Herbicides In Soil Research Articles

Validation and application of a QuEChERS based method for estimation of half-life of imidazolinone herbicides in soils by LC-ESI-MS/MS

A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method was validated and applied for the estimation of half-lives of two imidazolinone group herbicides, imazethapyr and imazapic, in the Dystric Plinthosol (FX) and Ferralsol (LVA) agricultural soils using liquid chromatography tandem mass spectrometry. The solutions were prepared in a matrix extract to avoid matrix effects. The analytical method showed satisfactory specificity, selectivity, linearity (R2 > 0.99), recoveries (range 85.0–117.0%), with RSD between 6.7% and 16.6%, and precision (range 94.7–108.5%), with RSD between 6.0% and 11.9%. The limit of detections for imazethapyr and imazapic in the soils were 2.2 µg kg−1 and 2.0 µg kg−1, and the limit of quantifications were 6.6 µg kg−1 and 6.1 µg kg−1. The half-lives of imazethapyr (35.7 and 97.9 days) and imazapic (40.4 and 64.4 days), in the FX and LVA soils, respectively, indicate that they are medium-persistence herbicides with possibility of leaching into groundwater. In addition, high concentrations of imazethapyr and imazapic were found in the soil samples after the time of application, meaning that there is a potential for prolonged soil residual activity due to carryover.

Changes in sorption and bioavailability of herbicides in soil amended with fresh and aged biochar

Knowledge of long-term pesticide behavior in biochar (BC) amended soil is still contradictory. In this work, we compared the sorption of three highly persistent and ionizable pesticides [two anionic (imazamox and picloram) and one weak base (terbuthylazine)] on both fresh and field-aged BC as well as on a soil amended with these biochars. The aging process was performed by burying the biochar at 10 cm in a silt loam soil [Upper Midwest USA (Wisconsin)] for six months. Field aged BC removed the three pesticides from solution to a higher extent (>85%) than the fresh BC (<16%). This removal was attributed to water-soluble components on the biochar. Laboratory incubation experiments demonstrated that dissipation in soil and biochar mixtures were both a function of pesticide and biochar type. The amounts of soil extractable (i.e, bioavailable) pesticide were inversely related to the extent of sorption. Similar dissipation and sorption of imazamox was observed in unamended and BC-amended soils. Terbuthylazine dissipated similarly in all treatments, but sorption increased with incubation time in the aged BC-amended soil. Conversely, picloram dissipated to a higher extent in aged BC-amended soil when compared to unamended or fresh BC-amended soil. This work demonstrates temporal variability of biochar sorption capacities due to soil exposure, which alters the efficacy and bioavailability of soil applied pesticides.

Contribution to the study of the dynamics of heterocyclic nitrogenated herbicides in soils treated with copper salts

The interaction between the Cu(II) ions and heterocyclic herbicides (triazines and imidazolinones) is studied by electrochemical and spectrophotometric measurements in relation to the environmental consequences of this interaction. The formation of very stable complexes between the herbicides and the metal ions is assessed. Due to the occurrence of acid–base reactions, the stability constants of the complexes were obtained at three pH values for the imidazolinone herbicides and at only in neutral media for triazine herbicides. Imidazolinones form 1:1 complexes in strongly acidic media and 1:2 complexes (one copper ion and two herbicide molecules) in the rest of pH values studied. Triazine herbicides form 1:2 complexes. The complexes formed in the pH range 5–10 (that is, the pH of most soils) are more stable for triazines than for imidazolinones, though in both cases this complex formation increases the low solubilities of the herbicides in water. This can lead to a decrease in the persistence of the herbicides and an increase in the ability of both the herbicides and the Cu(II) ions to reach groundwater and, consequently, to unwanted areas of crops.

