Herbicides In Soil Research Articles

Diuron Sorption, Desorption and Degradation in Anthropogenic Soils Compared to Sandy Soil

ABSTRACT: The aim of this study was to evaluate diuron sorption, desorption and degradation in two anthropogenic soils (Terra Preta de Índio - TPI) in contrast to a sandy soil (Quartzarenic Neosol - NQo). Sorption-desorption studies were performed by the batch equilibrium method and biodegradation in biometric bottles using radiolabeled diuron in 14C. Freundlich coefficient (Kf) values ranged from 13.50 to 50.41 µmol(1-1/n) L1/n kg-1 in TPI-2 and TPI-1, respectively, indicating very high diuron sorption in anthropogenic soils, following the order: TPI-1 ≥ TPI-2 > NQo (99.10, 98.95 and 60.8%, respectively). Diuron desorption was very low in anthropogenic soils, ranging from 1.36 (TPI-1) to 1.70% (TPI-2), and 24% to NQo. Accumulated diuron mineralization to 14C-CO2 was < 3% at 70 days after herbicide application, regardless of the assessed soil. Formation of 35 and 44% residue bound to TPI-2 and TPI-1 was observed, higher than to NQo (17%). In contrast, the residue extracted from NQo varied from 72 to 91%, ranging from 48 to 83% for TPI-1 and TPI-2 during the incubation period. The degradation half-life (DT50) of diuron in anthropogenic soils was of 66.65 and 68.63 days for TPI-1 and TPI-2, respectively, while a period of 88.86 days was observed for NQo. The formation of only one herbicide metabolite in all soils was evidenced. The application of diuron in arable areas in the presence of anthropogenic Amazonian soils may lead to inefficient chemical weed control, since these soils may reduce herbicide soil bioavailability due to high OC contents, where high sorption and low herbicide desorption are noted, as well as faster degradation compared to sandy soil.

CHANGE IN THE TYPICAL BLACK FERTILITY INDICATORS FOR THE CONVERSIONAL GROWING OF MAIZE

The change of the agrochemical parameters of the typical black soil is investigated and the balance and the efficiency of using NPK for the cultivation of corn in the technology of constant sowing using different systems of chemical protection of plants in the conditions of the Left Bank Forest Steppe were calculated. It was found that in three years humus content in soil decreased by 0.2%, nitrogen content of easily hydrolyzed compounds — by 2.9–18.6%, mobile phosphorus — by 2–8.1%, exchangeable potassium — by 10.2–19.5% and increased soil acidity by 0.5 units compared to baseline. A significant decrease in the content of basic macronutrients in soil, depending on the system of chemical protection of plants, is shown. In maize cultivation technology with application of only soil herbicides (Harnes, KE, Stomp 330, KE), Nleg losses in soil were 5–9 mg/kg, P2O5 — 8–10 mg/kg and K2O — 15– 16 mg/kg soil; for application only of insurance herbicides (Callisto 480 SC, KS; Milagro 040 SC hp; Dianate, VRK; Estero 60 ke) losses were: Nleg — 3–8 mg/kg, P2O5 — 3–7 mg/kg, K2O — 12–18 mg/kg soil; for combination in the system of chemical protection of maize plants soil and insurance herbicides: Nleg — 5–19 mg/kg, P2O5 — 5– 12 mg/kg, K2O — 17–23 mg/kg of soil. The lowest nutrient content in soil was recorded by application of pre-harvest herbicides Milagro 040 SC hp and Callisto 480 SC, COP on the background of the soil herbicide Harnes, ke, as well as the preparation Callisto 480 SC, COP on the background of the herbicide Stump 330, ke. — Nleg 83–90 mg/kg, P2O5 147–149 mg/kg and K2O 95–98 mg/kg soil. The calculations confirmed a negative balance of N to –176.1 kg/ha/year and P2O5 to –50.3 kg/ha/year. It was determined that weed vegetation in maize agrocenosis on average per year is able to carry 15,06–53,53 kg/ha of nitrogen, 5,21–18,51 kg/ha of phosphorus, 23,02–81,79 kg/ha of potassium and 78.1–277.6 mm/ha of moisture, creating significant competition for nutrients for maize plants.

