Herbicides In Soil Research Articles

Sustainable Control of Galinsoga parviflora with Oxyfluorfen, Flumioxazin, and Linuron Application in Two Soils Cultivated with Garlic

Herbicides applied in PRE-emergence enables sustainable weed control. The objective of this study was to evaluate the control of gallant soldier (Galinsoga parviflora) with the residual herbicides oxyfluorfen, flumioxazin, and linuron in soils cultivated with garlic from two regions of Brazil: Rio Paranaíba-MG (Oxisol) and Curitibanos-SC (Ultisol). The efficiency of the herbicides was evaluated at the following doses: oxyfluorfen (0, 3, 6, 12, 24, 48, 96, 192, 384, and 768 g a.i. ha−1), flumioxazin (0, 2, 4, 6, 8, 15, 30, 40, 60, and 120 g a.i. ha−1), and linuron (0, 30, 40, 50, 100, 200, 400, 800, 1600, and 2430 g a.i. ha−1). The degree of damage on the 7th, 14th, and 21st day after emergence (DAE) and dry matter on the 21st day after emergence (DAE) were determined to evaluate the control (C80) and the growth reduction (GR80) of 80% of the plant, respectively, compared to the treatment without herbicide. Three herbicides were effective at the control of G. parviflora, with the C80 at 21 DAE on Ultisol being 81.82, 4.59, and 141.26 g a.i. ha−1, and a GR80 of 61, 8.3, and 151.3 g a.i. ha−1 for oxyfluorfen, flumioxazin, and linuron, respectively. On the other hand, on Oxisol (lower clay content and soil organic matter), the doses were lower, with the C80 at 21 DAE at 20.85, 3.50, and 118 g a.i. ha−1, and a GR80 of 54, 4.03, and 101.23 g a.i. ha−1, respectively. This weed showed higher control under flumioxazin compared to the other herbicides in both soils. The use of low doses of residual herbicides contributes to sustainable weed control in garlic growing in the field.

Management practice and soil properties affect plant productivity and root biomass in endophyte‐symbiotic and endophyte‐free meadow fescue grasses

AbstractIntroductionPesticides are increasingly used in intensely managed agro‐environments, with an increasingly acknowledged impact on crop production, root establishment and plant resilience. At the same time management practices are intensified with the goal to maximize productivity.Materials and MethodsIn a greenhouse, we studied the effects of three mowing regimes (uncut, and cutting 5 or 15 cm) employed three times during the season on root and shoot biomass and chlorophyll content of the cool‐season grass Festuca pratensis (meadow fescue) growing in soil with a history of glyphosate‐based herbicide (GBH) use, the corresponding control soil, and sterilized control soil. Half of the plants hosted a systemic and vertically transmitted fungal endophyte, Epichloë uncinata, which is known to promote host grass growth.ResultsEndophyte symbiosis did not affect any tested plant parameters. Cutting the plants to 5 cm decreased both root and cumulative shoot biomass. Herbicide soil history, together with intense cutting (5 cm), caused a decrease in shoot biomass and lowered the chlorophyll content. Surprisingly, soil sterilization boosted shoot biomass and chlorophyll concentrations during less intense cutting (15 cm) and noncutting when compared to the control soil. Root biomass reduced in uncut plants when growing in soil with a history of glyphosate use.ConclusionOur results indicate that GBH residues in the soil can diminish shoot biomass when grass is frequently cut. Decreased root biomass caused by soil glyphosate history goes together with a reduction of carbon allocation belowground, which decreases grassland resilience to climate warming, increasingly occurring droughts and extreme weather events.