Herbicides degradation kinetics in soil under different herbigation systems at field scale

Application of pesticides in agriculture is one of the main sources of soil and water contamination. Herbicides used by herbigation increases the possibility of water and soil contamination by these toxins. Thus, knowledge on degradation of herbicides in soil for selecting more efficient management strategies is necessary. The objective of this study was to quantitatively describe herbicides degradation in soil under different herbigation and conventional spraying systems in actual field conditions. Consequently, Metribuzin was applied to soil by herbigation and conventional spraying via four methods. The degradation kinetics of herbicide was determined by soil sampling of four layers over a period of 70 days. Results indicated that the herbicide degradation kinetics depends on application method and studying scale. Based on these results, at each of soil layer, degradation rate remained constant due to no changes in soil physical and chemical properties and soil moisture conditions during the experiment. In these conditions, degradation trends followed a single first order kinetics model. However, herbicide degradation kinetics at entire soil profile was different depending on application method. Once the herbicide was applied via the first irrigation, large portion of herbicide was leached out to the second, third and fourth soil layers. Owing to roughly similar clay, organic matter, moisture content along with microbial activity and population in these three layers, the degradation rate was constant, during the experiment, and degradation trend followed the single first order kinetics model. However, in other application methods, the degradation rate was inconstant as a result of remaining a large portion of herbicide in the first soil layer, as well as different soil physical, chemical and biological properties of this layer compared to other layers. This contributed to a deviation from first order kinetics. The degradation kinetics was described much better by bi-exponential model.

THE EFFECT OF SOIL HERBICIDES ON NODULE-FORMING ABILITY AND OTHER CONDITIONS FOR SOYBEAN YIELD

The effect of soil herbicides on nodule-forming ability and other conditions for soybean yield isgiven. It has been established that modern soil herbicides, especially Fabian and Prymekstra TZ 500Gold SC were inferior than herbicide Harnes by the efficiency of control of annual cereals and bilobatedshort-living weeds soybean crops. Harnes had a greater negative effect on the formation of the amountand weight of nitrogen-fixing nodules on soybean root than other herbicides. At the same time, the use ofHarnes produced the highest yield of soybeans. Morphological signs of plants and signs of soybeanproductivity depended on the effectiveness of soil herbicides and tolerance of culture to them. There wasno significant effect of soil herbicides on the quality of the cultivated soybean seeds.

Imidazolinone and triazine herbicides in soils in relation to the complexes formed with Cu(II) ions

Imidazolinone and triazine herbicides are used in many countries and may have a great impact on metal biocycles in soil. This article deals with the dynamics of imidazolinone and triazine herbicides in soils related to the formation of complexes with Cu(II) ions, which can be very stable. The stability constants of the complexes formed by five imidazolinone herbicides and ten triazine herbicides with Cu(II) ions are determined by means of fast, easy, and inexpensive measurements performed by ultraviolet–visible spectroscopy, for imidazolinones, and voltammetry (cyclic and differential pulse), for triazines. Because of the occurrence of dissociation reactions, the determinations were performed at three pH values for imidazolinones and at one pH value for triazines. In aqueous solutions of 5 < pH < 10 (corresponding to the majority of soils of agricultural use), the herbicides form very stable complexes with the Cu(II) ions, the complexes being integrated by two ligands (herbicides) and one copper ion. In conclusion, crops treated with such herbicides in conjunction with Cu(II) salts experience a decrease in its persistence and effectiveness. In addition, the herbicides and the copper ions may pass to the phreatic layer of the soil, increasing the chance of pollution.

Degradation of atrazine and structurally related s-triazine herbicides in soils by ferrous-activated persulfate: Kinetics, mechanisms and soil-types effects

