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Biochar (BC), solid biomass subjected to pyrolysis, can alter the fate of pesticides in soil. We investigated the effect of soil amendment with several biochars on the efficacy of two herbicides, clomazone (CMZ) and bispyribac sodium (BYP). To this aim, we evaluated CMZ and BYP sorption, persistence, and leaching in biochar-amended soil. Sorption of CMZ and BYP was greater in soil amended with BC produced at high temperature (700 °C). Significant sorption of the neutral CMZ herbicide also occurred in amended soil with BC prepared at low temperature (350 and 500 °C). For both herbicides, desorption possessed higher hysteretic behavior in soil amended with BC made at 700 °C (pyrolysis temperature). Dissipation of CMZ was enhanced after addition of BCs to soil, but no correlation between persistence and sorption was observed. Persistence of BYP was up to 3 times greater when BC made at 700 °C was added to soil. All BCs suppressed the leaching of CMZ and BYP as compared to the unamended soil. Amendment with 700 °C BC inhibited the action of CMZ against weeds, but 350 and 500 °C BCs had no such effect when added to soil. BYP activity was similar to that exhibited by unamended soil after the addition of 700 °C BC. From these results, biochar amendments can be a successful strategy to reduce the environmental impact of CMZ and BYP in soil. However, the phytotoxicity of soil-applied herbicides will depend on BC sorption characteristics and the pesticide's chemical properties, as well as the pesticide application timing (e.g., pre- or postemergence). According to our results, proper biochar screening with intended pesticides in light of the application mode (pre- or postemergence) is required prior to use to ensure adequate efficacy.

The potential use of allelopathic and signaling compounds as environmentally friendly agrochemicals is a subject of increasing interest, but the fate of these compounds once they reach the soil environment is poorly understood. This work studied how the sorption, persistence, and leaching of the two enantiomers of the phytohormone abscisic acid (ABA) in agricultural soil was affected by the amendments of two organoclays (SA-HDTMA and Cloi10) and a biochar derived from apple wood (BC). In conventional 24-h batch sorption experiments, higher affinity toward ABA enantiomers was displayed by SA-HDTMA followed by Cloi10 and then BC. Desorption could be ascertained only in BC, where ABA enantiomers presented difficulties to be desorbed. Dissipation of ABA in the soil was enantioselective with S-ABA being degraded more quickly than R-ABA, and followed the order unamended > Cloi10-amended > BC-amended > SA-HDTMA-amended soil for both enantiomers. Sorption determined during the incubation experiment indicated some loss of sorption capacity with time in organoclay-amended soil and increasing sorption in BC-amended soil, suggesting surface sorption mechanisms for organoclays and slow (potentially pore filling) kinetics in BC-amended soil. The leaching of ABA enantiomers was delayed after amendment of soil to an extent that depended on the amendment sorption capacity, and it was almost completely suppressed by addition of BC due to its irreversible sorption. Organoclays and BC affected differently the final behavior and enantioselectivity of ABA in soil as a consequence of dissimilar sorption capacities and alterations in sorption with time, which will affect the plant and microbial availability of endogenous and exogenous ABA in the rhizosphere.

Azimsulfuron is an acidic herbicide with a high water solubility which makes risk of groundwater contamination a concern. Various wood based biochars produced at different pyrolysis temperatures were characterized along with their sorption capacity for the herbicide azimsulfuron. In addition, we compared sorption on biochars with sorption on mineral sorbents such as clay minerals and iron oxides. In biochar formed at high temperatures (500 °C and 700 °C), FT-IR studies confirmed the increase in aromaticity. Scanning electron microscope (SEM) images of the biochars showed differences in the macroporous structure and lower size pores at higher temperatures. SSA (Specific Surface Area) of the biochars increased with pyrolysis temperature and, for all different biochars, this resulted in higher sorption of azimsulfuron. In the case of mineral sorbents, sorption is not related to SSA. Higher sorption is observed in a montmorillonite, of lower SSA, than in mixture of clay minerals with 30% smectite (w/w). On the contrary as with the clays, sorption on the two iron oxyhydroxides increased with SSA. Desorption studies showed hysteresis. Leaching studies showed no effect on azimsulfuron retention on soil column amended with apple wood biochar, while a reduction of azimsulfuron in leachates in soil columns amended with the modified montmorillonite and alder wood biochar (500 °C). Total retention was shown for alder wood biochar.

The objective of this work was to search for low cost materials to be used as sorbents of contaminants. Biochar is the solid residual remaining after the thermo-chemical transformation of biomass. In this work, we obtained biochar from two residues from olive oil extraction known as “alperujo” (BCA) and “orujo” (BCO). Biochars were obtained by heating these residues at 550 oC 50 min. In order to evaluate sorption capacity of the biochars, we selected different contaminants: three organic contaminants (OCs) and two heavy metals (HMs). The OCs were two pesticides (tebuconazole and MCPA) and a dioxin (dibenzofuran) and the HMs selected were Cu And Zn. Removal of dibenzofuran from water reached 60 % of the initial concentration for both BCA and BCO, whereas in the case of tebuconazole BCA removed only 20% of the initially applied fungicide and BCO 10 %. Sorption of the acidic herbicide MCPA by BCA and BCO was very low (< 5%), probably due to repulsion between MCPA and negatively charged surfaces. These results suggest that sorption of OCs to the studied biochars is related to their hydrophobicity. When compared to OCs, these biochars were more effective in sorption of HMs: BCA sorbed 90 % of the Cu and Zn present in water and BCO more than 70 % of both HMs. Sorption of HMs on biochars surface can be through polar bonds between carboxylate or carbonyl groups from biochars surfaces and the metals.