Economic efficienty and agro-ecological assessment of herbicides usage for the cultivation of white cabbage parent plants

The composition of agrobiological groups of weeds in the agrocenosis of white head cabbage queen-cell under conditions of irrigation of the Left-Bank Forest-Steppe of Ukraine is analyzed. It was proved the effectiveness of soil herbicides Stomp and Butisan in reduction of weed spreading in the phase of two or three leaves of the crop by 71.5–76.2 %. The introduction of the Fusilade Super herbicide causes a decrease in the number of grass weeds at the time of formation of cabbage leaf rosette by 80.2 %, the use of Lontrel – a decrease in the number of dicotyledonous weeds by 83.6 %. At the use of herbicides, there is a tendency to increase the interphase growth periods and biometric parameters of white head cabbage plants. The use of Stomp and Butisan ensures the preservation of the yield of cabbage queen-cells at the level of 9.3–10.3 t/ha and forms a low-risk level of agrocenosis contamination (agroecotoxicological index ranged from 0.003–0.063). Key words: herbicides, white head cabbage, biometric parameters, yield, agroecotoxycology index.

Constructing sustained-release herbicide formulations based on poly-3-hydroxybutyrate and natural materials as a degradable matrix.

The purpose of the present study was to develop ecofriendly herbicide formulations. Its main aim was to develop and investigate slow-release formulations of herbicides (metribuzin, tribenuron-methyl, and fenoxaprop-P-ethyl) of different structure, solubility, and specificity, which were loaded into a degradable matrix of poly-3-hydroxybutyrate (P(3HB)) blended with available natural materials (peat, clay, and wood flour). Differences in the structure and physicochemical properties of the formulations were studied depending on the type of the matrix. Herbicide release and accumulation in soil were associated with the solubility of the herbicide. Fourier-transform infrared spectroscopy showed that no chemical bonds were formed between the components in the experimental formulations. Degradation of the formulations in agro-transformed soil in laboratory conditions was chiefly influenced by the shape of the specimens (granules or pellets) while the effect of the type of filler (peat, clay, or wood flour) was insignificant. The use of granules enabled more rapid accumulation of the herbicides in soil: their peak concentrations were reached after 3 weeks of incubation while the concentrations of the herbicides released from the pellets were the highest after 5-7 weeks. Loading of the herbicides into the polymer matrix composed of the slowly degraded P(3HB) and natural materials enabled both sustained function of the formulations in soil (lasting between 1.5 and ≥3 months) and stable activity of the otherwise rapidly inactivated herbicides such as tribenuron-methyl and fenoxaprop-P-ethyl. The experimental herbicide formulations enabled slow release of the active ingredients to soil. © 2019 Society of Chemical Industry.

How to get rid of Gallant Soldier?