The occurrence of s-triazine herbicides in soils and groundwaters has been reported globally and remediation of these contaminated sites are essentially imperative, especially at accidental spill sites. Present work investigated the feasibility of using Fe2+ catalyzed persulfate (PS) to effectively degrade s-triazine herbicides (e.g., atrazine (ATZ), terbuthylazine (TEA) and ametryn (AMT)) in soils. The degradation kinetics, mechanisms and soil-types effects were systematically investigated. For arable soil A1, extent of degradation reached 80% for 100 mg kg−1 ATZ contaminated soil after 600 min (PS/Fe2+ of 16.6 mM/16.6 mM) at 23 °C. Increasing PS and Fe2+ dosages could enhance ATZ degradation. Acidic condition was favorable for the degradation of ATZ with Fe2+/PS process and the contribution of SO4− to the overall degradation of ATZ decreased as initial pH increased. The ethyl group and chloride substituent on molecular structure of ATZ affected its degradation comparing to other two s-triazine herbicides. ATZ degradations in two arable soils and one paddy soil indicated that different soils with various physical-chemical properties, such as soil organic matter, available and total Fe contents, may influence the ATZ degradation. Moreover, a total of five degradation products of ATZ were identified in soil A1 by Fe2+/PS process. Three degradation pathways including alkyl chain oxidation, dealkylation and dechlorination-hydroxylation reactions with the underlying oxidation mechanisms were tentatively proposed.

Time and temperature dependent adsorption-desorption behaviour of pretilachlor in soil

Understanding and quantifying the adsorption-desorption behaviour of herbicide in soil is imperative for predicting their fate and transport in the environment. In the present study, the effect of time and temperature on the adsorption–desorption behaviour of pretilachlor in soils was investigated using batch equilibration technique. The adsorption–desorption kinetics of pretilachlor in soils was two step process and was well described by pseudo-second-order kinetic model. Freundlich model accurately predicted the sorption behaviour of pretilachlor. The adsorption–desorption of pretilachlor varied significantly with the concentration, temperature and properties of soil viz. organic matter and clay content. All the studied soils had non-linear slopes (n < 1) and degree of nonlinearity increased with increase in clay, organic matter content and temperature (p < 0.05). Desorption of pretilachlor was hysteretic in studied soils and hysteresis coefficient varied from 0.023 to 0.275. Thermodynamic analysis showed that pretilachlor adsorption onto soils was a feasible, spontaneous and endothermic process which becomes more favourable at high temperature. It could be inferred that the adsorption of pretilachlor on soils was physical in nature.

Preparation of a monolithic magnetic stir bar for the determination of sulfonylurea herbicides coupled with HPLC

A hybrid material of metal organic frameworks (MOFs) and monoliths was developed and used for stir bar sorption extraction (SBSE) of five sulfonylurea herbicides. It was prepared in a glass tube (4 mm I.D.) by thermal polymerization using modified neodymium supermagnetic (Nd2Fe14B) powders as the component substrates, the organic polymerization solutions and ethyl cellulose as the adhesion agent. The prepared stir bar was characterized by scanning electron micrography (SEM) and X-ray diffraction (XRD). It was successfully applied for the determination of sulfonylurea herbicides in soil and lake water samples coupled with high-performance liquid chromatography (HPLC). The extraction and desorption factors affecting the performance of sulfonylurea herbicides were evaluated in detail. Under the optimum conditions, the extraction efficiency of the hybrid stir bar was obviously higher than the blank stir bar without UIO-66(Zr)-NH2. Linear ranges were 10–700 μg/L for thifensulfuron-methyl (TIM), amidosulfuron (AS) and metsulfuron-methyl (MSM) and 10–800 μg/L for sulfosulfuron (SSF) and tribenuron-methyl (TBM), respectively. The obtained detection limits were in the ranges of 0.04–0.84 μg/L with the recoveries of 68.8–98.1% for the real samples. The novel stir bar possessed excellent advantages of both supermagnetic performance and large specific surface areas in the presence of MOFs and monoliths, which was potentially an optimal adsorbent for environmental analysis.

Assessing the Effects of Alloxydim Phototransformation Products by QSAR Models and a Phytotoxicity Study.