Three natural smectitic clays (SWy-2, CTI and SH) were modified with one inorganic cation (FE3+) and one biopolymeric (chitosan, ch) cation with the aim to increase the adsorption capacity of those mineral clays for tricyclazole. The sorption capacity of the clays was assessed to increase, with the greatest adsorption (>93%) for natural clays modified with Fe3+ . Three types of clay-tricyclazol complexes (ground mixing, GM; weak complex, WC; and strong complex,SC) were prepared and tested as controlled release formulations (çCRFs). The release of tricyclazole in water decreased from the GMs of the CTIFe (85%), SWch4 (84%) and SWch6 (77%), showing lower values than the commercial product (100%) . Soil leaching depended on the soil type: Triciclazole was not detected in any leachate and alluvial soil, but in the sandy the SWch6 WC reduced tricyclazole leaching (65%) from the commercial formulation (75%). Clay tricyclzol complexes andr shown as usefull CRFs to minimize water contamination potential of this fungicide.

La presencia de plaguicidas en las aguas del Valle del Guadalquivir se ha puesto de manifiesto en diversos estudios de monitorización de aguas (Hermosín et al., 2013; Robles MoIina el at, 2014). De esta problemática nace el interés en el diseño de tecnologías que permitan su purificación como el desarrollo de sistemas filtrantes basados en materiales adecuados posibilite esta utilidad. Las arcillas de tipo esméctico presentan buenas propiedades absorbentes y su estructura laminar con carga negativa compensada con cationes interlaminares permite procesos fáciles para mejorarlas (Lagaly, 2001) Este trabajo contempla y evalúa diversos procesos de modificación de una arcilla local como componente en un filtro para la descontaminación de la agua

The use of biopesticides in agriculture is encouraged as a less harmful alternative to synthetic pesticides. It is known that certain amendments can dictate the final behavior and enantioselectivity of chiral agrochemicals in soils. In this sense, more information is needed regarding biopesticides. The aim of this work was to evaluate the effect of amending an agricultural soil with two organoclays, SA-HDTMA and Cloisite10A (Cloi10), and a biochar from apple wood (BC) on the sorption, dissipation and leaching of the biopesticide abscisic acid (ABA). Firstly, sorption-desorption isotherms of racemic ABA on the three sorbents were obtained. Sorption isotherms confirmed non-enantioselective sorption process and showed that SA-HDTMA displayed higher sorption towards ABA followed by Cloi10 and BC. The study was completed with incubation and leaching experiments with unamended soil and with soil amended with SA-HDTMA, Cloi10 and BC at a rate of 2% (w:w). Dissipation was always enantioselective, with S-ABA being degraded faster than R-ABA, and followed the same order for both enantiomers: unamended > Cloi10-amended >BC-amended >SA-HDTMA-amended soil. The leaching of both R- and S-ABA was delayed after amending soil, according to the sorption capacity of the sorbents. Only ABA leaching was almost suppressed only by addition of BC, likely due to a greater contribution of irreversible sorption. Our findings show that organoclays and BC affected differently the final behavior and enantioselectivity of ABA after its addition to soil. These amendments could impact the overall effectiveness of ABA, through different pathways, aspects to account for when used for agriculture purposes.

Laboratory and field experiments were conducted to assess how the addition of oleate-modified hydrotalcite (clay) and biochar (BC) to an agricultural soil affected the sorption, leaching, persistence, and enantiomeric composition of soil residues of two chiral fungicides, tebuconazole and metalaxyl. Laboratory experiments showed that the sorption of both fungicides ranked as follows: unamended soil < BC-amended soil < clay-amended soil. The addition of clay at a rate of 1% increased metalaxyl soil sorption coefficient (Kd) from 0.34 to 3.14 L kg−1 and that of tebuconazole from 2.4 to 47.4 L kg−1. In our experimental set-up, field plots were either unamended or amended with clay (2 t ha−1) or BC (4 t ha−1), and subsequently treated with a mixture of tebuconazole and metalaxyl at 3 and 6 kg ha−1, respectively. The leaching, persistence, and enantiomer composition of fungicides residues were monitored by sampling at different soil depths (0–5, 5–10, 10–20 cm) for 98 days. No significant changes in the scarce mobility and long persistence of tebuconazole upon amending the soil with clay or BC were observed. In contrast, sorption to clay and BC particles reduced the leaching and degradation of metalaxyl and the clay increased its persistence in the topsoil compared to the unamended soil. The enantioselective analysis of tebuconazole and metalaxyl soil residues indicated that tebuconazole remained mostly racemic along the experiment, whereas for metalaxyl the concentration of S-enantiomer was greater than the concentration of R-enantiomer, more so at longer experimental times and deeper horizons. Nevertheless, for the top 0–5 cm soil layer metalaxyl remained more racemic in clay- and BC-amended soil than in unamended soil. Our results show that addition of amendments with high sorptive capacities can be beneficial in reducing leaching and degradation losses of chiral pesticide enantiomers from the topsoil, and that sorption by the amendments can influence the final enanti

Addition of organic amendments such as biochar to soils can influence pesticide sorption-desorption processes and, in turn, the amount of pesticide readily availability for transport and biodegradation. Sorption-desorption processes are affected by both the physical and chemical properties of soils and pesticides, as well as soil-pesticide contact time, or aging. Changes in sorption-desorption of metolachlor with aging in soil amended with three macadamia nut shell biochars aged 0 (BCmac-fr), 1 year (BCmac-1yr), and 2 years (BCmac-2yr) and two wood biochars aged 0 (BCwood-fr) and 5 years (BCwood-5yr) were determined. Apparent sorption coefficient (Kd-app) values increased with incubation time to a greater extent in amended soil as compared to unamended soils; Kd-app increased by 1.2-fold for the unamended soil, 2.0-fold for BCwood-fr, 1.4-fold for BCwood-5yr, 2.4-fold for BCmac-fr, 2.5-fold for BCmac-1yr, and 1.9-fold for BCmac-4yr. The increase in calculated Kd-app value was the result of a 15% decrease in the metolachlor solution concentration extractable with CaCl2 solution with incubation time in soil as compared to a 50% decrease in amended soil with very little change in the sorbed concentration. Differences could possibly be due to diffusion to less accessible or stronger binding sites with time, a faster rate of degradation (in solution and on labile sites) than desorption, or a combination of the two in the amended soils. These data show that transport models would overpredict the depth of movement of metolachlor in soil if effects of aging or biochar amendments are not considered

