@article{gannon_hixson_keller_weber_knezevic_yelverton_2014, title={Soil Properties Influence Saflufenacil Phytotoxicity}, volume={62}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-13-00171.1}, abstractNote={Saflufenacil, a pyrimidinedione herbicide, is used for contact and residual broadleaf weed control in various crops. Bioactivity of saflufenacil in soil was tested in greenhouse and laboratory studies on 29 soils representing a wide range of soil properties and geographic areas across the United States. A greenhouse bioassay method was developed using various concentrations of saflufenacil applied PPI to each soil. Whole canola plants were harvested 14 d after treatment, and fresh and dry weights were recorded. Nonlinear regression analysis was used to determine the effective saflufenacil doses for 50% (ED 50 ,), 80% (ED 80 ), and 90% (ED 90 ) inhibition of total plant fresh weight. Bioactivity of saflufenacil in soil was strongly correlated to soil organic ( R = 0.85) and humic matter ( R = 0.81), and less correlated to cation exchange capacity ( R = 0.49) and sand content ( R = −0.32). Stepwise regression analysis indicated that organic matter was the major soil constituent controlling bioactivity in soil and could be used to predict the bioactivity of saflufenacil. Saflufenacil phytotoxicity was found to be dependent on soil property; therefore, efficacy and crop tolerance from PRE and PPI applications may vary based on soil organic matter content and texture classification.}, number={4}, journal={WEED SCIENCE}, author={Gannon, Travis W. and Hixson, Adam C. and Keller, Kyle E. and Weber, Jerome B. and Knezevic, Stevan Z. and Yelverton, Fred H.}, year={2014}, pages={657–663} }
 @article{gannon_hixson_weber_shi_yelverton_rufty_2013, title={Sorption of Simazine and S-Metolachlor to Soils from a Chronosequence of Turfgrass Systems}, volume={61}, ISSN={["1550-2759"]}, DOI={10.1614/ws-d-12-00173.1}, abstractNote={Pesticide sorption by soil is among the most sensitive input parameters in many pesticide-leaching models. For many pesticides, organic matter is the most important soil constituent influencing pesticide sorption. Increased fertility, irrigation, and mowing associated with highly maintained turfgrass areas result in constant deposition of organic material, creating a soil system that can change drastically with time. Changes in soil characteristics could affect the environmental fate of pesticides applied to turfgrass systems of varying ages. Sorption characteristics of simazine and S -metolachlor were determined on five soils from bermudagrass systems of increasing ages (1, 4, 10, 21, and 99 yr) and compared to adjacent native pine and bare-ground areas. Surface soil (0 to 5 cm) and subsurface soil (5 to 15 cm) from all sites were air-dried and passed through a 4-mm sieve for separation from plant material. Using a batch-equilibrium method, sorption isotherms were determined for each soil. Data were fit to the Freundlich equation, and K d (soil sorption coefficient) and K oc (organic carbon sorption coefficient) values were determined. Sorption and soil system age were directly related to organic matter content in the soil. Sorption of both herbicides increased with age of the soil system and was greatest on the surface soil from the oldest bermudagrass soil system. Herbicide sorption decreased at greater soil depths with lower organic matter. Greater amount of 14 C–simazine sorbed to subsurface soil of the oldest turfgrass system compared to 14 C– S -metolachlor. Results indicate that as bermudagrass systems age and accumulate higher organic matter levels increased herbicide sorption may decrease the leaching potential and bioavailability of simazine and S -metolachlor.}, number={3}, journal={WEED SCIENCE}, author={Gannon, Travis W. and Hixson, Adam C. and Weber, Jerome B. and Shi, Wei and Yelverton, Fred H. and Rufty, Thomas W.}, year={2013}, pages={508–514} }