Once applied, an herbicide first makes contact with leaves and soil. It is known that photolysis can be one of the most important processes of dissipation of herbicides in the field. However, degradation does not guarantee detoxification and can give rise to byproducts that could be more toxic and/or persistent than the active substance. In this work, the photodegradation of alloxydim herbicide in soil and leaf cuticle surrogates was studied and a detailed study on the phytotoxicity of the main byproduct on sugar beet, tomato, and rotational crops was performed. Quantitative structure–activity relationship (QSAR) models were used to obtain a first approximation of the possible ecotoxicological and environmental implications of the alloxydim and its degradation product. The results show that alloxydim is rapidly degraded on carnauba and sandy loam soil surfaces, two difficult matrices to analyze and not previously studied with alloxydim. Two transformation products that formed in both matrices were identified: alloxydim Z-isomer and imine derivative (mixture of two tautomers). The phytotoxicity of alloxydim and the major byproduct shows that tomato possesses high sensitivity to the imine byproduct, while wheat crops are inhibited by the parent compound. This paper demonstrates the need to further investigate the behavior of herbicide degradation products on target and nontarget species to determine the adequate use of herbicidal products to maximize productivity in the context of sustainable agriculture.

The effect of antibiotics on the persistence of herbicides in soil under the combined pollution

Antibiotic contamination in agricultural lands through manure application causes changes in soil enzyme activity and the abundance of microbes, which may affect the fate of agrochemicals. A clear understanding of antibiotic–pesticide interactions is very limited. The objective of this study was to investigate the effect of oxytetracycline (OTC) on the persistence of triazine and chloroacetanilide herbicides in soil under a combined application scenario. Soil enzyme activity and the abundance of soil microbes disturbed by OTC were measured. The results showed that OTC inhibited the dissipation of the herbicides and the effect depended on OTC concentration. For example, the half-lives of acetochlor increased from 6.9 days to 21.6 days with the presence of OTC at 50 mg/kg. It was also found the dissipation of the herbicides would still be affected after a month of OTC exposure at high concentration. Co-application also decreased activity of soil urease, dehydrogenase and catalase during earlier incubation periods, then recovered gradually. Furthermore, OTC reduced the abundance of fungi and bacteria, which might relate to inhibition of herbicide dissipation. Co-application of antibiotics and herbicides resulted in greater herbicide persistence, possibly increasing risk of environmental contamination.

Biochar impact on herbicides behavior in the soils: an approach in Brazil

A aplicação de biochar (biocarvão) em solos por causa dos efeitos benéficos é comprovada por muitos pesquisadores internacionais e isto pode aumentar a sorção dos herbicidas e reduzir a eficácia destes no manejo das plantas daninhas. Impactos positivos são relatados em relação ao comportamento ambiental dos herbicidas, pois o aumento da sorção reduz a lixiviação destes produtos para as águas subterrâneas. Impactos negativos são relatados em relação ao manejo agronômico dos herbicidas, pois o aumento da sorção reduz a disponibilidade destes produtos no solo, diminuindo o efeito residual para o controle das plantas daninhas. No Brasil, o biochar é produzido por várias empresas privadas e unidades de pirólise, entretanto, o custo para produção ainda é muito alto, provavelmente por falta de incentivo do governo, baixo uso dos produtores e consciência dos benefícios. Embora o biochar seja utilizado há várias décadas em outros países, no Brasil ainda há poucos estudos desenvolvidos por pesquisadores na área de solos, e a eficiência do biochar na biodisponibilidade de herbicidas no solo ainda é desconhecida por muitos pesquisadores brasileiros na área de plantas daninhas. Diante do exposto, o objetivo desta revisão foi avaliar a biodisponibilidade de herbicidas em solos modificados com biochar e destacar a pesquisa com biochar em condições brasileiras, além de apresentar os benefícios ao solo com a adição do biochar. Pouco se sabe sobre o comportamento de herbicidas em solos brasileiros modificados com biochar, que pode ser utilizado com maior intensidade na agricultura moderna. Então, mais pesquisas são necessárias sob nossas condições para realmente entender a dinâmica deste produto no solo.