Concerns have been raised over the sustainability of intensive rice cultivation, where the use of chemical fertilizers and pesticides has been associated with numerous environmental problems. The objective of this study was to test the effect of the herbicide azimsulfuron on important soil functions as affected by amendment with a byproduct of the olive oil industry. Soil was collected from a Mediterranean rice field. Part of it was amended with alperujo compost (AC). Amended and unamended soils were incubated for 43 days in presence or not of azimsulfuron, under anoxic-flooded (AF) and oxic-unflooded (OU) conditions. We monitored the dissipation of the herbicide azimsulfuron, C mineralization, soil microbial biomass (SMB) and dissolved organic carbon (DOC) content and its nature. Under AF conditions, the application of compost produced an increase in the dissipation of the herbicide (up to 12.4%). It was related with the higher DOC content, 4 times higher than under OU conditions. Though increases in carbon turnover (under AF and OU conditions) and reduction of SMBC after herbicide application (only under AF conditions) were observed, the differences were not statistically significant. The application of this organic amendment is presented as an efficient management strategy to increase C turnover in agricultural soils and reduce some of the negative effects derived from the application of azimsulfuron under flooded conditions.

The presence of pesticides in surface and groundwater has grown considerably in the last decades as a consequence of the intensive farming activity. Several studies have shown the benefits of using organic amendments to prevent losses of pesticides from runoff or leaching. A particular soil from the Guadalquivir valley was placed in open air ponds and amended at 1 or 2% (w/w) with alperujo compost (AC), a byproduct from the olive oil industry. Tricyclazole dissipation, rice growth and microbial diversity were monitored along an entire rice growing season. An increase in the net photosynthetic rate of Oryza sativa plants grown in the ponds with AC was observed. These plants produced between 1100 and 1300 kg ha-1 more rice than plants from the unamended ponds. No significant differences were observed in tricyclazole dissipation, monitored for a month in soil, surface and drainage water, between the amended and unamended ponds. The structure and diversity of bacteria and fungi communities were also studied by the use of the polymerase chain reaction denaturing gel electrophoresis (PCR-DGGE) from DNA extracted directly from soil samples. The banding pattern was similar for all treatments, although the density of bands varied throughout the time. Apparently, tricyclazole did not affect the structure and diversity of bacteria and fungi communities, and this was attributed to its low bioavailability. Rice cultivation under paddy field conditions may be more efficient under the effects of this compost, due to its positive effects on soil properties, rice yield, and soil microbial diversity.

Existen numerosos trabajos que abordan las aplicaciones de arcillas naturales, inalteradas o modificadas, como adsorbentes de pesticidas para la depuración de aguas e incluso para actuar como soportes en formulaciones de liberación lenta del pesticida o como barreras inmovilizantes en suelos (Cornejo et al., 2008). La mayoría de estos estudios se han realizado bajo condiciones controladas en el laboratorio y usando minerales de la arcilla naturales del grupo de las esmectitas. En los últimos años, ha aumentado el interés por explotar las propiedades adsorbentes de los hidróxidos dobles laminares (HDLs), también conocidos como hidrotalcitas (HTs) o arcillas aniónicas, cuyas características estructurales guardan cierta relación con las de las esmectitas (Cornejo et al., 2008). Los LDHs consisten en láminas del tipo brucita de un metal divalente con sustituciones isomórficas que proporcionan a las láminas una carga permanente positiva y que es compensada con aniones intercambiables que se sitúan en el espacio interlaminar. Aunque los resultados obtenidos hasta ahora ponen de manifiesto la elevada capacidad de adsorción de los LDHs para muchos pesticidas y la versatilidad que les confiere la posibilidad de modificarlos mediante la intercalación de aniones orgánicos en el espacio interlaminar (Celis et al., 2014), su utilidad como enmendantes para aumentar la capacidad de adsorción de los suelos bajo condiciones ambientales reales aún no ha sido evaluada.

Natural mineral clays (SWy-2, CTI and SH) were modified with natural inorganic cation (Fe3+) and the biopolymer (chitosan (ch)) to increase the adsorption capacity for tricyclazole. Three ways to prepare tricyclazole-clay complexes (ground mixing, GM, weak complex, WC and strong complex, SC) were assayed with the aim to develop possible components for controlled release formulations (CRFs) of this fungicide. The greatest adsorption (> 93%) was measured in the natural clays modified with Fe3+. The release of tricyclazole in water was higher for GMs of SWch6 (77%), SWch4 (84%) and CTIFe (85%). No significant differences were observed in the dissipation in soil of tricyclazole applied as commercial product or as formulation. However, the leaching of the fungicide depended on the type of soil: tricyclazole was not detected in any leachate from the soil with higher clay content (alluvial) whereas the SWch6 weak complex (WC) reduced the leaching of tricyclazole (65%) as compared to the commercial formulation (75%) in a sandy soil after 60 days. This last tricyclazol-clay complex could be considered as appropriate component for CRF, to be used in sandy soils. The other modified clays assayed, showing very high, strong and irreversible adsorption could find application as filters to eliminate tricyclazole from contaminated waters. Clay-fungicide interaction mechanisms are discussed and related to their soil and water behavior.