Goal. The goal of the research was to develop effective Galinsoga parviflora control techniques in crops of field and vegetable crops, taking into account its biological and environmental features.
 Methods. Studies were perform 2010—2018 in industrial crops of 6 farms of the Steppe- and Forest-Steppe zones of Ukraine on ordinary black soil. Establishment of experiments, observations and counts in them carried out according to generally accepted methods.
 Results. The germination of G. parviflora seeds began when the soil was heated to 5°C. The number of seedlings increased until the end of May, reaching 56—149 pcs/m2, in the summer period it did not exceed 4.7—5.8 pcs/m2, and at the end of summer and early autumn it increased again to 96—322 pcs/m2, much of which had a dwarf form. The pre-sowing, post-sowing treatment and loosening of the soil or post-emergence herbicides during the period of planting, the second one — the main processing and mulching of the soil in the sowing were decisive in the control system of the first wave of the G. parviflora seedlings. Early autumn plowing (in August) with preliminary peeling, spring harrowing and leveling of the ЛК-2 soil reduced the potential debris by 58—63%, and the actual one by 1.1—1.6 times. Minimalization of the main tillage led to an increase in debris in crops twice. The efficiency of pre-emergence harrowing of crops in cloudy weather and with good soil moisture did not exceed 72%, and in warm sunny it was 93%. On irrigated lands and heavy soils, two loosening of the soil in between rows reduced the contamination of crops in comparison with the variant without loosening in 1.3—1.4, three — in 1.7—1.9, four–five — in 3.5—4.2 times. When mulching between crops 4—5 cm with a layer of straw at a height of cultivated plants of 8—15 cm, all the weeds died completely, 96% sawdust, 92% with agrofiber. In the years with cold spring, pre-emergence herbicides controlled 72—76%, and in warm years, 89—98% weeds. Post-harvest 3—4 spraying of crops of beets with Goltix herbicides (1.5—2.0 kg/ha) + Belvedere Forte (0.7—1.0 l/ha) starting from the seed of the cotyledon leaves at the weeds and every 7—14 days or 2 sprays in 10—15 days Betanal Progres (1.0—3.0 l/ha) + Caribou (0.03 kg/ ha) ensured their complete suppression. In oni­on crops, 90—95% of weeds were controlled by Galigan (0.75 l/ ha), carrots and green crops — Gezagard (2.5 l/ha), tomatoes and potatoes — Zenkor (0.5 l/ ha), corn sugar — Chaser-P (2.5 l/ ha) or Secateurs (0.15 kg/ha). Tape application of herbicides in combination with inter-row loosening ensured the destruction of 97—99% of weeds while reducing the costs of herbicides by 68—73%.
 Conclusions. The most effective control of G. parviflora is achieved by conducting double-peeling, early plowing, autumn cultivation, spring harrowing, leveling the soil and 3—4 times loose­ning the inter-row spacing of crops. The high control effect of G. parviflora in crops of beets is given by the use of post-harvest herbicides Holtix + Belvedere Forte, Betanal Progres + Caribou, onions — Galigan, carrots and green crops — Gezagard, tomatoes and potatoes — Zencore, sugar corn — Chaser-P or Secateurs. The total death of G. parviflora and other weeds is ensured by mulching of crops 4—5 cm with a layer of straw or sawdust.

Sorption and desorption of ametryn in different types of soils

Knowledge of factors related to the dynamics of herbicides in the environment is of fundamental importance to predicting the behavior of herbicides in soils with different attributes, to select appropriate dosages, as well as to avoid harmful effects on the environment and subsequent crops. The objective of this work was to evaluate the sorption and desorption of ametryn in seven soils with different attributes. Initially, the equilibrium time was determined by the "Batch Equilibrium". Then, it was performed the sorption test with different concentrations (0.5; 1; 2; 4; 8; 16; 24 and 32 mg L-1) of ametryn in 0.01 mol L-1 CaCl2. 10 mL of these solutions were added to samples of 2.00 g of each soil, remaining under rotary shaking for 4 hours. After centrifugation and filtration, the ametryn concentration in the supernatant was determined by high-performance liquid chromatography. Desorption was evaluated using the tubes containing 16 mg L-1 prior to sorption testing. The results indicated that the sorption and desorption of ametryn depend on the physicochemical attributes of the soil. Sorption was higher in soils with high organic matter content and high ion exchange capacity, while desorption was inversely proportional to sorption.