Unmanned aerial vehicles to determine soybean plant injury caused by pre-emergence herbicides

Images from unmanned aerial vehicles (UAV) can serve as a baseline for studies in weed science, complementing observations obtained in the ground. The objective of this work was to determine soybean (Glycine max (L.) Merr.) plant injury caused by pre-emergence herbicides in sandy and clayey soils, using a low-cost UAV. The experiment was conducted in a randomized complete block design, with four replicates and seven treatments consisted of herbicides (diclosulam, chlorimuron, sulfentrazone, flumioxazin, and S-metolachlor), hand weeded and untreated treatments. Ground-based evaluations were carried out to assess soybean crop injury, plant stand, leaf chlorophyll content, plant height, canopy distance and grain yield. Images were taken using a UAV equipped with an RGB (red green and blue) camera. Soybean plants sprayed with diclosulam had lower plant reflectance in the R (98.9), G (147.1) and B (74.3) range than the other treatments in sandy soil. In clayey soil, hand weeded treatment had higher plants (30.8 cm) and untreated favored smaller plants (24.9 cm) compared to herbicide treatments. In sandy soil, soybean yield of all treatments was similar, however in clayey soil, soybean yield treated with chlorimuron and flumioxazin was higher than 5000 kg ha-1 and better than the others treatments. The nutrient-poor soil (sandy) may have aggravated the plant injury caused by herbicides and explain the lower yield observed compared to clayey soil. It was determined soybean plant injury caused by pre-emergence herbicides with the use of unmanned aerial vehicles, providing complementary results to ground-based measurements, indicating the potential of this technology for low-cost evaluations in weed science.

Effect of Calcium Carbonate Content on Potential Pesticide Adsorption and Desorption in Calcareous Soil

ABSTRACT The presence of calcium carbonate (CaCO3) in soil plays an essential role in regulating many processes whether chemical, physical, or biological. The effect of calcium carbonate content on the adsorption and desorption characteristics of insecticides (chlorantraniliprole, CAP, dinotefuran, DNF) and herbicides (bispyribac-sodium, BPS, metribuzin, MBZ) in calcareous soil has been studied. Adsorption and desorption isotherms of tested pesticides were quantified using the batch equilibration technique. The data were modeled with the Freundlich model to obtain the adsorption parameters. The results showed that the adsorption of DNF and BPS was the highest in intact calcareous soil (IS), while the adsorption of CAP and MBZ was the highest in calcium carbonate free calcareous soil (FS). The desorption from IS and FS was highest for MBZ, whereas it was lowest for BPS. Therefore, we demonstrate that the soil calcium carbonate could block the adsorption sites available for certain pesticides like CAP and MBZ, while it could be shared in the adsorption of other pesticides like DNF and BPS.

Herbicides in unexpected places: non-target impacts from tree root exudation of aminopyralid and triclopyr following basal bark treatments of invasive chokecherry (Prunus padus) in Alaska

AbstractBasal bark treatment of invasive trees is an approach designed to limit damage to non-target vegetation in the vicinity, but non-target injury is still documented. No study of basal bark treatments has examined the release of herbicide residues from roots of treated plants and resulting non-target impacts. Studies were conducted in Alaska interior and coastal boreal forests on basal bark treatments with aminopyralid and triclopyr on active-growth and dormant invasive chokecherry (Prunus padus L.). The study assessed non-target damage and soil herbicide residue using a combination of visual evaluations, bioassays, and soil residue analyses. Non-target damage from herbicide residues were identified in 40% of treatments containing aminopyralid with triclopyr, 60% of treatments containing aminopyralid alone, and 5% of treatments containing only triclopyr. Laboratory studies of aminopyralid treatments to saplings isolated the effects of herbicide exudation from roots, which was found to be significant, and the magnitude was dependent on dose. Herbicide soil residues in field and laboratory experiments were quantified with analytical detection and plant bioassays. Aminopyralid soil residues were identified in 57% of field treatments receiving 8 to 60 ml of herbicide solution (2% ai) and 70% of laboratory treatments receiving 10 µl of herbicide solution (2% to 16% ai). Triclopyr residues were found from one field treatment following dosage with 28 ml of herbicide solution (18.5% ai). Anatomically, plants grown in soils associated with herbicide-treated trees, both in the field and lab, grew less dry mass than non–herbicide treated controls. This study provides the first evidence that root exudation of herbicide following basal bark treatments contributes to non-target damage of adjacent vegetation and to accumulation of soil herbicide residues. This is an important new factor for integrated pest management within basal bark treatment systems and has implications for other herbicide application types such as injections and frill, as well as determining whether root exudation is species or herbicide specific.

