Herbicide Clomazone Research Articles

Clomazone herbicide impairs bioenergetics in mitochondria isolated from the thorax of honey bees (Apis mellifera L.)

The excessive use of pesticides on crops has caused an increase in animal mortality, contamination of soil, water and food, in addition to being identified as one of the causes of death of bees. Despite being quite effective, the herbicide clomazone (CLZ) causes widespread environmental contamination due to its high solubility in water (1,100 mg.L-1), and its residues can remain in the environment for up to 130 days. Mitochondria are responsible for producing the majority of the ATP in cells, and in bees, the thorax, as it is where the wings are located, is the place with the greatest ATP production. The objective of this work was to evaluate the effects of the herbicide CLZ on mitochondria isolated from the thorax of honey bees (Apis mellifera). The effects of CLZ (100, 125, 150, 200 and 250 µM) on mitochondria were evaluated by determining oxygen consumption, ATP production and generation of reactive oxygen species (ROS). When energized with pyruvate + malate (complex I substrates of the respiratory chain) CLZ did not show significant results in any of the concentrations used, however, when energized with succinate (complex II substrate of the respiratory chain) a dose-dependent stimulus in mitochondrial respiration was observed. Mitochondrial ATP levels were significantly reduced in a dose-dependent manner at concentrations above 125 µM. CLZ did not significantly induce the generation of ROS at any of the concentrations studied. Thus, the results of this study indicate that CLZ toxicity in honey bees may be related to changes in mitochondrial bioenergetics.

Comparative Study on the Removal Efficiency of Clomazone and Amitriptyline via Adsorption and Photocatalysis in Aqueous Media: Kinetic Models and Toxicity Assessment.

This study aimed to compare the effectiveness of adsorption and photocatalysis techniques at removing the herbicide clomazone (CLO) and the antidepressant known as amitriptyline (AMI) from water. This study employed kinetic models to analyze the removal processes and assess the potential toxicity of the treated water. The structure and morphology of the prepared multi-walled carbon nanotubes were characterized as adsorbents by transmission electron microscopy, X-ray diffraction, Fourier transform infrared techniques, and Raman spectroscopy. The adsorption kinetics of CLO and AMI were studied on the pristine and functionalized multi-walled carbon nanotubes. Kinetic studies were performed by modeling the obtained experimental data using three kinetic models: pseudo-first-order, pseudo-second-order, and Elovich kinetic models. On the other hand, the efficiency of CLO and AMI photodegradation was examined as a function of the type of irradiation (UV and simulated solar irradiation) and type of TiO2 photocatalyst (Aeroxide and Kronos). Under the experimental conditions employed, the reaction followed pseudo-first-order kinetics. Additionally, in order to assess the toxicity of water containing CLO, AMI, and their intermediates, toxicity assessments were conducted using human fetal lung fibroblast cells. The results obtained indicate the effectiveness of both methods and provide valuable insights into their removal mechanisms, contributing to the advancement of sustainable water treatment strategies.

Mitochondrial impairment related to the immunotoxicity of the herbicides clomazone, glyphosate and sulfentrazone in THP-1 cells.

Pesticides are indispensable for the cultivation of crops, especially those of economic importance, such as soybeans. Data on the annual use of herbicides in crops show that they correspond to 50%, making it the most used in agriculture. Therefore, the aim of this study was to evaluate the toxicity of the three commercial herbicides (clomazone, glyphosate, and sulfentrazone) in THP-1 cells. Cells were incubated with 0-5,000mg/L of the herbicides for 24h at 37°C for cytotoxicity evaluation. Additionally, a few toxicological pathways such as reactive species generation, mitochondrial impairment, and interleukin profile, which have been previously involved in the toxicity of pesticides, were also evaluated. A potential immunotoxic effect of the herbicides on THP-1 cells was observed, especially glyphosate, as it is a powerful agent of cellular immunotoxicity. It was also possible to verify an increase in oxidative stress and IL-8 levels and mitochondrial dysfunction. All herbicides showed cytotoxic effects in THP-1 monocytes, which were related to mitochondrial impairment.