Experimental methods to evaluate herbicides behavior in soil

O uso de agrotóxicos na agricultura é praticamente indispensável, contudo, estudos estimam que somente 45% do produto aplicado atinge a cultura, sendo que aproximadamente 30% sofrem deriva, 10% são perdidos por algum processo de transporte (lixiviação, volatilização e escoamento) e 15% atingem o solo. Além disso, do total aplicado, apenas 1% atinge o alvo, ou seja, patógenos, plantas daninhas e insetos. Embora avaliações de riscos de contaminação ambiental de agrotóxicos sejam obrigatórios para o registro e comercialização, frequentemente estudos relatam a presença destes em locais não alvos, sendo os corpos de água os principais prejudicados. Vários processos biológicos, físicos e químicos determinam o destino ambiental e a eficiência desses. Assim, diversos métodos experimentais podem ser utilizados para avaliar o comportamento de agrotóxicos no ambiente. Essa revisão objetiva resumir os métodos mais comumente utilizados para descrever e avaliar os processos nos quais o herbicida está sujeito quando presente no solo, bem como, as vantagens e desvantagens de cada um desses. No geral, em se tratando de destino de agrotóxicos no ambiente, os experimentos em laboratórios fornecem informações mais precisas, pois é possível controlar melhor as condições ambientais e isolar fatores de interesse. Mas é importante salientar que não existe um método mais eficiente, o que existe são métodos que podem fornecer um melhor resultado em determinada situação. Por tanto, a escolha do método vai depender do objetivo do estudo e da estrutura disponível.

Reliable analysis of chlorophenoxy herbicides in soil and water by magnetic solid phase extraction and liquid chromatography

There is no previous work on the determination of chlorophenoxy acid herbicides in soils. Here we analysed six chlorophenoxy acid herbicides using magnetic solid phase extraction for their preconcentration, then liquid chromatography and tandem mass spectrometry with a triple-quadrupole (LC-QqQ-MS/MS) in the multiple reaction monitoring mode. 40 mg of CoFe2O4@polypyrrole magnetic nanoparticles was added to a 30-mL sample, and vortex stirring was applied for 10 min. Analytes were desorbed using acidified methanol. The reliability of the results was validated through recovery assays, giving mean values in the 80–117 range. The intraday precision was in the 6.3–14% range, in terms of relative standard deviation.

Tebuthiuron leaching in three Brazilian soils as affected by soil pH

Underground contamination water by herbicides depends on the interactions between their molecules with physical and chemical soil characteristics and climatic conditions. Studies with columns can estimate the leaching potential of herbicides in soils. This study aimed to determine the effect of soil pH on tebuthiuron leaching, and capacity of bioindicators to detect tebuthiuron residues in three Brazilian soils. Cucumber plants (Cucumis sativus) were more negatively affected when grown in soils with lower amounts of organic matter and clay, and in these soils, the tebuthiuron levels reached greater depths in the column. There was a positive correlation between tebuthiuron concentration and cucumber intoxication, and a negative correlation between tebuthiuron concentration and dry matter cucumber in all soils. The tebuthiuron leached up to 50 cm depth even in soils with higher organic matter and clay content. The increasing of soil pH can affect the leaching of nonionic herbicides, and liming practice may elevate the environmental contamination risk by tebuthiuron. The bioindicator method using Cucumis sativus is viable and can be recommended to detect tebuthiuron concentrations above 0.2 mg kg−1.

Hydrolysis, adsorption, and biodegradation of bensulfuron methyl under methanogenic conditions

Bensulfuron methyl (BSM), one of the most widely used herbicides in paddy soils, is frequently detected in natural and artificial aquatic systems. However, BSM transformation under methanogenic conditions has not been given sufficient attention. In this study, BSM elimination and transformation by anaerobic enrichment cultures were investigated. The results showed that BSM can be mineralized to methane through hydrolysis, adsorption, and biodegradation under a methanogenic environment. The adsorption led to protein static quenching in the extracellular polymeric substances (EPSs) of the enrichment cultures. Specifically, BSM mainly reacted with the amine, amide, amino acid, and amino sugar functional groups in proteins. BSM hydrolysis and biodegradation occurred through the breakage of the sulfonylurea bridge and sulfonyl amide linkage. The cleavage of the sulfonylurea bridge occurred in both hydrolysis and biodegradation, while the cleavage of the sulfonyl amide linkage only occurred in hydrolysis. These results elucidated the complex transformation of BSM under methanogenic conditions, which will advance the studies on sulfonylurea herbicide biotransformation and hazard assessment in the environment.