Increasing knowledge of the factors controlling the environmental fate of chiral pesticide enantiomers is a recent matter of concern because a large number of pesticides are chiral and reach the environment as mixtures of optical isomers or enantiomers. Use of organic amendments is a common agricultural practice to increase fertility of soils, particularly in areas where soils are poor in organic matter, and can also be used to prevent and remediate soil and water contamination by pesticides and other organic pollutants by reducing their mobility. This is the case of the composted Olive-Mill Waste (OMWc), composted residue from olive oil production, and biochar (BC), the solid residue remaining after pyrolysis of biomass. In this work, we investigated how amending a sandy loam agricultural soil with composted olive mill waste (OMWc) or its biochar (BC) at a rate of 2% (w:w) affected the enantioselectivity of the sorption, dissipation, and leaching processes of the fungicide metalaxyl.

Chiral pesticides comprise an emerging and important class of organic pollutants currently, accounting for more than a quarter of used pesticides. Consequently, the contamination problems caused by chiral pesticides are concern matter and factors affecting enantioselective processes of chiral pesticides in soil need to be understood. For example, certain soil management practices, such as the use of organic amendments, can affect the enantioselective behavior of chiral pesticides in soils. Recently, biochar (BC), i.e. organic matter subjected to pyrolysis, has been proposed as organic amendment due to beneficial properties such as its high stability against decay in soil environments and its apparent ability to influence the availability of nutrients. BC is considered to be more biologically inert as compared to otherforms of organic carbon. However, its side-effects on the enantioselectivity of processes affecting the fate of chiral pesticides is unknown. The aim of this study was to assess the effect of biochar (BC) on the enantioselectivity of sorption, degradation, and leaching of the chiral fungicide metalaxyl in an agricultural soil. Amending the soil with BC (2% w/w) resulted in 3 times higher sorption of metalaxyl enantiomers compared to unamended soil, but no enantioselectivity in the process was observed. Moreover, both enantiomers showed some resistance to be desorbed in BC-amended soil compared to unamended soil. Dissipation studies revealed that the degradation of metalaxylwas more enantioselective in the unamended soil than in BC-amended soil. In unamended soil, R-metalaxyl(biologically active) and S- metalaxyl had half-lives (t1/2) of 3 and 34 days, respectively. BC enhanced the persistence of both enantiomers in the soil, with R-metalaxyl being degraded faster (t1/2=43 days) than S-metalaxyl (t1/2= 100 days). The leaching of both S-and R-metalaxyl was almost suppressed after amending the soil with BC; less than 10% of the fungicide applied to soil co

La contaminación por metales pesados es un tema de gran preocupación. Entre las diversas actividades que contribuyen a aumentar la presencia de metales pesados en el medio ambiente, se encuentra la agricultura. Por ejemplo, el uso de fertilizantes de tipo fosforados y algunos fungicidas incrementan la aparición Cu y Zn en aguas de zonas agrícolas e incluso residuales de la industria agroalimentaria. La eliminación de metales pesados mediante el uso de minerales de la arcilla tipo montmorillonita ha sido objeto de numerosos trabajos (Barbier et al., 2000) dada su alta capacidad de adsorción principalmente asociada a su capacidad de intercambio catiónico (CIC), fácil accesibilidad de su interlámina y a la presencia de grupos hidroxilos de los bordes de ruptura de la capa octaédrica.

Clays, as natural materials or after diverse chemical modifications, have been widely studied in the last decades as possible adsorbents to remove pesticides or other organic contaminants from water1,2. The contamination of water, besides its scarcity, is encouraging research in water purification technologies. Rural environments suffer especially from water contamination because intensive crop management has increased the pesticide use, which then contaminate the surface and ground waters. Also, the after-crop processing industries produce waste water containing pesticides. This is a very serious concern in a region where a monoculture is established, as in Andalusia and many regions of the Mediterranean countries where hundreds of thousands of olives orchard are set up, causing contamination in their water bodies. These rural environments need the development of low-cost water purification technologies for small villages, scattered farmer houses or even small agro-industrial installations. This is the final target of our research, to look for low cost adsorbents to be used in filter systems for medium and small scale enterprises to remove pesticides from water. Several commercial clays (Cloisites and Bentonites SD, >95% smectite content) were assayed together with a local clay sample of low value because of its low 30%) smectitecontent (CTI from Bailen, Jaen, Spain), which was increased up to 60% after carbonate removing (CTIwc). The CTIwc sample was saturated in Fe3+, hexadecyltrimethylammonium (CTI-Fe3+ and CTI-HDTMA) and the polymer chitosan (CTI-CH4 and CTICH6). The clays assayed and their organic elemental analyses are summarized in TB1. The modified CTI clay was subjected to a granulation process with a natural polymer (carboxymehyl cellulose and wax) in order to get water resistance. The pesticides were selected as having a representative diverse chemical character as shown in TB2. The water was artificially contaminated with 1ppm of each compound and the a

Layered double hydroxides (LDHs), also known as hydrotalcite-like compounds (HTs), comprise a special group of layered materials. Their structure consists of positively charged layers of mixed divalent (MII) and trivalent (MIII) metal hydroxide [MII1-xMIIIx(OH)2]x+, with the positive charge being balanced by inorganic hydrated anions (An-x/nmH2O), which occupy the interlayer space. LDHs have anion exchange properties and, therefore, are good sorbents for anionic pollutants. In addition, the anionic exchange properties of LDHs allow the intercalation of organic anions in the interlayer space to render the LDH surface hydrophobic. This increases its affinity to hydrophobic organic compounds

The herbicides bentazone and S-metolachlor used for the control of broad leaf weeds in crops, such as corn and soybean have been detected in surface and ground waters in Europe and USA. The aim of this work was to evaluate the effect of an olive oil mill waste used as soil amendment at two rates (5 and 10% w/w) on soil porosity, and the fate of the herbicides in two different soils. Soil porosity increased upon amendment. The organic waste favored S-metolachlor sorption with a 5-6 fold increase and leaching decreased (from 61 to 4% in sandy soil and 40 to 10 in alluvial soil). However, we did not observe any effect on sorption and leaching of bentazone as compared to the unamended soil. Dissipation of both herbicides decreased on the soils amended with the olive oil by-product. Thus, this waste can be used to prevent water contamination by S-metolachlor.