Synthesis, Herbicidal Activity, Mode of Action, and In Silico Analysis of Novel Pyrido[2,3-d]pyrimidine Compounds.

Natural products are a main source of new chemical entities for use in drug and pesticide discovery. In order to discover lead compounds with high herbicidal activity, a series of new pyrido[2,3-d] pyrimidine derivatives were designed and synthesized using 2-chloronicotinic acid as the starting material. Their structures were characterized with 1H NMR, 13C NMR and HRMS, and the herbicidal activities against dicotyledonous lettuce (Lactuca sativa), field mustard (Brassica campestris), monocotyledonous bentgrass (Agrostis stolonifera) and wheat (Triticum aestivum) were determined. The results indicated that most of the pyrido[2,3-d] pyrimidine derivatives had no marked inhibitory effect on lettuce at 1 mM. However, most of the pyrido[2,3-d] pyrimidine derivatives possessed good activity against bentgrass at 1 mM. Among them, the most active compound, 3-methyl-1-(2,3,4-trifluorophenyl)pyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione (2o), was as active as the positive controls, the commercial herbicides clomazone and flumioxazin. Molecular simulation was performed with molecular docking and DFT calculations. The docking studies provided strong evidence that 2o acts as an herbicide by inhibition of protoporphyrinogen oxidase. However, the physiological results indicate that it does not act on this target in vivo, implying that it could be metabolically converted to a compound with a different molecular target.

Efficacy of the herbicides indaziflam and clomazone on problematic weeds of family poaceae to sugarcane crop

It is believed that indaziflam gives a longer period of weed control compared to clomazone, irrespective of the type or texture of the soil. Thus, the aim of this study was to evaluate pre-emergent control in five problematic weed species of family Poaceae to sugarcane, using the herbicides indaziflam and clomazone in two soils of different textures. Two experiments were carried out, one in a soil of a sandy-loam texture and the other in a clayey soil. For both experiments, a randomised block design of split plots was chosen, with four replications. The treatments consisted of the herbicides indaziflam (75 and 100 g ai ha-1), clomazone (1080 g ai ha-1) and a control with no herbicide. In the subplots, the treatments were Digitaria horizontalis, Panicum maximum, Rottboellia cochinchinensis, Urochloa decumbens and Urochloa plantaginea. Both herbicides were more effective in the clayey soil, but with indaziflam (100 g ai ha-1), more than 90% control of the weeds remained after 240 days after application (DAA), whereas for clomazone, control remained only up to 90 DAA. The herbicide clomazone did not satisfactorily control the weeds in the sandy-loam soil. The herbicide indaziflam did not control U. decumbens in the sandy-loam soil. D. horizontalis and R. cochinchinensis were the most sensitive species to the herbicide indaziflam, irrespective of soil texture.

Efficacy of the New Herbicide Clomazone Against Weeds in Potato (Solanum tuberosum L.), Its Effect On Quality and Its Residues in Tubers and Soil

Efficacy of the New Herbicide Clomazone Against Weeds in Potato (Solanum tuberosum L.), Its Effect On Quality and Its Residues in Tubers and Soil

Glycoalkaloids in leaves and potato tubers depending on herbicide application with biostimulants

