The use of pre-emergence herbicides, such as S-metolachlor, has stood out in the management of hard-to-control weed species. Its behavior in the soil, influenced by environmental and physicochemical factors, determines both the efficacy and the safety of weed management. In this context, the aim of this study was to determine the residual effect by bioassay and the degradation of S-metolachlor by high-performance liquid chromatography (HPLC) in two soils (Oxisol and Ultisol). Soil samples were collected from Pato Branco/PR (Oxisol) and Paranavaí/PR (Ultisol), without prior herbicide application. A completely randomized design with a 2 × 10 factorial scheme (two soils and ten application times: 0, 7, 14, 21, 28, 35, 70, 90, and 120 days) was used. The residual effect was analyzed via a Sorghum bicolor bioassay, while degradation was assessed through HPLC. The main parameters included residual half-life (RL50, RL90), dry matter reduction (GR50, GR90), and degradation time (DT50, DT90). In Oxisol, which had higher organic matter and clay content, values were lower (RL50 = 32 days, RL90 = 107 days, GR50 = 28 days, GR90 = 29 days, DT50 = 32 days, DT90 = 106 days) than in Ultisol (DT50 = 53 days, RL50, RL90, GR50, GR90, and DT90 > 120 days). The physicochemical properties of these soils influenced S-metolachlor behavior, primarily due to differences in bioavailability within the soil solution, as reflected in bioindicator species response. While residual effect denotes the duration of herbicide activity, degradation refers to molecular breakdown over time. Both factors are essential for weed management strategies.

The objective of this study was to assess the performance of indaziflam under different soil cover materials in coffee cultivation, focusing on its agronomic efficacy, residual effects, and influence on the weed community. The studies were carried out at two farms: IPACER (sandy clay Oxisol - OXIsc) and Glória (clay Oxisol - OXIcl). Evaluation factors included the application of indaziflam (75 g a.i. ha-1), different soil cover materials (crop debris, organic compost, and bare soil), and the evaluation period was from 30 to 180 d after application (DAA). The agronomic efficacy and residual effect were assessed by injury level, and the indaziflam's residual lifetime (RL50) was estimated using a first-order model. Phytosociological parameters, including absolute and relative frequency, density, abundance, and the importance value index, were evaluated. The results indicated that agronomic efficacy remained above 90% until 120 DAA in all treatments with indaziflam application, with RL50 exceeding 180 days. Weed indices were higher in areas without indaziflam, but treatment similarity analysis revealed that the weed community was primarily influenced by soil type, with a lesser impact from soil cover. Neither crop residues nor organic compost compromised indaziflam efficacy, indicating their suitability for coffee cultivation without the need to increase herbicide doses.

The increasing presence of microplastics (MPs) in agricultural systems may influence the environmental behavior of herbicides by affecting processes such as sorption and desorption, depending on the specific compound involved. This study aimed to evaluate the influence of different MP proportions on the sorption and desorption of three herbicides in soil. Hexazinone, diuron, and S-metolachlor were introduced into soil at concentrations of 0 % (control - unmodified soil), 1, 5, 10, 15, 20, and 100 % (w w-1) MPs, with the addition of 2 g of material (soil or MPs). Sorption and desorption isotherms were determined using the batch equilibrium method, followed by herbicide analysis via high-performance liquid chromatography (HPLC). The results indicated that the presence of MPs altered S-metolachlor sorption by approximately 10 % in soil amended with 5 % MPs, with Kd values ranging from 3.20 L kg-1 to 4.85 L kg-1 in unamended soil, suggesting increased herbicide retention in the presence of MPs. For hexazinone and diuron, sorption in the MPs treatments was comparable to the control, with similar behavior observed in desorption. These findings suggest that the presence of MPs in soil can modify the environmental fate of herbicides, potentially affecting their efficacy in weed control and increasing the risk of environmental contamination, particularly in agricultural soils polluted with these polymers.