EFFICIENCY OF SOIL APPLIED HERBICIDES IN SUNFLOWER PLANTS

The paper presents the results of the research on identifying the biological efficiency of soil applied herbicides in oil sunflower under the conditions of Gomel and Brest regions. In the technology of protecting sunflower from weed plants it’s advisable to use soil herbicides which can control almost completely plant infestation during the whole vulnerable period of the crop, in particular within the first 40 days of vegetation.

EFFECT OF HERBICIDES AND BIOLOGICAL PREPARATIONS ON GROWTH PROCESSES AND GRAIN PRODUCTIVITY OF NUTU

Chickpeas are a high-tech legume crop, so the improvement of scientifically sound technology of chickpea cultivation is a priority among agricultural producers. The article presents the results of the study of the effect of soil herbicides, the microbial preparation Rhizobophyte and the biofungicide preparation Biopolicide on the growth, development and productivity of chickpea plants. There is a clear dependence and positive effect of microbial preparations on the height of chickpea plants, grain yield of chickpea varieties Triumph and Rosanna when used in combination with herbicides. When combined before sowing chickpea seeds with the microbial drug Rhizobophyte (1,0 l/t) and biofungicide Biopolicide (100 ml/t) and application of this background soil herbicide Frontier Optima, 72% k.e., at the rate of 1,2 l/ha contribute to the control of weeds in chickpea crops, intensive growth and development of cultivated plants in height, a significant increase in the yield of chickpea seeds. In particular, the height of the plants of chickpea variety Rosanna in the phase of full flowering on average over the years of research was within 59.4 cm, and the increase before control was 23,6 cm. The number of beans formed per plant was within 19,41 pieces. The yield of chickpeas of Rosanna variety in these areas was within 2,28 t/ha, the increase before control was 1,74 t/ha or 322%. Thus, the effectiveness of the basic physiological and biochemical processes of the phases of growth and development of chickpea plants depends on a number of elements: agronomic, seed inoculation, the use of chemical and biological pesticides. The yield of chickpea seeds depends on the control of weeds in its crops, in particular, the application of the soil herbicide Frontier Optima, 72% of the active ingredient, at the consumption rate of 1.2 l/ha, as well as the complex pre-sowing treatment of chickpea seeds with the biological preparation Rhizobophyt, 1.0 l/t + biofungicidal drug Biopolicid, 100 ml/t. These measures contribute to the yield of Rosanna chickpea seeds at the level of 2.28 t/ha.