 @article{cummings_weber_yelverton_leidy_2009, title={Downward Mobility of C-14-Labeled Simazine in a Bermudagrass System vs. a Fallow Soil System}, volume={49}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2008.05.0297}, abstractNote={Pesticides applied to bermudagrass ( Cynodon dactylon L.) can be captured by the canopy, absorbed by the roots, or bound in the thatch layer, which reduces the amount available to leach compared with a fallow soil system where pesticides may be applied directly to soil. 14 C‐Simazine was applied to dormant bermudagrass and fallow soil in lysimeters in a cold growth chamber (5°C) (cold‐fallow soil) and to actively growing bermudagrass and fallow soil in lysimeters in a greenhouse (25°C) (warm‐fallow soil) in April. Following clipping collection, lysimeters were irrigated with 5 cm of water every 3–4 d, and leachate was collected. After 25 d, lysimeters were divided into 2‐cm increments from 0 to 10 cm, then 5‐cm increments from 10 to 30 cm. Because of evapotranspiration, actively growing bermudagrass and warm‐fallow soil yielded significantly less leachate than dormant bermudagrass and cold‐fallow soil indicating less moisture is available for downward movement during summer. After the addition of 31 cm of irrigation, the greatest quantities of 14 C‐simazine were in the 0‐ to 2‐cm increment for all treatments and decreased with depth. Although the greatest quantities of 14 C‐simazine in leachate occurred in dormant bermudagrass, the reached factor was greatest for cold‐fallow soil (0.20), followed by dormant bermudagrass (0.17), warm‐fallow soil (0.16), and actively growing bermudagrass (0.14). Therefore, simazine is least mobile in bermudagrass during summer and most mobile in fallow soil in winter.}, number={2}, journal={CROP SCIENCE}, author={Cummings, H. D. and Weber, J. B. and Yelverton, F. H. and Leidy, R. B.}, year={2009}, pages={704–713} }
 @article{hixson_shi_weber_yelverton_rufty_2009, title={Soil Organic Matter Changes in Turfgrass Systems Affect Binding and Biodegradation of Simazine}, volume={49}, ISSN={["0011-183X"]}, DOI={10.2135/cropsci2008.09.0541}, abstractNote={Concern about pesticide losses from maintained turfgrass areas led us to examine the fate of the triazine herbicide simazine in turfgrass systems and, specifically, interactions between simazine binding to soil organic matter and biodegradation. Soil samples were removed from turfgrass systems of different ages, placed in microcosms, conditioned as sterile or nonsterile, and exposed to 14 C‐simazine. At seven sampling intervals, the soil was extracted and 14 C was separated into three pools; bound, extractable, and CO 2 With sterilized surface soil (0–5 cm), 52, 70, and 71% of applied 14 C‐simazine was bound to soil from the 4‐, 21‐, and 99‐yr‐old turfgrass systems, respectively, after 16 wk. With nonsterile conditions, biodegradation became dominant, as 60 to 80% of the 14 C was recovered in the CO 2 fraction and binding was held at ∼20%. Among all soils evaluated, bound 14 C and 14 CO 2 production was lower in subsurface soil (5–15 cm) from the 4‐ and 21‐yr‐old turfgrass systems. 14 C‐simazine disappearance time (DT 50 ) values under nonsterile conditions ranged from 0.9 to 5.8 wk. Results indicate that turfgrass systems have a relatively low amount of simazine available for leaching as the systems age due to a large capacity for biodegradation and binding to organic matter.}, number={4}, journal={CROP SCIENCE}, author={Hixson, Adam C. and Shi, Wei and Weber, Jerome B. and Yelverton, Fred H. and Rufty, Thomas W.}, year={2009}, pages={1481–1488} }
 @article{weber_warren_swain_yelverton_2007, title={Physicochemical property effects of three herbicides and three soils on herbicide mobility in field lysimeters}, volume={26}, ISSN={["1873-6904"]}, DOI={10.1016/j.cropro.2006.01.020}, abstractNote={Understanding herbicide mobility in soils is necessary to prevent ground water contamination. We studied the mass balance distribution of three 14C-labeled herbicides (atrazine, metolachlor, and primisulfuron-methyl) in three soils (Blanton, Norfolk, and Rains) 128 days after treatment (DAT) to fallow soil column field lysimeters. Analyses were made of surface soil, subsoil, and leachate samples. Volatilization losses were calculated by difference. Our objectives were to examine, measure, and correlate the leaching patterns of the chemicals and correlate their leaching characteristics with physicochemical and biological properties of the herbicides and the physicochemical properties of the soils. Metolachlor was the most mobile herbicide, as indicated by the retardation factor (Rf) (Rf=0.48 in 1992 and 0.19 in 1993), followed by primisulfuron-methyl (Rf=0.41 in 1992 and 0.12 in 1993), and atrazine (Rf=0.38 in 1992 and 0.15 in 1993), where mobility was greatly affected by water input (637 mm in 1992 and 509 mm in 1993). Herbicide mobility (Rf) was related to 14C-parent compound in leachate (0.02–6.9% of 14C applied), 14C in the subsoil (9–24%), and the pesticide leaching potential (PLP) index of each herbicide, as computed using a simple decision-aid model. The herbicides were most mobile through Blanton, followed by Norfolk and Rains soils and mobility (Rf) was inversely related to mean % organic matter (OM) content of the soil profiles and directly related to soil pH and soil leaching potential (SLP) indices of the soils. Physicochemical and biological properties of the herbicides and soils were related to many of the measured herbicide distribution parameters.