Rhizoremediation of residual sulfonylurea herbicides in agricultural soils using Lens culinaris and a commercial supplement

ABSTRACTSulfonylureas (SU) are a popular herbicide used today for controlling weeds. While beneficial for this purpose they present a persistent problem in agricultural treated areas, with this treatment proving detrimental for successive crops. This study assessed the phytoremediative properties of lentils (Lens culinaris) grown in uncontaminated and chlorsulfuron-contaminated soil, with and without the addition of a growth supplement, PulseAider™. The results show that in the presence of lentils the degradation of chlorsulfuron is enhanced and this degradation rate is significantly increased when the PulseAider™ supplement was included during seed sowing. The supplement PulseAider™ also significantly increased shoot and root biomass, root branching, and nodule number under control conditions. While this was not so for plants grown in contaminated soils, the PulseAider™ supplement seemed to alter root branching and morphology. Most Probable Number (MPN) assays showed increased numbers of potential chlorsulfuron-degrading bacteria in soil treated with PulseAider™, although this was found to be significant only in the control soil. Sequencing of the 16S ribosomal gene showed the presence of Pseudomonas fluorescens bacterial species which is a known chlorsulfuron-degrading bacterium. This study is one of the first to address the remediation of residual SU herbicides and offers an economically feasible solution that may have an impact on global food security.

Dissipation and fate of ready mix combination of pyrazosulfuron-ethyl and pretilachlor in rice field

Application of ready-mix herbicides containing two active ingredients in rice to manage broad group of weeds is in practice currently. Among different ready mix formulations, one comprising pyrazosulfuron-ethyl and pretilachlor have been recently registered in India. Though, the persistence of each herbicide in soil under rice as single formulation was reported, the information on persistence of herbicides from ready-mix formulations is not reported under semi-arid tropical conditions of India. Hence, an experiment was conducted to study the dissipation and fate of these ready-mix formulation herbicides in rice soil, water and in rice grain. Pyrazosulfuron-ethyl and pretilachlor residues were determined using high performance liquid chromatograph (HPLC) and gas chromatograph (GC), respectively. The average recoveries of pyrazosulfuron-ethyl and pretilachlor from matrix ranged from 80.3–103.3% with less than 10% standard deviation and sensitivity up to 0.001 μg/g. Both herbicides showed rapid dissipation in rice field water than soil and the degradation followed first order reaction kinetics. While pyrazosulfuron-ethyl dissipated with a half-life of 2.17–5.45 and 0.77–0.79 days respectively in rice field soil and water, pretilachlor dissipated with a half-life of 5.18–6.68 days in soil and 2.59–3.00 days in field water. Pyrazosulfuron-ethyl has shorter half-life than pretilachlor and both the active ingredients dissipated rapidly in rice field soil than water. At harvest, the residues of both the herbicides in rice grain and straw were below the MRLs set by FSSAI.

ВЛИЯНИЕ ПЛОДОРОДИЯ ПОЧВЫ, УДОБРЕНИЙ И ГЕРБИЦИДОВ НА УРОЖАЙНОСТЬ И КАЧЕСТВО ЗЕРНА ОЗИМОЙ ПШЕНИЦЫ ПО РАЗЛИЧНЫМ ПРОПАШНЫМ ПРЕДШЕСТВЕННИКАМ

ВЛИЯНИЕ ПЛОДОРОДИЯ ПОЧВЫ, УДОБРЕНИЙ И ГЕРБИЦИДОВ НА УРОЖАЙНОСТЬ И КАЧЕСТВО ЗЕРНА ОЗИМОЙ ПШЕНИЦЫ ПО РАЗЛИЧНЫМ ПРОПАШНЫМ ПРЕДШЕСТВЕННИКАМ

Kvantifikacija depozita zemljišnog herbicida i redukcija drifta u vetrovitim uslovima

Kvantifikacija depozita zemljišnog herbicida i redukcija drifta u vetrovitim uslovima