INFLUENCE OF WEED CONTROL AND MICROFERTILIZERS ON VEGETABLE YIELD

The article summarizes the results of research on the structure of weed agrocenosis of vegetable peas; controlling the level of its weeding by performing pre-emergence and post-emergence harrowing with medium toothed harrows; evaluation of the chemical method of protection of vegetable peas from weeds, which involved the introduction of 2 types of herbicides, which contained such active substances as S-metallochlor and Imazamox. Part of the study areas was treated with the microfertilizer Reacoma-chelate of boron + molybdenum with a rate of 1.0 l / ha before flowering peas. As a result of research, it was found that in the structure of weed agrocenosis of vegetable peas the share of monocotyledonous weeds averaged 71.4% in two years of research and, accordingly, dicotyledonous - 28.6%. But the air-dry mass of cereal weeds was much lower than that of deciduous weeds. The implementation of agronomic measures alone did not allow to keep the presence of weeds in crops below the level of economic damage throughout the growing season. Prior to harvesting, this variant accounted for 18 weeds / m2 of weed stalks. This agricultural measure reduced the level of their presence by 69.5% and 45.8% of air-dry weight compared to the control option. The application of a soil herbicide based on S-metallochlorine provided a reduction in the number of weeds in the month after spraying by 85.7% compared to the control version. Before harvesting vegetable peas, the number of weeds in the areas where the soil herbicide was applied was 11 pieces / m2, and the level of weeding decreased by 81.4% compared to the control variant. At the time of the second weed count, we found that the herbicide with the active ingredient Imazamox was 89.8% effective. Consecutive application of S-metallochlor and Imazamox with reduced consumption rates allowed to control the presence of weeds in agrophytocenoses throughout the growing season of vegetable peas. Weed mortality at the time of harvest in this variant averaged 89.8% over two years of research, and their above-ground air-dry mass was 95 g / m2. On average, in two years of our research, the yield of peas in the variants with the application of herbicides was 5.00-5,64 t / ha, which was 35.5-52.8% higher than in the control areas. The highest increase in pea yield was obtained with the successive application of S-metallochlor and Imazamox with reduced consumption rates. On the average for two years of researches it made 1.95 t / hectare. Before flowering of vegetables, the application of micro-fertilizer Reacom-chelate of boron + molybdenum with a consumption rate of 1.0 l / ha made it possible to obtain higher yields of 3.7-6.1% compared to uncultivated areas on agronomic and chemical weed protection options.

Effectiveness of herbicides application on soybean

Goal. To establish the effectiveness of the use of herbicides against weeds in soybean crops.
 Methods. Field and laboratory.
 Results. The main technologies for growing soybeans are based on the application of soil herbicides after sowing but before the appearance of crop seedlings. The main task of the research was to study the effectiveness of soil action and post-emergence herbicides on the destruction of weeds in soybean crops during the growing season. Establishing the specifics of the application of post-emergence herbicides makes it possible to reliably protect soybeans in case of impossibility or ineffective application of soil herbicides. Separate application of herbicides in smaller doses was used: Nabob, s.c. (bentazone, 480 g/l) 1.0 l/ha on the 4th day after sowing + 1.2 l/ha in the phase of 1—2 soybean leaves; Pari, s.c. (ima-zetapyr, 100 g/l) 0.3 l/ha on the 4th day after sowing + 0.4 l/ha in the phase of 1—2 soybean leaves; Pulsar 40, s.c. (imazamox, 40 g/l) 0.3 l/ha + 0.4 l/ha in the phase of 1—2 soybean leaves; Fabian, w.g. (imazethapyr, 450 g/kg + chlorimuron-ethyl, 150 g/kg) 0.03 kg/ha on the 4th day after sowing + 0.04 kg/ha in the phase of 1—2 soybean leaves; Harmony 75, w.g., (thifensu-lfuron-methyl, 750 g/kg) 0.003 kg/ha + surfactant Trend, 0.2 l/ha twice — after sowing on the 4th day and in the phase of 1—2 soybean leaves.
 Conclusions. The effectiveness of the imadazoline group of herbicides with split application, where the active substance acts both through the leaves and through the root system of weeds, was lower on average by 11%, than with single application. On average, during the years of research, for the application of the herbicide Pari in the phase of 1—2 soybean leaves, s.c. (1.0 l/ha) destroyed 89.0% of weed seedlings, and with separate application at lower rates (0.3 l/ha on the 4th day after sowing and 0.4 l/ha in phase 1—2 soybean leaves) 78.3% of weeds died. Similarly, for the introduction of Fabian herbicide in phase 1—2 soybean leaves, w.g. (0.1 kg/ha) the efficiency of using the full rate of the drug was 83.8%, and with separate application (0.03 kg/ha on the 4th day after sowing + 0.04 kg/ha in the phase of 1—2 leaves) soybean weed destruction was 72.6%. The use of herbicides with a contact action showed a better efficiency of action with a two-time application. After applying the full dose of the drug Nabob, s.c. (3.0 l/ha) once reduced the number of weeds by 68.7%, and with two applications (1.0 l/ ha on the 4th day after sowing + 1.2 l/ ha in phase 1—2 soybean leaves) the effectiveness of the drug was 83.0%. For Harmony, w.g. with a one-time application of the full rate of the drug, it's overall effectiveness was 67.6%, and when using 3.0 g/ha on the 4th day after sowing and 3.0 g/ ha + 0.2 l/ha of surfactant Trend in phase 1—2 leaves of soybeans — 80.4%.