}, number={3}, journal={CROP PROTECTION}, author={Weber, Jerome B. and Warren, Ralph L. and Swain, Len R. and Yelverton, Fred H.}, year={2007}, month={Mar}, pages={299–311} }
 @article{weber_taylor_wilkerson_2006, title={Soil and herbicide properties influenced mobility of atrazine, metolachlor, and primisulfuron-methyl in field lysimeters}, volume={98}, DOI={10.2134/argonj2004.0221}, number={1}, journal={Agronomy Journal}, author={Weber, J. B. and Taylor, K. A. and Wilkerson, G. G.}, year={2006}, pages={8–18} }
 @article{weber_taylor_wilkerson_2006, title={Soil cover and tillage influenced metolachlor mobility and dissipation in field lysimeters}, volume={98}, DOI={10.2134/argonj2004.0222}, number={1}, journal={Agronomy Journal}, author={Weber, J. B. and Taylor, K. A. and Wilkerson, G. G.}, year={2006}, pages={19–25} }
 @article{weber_wilkerson_reinhardt_2004, title={Calculating pesticide sorption coefficients (K-d) using selected soil properties}, volume={55}, ISSN={["0045-6535"]}, DOI={10.1016/j.chemosphere.2003.10.049}, abstractNote={Pesticide soil/solution distribution coefficients ( Kd values), commonly referred to as pesticide soil sorption values, are utilized in computer and decision aid models to predict soil mobility of the compounds. The values are specific for a given chemical in a given soil sample, normally taken from surface soil, a selected soil horizon, or at a specific soil depth, and are normally related to selected soil properties. Pesticide databases provide Kd values for each chemical, but the values vary widely depending on the soil sample on which the chemicals were tested. We have correlated Kd values reported in the literature with the reported soil properties for an assortment of pesticides in an attempt to improve the accuracy of a Kd value for a specific chemical in a soil with known soil properties. Mathematical equations were developed from regression equations for the related properties. Soil properties that were correlated included organic matter content, clay mineral content, and/or soil pH, depending on the chemical properties of the pesticide. Pesticide families for which Kd equations were developed for 57 pesticides include the following: Carboxy acid, amino sulfonyl acid, hydroxy acid, weakly basic compounds and nonionizable amide/anilide, carbamate, dinitroaniline, organochlorine, organophosphate, and phenylurea compounds. Mean Kd values for 32 additional pesticides, many of which had Kd values that were correlated with specific soil properties but for which no significant Kd equations could be developed are also included.}, number={2}, journal={CHEMOSPHERE}, author={Weber, JB and Wilkerson, GG and Reinhardt, CF}, year={2004}, month={Apr}, pages={157–166} }
 @article{judge_neal_weber_2004, title={Dose and concentration responses of common nursery weeds to Gallery, Surflan and Treflan}, volume={22}, ISBN={0738-2898}, number={2}, journal={Journal of Environmental Horticulture}, author={Judge, C. A. and Neal, J. C. and Weber, J. B.}, year={2004}, pages={106} }
 @article{weber_mckinnon_swain_2003, title={Sorption and mobility of C-14-labeled imazaquin and metolachlor in four soils as influenced by soil properties}, volume={51}, ISSN={["0021-8561"]}, DOI={10.1021/jf021210t}, abstractNote={Aqueous batch-type sorption−desorption studies and soil column leaching studies were conducted to determine the influence of soil properties, soil and suspension pH, and ionic concentration on the retention, release, and mobility of [14C]imazaquin in Cape Fear sandy clay loam, Norfolk loamy sand, Rion sandy loam, and Webster clay loam. Sorption of [14C]metolachlor was also included as a reference standard. L-type sorption isotherms, which were well described by the Freundlich equation, were observed for both compounds on all soils. Metolachlor was sorbed to soils in amounts 2−8 times that of imazaquin, and retention of both herbicides was related to soil organic matter (OM) and humic matter (HM) contents and