Persistence Of Herbicides In Soil Research Articles

Behaviour of ionic herbicides in different forestry soils derived from volcanic ash

Background: Weed control has been one of the most significant factors in forest establishment practices that can improve biomass production, and herbicides represent the most effective and convenient way to control weeds. The environmental concern about herbicides in this industry is because the herbicide-treated area is often located near water reservoirs or areas where rivers and creeks originate. This study aimed to determine the adsorption and degradation behaviours of seven ionic herbicides used in forestry production in five Chilean forestry soils and their relation to the leaching and to generate information to validate environmental predictive models. Methods: Adsorption and degradation of ionisable herbicides such as simazine, terbuthylazine, hexazinone, metsulfuron-methyl, indaziflam, flazasulfuron and glyphosate were studied in Andisol, Ultisol, Inceptisol, Entisol and Alfisol forestry soils, to be related to their leaching in 100-cm high and 11-cm diameter soil disturbed lysimeters. Herbicides were quantified using high-pressure liquid chromatography and gas chromatography. Relationships between soil physicochemical properties, herbicide adsorption and degradation, and herbicide leaching were determined. Results: In decreasing order, the herbicides were mobile in Entisol>Alfisol>Ultisol>Inceptisol>Andisol soils. On the other hand, the more leachable herbicides, from high to low, were: hexazinone, metsulfuron-methyl, simazine, glyphosate, terbuthylazine, flazasulfuron and indaziflam. The last two herbicides were not detected below 60 cm soil depth. In general, the maximum soil depth herbicide reached and the percentage mass leached up to 90 cm soil depth were inversely related to soil adsorption (1/Kd), soil porosity, humidity, silt, aluminium, and calcium soil content. Herbicide degradations were generally faster than referential published values. Conclusions: The environmental coefficients of ionic herbicides were more related to soil properties than their physicochemical properties. Persistence of herbicides in soil was smaller than that commonly reported in other studies or international databases and soil adsorption averages were generally higher than international reference values. The stronger relationship between ionic herbicide behaviour and forestry soil properties endorses the requirement to determine the environmental herbicides parameters in situ, avoiding using parameters estimated in other soils.

Impact of long-term conservation agriculture induced changes in soil properties on persistence of pendimethalin under different cropping systems

Increasing use of herbicides in modern agriculture poses potential risks of crop phytotoxicity, contamination of land and water resources, and adverse impacts on human and ecosystem health. Apart from climatic conditions and soil properties, agronomic practices can significantly influence the persistence of herbicides in soil. Therefore, we assessed the impact of 13-year conservation agriculture (CA) on soil properties as well as on the fate (persistence and leaching) of pendimethalin herbicide in an alluvial sandy loam soil (Typic Haplustept) in comparison with an intensively tillage-based conventional system. The experiment involved two cropping systems (mungbean (Vigna radiata L.)–wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L.)–wheat as summer and winter crops respectively) and three tillage practices: zero tillage with crop residue retention in both summer and winter seasons (ZT-ZT), conventional tillage in summer and zero tillage with residue retention in winter (CT-ZT) and conventional tillage in both seasons (CT-CT). The adoption of ZT-ZT system resulted in a 24% increase in infiltration rate, 13% greater moisture retention and 69% higher organic carbon content in surface (0–0.05 m) soil over CT-CT. In contrast, under the CT-ZT treatment, only a small change in the above soil properties was observed, which indicated that the benefits associated with CA were negated as soon as the soil was tilled in the subsequent season. In terms of herbicide leaching, under ZT-ZT, a greater fraction (4.1% vs 2.6%) of pendimethalin residues percolated down into the subsurface soil (0.15–0.30 m) than under the CT-CT system, most likely due to greater pore connectivity with the zero-till situation. However, there was a non-significant difference in the overall dissipation of the herbicide from the surface soil (0–0.05 m) under different systems. The field study illustrated that long-term adoption of CA under mungbean–wheat and sorghum–wheat cropping systems can lead to a significant change in soil properties and these in turn can influence the fate of herbicides in soils.