The contamination of agricultural soils by microplastics (MPs) has significant implications for herbicide efficacy and soil health. This study investigates the effects of MPs on critical processes such as the sorption, desorption, and degradation of herbicides, highlighting their influence on these compounds’ mobility, persistence, and bioavailability. MPs interact with herbicides through sorption mechanisms, often reducing the availability of these compounds for weed control by retaining them on their surfaces. This sorption not only limits the immediate efficacy of herbicides but also alters their desorption process, resulting in a prolonged release into the soil environment. Additionally, MPs can inhibit microbial activity involved in herbicide degradation, increasing the time degradation of the half-life of these substances and extending their persistence in the environment. These processes collectively enhance the risks of bioaccumulation and environmental contamination. Understanding these interactions is essential for developing strategies to mitigate the impacts of MPs on herbicide performance and promote sustainable agricultural practices.

The objective of the study was to assess the phytoremediation potential in two remineralized soils contaminated with sulfentrazone. Two soil types were evaluated: Oxisol (clayey) and Inceptisol (sandy loam), in pots, with and without the incorporation of the rock powder, at rates of 0, 4, and 8 t ha−1. Following this, sulfentrazone was applied at rates of 200, 400, 600, and 800 g a. i. ha−1, in addition to the control treatment without herbicide application, followed by the sowing of Canavalia ensiformis (jack bean). Injury level (IL) was assessed at 42 days after emergence (DAE), and biometric evaluations of the phytoremediating species were conducted at 70 and 120 DAE in the Oxisol and Inceptisol, respectively, for the following variables: height (HT), diameter (DM), trifoliate leaf number (TN), leaf area (LA), above-ground dry biomass (DB), and root dry biomass (RDB). At the end of the phytoremediation experiment, the soils were analyzed using High-Performance Liquid Chromatography (HPLC) and with Sorghum bicolor (sorghum) as a bioindicator to verify the residue of sulfentrazone. IL and DB assessments of the bioindicator species were conducted at 21 DAE. In both soils, higher herbicide rates (600 and 800 g a. i. ha−1) resulted in greater IL and reduced HT, LA, DB, and RDB of the phytoremediating species. C. ensiformis reduced the sulfentrazone residues in the soils. Although it did not directly influence phytoremediation, the rock powder improved soil fertility. In conclusion, C. ensiformis has the potential for effective phytoremediation of soils contaminated with sulfentrazone, providing safety for cultivating sensitive crops and benefiting the environment.

The increasing concern over microplastics (MPs) contamination in agricultural soils due to excessive plastic use is a worldwide concern. The objective of this study was to determine which analytical technique is most effective for the analysis of MPs in agricultural soils. Near-infrared spectroscopy (NIR), scanning electron microscopy (SEM), multispectral analysis, and X-ray diffraction were used to analyze sections of clay soil containing varying percentages of virgin white MPs from 0 to 100

The selectivity of diuron for most crops, is due to the positioning of its molecule in the soil profile. Therefore, it is necessary to know the interactions of diuron's molecule with soil matrix to define recommended doses from an agronomic and environmental standpoint. This research aimed to estimate the influence of soil attributes and sorption coefficient (Kf) on the definition of diuron doses. Experiments were conducted to quantify the Kf of diuron in different soils and determine the doses in each soil that caused 80% intoxication (C80 intoxication) and 80% decreased accumulation of aerial parts plants (C80 DMAP) of Eleusine indica. After that, a correlation analysis was performed between the soil physical-chemical attributes, diuron Kf, and C80 of E. indica intoxication. Diuron Kf ranged from 1.8, in the ultisol with 0% of manure content, to 8.8, in the oxisol with 40% of manure content. Eleusine indica C80 ranged from 66.3, in the oxisol with 0% of manure content, to 568.3 g a.i. ha-1, in the ultisol with 40% of manure content, while C80 of aerial part dry matter reduction ranged from 57.5 to 521.6 g a.i. ha-1 in the same soils. C80 intoxication positively correlated with organic matter content and Kf. It was concluded that organic matter content was determinant in diuron sorption and intoxication for E. indica. Changes are necessary in the dosing recommendation criteria in the label of diuron, with its recommendation being primarily based on the organic matter content.