to herbicide concentration. Metolachlor retention was also related to soil clay content. Imazaquin sorption to one soil (Cape Fear) increased as concentration increased and as suspension pH decreased, with maximum sorption occurring in the vicinity of pKa1 = (1.8). At pH levels below pKa1 imazaquin sorption decreased as hydronium ions (H3O+) increased and competed for sites. NaCl was more effective than water in desorption of imazaquin at pH levels near the pKa1. Mechanisms of bonding are postulated and discussed. The mobility of imazaquin through soil columns was in the order Rion ≥ Norfolk > Cape Fear ≥ Webster, whereas for metolachlor it was Rion ≥ Norfolk ≫ Webster ≥ Cape Fear. Imazaquin was from 2 to 10 times as mobile as metolachlor. Keywords: Sorption−desorption; soil mobility; imazaquin; metolachlor; soil pH}, number={19}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={Weber, JB and McKinnon, EJ and Swain, LR}, year={2003}, month={Sep}, pages={5752–5759} }
 @article{weber_wilkerson_linker_wilcut_leidy_senseman_witt_barrett_vencill_shaw_et al._2000, title={A proposal to standardize soil/solution herbicide distribution coefficients}, volume={48}, ISSN={["0043-1745"]}, DOI={10.1614/0043-1745(2000)048[0075:APTSSS]2.0.CO;2}, abstractNote={Herbicide soil/solution distribution coefficients (Kd) are used in mathematical models to predict the movement of herbicides in soil and groundwater. Herbicides bind to various soil constituents to differing degrees. The universal soil colloid that binds most herbicides is organic matter (OM), however clay minerals (CM) and metallic hydrous oxides are more retentive for cationic, phosphoric, and arsenic acid compounds. Weakly basic herbicides bind to both organic and inorganic soil colloids. The soil organic carbon (OC) affinity coefficient (Koc) has become a common parameter for comparing herbicide binding in soil; however, because OM and OC determinations vary greatly between methods and laboratories, Koc values may vary greatly. This proposal discusses this issue and offers suggestions for obtaining the most accurate Kd, Freundlich constant (Kf), and Koc values for herbicides listed in the WSSA Herbicide Handbook and Supplement.}, number={1}, journal={WEED SCIENCE}, author={Weber, JB and Wilkerson, GG and Linker, HM and Wilcut, JW and Leidy, RB and Senseman, S and Witt, WW and Barrett, M and Vencill, WK and Shaw, DR and et al.}, year={2000}, pages={75–88} }
 @article{weber_mahnken_swain_1999, title={Evaporative effects on mobility of C-14-labeled triasulfuron and chlorsulfuron in soils.}, volume={164}, ISSN={["1538-9243"]}, DOI={10.1097/00010694-199906000-00006}, abstractNote={A laboratory soil column experiment was conducted to determine the mobility of 14C-triasulfuron in A horizon material of Farnum loam, fine-loamy, mixed, thermic Pachic Argiustoll from Kansas, Norfolk loamy sand, fine-loamy, siliceous, thermic Typic Hapludult, and Rion sandy loam, fine-loamy, mixed, thermic Typic Hapludult from North Carolina, and Webster silt loam, fine-loamy, mixed, mesic Typic Haplaquoll from Iowa as well as 14C-chlorsulfuron in Rion sandy loam and to measure the effects of evaporation on capillary transport of the leached herbicides upward when soil columns were in contact with free water and not over free water. Triasulfuron mobility was in the order Norfolk (Rf = 0.52) = Rion (Rf = 0.48) > Farnum (Rf = 0.40) > Webster (Rf = 0.26), and Rf was inversely related to the organic and humic matter contents of the soils. Evaporation of water from the soil surface of leached triasulfuron-treated Rion and Norfolk soils over a 2-week period had pronounced effects on herbicide transported upward, particularly when soil columns were in contact with free water simulating a shallow water table. Evaporation had no effects on capillary transport upward in Farnum and Webster soils, probably because of their higher contents of organic and humic matter. Chlorsulfuron was 18% more mobile than triasulfuron in Rion sandy loam, and both herbicides were distributed in a similar pattern in the soil when water was applied to the surface and leached or applied to the base of the columns and transported upward by capillary action. Redistribution of the herbicides upward in capillary water will likely influence persistence of the chemicals, particularly in soils over shallow water tables.}, number={6}, journal={SOIL SCIENCE}, author={Weber, JB and Mahnken, GE and Swain, LR}, year={1999}, month={Jun}, pages={417–427} }