Efeito do Residual de Atrazina e Atrazina + Simazina em Soja

A persistência no solo de herbicidas do grupo das triazinas é dependente de basicamente de condições de precipitação e características do solo. Objetivou-se avaliar o efeito residual de diferentes épocas de aplicação e doses de atrazina e atrazina + simazina para a cultura da soja. Conduziram-se experimentos a campo e casa de vegetação. A campo utilizou-se o delineamento de parcelas subdivididas com quatro repetições, sendo o fator A composto por épocas de aplicação 56, 49, 42, 35, 28, 21 e 14 dias antes da semeadura da soja; e fator B, pelos herbicidas atrazina e atrazina + simazina. Para o experimento em casa de vegetação o delineamento inteiramente casualizados, o fator A foi constituído de doses 0, 570, 1.140, 1.715, 2.285, 2.860, 3.430 e 4.000 g i.a.ha-1; e fator B pelos herbicidas atrazina e atrazina + simazina. A aplicação dos tratamentos foi realizada com pulverizador costal pressurizado por CO2, após a aplicação realizou-se a semeadura da soja. A campo avaliou-se o estande de plantas, fitotoxicidade, estatura, altura de inserção do primeiro entrenó, teor de clorofila e produtividade. Em casa de vegetação foram avaliados fitotoxicidade, estatura de plantas, área foliar e massa seca. Após os dados foram submetidos a análise de variância e quando significativas as medias foram comparadas pelo teste Tukey a 5%. A simulação de residual dos herbicidas atrazina e atrazina + simazina no solo apresentam comportamento similares quanto aos efeitos na soja. No experimento a campo, devido às altas precipitações ocorridas no intervalo entre as aplicações dos herbicidas e a semeadura da soja, não foram observados efeitos fitotóxicos ou redução na produtividade da cultura. Em casa de vegetação, o aumento da dose residual dos herbicidas no solo incrementou os efeitos tóxicos na soja.

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.

Persistence of herbicides in soil

While it is desirable for the chemicals to control weeds during the season of application, it is not desirable for them to persist and affect subsequent crop growth. Factors that determine the length of time herbicides persist fall into three categories: soil factors, climatic conditions, and herbicidal properties. Factors from each category strongly interact with one another. Earn 1 CEU in Integrated Pest Management by reading this article and taking the quiz at www.certifiedcropadviser.org/certifications/self‐study/796.

Proposición de un modelo matemático simple de persistencia de herbicidas en el suelo

El estudio propone un modelo simple de persistencia de herbicidas en el suelo basado en una serie de modificaciones al modelo desarrollado por Walker & Barnes. El modelo que se propone simula la degradación diaria de un herbicida en el suelo, a través del funcionamiento de tres submodelos: a) submodelo que estima la temperatura del suelo, b) submodelo del cálculo del contenido de humedad del suelo y c) submodelo que calcula la degradación del producto. Se entrega una descripción teórica de las modificaciones introducidas al modelo y un detalle del programa computacional en lenguaje BASIC. Se hizo una validación independiente de cada uno de los submodelos modificados y se concluye que todos ellos mejoran su eficiencia de predicción respecto al modelo original. La validación del submodelo de degradación se realizó utilizando información obtenida en campo en dos suelos diferentes de los herbicidas metsulfuron-metil y triasulfuron. Finalmente se concluye que el modelo propuesto sería eficiente en la simulación de la persistencia de estas sulfonilureas en el suelo, utilizando una cinética de primer grado para metsulfuron-metil y una de segundo grado para triasulfuron.

Persistence of metolachlor, atrazine and deethylatrazine in soil and its simulation by deterministic models

Abstract Laboratory and field experiments were carried out on a loam soil and a sandy loam soil to study the persistence of metolachlor, atrazine and deethylatrazine in soil under Spanish conditions of maize cultivation. Herbicide levels in soil were studied for about 90 days at two different soil depths: 0–10 cm and 10–20 cm. Field half‐lives varied from 23 to 57 days for atrazine and from 22 to 42 days for metolachlor in the first layer. The highest deethylatrazine level in the first layer was 8% of the initial atrazine concentration. Maximum concentration in the second layer ranged from 5% to 17% for atrazine, from 3.5% to 31% for metolachlor and from 0.75% to 4.5% for deethylatrazine, in the conditions studied. Results were compared with outputs of two versions of the simulation model LEACHMV3: LEACHP and LEACHA. Laboratory assays were performed at different conditions to determine the atrazine and metolachlor degradation rates and the formation and disappearance rate of deethylatrazine, which were used in the computer programs. LEACHP predicted the herbicide persistence in soil with reasonable accuracy in the studied fields. Values from LEACHA model were also in agreement with the experimental data for these herbicides in one field, but in the other field, under a higher irrigation, this model overestimated the residues of these herbicides in the first layer.