The aim of the study was to determine the influence of herbicide application with biostimulants on total glycoalkaloid (TGA) content in potato leaves and tubers. The study was based on a two-factor field experiment established in a split-plot arrangement in three replications. The factors were as follows: factor I – two cultivars of edible potato – Oberon and Malaga; factor II – five methods of using herbicide and biostimulants: 1. control object; 2. herbicide clomazone + metribuzin (Avatar 293 ZC); 3. herbicide clomazone + metribuzin and biostimulant PlonoStart; 4. herbicide clomazone + metribuzin and biostimulant Aminoplant; 5. herbicide clomazone + metribuzin and biostimulant Agro-Sorb Folium. The herbicide clomazone + metribuzin significantly increased the concentration of glycoalkaloids in potato leaves, and the herbicide used together with the biostimulant Aminoplant significantly reduced the content of TGA in potato leaves compared to the control. The herbicide whether applied with the biostimulants (PlonoStart, Aminoplant, Agro-Sorb Folium) contributed to a reduction in the concentration of glycoalkaloids in tubers compared to the control. Leaves and tubers of the cultivar Malaga were characterised by a significantly lower TGA content than the cultivar Oberon.

Detection of Herbicide Clomazone in Freshwater Teleost by Using HPLC Method

Clomazone is widely used in cotton, soybean, tobacco and rice fields to control broadleaf weeds. The present study shows the accumulation of the herbicide clomazone in the tissues of the non-target organism, i.e. the fish Channa punctatus. After determining the LC50 of clomazone, different dosages for treating the fish with the herbicide were calculated. The fish were treated with three different concentrations, i.e. treated with high (0.5 ppm), mild (0.25 ppm) and low (0.08 ppm) doses of the herbicide. The fish were exposed to the three concentrations for 28 days and were sacrificed after 7, 14, 21 and 28 days. The herbicide clomazone was detected and quantified in gills, kidneys and liver extracted from fish by HPLC using the mobile phase (methanol:water) at a flow rate of 1 ml/min measured at 220 nm. This study gave an RSD of less than 1%, reflecting the accuracy of the method. The standard curve was linear in the range of 0.1 to 0.006 ppm. The detection and determination limits were 0.004 and 0.015 ppm, respectively. The study showed that gill accumulation of clomazone occurs after each fixed interval and at each dose. In contrast, kidney and liver only showed dose independent accumulation after prolonged exposure.

Do phytoplankton and epiphyton communities differ between organic and conventional rice fields?

This study aimed to determine if there are any differences in the attributes and composition of the phytoplankton and epiphyton communities between organic (OF) and conventional (CF) rice fields. We also strove to identify if there were any variations in these communities by comparing samples taken from two different periods (12 and 35 days) after the application of the herbicide clomazone and penoxsulam in CF. The farms are located in the Pampa Biome, Southern Brazil. Phytoplankton samples from the subsurface water and epiphyton samples from the rice stems were analyzed using the Utermöhl method. The CF and OF had distinct environmental conditions (pH, conductivity, and turbidity values), and the residual concentration of the herbicides decreased over time. There were no significant differences in epiphyton and phytoplankton density, or in phytoplankton richness, between the rice fields; only the epiphyton richness and taxonomic composition showed differences between the rice fields. Cyanobacteria and Chlorophyceae comprised a large proportion of the epiphytic density in CF and OF, respectively. However, Bacillariophyceae and Chlorophyceae had greater phytoplankton densities in CF and OF, respectively. The taxonomic composition of communities should be considered an effective tool to show the differences between the two cultivation systems.

Dynamics of Clomazone Formulations Combined with Sulfentrazone in Sugarcane (Saccharum spp.) Straw

Herbicide formulations can alter the herbicide performance, affecting the application safety and weed control efficiency. Thus, the objective of this work was to compare the dynamics of clomazone herbicide applied single and combined with sulfentrazone on sugarcane (Saccharum spp.) straw. Laminated polypropylene containers filled with sugarcane straw (10 t ha−1) were subjected to two clomazone formulations (microencapsulated and conventional formulations; 1200 g ha−1) applied single or combined with sulfentrazone (600 g ha−1) with four replications, and the experiment was duplicated. The application was performed indoors with an automated sprayer. After application, accumulated rainfall depths (0, 5, 10, 20, 50, and 100 mm) on the treated containers were simulated soon after the herbicide applications, and the percolated waters were subsequently collected for herbicide quantification by chromatography and mass spectrometry (LC-MS/MS). The microencapsulated formulation of clomazone applied single or combined with sulfentrazone enabled the recovery of higher quantity of clomazone (>80%), with the advantage that a large percentage remained encapsulated (>70%), thus decreasing losses and increasing the product efficiency. The 30 mm simulated rainfall efficiently carried the clomazone herbicide when its microencapsulated formulation was applied, whereas its conventional formulation required higher rainfall depths (60 mm). Sulfentrazone was easily carried through the sugarcane straw by the rainfall depths when it was combined with clomazone, regardless of the clomazone formulation. The clomazone formulation affect the percolation dynamics of this herbicide through the sugarcane straw.