 @inbook{van wesenbeeck_schabacker_winton_heim_winberry_williams_weber_swain_velagaleti_1998, title={Demonstration of the functionality of a self-contained modular lysimeter design for studying the fate and transport of chemicals in soil under field conditions}, DOI={10.1021/bk-1998-0699.ch009}, abstractNote={Analytical Bio-Chemistry (ABC) Laboratories, Inc. has developed a modular lysimeter design and has instrumented and installed the lysimeters at four field sites in the United States: Missouri (MO), Iowa (IA), Illinois (IL), North Carolina (NC) and Ontario (ON), Canada. The modular lysimeter design consists of three components that are readily assembled and installed in the field; an intact soil core, a run-off (overflow) collection system, and a leachate collection system. In NC, the lysimeters were installed at the NC State University Experimental Station site in Clayton with a Novartis Crop Protection development compound, designated as 14C-XYZ for confidentiality reasons. The fate and transport of the chemical was studied over a period of 90 days using intact 90 cm deep, 15 cm diameter soil columns containing sandy soil. Parent compound degraded into an acid metabolite that was detected down to 60 cm in the soil profile. Parent compound was not observed at a soil depth below 15 cm. The decline of the parent compound coincided with the formation of the acid metabolite which degraded into four additional metabolites. Lysimeters 30 cm in diameter and 75-90 cm deep were instrumented and installed at four locations (MO, IA, IL, and ON) to study the fate and transport of a DowElanco development compound, designated as 14C-DEC for confidentiality reasons. In these experiments, the fate and transport of the test compound and a bromide tracer in the lysimeters were compared with that in the field plots for 12 months. Preliminary results from IA and MO suggest that degradation and solute transport processes were similar in the soil plots and lysimeters, and that the 30 cm diameter pipe lysimeters approach the representative elementary volume (REV) for solute transport processes at the IA site. The modular pipe lysimeter design offers significant advantages in terms of assessing solute mass balance, mobility, variability (through increased replication) and reduced cost of radioactive waste compared to soil plot studies.}, number={699}, booktitle={The lysimeter concept: Environmental behavior of pesticides}, publisher={Washington, DC: American Chemical Society}, author={Van Wesenbeeck, I. and Schabacker, D. J. and Winton, K. and Heim, L. and Winberry, M. W. and Williams, M. D. and Weber, J. B. and Swain, L. R. and Velagaleti, R.}, year={1998}, pages={122–135} }
 @article{gonese_weber_1998, title={Herbicide rate recommendations: Soil parameter equations vs. registered rate recommendations}, volume={12}, ISSN={["1550-2740"]}, DOI={10.1017/s0890037x00043748}, abstractNote={Chlorimuron, clomazone, imazaquin, imazethapyr, and pendimethalin were each applied at five rates to soils at 10 different sites each year for three years to determine which soil properties influenced their bioactivity. Six soils in the U.S. (NC) and four in Zimbabwe were characterized for their plow-layer contents of organic matter (OM), humic matter (HM), clay mineral (CM), and silt and for pH and cation exchange capacity (CEC). At each site, the rate of each herbicide yielding 80% weed control (I 80 ) was determined by visually evaluating the treated plots. The I 80 values were then regressed with the various soil properties to determine which of them contributed to this rate. In the U.S. soils, the I 80 was highly correlated with % OM ( r 2 = 0.64–0.72) and % HM ( r 2 = 0.55–0.69) for chlorimuron, imazaquin, and pendimethalin but was less correlated with % OM ( r 2 = 0.30) and pH ( r 2 = 0.31) for imazethapyr. Equations relating the herbicide rate for 100% weed control to soil properties were derived for chlorimuron, imazaquin, imazethapyr, and pendimethalin then compared with registered recommended rates for each chemical from the label. Herbicide rate equations based on similar soil parameters were taken from the literature to compare with our rate equations and with registered rate recommendations for comparison purposes and to add validity to the use of soil parameters for making herbicide rate recommendations. The rate equations, based on selected soil parameters, produced rates comparable with registered rates for chlorimuron, pendimethalin, and metribuzin and lower rates of application than registered rates for imazaquin, imazethapyr, alachlor, and metolachlor for soils with OM levels below 3.5%.}, number={2}, journal={WEED TECHNOLOGY}, author={Gonese, JU and Weber, JB}, year={1998}, pages={235–242} }