Herbicide dissipation studies in southern forest ecosystems

AbstractResults of research on the movement of hexazinone, imazapyr, picloram, and sulfometuron in first‐order watersheds in the southern United States are presented. Herbicides contaminate surface waters to varying degrees, depending on application rate, method of application, product formulation, and site‐specific characteristics. Highest concentrations are observed in streams in ephemeral pulses during the first three storm events after application. Streamside management zones greatly reduce the amount of herbicide entering streams from forestry applications. Soil persistence of herbicides is highly variable and a function of many site characteristics. Plant residues have been monitored and found to dissipate rapidly, with half‐lives < 40 d.

Persistencia de tres herbicidas en un guineal regado por goteo

Los herbicidas ametryn, diuron y oxifluorfen a la dosis recomendada se la aplicaron a un campo de banano regado por goteo. Las muestras de suelo se recogieron uno, dos, cuatro y ocho meses después de la aplicación inicial. Las muestras recogidas se bioensayaron con pepinillo en el invernadero. La persistencia de estos herbicidas en el suelo se midió a base del peso seco de la planta. Los resultados indican que los pesos se redujeron significativamente cuando crecieron en las muestras de suelo recogidas un mes después del tratamiento con diuron. Sin embargo, no hubo una reducción significativa en peso seco cuando crecieron en las muestras recogidas en un mes después de la aplicación de ametryn y oxifluorfen. Tampoco se notaron reducciones significativas en pesos secos del pepinillo cuando crecieron en las muestras de suelo recogidas durante los períodos de 2, 4 y 8 meses después de los tratamientos de los tres herbicidas. El orden de la persistencia de estos herbicidas en el suelo se estableció así; diuron> ametryn> oxifluorfen. La corta persistencia de estos herbicidas en un campo de banano regado por goteo se confirmó por los resultados de este estudio.

Effects of herbicide‐fertiliser interactions on nitrogen and phosphorus transformations and herbicide persistence in soil

AbstractThe effects of seven herbicides, alone or combined with a commercial compound fertiliser, on nitrogen and phosphorus transformations in soil, were investigated in the laboratory. No significant effect was observed without the fertiliser. When the fertiliser (N:P:K ratio 20:14:14) was applied (2 gkg−1 of soil), asulam markedly reduced nitrification, while increasing the mineralisation of nitrogen; chloridazon, glyphosate, isoproturon and paraquat all prevented the reduction in available phosphate that occurred in the control soil in the first 2 weeks. The rates of degradation of dalapon and isoproturon were greatly reduced in fertilised soil. The importance of these results is discussed in the context of the requirements of registration authorities.

Simulation of herbicide persistence in soil; a revised computer model

AbstractEmpirical equations were used to calculate the moisture content of surface soil from measurements of rainfall and daily maximum and minimum air temperatures. Air temperatures were also used to calculate soil temperatures. There was good agreement between calculated and measured moisture contents and temperatures from Wellesbourne and from some sites in North America. The equations were incorporated into a simulation model for the prediction of herbicide persistence. Results from the model were essentially the same, whether calculated or measured soil moistures and temperatures were used in the calculations.

Soil Persistence of Herbicides for Corn, Sorghum, and Soybeans during the Year of Application

Herbicides used in corn(Zea maysL.), sorghum [Sorghum bicolor(L.) Moench], and soybeans [Glycinemax (L.) Merr.] were applied in the spring and their persistence into late summer was determined during 1974 to 1976. Composite soil samples from the top 5 cm of field plots were taken each August and bioassayed in the greenhouse. Bioassay species used were winter wheat [Triticum aestivumL.) and soybeans for herbicides used in corn and sorghum, and winter wheat and white mustard(Brassica hirtaMoench) for herbicides used in soybeans. Soil persistence of triazine herbicides caused more injury to winter wheat, soybeans, and white mustard than any other class of herbicides tested. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] showed the most soil persistence of the five triazines evaluated. At normal field application rates, herbicides other than the triazines showed little injury to the bioassay plants. Soil persistence of herbicides was further reduced when combinations of reduced rates of each herbicide were utilized. Herbicides used for spring applications in corn showed more soil persistence in August than did the herbicides for sorghum, while herbicides for soybeans generally were least persistent. Postemergence herbicide applications resulted in more injury in bioassay species than preplant incorporated or preemergence applications. Persistence of some herbicides will restrict certain options to the grower such as changing crops in case of crop failure, fall planting of winter wheat, double cropping, or certain crop rotations.