Crop residue and rainfall timing effect on pre-emergence herbicides efficacy using different spray nozzle types

Weed control success with pre-emergence (PRE) herbicides is affected by environmental factors including rainfall and plant residue. Two greenhouse experiments were conducted to evaluate PRE herbicide efficacy against johnsongrass [Sorghum halepense (L.) Pers.], prickly sida (Sida spinosa L.) and velvetleaf (Abutilon theophrasti Medik.). One experiment investigated herbicide efficacy under two crop residue amounts (2500 and 5000 kg ha−1) and the second examined herbicide efficacy influenced by simulated rain at two, four, and eight days after application (DAA). Five herbicides (pendimethalin, metribuzin, clomazone, imazethapyr and pyroxasulfone) and four nozzles types (XR, ULD, TTI and TTI60) were used. Nozzle type did not affect weed control across residue levels. Pendimethalin better controlled S. halepense under the low residue level. Imazethapyr efficacy for S. spinosa and A. theophrasti increased under high residue level. Imazethapyr applications for S. spinosa and A. theophrasti control were more effective when sprayed with the TTI nozzle regardless of rainfall timing. Longer periods without rain after application improved pendimethalin efficacy against S. spinosa and A. theophrasti, while pyroxasulfone better controlled S. spinosa with rain two DAA. Metribuzin and clomazone provided the best weed control among herbicides for all residue levels and rainfall scenarios.

Synthesis, Crystal Structure, Herbicidal Activity, and SAR Study of Novel N-(Arylmethoxy)-2-chloronicotinamides Derived from Nicotinic Acid.

Nicotinic acid, also known as niacin, is a natural product, which is widely found in plants and animals. To discover novel natural-product-based herbicides, a series of N-(arylmethoxy)-2-chloronicotinamides were designed and synthesized. Some of the new N-(arylmethoxy)-2-chloronicotinamides exhibited excellent herbicidal activity against Agrostis stolonifera (bentgrass) at 100 μM. Compound 5f (2-chloro-N-((3,4-dichlorobenzyl)oxy)nicotinamide) possessed excellent herbicidal activity against Lemna paucicostata (duckweed), with an IC50 value of 7.8 μM, whereas the commercial herbicides clomazone and propanil had values of 125 and 2 μM, respectively. The structure-activity relationships reported in this paper could be used for the development of new herbicides against monocotyledonous weeds.

Adsorption behaviour of clomazone on inorganic and organically modified natural montmorillonite from Bogovina (Serbia)