 @article{keller_weber_cassel_wollum_miller_1998, title={Temporal distribution of C-14 in soil water from field lysimeters treated with C-14-metolachlor}, volume={163}, ISSN={["1538-9243"]}, DOI={10.1097/00010694-199811000-00004}, abstractNote={In a previous study utilizing fallow field lysimeters of an undisturbed, loamy sand soil treated with 14C-metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide], 2 to 5% of the applied 14C was mobile to soil depths of 56 to 96 cm. The objective of this 120-day study was to determine the temporal distribution of 14C-metolachlor and/or metabolite(s) in soil water from similar field lysimeters and their possible contribution to groundwater contamination. Undisturbed soil column field lysimeters (20.3-cm i.d. × 101-cm long; 16 gauge steel) were driven into a conventionally tilled Dothan loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudult) and treated with 14C-metolachlor and tritiated water (3H2O) and subjected to natural rainfall or irrigation. Percent recovery of metolachlor and/or metabolite(s) in the soil, as based on 14C measurement, was 62% at 30 days, 63% at 60 days, 51% at 90 days, and 49% at 120 days. Recovery of 3H2O was 36, 24, 6 and 0.25% of the applied for the same time periods. By 30 and 60 days after application (DAA), 3H2O had distributed symmetrically in the soil profile, whereas, a large percentage of the 14C was retained in the upper 24 cm. No 14C and <1% of the applied 3H2O was recovered in leachate the first 30 days. Cumulative recovery of 14C in leachate was <1% of that applied at 60 days, 3% at 90 days, and 7% at 120 days. Cumulative recovery of 3H2O in leachate for the same time periods was 22, 39, and 39% of that applied. The symmetrical breakthrough curve for 3H2O indicated no preferential flow or immobile water, whereas the breakthrough curve for 14C was asymmetrical as a result of the sorption-desorption processes. Peak concentrations of 14C and 3H2O in the leachate occurred at 94 and 63 DAA, respectively. The sorptive tendencies of both radiolabeled species distinguished the magnitude of movement, with 3H2O much more mobile than 14C-metolachlor and/or metabolite(s). Assuming that all 14C in leachate was parent, average metolachlor concentrations in leachate were less than the National Health Advisory level, which may indicate that metolachlor should be considered a low risk chemical because of its potential to contaminate groundwater in soils with low organic matter and high clay content in the subsoil.}, number={11}, journal={SOIL SCIENCE}, author={Keller, KE and Weber, JB and Cassel, DK and Wollum, AG and Miller, CT}, year={1998}, month={Nov}, pages={872–882} }
 @article{miller_wollum_weber_1997, title={Degradation of carbon-14-atrazine and carbon-14-metolachlor in soil from four depths}, volume={26}, ISSN={["1537-2537"]}, DOI={10.2134/jeq1997.00472425002600030007x}, abstractNote={Degradation of 14C-atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] and 14C-metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] was monitored for 6 and 2 mo, respectively, using sterile and nonsterile soil microcosms. Both chemical and biological degradation were observed for atrazine, metolachlor degraded only biologically. The calculated halflife of atrazine was 3.6 wk in nonsterile surface samples (0–5 cm). At the surface, after 22 wk, bound residues accounted for almost 60% of the recovered radioactivity while 36% was recovered as 14CO2, indicating significant cleavage of the triazine ring. For sterilized surface samples, atrazine degraded chemically with bound residues accounting for 63% of the recovered label and had a calculated halflife of 6.2 wk. Degradation and binding were somewhat lower in soil samples from 20 to 25 cm and deeper subsurface samples (45 and 75 cm) showed almost no degradation and very little binding. Metolachlor degraded only in the surface nonsterile samples; no degradation was observed in subsurface samples or in sterile samples from any depth. Bound residues occurred in high amounts in the surface soil (31%) but declined rapidly with depth, indicating that organic matter is the primary binding site for metolachlor. Very little 14CO2 (<1.6%) was produced from metolachlor in any sample. This study showed that both herbicides degraded slower and sorbed less to the soil with increasing soil depth, especially below 25 cm. Quantifying degradation rates of agricultural chemicals in the vadose zone is important for predicting and preventing groundwater contamination as well as for successful implementation of in-situ bioremediation of contaminated subsoils.}, number={3}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Miller, JL and Wollum, AG and Weber, JB}, year={1997}, pages={633–638} }