Modeling and simulation of trifluralin herbicide movement due to its application on soils by chemigation

The Trifluralin (TFN) is a pre-emergent herbicide which is widely used in agriculture. Usually, this pesticide is directly applied to the soil, where it can remain for long periods or can be transported. In this sense, knowing the dynamics of an herbicide soil transport is essential to avoid environmental contamination problems and risks to human health. Thus, this study aims to model and simulate TFN movement on soils with two different textures, a sandy loam and clay loam soil. It was considered that the herbicide was applied via chemigation trough a subsurface drip irrigation system, under a non-steady regime. Therefore, the transport parameters of TFN in these soils and physical-hydric characteristics of these were used, while the physical environment modeling were conducted using the Hydrus 2D software. The results showed that both in sandy and clayey soils, the TFN tends to be retained by the soil, close to where it was applied, not exceeding a layer greater than 2.5 mm outside the dripper radius, even in more favorable conditions such as the presence of irrigation. Finally, it could be concluded that this herbicide movement in the soil is of low potential, due to this product high solid-liquid partition coefficient (Kd), even in sandy soil, which has low cation exchange capacity (CEC).

Leaching of saflufenacil in soils with different organic matter contents

Saflufenacil is a herbicide recommended for use in the main agricultural crops in Brazil to control eudicotyledonous weeds. However, the application of saflufenacil has been carried out without previous knowledge of this herbicide interactions with soil colloids, which may increase environmental contamination risks. In this study, the leaching of saflufenacil in soil samples was estimated with different organic matter contents. Therefore, PVC columns were filled with samples of Xanthic Ferralsol (XF) and Ferralsol (F), with different physical and chemical attributes. Twelve hours after herbicide (70 g i.a. ha-1) application, the PVC columns were subjected to a rainfall of 60 mm. For the evaluation of saflufenacil leaching, the columns were sectioned in ten parts with 5-cm each. Saflufenacil leached up to 50 and 40 cm deep in the samples, with the lowest contents of organic matter of XF and F, respectively. The increase in organic matter content of Ferralsol and Xanthic Ferralsol samples reduced saflufenacil leaching and the symptoms of intoxication in the indicator species. There was an inverse relation between the content of organic matter and the leaching of the herbicide in both soils studied. It was observed that the application of saflufenacil in soils with low organic matter contents may represent a significant environmental contamination risk of soils and watercourses.

Effect of Long Term Fertilization Practices on Tembotrione Movement in Soil: Assessment by Plant Bioassay

The herbicide behavior in soils is executed nowadays via the chemical extraction and instrumental analysis. However, the biological availability and the dynamics of herbicide in soil could be studied effectively through bioassay in the absence of sophisticated techniques and also in situ conditions. Tembotrione is one of the recently registered triketone herbicide and its movement behavior was not studied much in India. Hence the present study was executed to understand the influence of long term fertilization practices on its transport and movement using the bioassay technique involving Randomized Block Design (RBD). The plot wise soil samples were collected from the 50 years old long term fertilization experiment, processed and used to conduct the leaching column (made of PVC) experiment under controlled condition for 30 days. Soil samples were dissected depth wise and residue of tembotrione in each depth was obtained by conducting bioassay using green gram and sunflower as test species. For calibration curve preparation, a separate bioassay was conducted by fortifying tembotrione in control soil at different concentrations. The recorded plant parameters viz., germination percent and biomass after 15th day of both the test species predicted the tembotrione transport efficiently and the results of both the test species were comparable. The tembotrione has shown movement upto 30 cm soil depth and the concentration of residue decreased with increase in soil depth. The long term fertilization practices with the balanced nutrients supply viz., 100% NPK with hand weeding, Zn, FYM showed significant effect on the transport of tembotrione in soil at various depths.
 The study concludes that the plant bioassay technique using green gram and sunflower could be very well used to investigate the transport behavior of Tembotrione in soil. Based on data, tembotrione was identified as moderately mobile compound in sandy clay loam and its movement has been altered by the long term fertilization practices.