Herbicides play a crucial role in weed control in various agricultural and non-agricultural settings. However, their behavior in the environment is complex and influenced by multiple factors. Understanding their fate and retention, transport, and transformation is essential for effective herbicide management and minimizing their impact on ecosystems. This chapter begins by emphasizing the importance of studying herbicide behavior in real-world conditions, considering physical, chemical, and biological amendments in soil. It highlights how these amendments can directly affect weed control efficacy when residual herbicides are applied in pre-emergence. Detailed knowledge of herbicide behavior in the environment enables the adjustment of application rates based on soil type and climatic conditions, which is a key aspect of precision agriculture. The study of herbicide interactions in the environment has experienced significant growth across various subfields, particularly in the last three decades. It can be considered a multidisciplinary subject that encompasses areas such as agricultural, environmental, and biological sciences, as well as technology, physics, chemistry, and biomedicine. Overall, there are over 35,000 papers on herbicide behavior in the environment, and the trend indicates that the number of publications will continue to grow in the coming years.

Tomatoes are often grown in proximity to other crops such as grain, which can increase their susceptibility to herbicide drift and subsequent crop. Therefore, the objective of this study was to evaluate the effect of simulated herbicide drift on tomato plants. Treatments were established in a 10 × 3 + 1 factorial scheme using a completely randomized design with four replications. The first factor consisted of ten herbicides, while the second was composed by three subdoses (1/4, 1/16, and 1/32) along with an additional treatment without herbicide application. The herbicides 2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, and isoxaflutole caused injury levels greater than 20% or reductions in plant biomass greater than 30% at the lowest subdose. Increasing the subdose resulted in a corresponding increase in injury level and a reduction in biomass. Tomato exposed to hexazinone, diuron, nicosulfuron, and diquat at a subdose of 1/64 exhibited low injury levels and biomass reductions. However, at other subdoses, these herbicides caused significant plant damage. Among the herbicides tested, the auxinic herbicides, particularly dicamba, presented a higher risk for the tomato crop. The documentation and description of the visual symptoms caused by each herbicide applied to tomatoes will aid producers to identify drift problems in the field.

Accidental herbicide drift onto neighboring crops, such as soybeans, can seriously harm non-target plants, affecting their growth and productivity. This study examined the impact of simulated drift from ten different herbicides (2,4-D, dicamba, glyphosate, saflufenacil, oxyfluorfen, hexazinone, diuron, diquat, nicosulfuron, and isoxaflutole) on young soybean plants. These herbicides were applied at three simulated drift levels (1/4, 1/16, and 1/32) equivalent to recommended commercial doses, and the resulting symptoms were carefully evaluated. Simulated drift caused distinctive symptoms, including chlorosis, twisting, necrosis, and growth abnormalities, varying depending on each herbicide's mode of action. Dicamba proved more toxic than 2,4-D, and symptom severity increased with drift proportion, with all herbicides causing over 30% injury at the 1/16 proportion. Notably, 2,4-D, dicamba, glyphosate, hexazinone, and diquat exceeded the half-maximal inhibitory concentration (IC50) value, significantly reducing total biomass. Dicamba consistently caused 50% injury at all proportions, while hexazinone, at the highest dose proportion, led to plant mortality. Dicamba also had biomass accumulation beyond the growth reduction (GR50), whereas hexazinone exhibited less than 10% accumulation due to its capacity to induce plant mortality. This study emphasizes the importance of understanding herbicide drift effects on non-target crops for more effective and safe weed management strategies.

Dinizia excelsa is one of the largest trees in the Amazon rainforest, with significant economic potential for the recovery of degraded areas. It is a key species for biodiversity and increased forest biomass. However, studies related to seedling production of this species are still scarce. In this study, we evaluated the production and quality of D. excelsa seedlings in response to the application of controlled-release fertilizer doses. The experimental design was completely randomized, applying different doses of Osmocote® (T1=0; T2=4.1; T3=8.2; and T4=12.3 g.dm-³) with four replicates, using vermiculite and coconut fiber (1:1 v/v) as the substrate. We assessed the number of leaves and leaflets, shoot and root length, stem diameter, seedling height, shoot-to-stem diameter ratio, leaf area, dry mass of shoot, root, and total biomass. The data were subjected to analysis of variance and regression analysis. The seedlings responded positively to the use of Osmocote®, and starting from the 4.1 g.dm-³ dose, biomass accumulation showed better results, making it a recommended practice that allows cost savings in seedling production of this species.