AbstractThe adsorption behaviour of the herbicide clomazone on inorganic and organically modified montmorillonite from the Bogovina deposit in Serbia was investigated. Montmorillonite was modified first with NaCl and then with organic complexes such as hexadecyltrimethylammonium bromide (HDTMA) and phenyltrimethylammonium chloride (PTMA). Changes in the surface properties and morphology of the montmorillonite before and after the modification with various concentrations of organic complexes were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Adsorption of clomazone on all examined samples was investigated using the batch adsorption method. Montmorillonite modified with HDTMA-bromide displayed greater uptake of the clomazone compared to the PTMA-montmorillonite, and both organically modified montmorillonites displayed greater uptake of the herbicide compared to the inorganic montmorillonite. Comparing the Freundlich coefficient and maximum adsorbed clomazone quantity values obtained by Langmuir model, the levels of adsorption of clomazone decreased in the following order: HDTMA-montmorillonite with 1.00 cation-exchange capacity (CEC) saturation > HDTMA-montmorillonite with 0.75 CEC saturation > PTMA-montmorillonite with 1.00 CEC saturation > PTMA-montmorillonite with 0.75 CEC saturation > HDTMA-montmorillonite with 0.50 CEC saturation > HDTMA-montmorillonite with 0.25 CEC saturation > PTMA-montmorillonite with 0.50 CEC saturation > PTMA-montmorillonite with 0.25 CEC saturation > Na-montmorillonite > raw sample. The type and content of an organic cation plays an important role in the behaviour of clomazone in a solid/liquid system. It is concluded that organically modified montmorillonite from Bogovina might be used as an effective adsorbent for clomazone.

Lixiviação de diferentes formulações de clomazone em resíduos de cana-de-açúcar

O objetivo do presente estudo foi avaliar a lixiviação de diferentes formulações de clomazone em função da densidade da palhada e diferentes lâminas de irrigação. Os experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial 2 x 6, com quatro repetições. O experimento I utilizou dois herbicidas Gamit (1.260 g ha-1 de clomazone) e Gamit 360 CS (1.260 g ha-1 de clomazone microencapsulado), seis densidades de palhada (0, 5, 10, 15, 20, 25 t ha-1). Para o experimento II utilizou-se dois herbicidas Gamit (1.260 g ha-1 de clomazone) e Gamit 360 CS (1.260 g ha-1 de clomazone microencapsulado), seis lâminas de irrigação (5, 10, 15, 20, 25 e 30 mm). Realizou-se avaliações visuais da porcentagem de intoxicação aos 7, 14, 21 e 28 dias, a matéria seca foi determinada aos 28 dias. A porcentagem de intoxicação em solos contaminados com lixiviado de herbicida em diferentes densidades de palhada (0 e 5 t ha-1) se manteve iguais para os herbicidas clomazone na formulação convencional e microencapsulada. Todavia, quando em formulação microencapsulado observou-se nível de intoxicação entorno de 90% demonstrando a capacidade que este tem para transpor acamada de palhada. O incremento da lâmina de água proporcionou a maior transposição do herbicida pela barreira física imposta pela palha, o que refletiu no incremento da porcentagem de controle. Concluiu-se que a lixiviação do clomazone quando em formulação microencapsulada é maior que em formulações convencionais, independente da barreira física imposta pela palhada e pela lâmina de água aplicada.

Tolerance of cassava to postemergence herbicides and determination of residues in the roots

Assessing the tolerance of cassava to herbicides is essential for the development of weed management programs. Nevertheless, this assessment must include analyses of herbicide residues in the food so as to guarantee safety to the final consumer. Thus, this study evaluates the selectivity of cassava to different herbicides and quantifies pesticide residues in cassava roots ( Manihot esculenta Crantz). The experimental design was randomized blocks with four replicates. The treatments were: control; mechanical weeding; bentazon (900 g a.i. ha -1 ); mesotrione (120 g a.i. ha -1 ); and imazethapyr (100 g a.i. ha -1 ), applied in postemergence. We used the herbicides clomazone (1080 g a.i. ha -1 ) and fluazifop (125 g a.i. ha -1 ) in pre-emergence and postemergence, respectively, in all treatments. Throughout the crop cycle, we assessed the following: cassava intoxication at 10, 20, and 30 days after the application (DAA) of postemergence herbicides; and plant height and stem diameter at 30 DAA. At the end of the crop cycle, we assessed the following: number of roots per plant; root length and diameter; root yield (kg/ha); starch content (%); and pesticide residues in cassava roots (multiresidue method). Despite its high phytotoxicity in the early development of cassava, mesotrione shows high selectivity and viability for weed control in this crop since, in general, it did not impair the other yield variables. Moreover, the study identified clomazone and sulfentrazone residues in cassava, indicating root contamination and high persistence of these herbicides in the environment.