Гербициды почвенного действия в системе защиты масличного льна от сорняков на юге России

Since there are no pre-emergence herbicides in “The State Catalogue of pesticides and agrochemicals” approved for use in the Russian Federation on oil flax, in 2018–2020, we studied the pre-emergence herbicides on crop sowings in the zone of unstable moistening on leached chernozem (VNIIMK, Kras-nodar) and in the zone of insufficient moistening on ordinary chernozem (Don experimental station of VNIIMK, Rostov region). We observed the decrease in weed infestation in oil flax sowings when we ap-plied pre-emergence herbicides. The highest biological effectiveness was observed in the zone of unstable moistening, when the plants were sprayed with Tifi, WDG (0.025 kg/ha) at the stage of true leaves development of flax on the background of pre-emergence application with Frontier Optima, EC (1.2 l/ha) – 63.2%; in the zone of insufficient moistening – at pre-emergence application with the tank mixture Dual Gold, EC (1.6 l/ha) + Gezagard, SC (3.5 l/ha) – 67.8%. However, we recorded the phytotoxic effect on oil flax at application of the tank mixture Dual Gold, EC (1.6 l/ha) + Gezagard, SC (3.5 l/ha) in the amount of 23.7–35.7% on the EWRC scale (Europe-an Weed Research Council). We established the positive effect of pre-emergence soil herbicides Frontier Optima, EC (1.2 l/ha) and Dual Gold, EC (1.6 l/ha) on the oil flax seed yield and economic indicators of its production. Herbicides Frontier Optima, EC (1.2 l/ha) and Dual Gold, EC (1.6 l/ha) are recommended for inclusion into the list of preparations approved for use on oil flax in the Russian Federation. Crop foliar treatment with herbicide Tifi, WDG (0.025 kg/ha) on the background of pre-emergence application of the preparation Frontier Optima, EC (1.2 l/ha) or Dual Gold, EC (1.6 l/ha) in the zone of unstable moistening led to yield decrease by 0.29 and 0.23 t/ha, respec-tively, it did not affect the oil flax yield in the zone of insufficient moistening.

Leaching of Herbicides in Soil under the Influence of Different Rainfall Intensities

Leaching of Herbicides in Soil under the Influence of Different Rainfall Intensities

Herbicidal activity of atrazine to barnyard grass depends upon soil characteristics.

The efficacy of a herbicide as soil treatment agent may be largely affected by soil characteristics. Understanding the relationship between herbicide efficacy and soil characteristics can provide decision basis for herbicide application according to local conditions. This study was aimed towards exploring the effect of soil characteristics on herbicidal activity of atrazine as a model herbicide to barnyard grass and thus to find an indicator for the herbicidal activity assessment of a herbicide against weeds. The herbicidal activity of atrazine to barnyard grass varied greatly among the tested soils with the medium inhibition concentration (IC50 ), based on the amended concentration, ranging from 1.07 to 10.91 mg kg-1 . Uptake of atrazine by barnyard grass was negatively correlated with its adsorption onto soils, whereas it was positively related to the concentration of the herbicide in in situ pore water (CIPW ). Comparable IC50 values ranging from 1.14 to 1.38 were obtained from CIPW in the tested soils with much smaller variation coefficient compared to those based on the traditional concentration (Csoil ) of this herbicide in soils determined by extraction with organic solvents. The concentration of atrazine in in situ pore water could be reliable to evaluate its bioavailability and herbicidal activity to barnyard grass. CIPW of a herbicide in soil could be an indicator for guiding the practical application rate. © 2022 Society of Chemical Industry.