 @article{keller_weber_1997, title={Soybean (Glycine max) influences metolachlor mobility in soil}, volume={45}, number={6}, journal={Weed Science}, author={Keller, K. E. and Weber, J. B.}, year={1997}, pages={833–841} }
 @article{miller_wollum_weber_1997, title={Sterile and nonsterile degradation of carbon-14-primisulfuron in soil from four depths}, volume={26}, ISSN={["0047-2425"]}, DOI={10.2134/jeq1997.00472425002600020015x}, abstractNote={Abstract The degradation of 14 C‐primisulfuron (2‐[[[[[4,6‐bis(difluoromethoxy)‐2‐pyrimidinyl]amino]carbonyl]amino]sulfonyl] benzoic acid) was monitored for 2 mo using soil microcosms under sterile and nonsterile conditions. Both chemical and biological degradation was detected. The half‐life was 2.1 wk for nonsterile samples from 0 to 5 cm, and 3.4 wk for nonsterile samples from 20 to 25 cm. After 7 wk, bound residues accounted for 48 and 27% of the recovered radioactivity in these samples, respectively. For sterile samples from the same depths, the half‐life was >7 wk and bound residues accounted for 7% of the recovered radiolabel. Disappearance and bound residue formation of primisulfuron were similar for both sterile and nonsterile samples from deeper in the profile (45–75 cm) indicating little biological degradation occurred in these subsurface samples. Chemical and microbial degradation of primisulfuron appeared to differ; the same metabolites were produced but at different times and in different amounts. Very little 14 CO 2 (<3%) was produced from any sample. These results indicate that initial hydrolyzation of the sulfonylurea bridge occurs both chemically and biologically, but does not occur readily in the subsoil. This may have implications for the prevention of groundwater contamination and for the bioremediation of contaminated soils.}, number={2}, journal={JOURNAL OF ENVIRONMENTAL QUALITY}, author={Miller, JL and Wollum, AG and Weber, JB}, year={1997}, pages={440–445} }
 @article{weber_1993, title={IONIZATION AND SORPTION OF FOMESAFEN AND ATRAZINE BY SOILS AND SOIL CONSTITUENTS}, volume={39}, ISSN={["0031-613X"]}, DOI={10.1002/ps.2780390105}, abstractNote={Abstract Fomesafen exhibited weakly acidic properties and was titrated spectrophotometrically and determined to have a pK A of 3.0. [ 14 C]fomesafen and [ 14 C]atrazine, as references, were used in slurry‐type sorption studies with H + ‐ and Ca 2+ ‐saturated soil organic matter, Ca 2+ ‐saturated montmorillonite clay, Norfolk sandy loan ( Typic Paleudult ) and Drummer silt loam ( Typic Haplaquoll ) at suspension pH values of 2.0 to 6.3. Sorption of atrazine was greater than that of fomesafen for the organic matter sorbents but similar for montmorillonite clay and the two soils. Sorption of both herbicides on the Drummer soil was much greater than on the Norfolk soil, due to the higher organic matter content of the former. Decreasing the suspension pH greatly increased sorption of both herbicides by all sorbents. Atrazine sorption was attributed to ionic bonding at low pH and physical bonding at neutral pH. Fomesafen sorption occurred by way of physical forces at near neutral pH and by way of hydrophobic bonding and/or precipitation at low pH. Mobility and bioavailability of the herbicides in soils is expected to be lower at low pH than at high or neutral pH.}, number={1}, journal={PESTICIDE SCIENCE}, author={WEBER, JB}, year={1993}, pages={31–38} }