Before using biochar as a soil amendment, it is important to understand its effect on soil bioavailability of allelochemicals, specifically phenolic acids. This study examines sorption of 14C-labeled ferulic acid, syringic acid, and chlorocatechol to four biochars prepared from individual feedstocks and four customized biochars produced from mixed feedstocks using batch equilibration. Pure feedstock biochar sorption order was: switchgrass< swine solids< poultry litter< pine chip for both ferulic (Kd= 1.4-75 L kg-1) and syringic acid (Kd = 0.07- 6.03 L kg-1). Both biochar properties and chemical structure appeared to influence sorption. Sorptive properties of biochars produced from combined feedstocks could not be predicted from their pure feedstock components; sorption coefficients were both higher and lower than individual parent materials' biochars. All biochar Kd values, except pine chip, were consistently lower than the reference silt loam soil, therefore incorporating these biochars would not likely alter bioavailability of phenolic acids in this soil.

La presencia en las aguas de contaminantes orgánicos de origen antropogénico diverso, procedentes de actividades tanto industrial como urbana o agrícola, es un problema abordado desde hace tiempo pero al que le quedan aún muchas facetas por solucionar. La escasez de agua junto al aumento de la población a nivel mundial actúa de motor para investigar nuevas metodologías que implementen la reutilización, la calidad y el aprovechamiento del agua, como lo demuestra la reciente convocatoria de la JPI-Water (2013). De aquí el interés actual en diseñar tecnologías que permitan la purificación o reutilización del agua.

© 2014 American Chemical Society. Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes.

El suelo es un recurso no-renovable y su contenido en materia orgánica es vital en el equilibrio entre los procesos de degradación y las prácticas de conservación. Aunque la materia orgánica constituye una pequeña proporción de los componentes del suelo, la in fluencia en su calidad (propiedades físicas, químicas y biológicas), así como sobre el desarrollo de las plantas, es crucial para la sostenibilidad del sistema suelo-planta. La materia orgánica en los suelos es un componente dinámico, cuya concentración depende de las condiciones edafoclimáticas, que en los suelos naturales puede permanecer más o menos constante, pero que en los suelos cultivados tiende a disminuir debido a prácticas agronómicas inadecuadas. La incorporación de materiales orgánicos exógenos (lodos de depuradora, residuos sólidos urbanos, residuos de plantas, etc.) puede contribuir a restablecer los niveles de materia orgánica. La aplicación de residuos orgánicos ofrece una muy buena posibilidad para restaurar los suelos agrícolas erosionados y los suelos marginales. Asimismo, las enmiendas orgánicas están jugando un papel muy importante en la recuperación de suelos contaminados mediante técnicas blandas de bajo impacto. La utilización de enmiendas contribuye además a la eliminación de residuos con alta carga orgánica, así como al secuestro del C, coadyuvando de esta forma a la disminución del CO2 atmosférico. Este volumen presenta el estado actual del uso residuos orgánicos para la restauración-rehabilitación de suelos degradados y contaminados. Está escrito por nueve investigadores españoles vinculados a tres centros de investigación, con reconocida experiencia sobre el tema, y autores de numerosos artículos cientícos en las más prestigiosas revistas internacionales. Este volumen constituye un gran esfuerzo por parte de los autores y de la REC para hacer llegar la información recopilada a los lectores castellano-parlantes, ya que no existe ningún libro sobre el tema en castellano.

Exponen la dinámica de los plaguicidas en el suelo, los procesos en que intervienen (adsorción-desorción, lixiviación, escorrentía, volatilización y absorción por las plantas y organismos de suelo), las transformaciones (degradación química, biodegradación y fotodegradación) que sufren y la importancia de la materia orgánica (contenido total y naturaleza de la misma). Asimismo, describen numerosos estudios de los efectos de la aplicación de enmiendas orgánicas en la dinámica de los plaguicidas en los suelos.

Se ha estudiado el impacto que tienen aplicaciones sucesivas a un suelo agrícola de olivar durante 9 años de dos residuos de almazara (un alperujo y un orujo) en las propiedades físicoquímicas del suelo, comparándolas con la aplicación de estos mismos residuos frescos bajo condiciones de laboratorio. Los resultados de este estudio indican que el envejecimiento de la materia orgánica exógena añadida al suelo con las enmiendas da lugar a cambios en las propiedades físicoquímicas principalmente en el contenido en materia orgánica soluble y en la porosidad de los suelos.