Применение гербицидов почвенного действия на льне масличном

Применение гербицидов почвенного действия на льне масличном

Adsorption-desorption characteristics of pyraclonil in eight agricultural soils

After the application of herbicides, their migration and transformation in the environment are closely related to their adsorption characteristics in the soil. The adsorption of herbicides in soil is also important when evaluating their environmental behaviors or risks. Pyraclonil is a contact herbicide widely used to control weeds in paddy fields, especially in Japan. This study investigated the adsorption and desorption behaviors of pyraclonil in eight typical agricultural soils across China. Surface soil samples (0–15 cm) were collected in farmland across China, including Hebei luvisols, Heilongjiang phaeozems, Sichuan gleysols, Zhejiang anthrosols, Jiangxi ferralsols, Shandong alisols, Hubei lixisols, and Hainan plinthosols. Adsorption-desorption experiments were conducted at 25 °C ± 1 °C using a batch equilibration method. Pyraclonil residue was analyzed using high-performance liquid chromatography-mass spectrometry. The adsorption and desorption isotherms of pyraclonil in the eight soils are fitted well by mathematical models. The isothermal adsorption-desorption curves of pyraclonil agree with the simulation results of the Freundlich model. The adsorption of pyraclonil is mainly physical, and all adsorption isotherms are of type L. The adsorption constants range from 3.2 to 28.6 mg1−1/n L1/n kg−1. The desorption curves of pyraclonil in all soils show positive hysteresis, as the hysteresis coefficients are in the range of 0.01–0.26. The adsorption and desorption constants increase with increasing soil organic matter content and cation exchange capacity, but they are not related to soil pH and clay content. Pyraclonil exhibits low adsorption in different agricultural soils, and the adsorption process is irreversible. Pyraclonil has moderate or high mobility in different agricultural soils (except phaeozems with high organic matter content) across China, and pyraclonil could be transported from soil to groundwater after its application. Therefore, pyraclonil poses some risks to surface water and groundwater.

An examination of the role of biochar and biochar water-extractable substances on the sorption of ionizable herbicides in rice paddy soils

The application of biochar as a soil amendment can increase concentrations of soil organic matter, especially water-extractable organic substances. Due to their mobility and reactivity, more studies are needed to address the potential impact of biochar water-extractable substances (BWES) on the sorption of herbicides in agricultural soils that are periodically flooded. Two paddy soils (100 and 700 years of paddy soil development), unamended or amended with raw (BC) or washed biochar (BCW), were used to test the influence of BWES on the sorption behavior of the herbicides azimsulfuron (AZ) and penoxsulam (PE). The adsorption of AZ to biochar was much stronger than that to the soils, and it was adsorbed to a much larger extent to BC than to BCW. The depletion of polar groups in the BWES from the washed biochar reduced AZ adsorption but had no effect on PE adsorption. The adsorption of AZ increased when the younger soil (P100) was amended with BC and decreased when it was amended with BCW. In P700, which has lower dissolved organic carbon (DOC) content than P100, the adsorption of AZ increased regardless of whether biochar was raw or washed. The adsorption of PE slightly decreased when P100 was amended with BC or BCW and slightly increased when P700 was amended with BC or BCW. In order to evaluate compositional differences in the biochar and BWES before and after the washing treatment, we performed solid-state 13C NMR spectroscopy of BC and BCW, and high resolution mass spectrometry of BWES. Our observations stress the importance of proper consideration of soil and biochar properties before their incorporation into paddy soils, since biochar may reduce or increase the mobility of AZ and PE depending on soil properties and time of application.

Development and Validation of a Liquid Chromatography–Tandem Mass Spectrometry Method for Multiresidue Determination of 25 Herbicides in Soil and Tobacco