 @article{weber_strek_sartori_1993, title={MOBILITY OF FOMESAFEN AND ATRAZINE IN SOIL COLUMNS UNDER SATURATED-FLOW AND UNSATURATED-FLOW CONDITIONS}, volume={39}, ISSN={["0031-613X"]}, DOI={10.1002/ps.2780390106}, abstractNote={Abstract The relative mobilities of 14 C‐labeled fomesafen and atrazine in Norfolk sandy loam ( Typic Paleudult ), Drummer silt loam ( Typic Haplaquoll ). Cape Fear sandy loam, ( Typic Umbraquult ), and a Brazilian Oxisol clay ( Typic Acrustox ) were studied using 50 cm of water applied to 30–5‐cm soil columns under unsaturated‐ and saturated‐flow conditions. Both herbicides were more mobile in Norfolk sandy loam than in Oxisol clay, Drummer silt loam, or Cape Fear sandy loam. Herbicide mobility was inversely related to organic and humic contents of the soils. Mobility of fomesafen was highly correlated with that of atrazine in the soils. Fomesafen was generally less mobile that atrazine under unsaturated‐flow conditions and more mobile under saturated‐flow conditions. Liming a Norfolk sandy loam increased, and oven drying decreased, fomesafen mobility.}, number={1}, journal={PESTICIDE SCIENCE}, author={WEBER, JB and STREK, HJ and SARTORI, JL}, year={1993}, pages={39–46} }
 @article{weber_swain_1993, title={SORPTION OF DINICONAZOLE AND METOLACHLOR BY 4 SOILS, CALCIUM-ORGANIC MATTER AND CALCIUM-MONTMORILLONITE}, volume={156}, ISSN={["0038-075X"]}, DOI={10.1097/00010694-199309000-00006}, abstractNote={Diniconazole was sorbed by four soils in amounts 7 to 20 times that for metolachlor, by Ca-organic matter (Ca-OM) in amounts twice that for metolachlor, and by Camontmorillonite (Ca-Mont.) in amounts similar to metolachlor. Sorption of diniconazole greatly increased and desorption decreased from Ca-OM and Ca-Mont as solution pH decreased. Sorption by the soils, as indicated by Freundlich K values, were highly correlated with the organic carbon content of the soils for diniconazole and with organic carbon and clay contents of soils for metolachlor. Sorption of diniconazole was through physical sorption forces at neutral pH levels and was by way of cation exchange forces at low pH levels.}, number={3}, journal={SOIL SCIENCE}, author={WEBER, JB and SWAIN, LR}, year={1993}, month={Sep}, pages={171–177} }
 @article{weber_1991, title={Fate and behaviour of herbicides in soils}, volume={5}, number={1}, journal={Applied Plant Science}, author={Weber, J. B.}, year={1991}, pages={28} }
 @article{weber_1982, title={IONIZATION AND ADSORPTION DESORPTION OF TRICYCLAZOLE BY SOIL ORGANIC-MATTER, MONTMORILLONITE CLAY, AND CAPE FEAR SANDY LOAM SOIL}, volume={30}, ISSN={["0021-8561"]}, DOI={10.1021/jf00111a042}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIonization and adsorption-desorption of tricyclazole by soil organic matter, montmorillonite clay and Cape Fear sandy loam soilJerome B. WeberCite this: J. Agric. Food Chem. 1982, 30, 3, 584–588Publication Date (Print):May 1, 1982Publication History Published online1 May 2002Published inissue 1 May 1982https://pubs.acs.org/doi/10.1021/jf00111a042https://doi.org/10.1021/jf00111a042research-articleACS PublicationsRequest reuse permissionsArticle Views102Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts}, number={3}, journal={JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY}, author={WEBER, JB}, year={1982}, pages={584–588} }
 @article{weber_mrozek_1979, title={POLYCHLORINATED BIPHENYLS - PHYTOTOXICITY, ABSORPTION AND TRANSLOCATION BY PLANTS, AND INACTIVATION BY ACTIVATED CARBON}, volume={23}, ISSN={["0007-4861"]}, DOI={10.1007/BF01769980}, number={3}, journal={BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY}, author={WEBER, JB and MROZEK, E}, year={1979}, pages={412–417} }
 @inbook{weber_weed_1974, title={Effects of soil on the biological activity of pesticides}, DOI={10.2136/1974.pesticides.c10}, abstractNote={Particulate matter in soils and aquatic systems reacts with and influences the biological activity of pesticides. Soil organic matter content and texture are the soil properties most highly associated with pesticide performance. A wide variety of organic pesticides are presently being used. The overall properties of each pesticide governs its behavior in a soil system and hence its biological activity. The nature of each pesticide is a composite function of its molecular structure as expressed by molecular size, ionizability, water solubility, lipophilicity, polarizability, and volatility. Particulate matter in soil systems consists of mixtures of inorganic (sand, silt, clay, metallic oxides) and organic (humus, peat, muck, ashes, carbon) constituents which range in particle size from colloidal to 2.0 mm in diameter. Herbicidal activity of the herbicides chlorpropham and propham decreased with increased organic matter content of soils. Cationic pesticides are ionically adsorbed to most clay minerals and soil organic matter.}, booktitle={Pesticides in soil and water}, publisher={Madison, Wis.: Soil Science Society of America}, author={Weber, J. B. and Weed, S. B.}, year={1974}, pages={223} }