Selectivity of pre-emergent herbicides in bird’s-foot trefoil crops

Competition with weeds and lack of selective herbicides registered for bird’s-foot trefoil crops affect their development and limit productivity. Therefore, this study aimed at evaluating selectivity of pre-emergent herbicides in bird’s-foot trefoil crops. Experiments were carried out in a greenhouse and on a field where the following herbicides were evaluated and compared with the control: imazethapyr, diclosulam, flumetsulam, metribuzin, s-metolachlor, sulfentrazone, clomazone and isoxaflutole. Regarding variables under evaluation, phytotoxicity (PHYTO), plant stature, dry mass of the aerial part (DMAP) and dry mass of roots (DMR) were evaluated in the greenhouse, while plant population, PHYTO and DMAP were assessed on the field. The criterion to determine selectivity were: PHYTO below 15% and not reducing the plant population nor morphological variables, by comparison with the control. The variables were negatively affected by the herbicides clomazone, metribuzin, isoxaflutole, diclosulam, s-metolachlor, in which the crop population was reduced in 98, 92, 83, 63, 48 and 22%, respectively. Following the criteria, only the herbicide sulfentrazone as a pre-emergente is selective to bird’s-foot trefoil crop (cultivar ‘Sao Gabriel’).

Contaminação dos recursos hídricos por agrotóxicos na região central do Rio Grande do Sul, Brasil

O aumento na utilização de agrotóxicos na agricultura pode trazer graves consequências ao meio ambiente e à saúde da população, que consumir alimentos e água com resíduos de tais substâncias. Desta forma, o presente estudo buscou avaliar a presença e a concentração de agrotóxicos na água para consumo humano e, com isso, compreender os riscos à saúde que a população do município de Cachoeira do Sul está submetida. A metodologia consistiu na coleta e análise de amostras de água, em cinco épocas do ano, entre agosto de 2017 a março de 2018, sendo realizadas duas coletas de água tratada (na estação de tratamento e numa instituição de ensino) e uma de água do rio Jacuí, que abastece a cidade, sendo um total de 15 amostras. As amostras foram submetidas a análise por extração em fase sólida e cromatografia gasosa e líquida acoplada a espectrometria de massas. Os resultados mostraram a presença de resíduos de agrotóxicos em todas as amostras, com período crítico para contaminação entre fevereiro e março. No total, foram identificados 18 princípios ativos de agrotóxicos nas amostras de água, sendo o inseticida imidacloprido o de maior incidência e concentração, seguido pelos herbicidas clomazone e quincloraque. Os poluentes analisados persistiram mesmo após o tratamento da água, expondo a população aos riscos potenciais pela ingestão diária destes componentes. Medidas que promovam a remoção destes compostos na água, bem como alternativas ao modelo agrícola convencional precisam ser desenvolvidas e ampliadas, para promover a redução ou eliminação do uso dos agrotóxicos e proteção da saúde e meio ambiente.