In an effort to customize biochars for soil amendments, multiple feedstocks have been combined in various ratios prior to pyrolysis at 350 °C. The resulting variation in the chemistry and structure can affect the adsorption capacity of biochar and thus influence the bioavailability of many chemical compounds in the soil system including phenolic acids. This study examines the sorption of 14C-labeled ferulic acid, syringic acid, and chlorocatechol to four biochars prepared from individual feedstocks and four biochars produced from mixed feedstocks using batch equilibration. Pure feedstock biochar sorption followed switchgrass < swine solids < poultry litter < pine chip for both ferulic (Kd = 1.4-75 L kg-1) and syringic acid (Kd = 0.07-6.03 L kg-1). Sorption appeared to be influenced by the properties of the biochars as well as the structure of the chemicals. All biochar Kd values, except pine chip, were consistently lower than that of the reference silt loam soil. The sorptive properties of biochars produced from combined feedstocks could not be predicted from their pure feedstock components, and sorption coefficients were both higher and lower than the individual parent materials' biochars. Further research is necessary to understand the characteristics of these combination biochars, particularly their sorption, which this study has shown is not merely an average of its components

The many advantageous properties of biochar have led to the recent interest in the use of this carbonaceous material as a soil amendment. However, there are limited studies dealing with the effect of biochar on the behavior of pesticides applied to crops. The objective of this work was to determine the effect of various biochars on the sorption-desorption of the herbicides aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinacarboxylic acid) and bentazone (3-isopropyl-1. H-2,1,3-benzothiadiazin-4(3. H)-one 2,2-dioxide) and the fungicide pyraclostrobin (methyl 2-[1-(4-chlorophenyl) pyrazol-3-yloxymethil]- N-methoxycarbanilate) to a silt loam soil. Aminocyclopyrachlor and bentazone were almost completely sorbed by the soils amended with the biochars produced from wood pellets. However, lower sorption of the herbicides was observed in the soils amended with the biochar made from macadamia nut shells as compared to the unamended soil, which was attributed to the competition between dissolved organic carbon (DOC) from the biochar and the herbicides for sorption sites. Our results showed that pyraclostrobin is highly sorbed to soil, and the addition of biochars to soil did not further increase its sorption. Thus, addition of biochars to increase the retention of low mobility pesticides in soil appears to not be necessary. On the other hand, biochars with high surface areas and low DOC contents can increase the sorption of highly mobile pesticides in soil. © 2013 Elsevier B.V.

The effect of soil amendment with different organic residues from olive oil production on the sorption and leaching of two pesticides used in rice crops (bentazone and tricyclazole) was compared in order to understand their behavior and to improve soil properties by recycling an abundant agricultural residue in Andalucía (S. Spain). A residue from olive oil production (AJ), the organic compost derived from this organic waste (CA) and a biochar (BA) made from CA were used. A soil devoted to rice cultivation, IFAPA (I), was amended at 2% (w/w) of each amendment individually (I. +. AJ, I. +. CA and I. +. BA). In order to evaluate the effect of dissolved organic matter (DOM) from these amendments on bentazone and tricyclazole behavior, the DOM from the amendments was extracted, quantified and characterized by fluorescence spectroscopy and FT-IR. The affinity of DOM for soil surfaces was evaluated with (I) soil and two other soils of different physicochemical properties, ARCO (A) and GUAD (G). These studies revealed differences in DOM quantity, quality and affinity for the used soils among amendments which can explain the different sorption behavior observed for tricyclazole in the amended soils. Leaching assays under saturated/unsaturated conditions revealed a slight delay of bentazone in I. +. CA and I. +. BA soils when compared to I. +. AJ, that can be related to the higher DOM content and much lower specific surface area of AJ. In contrast, tricyclazole was not detected in any of the leachates during the leaching assay. Extraction of tricyclazole residues from soil columns showed that the fungicide did not move below 5. cm in the higher sorptive systems (I. +. CA, I. +. BA). The sorption of DOM from amendments on soil during the transport process can decrease the mobility of the fungicide by changing the physicochemical properties of the soil surface whose behavior may be dominated by the adsorbed DOM.

En este trabajo se han estudiado los principales efectos derivados de la enmienda con un residuo orgánico del olivar andaluz sobre la dinámica de dos plaguicidas empleados en el cultivo de arroz, el herbicida bentazona (2,2-Dióxido de 3-isopropil- 2,1,3-benzotiodiazina-4-ona) y el fungicida triciclazol (5-metil 1,2,4-triazol (3,4-b)-benzotiazol). Hemos comparado el efecto de una posible enmienda de suelos con un compost y un biochar, ambos obtenidos a partir de un alperujo. El principal objetivo fue estudiar la eficacia en la retención de plaguicidas, minimizando de esta manera las pérdidas por lixiviación. En los estudios de laboratorio la adsorción de triciclazol aumentó en los suelos enmendados, mientras que la adsorción de bentazona a penas se vio modificada. Estos estudios muestran que la naturaleza de la materia orgánica juega un papel fundamental en la dinámica de plaguicidas, sobre todo en el caso del triciclazol. En los estudios de campo se observó que la enmienda con compost de alperujo puede modificar la persistencia de la bentazona en condiciones de inundación, mientras que la de triciclazol no se ve afectada

The aminocyclopyrachlor herbicide was aproved by the US-EPA for its use in non cultivated areas, greens and non residencial gardens. This herbicide with a pKa 4.65 presents an anionic character at the pH of most soils. The anionic compounds are weakly retained by the active soil components and hence they are easily transported to different compartments. In this context this herbicide could not be active in the target plants and be transported to ground and /or surface waters. In order to increase the retention of aminocyclopyrachlor by soils some organic amendments like “biochars” and “alperujos” from different industrial sources and prepared in different ways could be added. Lab experiment on adsorption-desorption of herbicide by amended soils were performed and compared with the corresponding unamended soils and with an active carbon amended soil. The higher herbicide sorption was observed in the soil amended with active carbon. On the other hand, the herbicide sorption only increased in soils amended with biochars originated from wood pellets. The adsorption reversibility of aminocyclopyrachlor herbicide was very low and generally inversely correlated with the adsorption capacity of amended soils.

