, including its ability to manage excessive algal blooms throughout the growing season. In stark contrast to previous results from FGD gypsum application in eutrophic waters, it was discovered that FGD gypsum-treated ponds experienced a large increase in soluble reactive phosphorus (SRP) that led to a spike in phytoplankton abundance, specifically cyanobacteria. Supplementary microcosm experiments aided in determining that FGD gypsum could extract legacy phosphorus out of the nutrient-rich flocculant sediment found in aquaculture ponds. While these results were unexpected and ultimately undesired, we did discover that the use of FGD gypsum at the 500 mg/L concentration does not produce any trace metal contamination in the water column or in the fish tissue. Overall, this experiment discovered new results that FGD gypsum could produce when used in hypereutrophic waters with nutrient-rich sediments and provides the foundation for future research directions to determine the specific mechanisms behind the interaction of FGD gypsum with the sediment.

In-situ soil carbon measurements would be beneficial when assessing carbon (C) sequestration practices and associated C credits. Neutron gamma analysis, which registers gamma rays that appear due to neutron irradiation, is a tool that can be used for such assessments. However, questions regarding post-effects of neutron irradiation on soil remain unexplored. Temporal post-irradiation effects (neutron flux 2⋅107 neutron/s, neutron energy 14 MeV) on soil chemical and physical attributes were investigated using a previously constructed pulsed fast-thermal neutron-gamma analysis system. Neutron and gamma dose rate distributions during stationary irradiation using this system and Monte-Carlo computer simulations were found to be in agreement; a stationary 1 h irradiation period (conservative or worse-case scenario) was utilized in these scenarios. Physical effects of activating new radioactive isotopes were experimentally determined by assessing changes in the post-irradiated soil gamma spectra ("hot background") over time; additional soil radioactivity decreased to natural background levels within ∼1 h. Radiolytic decomposition estimates of soil water and soil organic material (primarily cellulosic residue), based on received dose loads and known radiation-chemical yields of water and organic material, were practically negligible. Results indicate that adsorbed radiation doses in scanning mode would be 500 to 1000 times less than in static mode. Thus, neutron gamma analysis does not impact physicochemical aspects of soil health and can be used for soil elemental content determinations without additional radiation safety concerns.

Flue gas desulfurization (FGD) gypsum, a by-product of carbon-based energy sources, has typically been incorporated as a component of concrete mixes and wallboard and beneficially used as an agricultural amendment to enhance terrestrial crop production and improve the quality of runoff. These various uses for the by-product aid in reducing the amount that is ultimately landfilled. Limited studies have investigated its benefits when used directly in aquatic settings, such as ponds and lakes, to increase hardness and potentially mitigate eutrophication. A 36-day field mesocosm experiment tested a larger range of FGD gypsum concentrations (500-2000 mg/L) than those previously tested in the literature to investigate its desired and potentially undesired impacts on water quality, including the algal community. High FGD gypsum concentrations, 1000 and 2000 mg/L, were found to have more undesired impacts than the 500 mg/L treatment, including an initial spike in cyanobacteria, a decrease in total zooplankton abundance, and an increase in certain trace metals in the highest treatment. Ultimately, the 500 mg/L FGD gypsum treatment was found to have fewer undesired impacts while still resulting in significant desired effects, including those on hardness and pH, as well as moderate reductions in algal abundance. This experiment provides a better understanding of the effects of FGD gypsum when directly used in an aquatic setting, determines an optimal dose for future field experiments, and helps provide the groundwork for developing an upper threshold on FGD gypsum so as to not have the negative effects outweigh the positive.

Numerous studies have investigated effects of long-term manure application on total phosphorus (P) and inorganic P (Pi ), but few have evaluated soil organic P (Po ). Little is known about crop management effects on Po in soils with varying minerology. In this study, sequential fractionation was used to characterize specific P forms after 25 years of broiler litter (BL) or ammonium nitrate (Con) applications to an Alabama Hartsells soil. Crops (corn [Zea mays L.], soybean [Glycine Willd.], and corn or soybean with a wheat [Triticum aestivum L.] cover crop) were under conventional tillage (CT) or no-tillage (NT). Regardless of crop, tillage, or fertilizer type, the proportion of extractable Pi was relatively stable at 21%-49% at 0-5 cm and 25%-45% at 5-10 cm. Extractable Pi ranged from 0.69 to 2.4 mg g-1 . BL increased total extractable Pi (p ≤ 0.001) at 0-5 cm and 5-10 cm. Total extractable P was influenced at 0-5 cm (p ≤ 0.006) by both tillage and fertilization type, but not at 5-10 cm or at either depth in soybean plots. Long-term BL application increased total extractable soil P at 0-5 cm. In corn systems, CT did not reduce P loading to topsoil or result in P leaching to lower soil depths, compared to NT. Soybean and soybean-wheat reduced P loading in BL plots, compared to corn and corn-wheat. Soil Po was classed in the order of monoesters > phytate and polyphosphates, where most was extractable with NaOH. BL increased extractable Po in all fractions. Care should be taken when applying BL to highly weathered soils to avoid legacy Po accumulation. Soybean rotations and cover crops could help remediate P-laden soils after repeated BL application.