Simulation of herbicide persistence in soil .III. Propyzamide in different soil types

AbstractThe effects of soil temperature and soil moisture content on the rate of degradation of propyzamide in five soils were examined under controlled laboratory conditions. Half‐lives in soils incubated at field capacity varied from 23 to 42 days at 25°C and from 63 to 112 days at 15°C. The variation in half‐life at 25°C and 50% of field capacity was from 56 to 94 days. When the laboratory data were used in conjunction with the relevant meteorological records and soil properties in a computer simulation program, predicted degradation curves for propyzamide in four of the soils in micro‐plots were in close agreement with those observed. Use of the program to predict residues of propyzamide in the fifth soil at crop maturity in a series of field experiments concerned with continuity of lettuce production gave values fairly close to those observed when appropriate corrections were made for initial recoveries.

Simulation of herbicide persistence in soil .II. Simazine and linuron in long‐term experiments

AbstractThe rates of degradation of simazine and linuron were measured in soil from plots not treated previously with these herbicides. Degradation of both compounds followed first‐order kinetics and soil temperature and soil moisture content had a marked effect on the rate of loss. With linuron, half‐lives increased from 36 to 106 days with a reduction in temperature from 30° to 5°C at 4% soil moisture, and from 29 to 83 days at 12% soil moisture. Similar temperature changes increased the half‐life of simazine from 29 to 209 days and from 16 to 125 days at soil moisture contents of 4 and 12% respectively. A computer program which has been developed for simulation of herbicide persistence was used in conjunction with the laboratory data and the relevant meteorological records for the years 1964 to 1968 in order to test the model against previously published field persistence data for the two herbicides. The results with simazine showed a close correspondence between observed and predicted residue levels but those for linuron, particularly in uncropped plots, were satisfactory for limited periods only.

Simulation of herbicide persistence in soil .I. Simazine and prometryne

AbstractThe effects of soil temperature and soil moisture content on the rates of degradation of simazine and prometryne were measured under controlled conditions. The time for 50% disappearance of simazine in a sandy loam soil varied from 37 days at 25°C and 13 % soil moisture to 234 days at 15°C and 7% soil moisture. With prometryne, changes in soil moisture content had a greater effect on the rate of loss than similar changes with simazine. The time for 50% disappearance at 25°C was increased from 30 to 590 days with a reduction in soil moisture content from 14 to 5%. With both herbicides, the rate of degradation increased as the initial herbicide concentration decreased and the data suggest that a hyperbolic rate law may be more appropriate than simple first‐order kinetics. Degradation curves for three separate field applications of the two herbicides were simulated using the laboratory data and the relevant meteorological records in a computer program. A close fit to the observed pattern of loss of incorporated prometryne was obtained, but prometryne surface‐applied was lost rapidly during the first 30–40 days after application. This initial rapid loss could not be predicted by the program. With simazine, the patterns of loss of surface and incorporated treatments were similar, but the simulation model tended to overestimate residue levels. Possible reasons for the discrepancies are discussed.

A Study of the Persistence of Herbicides in Soil

SUMMARY The presence of Tordon SOD and 2,4,5-T in soil reduced emergence and survival of radiata pine (Pinus radiata D.Don) seedlings, the major effect being on survival. Effects of 2,4,5-T disappeared rapidly (within two months of application), whereas some effects of Tordon 50D persisted for at least 6 months. Sterilization of the soil by autoclaving did not delay breakdown of the herbicide, nor did leaching of the soil hasten the decline of its activity. The herbicides affected initial growth of seedlings but older seedlings of radiata pine would suffer little or no damage if planted on sites treated with these herbicides a few months previously.

Persistence of herbicides in soil.

AbstractA survey has been made of some of the physical, chemical and biological interactions that influence the persistence and availability of herbicides applied to the soil. The most important physical interaction between herbicides and soil is considered to be sorption of the pesticide to the soil surface. This influences not only the rate of leaching of the herbicide through the soil and its movement in the vapour phase, but also the rate of chemical and microbial decomposition. An attempt has been made to construct a model for the persistence of some hydrolytically sensitive herbicides to enable their persistence in soils to be deduced from hydrolysis rate‐constants and adsorption data.The formulation used and the method of application of the herbicide to the soil can also have an important influence on its persistence.