Use of carbonaceous amendments in soil has been proposed to decrease potential off-site transport of weak acid herbicides and metabolites by increasing their sorption to soil. The effects of organic olive mill waste, biochars from different feed stocks, and humic acid bound to clay on sorption of 4-chloro-2-methylphenoxyacetic acid (MCPA), aminocyclopyrachlor, or indaziflam acid metabolite to soils with varying physical and chemical properties were determined. At natural agricultural pH soil levels, these chemicals are anionic and weakly sorbed to soils; sorption of the three weak acids on soil was in the order MCPA (K f = 0.1) < aminocyclopyrachlor (K f = 0.3) < indaziflam acid (K f = 1.6). Results indicate that not all carbonaceous amendments, including biochars, increase sorption, thereby decreasing the potential for off-site transport. The amount and composition of the organic amendment, along with pH of the system, affect sorption and potential off-site transport. For instance, depending on the feedstock of the biochar and the method of production, changes in sorption ranged from no effect, to a decrease by a factor of 3.3×, to an increase of 383× upon addition of amendment to soil. In contrast, activated charcoal increased sorption by >10,000×. While generalizations have been made that soil sorption of nonpolar, neutral, or weakly basic chemicals increases by the addition of different carbonaceous amendments, no such generalizations can be made for weak acids. More work on properties of these amendments, biochars in particular, and how they affect weak acid sorption is required.

En regiones del sur de España, cuyos suelos presentan bajo contenido en materia orgánica, el uso intensivo de plaguicidas en áreas agrícolas genera grandes problemas de contaminación de suelos y aguas, tanto puntual como difusa, especialmente cuando su aplicación coincide con periodos de lluvia (Lagana et al., 2002; Hermosín et al., 2009). Sin embargo, el uso de plaguicidas, en especial de herbicidas, se ha convertido en un recurso indispensable en el sector agrícola a nivel mundial durante los últimos 50 años (Arias-Estévez et al., 2008). A lo largo de las últimas décadas se han desarrollado técnicas para disminuir el efecto contaminante de plaguicidas en el suelo, y entre ellas se ha encontrado recientemente que la adición de alperujo, aunque no siempre constituya garantía de control, reduce la movilidad o transporte de estas sustancias a otros compartimentos del suelo. En trabajos anteriores, se ha visto que la adición de alperujo reduce la dispersión de herbicidas utilizados en la actualidad y el pasado en el olivar (terbutilazina y diurón) al aumentar su capacidad de adsorción a las partículas del suelo, al mismo tiempo que aumenta la persistencia de estos herbicidas en el suelo, limitando por tanto los tratamientos repetitivos (Cabrera et al., 2009).

Aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylic acid), a new herbicide, was approved by US-EPA (United States Environmental Protection Agency) in September 2010 for the control of broadleaf weeds, grasses, vines and woody species in non-crops, turf, sod farms and residential areas. At typical soil pH levels, aminocyclopyrachlor is anionic. Anionic pesticides are generally weakly retained by most soil and sediment components and are subject to potential transport offsite. One strategy to minimize the risk of offsite transport associated with weakly sorbed, highly mobile pesticides is the application of these chemicals supported on a sorbent, such as modified clay minerals which contain exchangeable inorganic and organic cations. The aim was to determine the ability of unmodified and modified clay minerals to sorb aminocyclopyrachlor. Two montmorillonites (Ca-Arizona montorillonite (SAz-1) and Na-Wyoming montmorillonite (SWy-2)) were used as unmodified clay minerals and were also modified with an inorganic cation (Fe 3+), soil constituents (ferrihydrite, humic acid) and organic cations (hexadecyltrimethylammonium (HDTMA), hexadimethrine, spermine). Greater sorption of aminocyclopyrachlor was observed in the sorbent-solution systems with lower pH values, presumably because of protonation of the herbicide anion at low pH and subsequent sorption of molecular species and cationic species. FeSWy-2 (SWy-2 montmorillonite saturated with Fe 3+; system pH = 4.6) was the best sorbent for aminocyclopyrachlor (86% of applied). The best organo-clay (SA-HDTMA) (system pH = 6.1) sorbed 53% of the applied herbicide. Binary and ternary model sorbents (system pH > 6.7) did not sorb aminocyclopyrachlor. At the lowest pH value studied (2.8), the organo-clay SW-Sper was the best sorbent system for aminocyclopyrachlor. Our recommendation for the best adsorbent is the clay mineral modified with Fe 3+, although at pH values <3, the use of the organo-clay SW-Sperm c

The aim of this study was to evaluate the impact of two organic wastes from olive oil production on the fate of bentazone in soil, and to assess the influence of the transformation of organic matter from these wastes under field conditions. Results on freshly laboratory-amended soils were compared to those with soils amended in the field for nine consecutive years. Two amendments and two doses were studied. Sorption of bentazone increased upon amendment with Kd values from 0.03 to 1.7. The increase was higher for freshly amended soils than for the field amended soils and for the higher dose. Degradation was correlated with sorption in the case of field amended soils, whereas higher persistence in freshly amended soils may be related to the easier microbial availability of DOC molecules than bentazone molecules. The increase in non-conducting pores in amended soils favours sorption and degradation processes reducing leaching. Important differences revealed in herbicide fate between freshly amended soils and aged field amended soils limit further extrapolation of laboratory studies to field studies.