BIOCARVÃO COMO ATENUANTE DA FITOTOXICIDADE DE HERBICIDAS EM MUDAS PRÉ-BROTADAS DE CANA-DEAÇÚCAR

O objetivo deste trabalho foi avaliar o efeito do biocarvão na sensibilidade de mudas pré-brotadas (MPB) ao clomazone, imazapic e indaziflam aplicados em pré-plantioisoladamente ou em associação. Foram avaliadas duas variedades de cana-de-açúcar (RB975952 e RB 985476). O delineamento experimental foi inteiramente casualizado com 4repetições, em esquema fatorial 9 x 2, sendo nove tratamentos (imazapic 52,5 e 200 g i.a. ha-1, clomazone 1000 g i.a. ha-1, indaziflam 100 g i.a. ha-1 e associações de imazapic +clomazone (52,5 + 600; 52,5 + 1000; 200 + 600 e 200 + 1000 g i.a. ha-1 e testemunha) e apresença ou ausência do biocarvão no sulco de plantio. A RB 985476 apresentousensibilidade aos herbicidas clomazone e imazapic. A toxicidade provocada pelosherbicidas imazapic + clomazone diminiu pelo efeito do biocarvão. Para o imazapic nãohouve efeito do biocarvão na redução da fitotoxicidade. Em relação a RB 975952 foiverificada sensibilidade ao clomazone + imazapic e clomazone isolado, sendo o biocarvãoeficaz na redução da fitotoxicidade. O indaziflam foi seletivo para as duas variedades. Podese concluir que o biocarvão atuou de forma efetiva para clomazone isolado ou emassociação com o imazapic, sendo pouco efetivo para o herbicida imazapic isolado.

Phytotoxicity in two sugarcane cultivars in the initial development as affected by selectivity to herbicides

ABSTRACT Sugarcane is a crop of great importance for human consumption, either for the production of sucrose or for the production of ethanol fuel. The objective of this work was to evaluate the phytotoxicity caused by the herbicides, the agronomic components in two sugarcane cultivars, at five evaluation times, during the 12-month and 18-month cultivation periods. The experimental design was randomized blocks with four replicates, in a 10 x 2 factorial scheme, with nine herbicides (tembotrione, mesotrione, clomazone, saflufenacil, 2,4 dichlorophenoxyacetic, fluroxypyr + picloram, metribuzin, isoxaflutole, sulfentrazone), two sugarcane cultivars (RB006995 and RB036153), and five evaluation times (7, 14, 21, 28 and 35 days after application – DAA). The most phytotoxic herbicides for the 12-month cultivation period in the cultivars RB036153 and RB006995 were clomazone and sulfentrazone. For 18-month cultivation period, the herbicides isoxaflutole, clomazone and sulfentrazone were the most phytotoxic, mainly for the cultivar RB006995. For most herbicides, phytotoxicity decreased along the days after application. The most selective herbicides for both cultivars and cultivation periods were tembotrione, mesotrione and fluroxypyr + picloram.

How the environmental fate of clomazone in rice fields is influenced by amendment with olive-mill waste under different regimes of irrigation and tillage.

Irrigation and tillage systems alone or in combination with organic amendments can strongly influence soil properties, which in turn may also modify the environmental fate of any pesticides applied. This study was aimed at determining how amendment with composted olive-mill waste (W) influenced leaching, sorption, and persistence of the herbicide clomazone in rice field soils under different tillage and irrigation management practices. The field trial conducted covered 3 years in succession, with six treatments: irrigation by sprinkler and conventional tillage without (ST) or with W application (80 Mg ha-1 ) (STW), irrigation by sprinkler but no tillage (SNT), irrigation by sprinkler but no tillage with W application (SNTW), and continuous flooding irrigation and tillage without (FT) and with W application (FTW). Application of W significantly increased the adsorption of clomazone to soil in the first and third years. In the first year, the persistence of clomazone under aerobic (t1/2 =33.1-36.3 days) and anaerobic incubation conditions (t1/2 =3.43-10.8 days) decreased after W application to t1/2 values in the ranges 18.1-29.7 and 3.06-5.44 days, respectively. However, in the third year, although clomazone persistence increased significantly in SNT and ST when W was applied under both incubation conditions, it decreased significantly in FT management under anaerobic incubation conditions. The addition of W led to less leaching of clomazone, particularly for the FT case where the herbicide leaching losses were 2.8 and 2.6 times lower in the first and third years after W addition, respectively. Using W as an organic amendment could be regarded as an invaluable strategy to reduce water contamination by clomazone in rice production, especially under traditional tillage and flooding management. © 2019 Society of Chemical Industry.