Preemergence herbicides are traditionally applied uniformly throughout the area; however, weed control may vary due to spatial variability of the soil within the same area. Precision agriculture tools such as variable rate applications of herbicides improve weed control, making it necessary to know the physicochemical characteristics of the soil. The objective of this study was to map the spatial variability of sorption–desorption and agronomic efficiency of indaziflam and metribuzin for weed management in a field of 17.5 ha of Minas Gerais, Brazil. Fifty-five soil samples were collected (0–10 cm depth) and based on their physicochemical characteristics and the sorption and desorption coefficients for indaziflam and metribuzin, determined by a batch equilibrium method, thematic maps were generated for each variable in QGIS (Quantum Geographic Information System). In addition, the bioavailability concentration of each herbicide was determined, and its efficacy was evaluated in controlling Amaranthus hybridus and Eleusine indica in a representative soil sample. The sorption coefficient (Kd(s)) of indaziflam ranged from 6.9 to 40.5 L kg−1, the sorbed percentage (S

The interaction of herbicides in the nitrogen cycle and their consequences on soil health and agricultural production are essential topics in agronomic research. In this systematic review article, we have synthesized recent studies on this subject. The results revealed that the indiscriminate use of herbicides can have negative effects on vital processes in the nitrogen cycle, such as reduced enzymatic activity and microbial respiration. Moreover, herbicides alter the soil microbial composition, affecting nitrogen cycling-related activities. Symbiotic nitrogen fixation is also impaired, resulting in a reduction in the population of nitrogen-fixing bacteria and a decrease in the availability of this nutrient in the soil. These effects compromise soil fertility and the release of nitrogen to plants. Therefore, sustainable agricultural practices must be adopted, considering nitrogen cycling efficiency and the preservation of soil and natural resources. This understanding is crucial for guiding appropriate management strategies aimed at minimizing the negative effects of herbicides on the nitrogen cycle and ensuring soil health and agricultural productivity.

The addition of carbonaceous material such as cow bonechar to the soil can affect the availability of applied pre-emergent herbicides such as indaziflam. However, how cow bonechar affects the bioavailability of indaziflam is not yet known. The aim of this study was to evaluate the effect of cow bonechar on herbicidal activity of indaziflam on weeds in a tropical soil. Cow bonechar was added homogeneously to top soil, at 1, 2, 5, 10, and 20 t ha(-1), in addition to treatment with unamended soil. At 21 days after indaziflam (75 g ha(-1)) application, injury weed levels, weed species that emerged spontaneously were identified and the weeds present in each sampling unit were collected. Only 1.4 t ha(-1) cow bonechar added to soil was enough to reduce the weed injury level by 50%. From the addition of 2 t ha(-1) cow bonechar the application of indaziflam was not efficient to weed control, being equivalent to treatments without herbicide application. Eight weed species (3 monocots and 5 dicots) were identified in all treatments. Eleusine indica and Digitaria horizontalis accounted for about 99.7% of the entire infestation of the weed community. Cow bonechar decreases indaziflam pre-emergence herbicidal activity in tropical soil for weed control, most likely due to the high sorption and unavailability of the product in the soil solution.