Laboratory and field experiments were conducted to evaluate the effect of olive-mill waste (OMW) addition to a Mediterranean olive grove soil on sorption, persistence, and mobility of two herbicides which are simultaneously applied for weed control in olive groves: terbuthylazine (TA) and fluometuron (FM). Laboratory batch sorption experiments showed that OMW addition to the soil at rates of 5 and 10% (w/w) greatly enhanced the sorption of both herbicides, thus suggesting that amendment with OMW could be useful to enhance the retention and reduce the mobility of FM and TA in the soil. Incubation experiments showed that OMW increased the persistence of FM and had little effect on the long persistence of TA in the soil studied. A demonstration field experiment was also conducted in field plots with a slope of about 5%, either unamended or amended with OMW at a rate of 10 kg m¿2, and then treated with a commercial formulation containing a mixture of TA and FM. Extraction of field soil samples, taken from different soil depths (0¿5, 5¿10, 10¿20, and 20¿30 cm) at different times after herbicide application, showed that both TA and FM moved deeper in unamended soil than in OMW-amended soil, and that OMW addition affected the persistence of FM in the toplayer, increasing its half-life from 24 to 58 days, while having little effect on the persistence of TA. Thus, data obtained under real field conditions were consistent with those obtained under controlled laboratory conditions. Preliminary herbicide runoff data indicated that the total herbicide runoff losses were also reduced upon OMW addition. Addition of OMW could be beneficial in reducing the mobility of TA and FM in olive grove soils, and also in increasing the persistence of FM in soils where this herbicide could be rapidly degraded.

El uso repetitivo y en exceso de plaguicidas, en especial de herbicidas, ha despertado la necesidad de conocer en profundidad el comportamiento de estas sustancias en el sistema de suelo, con el fin de reducir su difusión hacia compartimentos donde no estaban destinados aparecieran, como son las aguas subterráneas.

Aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinecarboxylic acid), a new DuPont herbicide, has been recently approved by US-EPA for the control of broadleaf weeds, grasses, vines and woody species in non-crops, turf, sod farms, and residential areas.

The purpose of this study was to understand the effect produced by the addition of the herbicides terbuthylazine (N2-tert-butyl-6-chloro- N4-ethyl-1,3,5-triazine-2,4-diamine) and glyphosate (N-(phosphonomethyl)glycine) on photosystem II photochemistry of young plants of Olea europaea L. under greenhouse conditions. The effect of soil amendment with an organic residue from olive oil production was also assessed. Terbuthylazine reduced the efficiency of photosystem II photochemistry of plants due to chronic photoinhibition, and this effect was counterbalanced by soil amendment with the organic waste, whereas the photosystem II photochemistry of olive plants was not affected by glyphosate or by glyphosate and organic waste addition. In this study, we have shown that the soil application of terbuthylazine is a source of indirect phytotoxicity for olive plants. We have also observed that the olive plants were not affected by higher amounts of glyphosate in the soil.

Metolachlor (2-chloro-6′-ethyl-N-(2-methoxy-1-methylethyl)aceto-o- toluidide) is a pre-emergent chloroacetanilide herbicide used to control broadleaf and annual grassy weeds in a variety of crops. The S enantiomer, S-metolachlor, is the most effective form for weed control. Although the degradation of metolachlor in soils is thought to occur primarily by microbial activity, little is known about the microorganisms that carry out this process and the mechanisms by which this occurs. This study examined a silty-clay soil (a Luvisol) from Spain, with 10 and 2 year histories of metolachlor and S-metolachlor applications, respectively, for microorganisms that had the ability to degrade this herbicide. Tis paper reports the isolation and characterization of pure cultures of Candida xestobii and Bacillus simplex that have the ability to use metolachlor as a sole source of carbon for growth. Species assignment was confirmed by morphological and biochemical criteria and by sequence analysis of 18S and 16S rRNA, respectively. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) analyses indicated that C. xestobii degraded 60% of the added metolachlor after 4 days of growth and converted up to 25% of the compound into CO2 after 10 days. In contrast, B. simplex biodegraded 30% of metolachlor following 5 days of growth in minimal medium. In contrast, moreover, the yeast degraded other acetanilide compounds and 80% of acetochlor (2-chloro-N-ethoxymethyl- 6′-ethylaceto-o-toluidide) and alachlor (2-chloro-2′,6′- diethyl-N-methoxymethylacetanilide) were degraded after 15 and 41 h of growth, respectively. The results of these studies indicate that microorganisms comprising two main branches of the tree of life have acquired the ability to degrade the same novel chlorinated herbicide that has been recently added to the biosphere.

Biochar, the solid residual remaining after the thermochemical transformation of biomass for carbon sequestration, has been proposed to be used as a soil amendment, because of its agronomic benefits. The effect of amending soil with six biochars made from different feedstocks on the sorption and leaching of fluometuron and 4-chloro-2-methylphenoxyacetic acid (MCPA) was compared to the effect of other sorbents: an activated carbon, a Ca-rich Arizona montmorillonite modified with hexadecyltrimethylammonium organic cation (SA-HDTMA), and an agricultural organic residue from olive oil production (OOW). Soil was amended at 2% (w/w), and studies were performed following a batch equilibration procedure. Sorption of both herbicides increased in all amended soils, but decreased in soil amended with a biochar produced from macadamia nut shells made with fast pyrolysis. Lower leaching of the herbicides was observed in the soils amended with the biochars with higher surface areas BC5 and BC6 and the organoclay (OCl). Despite the increase in herbicide sorption in soils amended with two hardwood biochars (BC1 and BC3) and OOW, leaching of fluometuron and MCPA was enhanced with the addition of these amendments as compared to the unamended soil. The increased leaching is due to some amendments' soluble organic compounds, which compete or associate with herbicide molecules, enhancing their soil mobility. Thus, the results indicate that not all biochar amendments will increase sorption and decrease leaching of fluometuron and MCPA. Furthermore, the amount and composition of the organic carbon (OC) content of the amendment, especially the soluble part (DOC), can play an important role in the sorption and leaching of these herbicides.