Evaluation of imazapic and flumioxazin carryover risk for Carinata (Brassica carinata) establishment

AbstractCarinata (Brassica carinata A. Braun) is a potential crop for biofuel production, but the risk of injury resulting from carryover of soil herbicides used in rotational crops is of concern. The present study evaluated the carryover risk of imazapic and flumioxazin for carinata. Label rates of imazapic (70 g ai ha−1) and flumioxazin (107 g ai ha−1) were applied 24, 18, 12, 6, and 3 mo before carinata planting (MBP). The same herbicides were applied preemergence right after carinata planting at 1X, 0.5X, 0.25X, 0.125X, 0.063X, and 0X the label rate. When either herbicide was applied earlier than 3 MBP, there was no difference in plant density compared with the nontreated control. Carinata damage was <25% when flumioxazin or imazapic was applied at least 6 MBP in Clayton, NC (sandy loam soil), while in Jackson Springs, NC (coarser-textured soil and higher precipitation), at least 12 MPB were needed to lower plant damage to <25%. Preemergence application of 0.063X each herbicide decreased plant density by 40%, with damage reaching >25%. Quantification of herbicide residues in both soils showed that imazapic moved deeper in the soil profile than flumioxazin. This was more evident in Jackson Springs, where 0.68, 3.52, and 7.77 ng of imazapic g−1 soil were detected (15- to 20-cm depth) when the herbicide was applied at 12, 6 and 3 MBP, respectively, while no flumioxazin residues were detected at the same soil depths and times. When residues were 7.78 and 6.90 ng herbicide g−1 soil in the top 10 cm of soil for imazapic and flumioxazin, respectively, carinata exhibited at least 25% damage. Rotational intervals to avoid imazapic and flumioxazin damage to carinata should be between 6 and 12 MBP depending on soil type and environmental conditions, with longer intervals for the former than the latter.

Surface Charge Governs the Adsorption Behaviour of Glyphosate in the Australian Oxisol Soil System

ABSTRACT Glyphosate adsorption pattern is important for determining its environmental fate. Oxisol soil systems adsorb maximum glyphosate in the presence of biochar, however, the mechanism was not known. This article provides information concerning the role of surface charge in the case of Oxisol soil systems. Potentiometric titrations were done to calculate the surface charge in the case of Oxisol soil systems. Maximum adsorption of glyphosate in the Oxisol soil systems in the presence of biochar was due to an increase in net positive surface charge. This finding is of great importance to understanding the mechanism of herbicide soil interactions.

Residue Behavior of Clopyralid Herbicide in Soil and Sugar Beet Crop under Subtropical Field Conditions

Sugar beet is a major crop for the sugar industry. With growing awareness of unsystematic use of pesticides, health problem, and environmental issues, assessment of pesticide residues in soil and crops has become necessary. Studies of subtropical conditions on dissipation and residue analysis of clopyralid have not yet been reported. Therefore, dissipation kinetics and terminal residues of clopyralid for two cropping seasons in the soil and the sugar beet crop were studied under field conditions. An experiment was laid out in a randomized block design, and a herbicide was applied as a postemergent. Clopyralid was extracted from the matrix by basic water, subjected to solid phase extraction cleanup, and quantified by high-pressure liquid chromatography-UV. The method was validated, and recovery percentage of pesticide ranged from 81 to 88, 77 to 85, 78 to 86, and 89 to 94% in the soil, sugar beet roots, sugar beet leaves, and water, respectively. After application in the soil, clopyralid dissipated rapidly following monophasic first-order kinetics, with a half-life of 13.39 days. Limits of detection and quantitation were 0.007 and 0.02 μg g-1, respectively. Clopyralid does not persist long in soil, and residues were below the European Union's maximum residue levels (0.5 mg kg-1) in the roots and leaves of sugar beet. Residues were also not detected in the groundwater. It can be concluded that clopyralid could be considered a safe herbicide from the environmental aspect due to its nonpersistence and that it would not have an adverse effect on human or animal health.