A presença de plantas daninhas na cultura da mandioca configura-se como um dos principais fatores atrelado ao baixo incremento na produção desta cultura, uma vez que, o crescimento inicial lento de grande parte das plantas cultivadas, facilita a competição com plantas daninhas, levando à redução da produtividade e consequentemente do lucro da produção. Objetivou-se com este trabalho realizar o levantamento fitossociológico de plantas daninhas, após a aplicação de diferentes misturas de tanque com fluazifop-P-Butil em área de cultivo de mandioca. Os tratamentos constituíram-se pela combinação de: Fluazifop-P-Butílico; Fluazifop-P-Butílico + Metsulfuron Metílico; Fluazifop-P-Butílico + Isoxaflutol; Fluazifope-P-Butílico + Flumioxazina e Controle (sem herbicida). Para o estudo fitossociológico, utilizou-se o método do quadrado inventário, aplicado por meio de um quadrado de 0,5m x 0,5m, lançado ao acaso, totalizando quatro lançamentos por tratamento. Com os dados obtidos, foi possível efetuar os cálculos de parâmetros fitossociológicos, entre eles o índice de valor de importância (IVI) de cada espécie, assim como, o agrupamento hierárquico de similaridade, pelo método UPGMA. Concluiu-se que o tratamento composto apenas pelo herbicida Fluazifop-P-Butílico apresentou o melhor controle para as plantas invasoras, principalmente a da espécie Paspalum maritimum, que apresentou os maiores valores de IVI.

Spray nozzles can be considered the most important items of sprayers, and the ideal nozzle-pressure combination plays a major role in the effectiveness of pest control in the field. Spray nozzle manufacturers often develop, and make new alternatives available on the market; however, studies are always important to verify the behavior of tríese new technologies concerning the spectrum of the droplets produced. Therefore, the present study aimed to evaluate the spectrum of droplets generated by four spray nozzles (FC3D 100-02; VP 110-02; TR 110-02 and TT 110-02) under different working pressures (138, 207, 276, 345, and 414 kPa). For this, a factorial scheme in a completely randomized design with four replications was used. The parameters evaluated were volumetric median diameter (VMD), relative amplitude (Span), and the percentage of droplets with a diameter smaller than 100 um (<100 um). The spray nozzles models and the working pressure had a direct effect on the droplet size. Furthermore, there were no significant differences between the TR 110-02 and VP 110-02 models for the percentage of spray volume containing droplets <100 um neither for the VMD. Lastly, the increase of pressure resulted in an increasing linear effect on the Span index for the FC3D 100-02 nozzle.

With the advent of precision agriculture, it was possible to integrate several technologies to develop the variable rate application (VRA). The use of VRA allows savings in the use of herbicides, better weed control, lower environmental impact and, indirectly, increased crop productivity. There are VRA techniques based on maps and sensors for herbicide application in preemergence (PRE) and postemergence (POST). The adoption of the type of system will depend on the investment capacity of the producer, skilled workforce available, and the modality of application. Although it still has some limitations, VRA has been widespread and has been occupying more and more space in chemical management, the tendency in the medium- and long term is that there is a gradual replacement of the conventional method of application. Given the benefits provided by VRA along with the engagement of companies and researchers, there will be constant evolution and improvement of this technology, cheapening the costs of implementation and providing its adoption by an increasing number of producers. Thus, the objective of this chapter was to address an overview of the use of herbicides in VRA for weed management in PRE and POST.

Introdução Originaria do Brasil, a mandioca (Manihot esculenta crantz), é uma cultura caracterizada pela rusticidade e adaptabilidade às diferentes condições edafoclimáticas (OTSUBO, 2012), diante disso, de acordo com Oliveira 2001, pela sua alta capacidade de produção e adaptação às condições climáticas e culturais diversas, é uma planta de grande importância fonte alimentícia nos trópicos, tanto suas folhas quanto as raízes são úteis como fonte de alimento humano e animal. Por ser uma cultura de crescimento inicial relativamente lento, deixando o solo descoberto, o desenvolvimento da mandioca pode ser afetado pela presença das plantas daninhas (OTSUBO, 2012). Segundo Albuquerque et al. (2008), um dos principais fatores que contribuem para a baixa produtividade da cultura de mandioca no Brasil é o manejo inadequado de plantas daninhas. Ademais, o controle químico é uma opção eficaz para o controle de plantas daninha caracterizado pela intervenção em grandes áreas, com pouca dependência de mão de obra e rapidez na aplicação (SILVA et al., 2012). Além disso, a capacidade de se desenvolver e produzir relativamente bem em solos de baixa fertilidade, talvez seja a principal característica dessa planta. Em solos pobres de