EVALUATION OF THE INFLUENCE OF HERBICIDES AND FERTILIZER ON POLLUTION AND YIELD OF SOYBEAN

The article summarizes the results of a three-year study on the feasibility and effectiveness of the use of herbicides of soil and insurance action and microfertilizer Quantum - Molybdenum Chelate on the infestation and yield of soybeans. It was established that in the agrophytocenosis of soybean, a mixed type of infestation was formed, in which dicotyledonous young weeds predominated. Weed control efficiency was 75.5% 60 days after application of Frontier Optima. Spraying crops with the insurance herbicide Korum (1.5 l / ha + surfactant Metholate 1.0 l / ha) reduced the number of weeds in soybean crops by 89.5%. Consistent application of the soil herbicide Frontier Optima (1.0 l/ha) and the insurance herbicide Corum (1.5 l/ha + surfactant Metolate 1.0 l/ha) made it possible to destroy up to 98.9% of weeds compared to the control variant, where there was a natural background of clogging. The combination of the use of the above herbicides with the concentrated molybdenum microfertilizer Quantum-Chelate Molybdenum provided the best conditions for the growth and development of soybean plants. The amount of undesirable vegetation did not change in the areas where the microfertilizer was applied. But the air-dry mass of weeds was lower by 17.1-32.4%. The average soybean yield for three years of research on the variants where herbicides were applied compared to the control was significantly higher. When crops were sprayed with Frontier Optima herbicide (1.0 l/ha), it was 2.26 t/ha, and with Korum herbicide (1.5 l/ha + surfactant Metolate 1.0 l/ha) - 2.75 t/ha . With the sequential application of Frontier Optima (1.0 l/ha) and Corum (1.5 l/ha + surfactant Metolate 1.0 l/ha), the soybean yield was the highest and amounted to 2.94 t/ha.The highest content of proteins and oil was in the variant of sequential application of herbicides Frontier Optima (1.0 l/ha) and Corum (1.5 l/ha + surfactant Metolate 1.0 l/ha) - respectively 33.3% and 22.5 %. As a result of the treatment of crops on a herbicidal background with microfertilizer Quantum - Molybdenum Chelate, an increase in the weight of 1000 seeds by 2 g and the content of proteins and oil by 0.6% was noted.

IMPACT OF HERBICIDES ON THE FORMATION OF CHICKPEA YIELD

One of the main reasons for the decline in the yield of chickpea seeds is the high weediness of crops. It is determined by the potential stock of weed seeds in the soil and its long-term viability. The presence of large amounts of weed seeds in the soil creates significant problems for growing chickpeas. Therefore, the assessment of weed efficiency of any farming system or its component should be based on quantitative changes in potential soil weeds. The interaction between crops and weeds in chickpea crops has its own characteristics, because in the first period of the growing season they grow very slowly and have little effect on the conditions of weed growth, so there is a rapid growth of segetal vegetation. In the technology of growing chickpeas in the plant protection system traditionally use the chemical method. However, even with high efficiency, this method does not always give the desired results, there is a violation of ecological balance in agrocenoses, reduction of species biodiversity, contamination of soil and plants with chemicals, reducing product quality. Observance of agrotechnologies, constant phytosanitary monitoring, effective diagnostics and forecast of development and spread of harmful organisms in chickpea crops are important in ensuring proper phytosanitary condition. Regulation of weeds and their harmful effects in agrophytocenoses of chickpea drawing them to an economically harmless level is a significant condition in the technology of its cultivation. The main control of weeds is done at the beginning of the growing season, because at this time chickpeas grow very slowly, and are in the rosette phase for a long time, and therefore cannot withstand competition from weeds. To increase the yield of chickpea seeds, an important place in the technology of cultivation belongs to the use of herbicides and biological products. Inoculation of chickpea seeds with Rhizobophyte at a rate of 1 l / t and a biofungicide Biopolicide at a rate of 100 ml / t and application of soil herbicide Frontier Optima, 72% e. c., at a rate of 1.2 l / ha help to reduce weeds up to 91%, and the capacity to obtain a yield of chickpea seeds at 2.12 t / ha