In the cultivation of tobacco, crop rotation patterns, such as tobacco/rice or tobacco/corn, are widely used. However, the use of herbicides in the rice or corn phase can lead to their being taken in during the tobacco phase by inner conduction action. In the present study, to monitor the use of herbicides in tobacco, a sensitive and simple analytical method coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS) has been established for determination of 25 herbicides in soil as well as fresh and flue-cured tobacco leaf. The herbicides analyzed include six aryloxy phenoxy propionate herbicides (APPs) and 19 sulfonylureas herbicides (SUs). The samples were extracted using acetonitrile and purified using C18 sorbent before analysis. Optimum separation of the analytes was achieved using an Agilent Eclipse XDB-C18 column at 40 °C and gradient elution with acetonitrile and 0.1% aqueous formic acid as the mobile phase at a flow rate of 0.8 mL min−1. The limits of quantification and detection are in the ranges 0.08–1.00 mg kg−1 and 0.024–0.30 mg kg−1, respectively, and matrix effects in the range − 70 to 50% were achieved. The recovery rates obtained from spiked soil and tobacco leaf samples ranged from 72.32 to 116.83% with intra-day and inter-day relative standard deviations of 0.44–11.55%. In addition, the method developed was applied to the determination of herbicides residues in actual soil and tobacco samples, revealing that the proposed method can detect trace amounts of APPs and SUs in soil as well as in fresh and flue-cured tobacco leaf.

Behavior of imidazolinone herbicide enantiomers in earthworm-soil microcosms: Degradation and bioaccumulation

Imidazolinone herbicides are a group of chiral herbicides that are widely used to control weeds in crops. Despite their wide use, few studies on the behavior of enantiomers in terrestrial systems have been reported. In this study, the bioaccumulation of imazamox, imazapic, and imazethapyr enantiomers in earthworm and their degradation in soils were assessed using earthworm-soil microcosms. The bioaccumulation of the three herbicides in earthworm was not significantly enantioselective. Imazamox and imazethapyr did not significant stereoselective degradation in soil (p > 0.05), while the enantioselectivity of the degradation of imazapic was significant (p < 0.05). Furthermore, biota to soil accumulation factor (BSAF) values were also calculated for three herbicides. Relationships between BSAF values and organic matter content of soil and log KOW of herbicides were investigated. The BSAFs values were negatively correlated with the log KOW of herbicides, and were positively correlated with organic matter content of soil in earthworm-soil microcosms. These relationships indicated that chemical hydrophobicity (Kow) and organic matter content of soil were good predictors to estimate the bioavailability of imidazolinone herbicides to earthworm.

The biological activity of chernozem typical in the application of herbicides in the technology in the cultivation of corn

Influence of soil and postemergent herbicides in the technology of continuous corn growing on activity of biological processes in chernozem typical is studied. It has been shown that using herbicides for three years in a row in the system of corn protection caused decreasing the contest of total biomass of microorganisms in the soil by 8–57% compared to lealand and increasing the emission intensity of СО2 from the soil by 2–13% compared to control depending on chemical preparation type. Applying preparation Esteron 60 k.e. (consumption rate 80 l/ha) caused decreasing of total biomass of microorganisms by 42.1% and oxidoreductase activity by 19–20% compared to control, increasing soil phytotoxicity up to 56.5%. Spraying the crops with postemergent herbicides Milagro 040 SC k.c. and Kallisto 480 SK, KC at recommended consumption rate of (1.0 and 0.2 l/ha correspondingly) does not cause essential depression of soil microbiota and activity of ferments polyphenol oxydase and peroxydase. Soil phytotoxicity in these variants was at the level of 31.9 and 36.3% which was 9.6 and 24.7% higher than in control correspondingly. According to soil phytotoxicity indices in the technology of continuous corn growing researched herbicides are placed in such row: Milagro 040 SC k.c. < Kallisto 480 SC, KC < Stomp 330, k.e. < Harnes, k.e. < Dianat, BRK < Esteron 60 k.е.

Quantification of the Fate of Aminocyclopyrachlor in Soil Amended with Organic Residues from a Sugarcane System

Aminocyclopyrachlor is a persistent herbicide in soil; in the presence of organic matter, this persistence can be increased and can contribute to environmental contamination. The objective of this study was to verify the effects of organic materials derived from the sugarcane cultivation system on the mineralization and degradation of aminocyclopyrachlor in the soil. 14C-aminocyclopyrachlor was applied to soil with organic residues (sugarcane straw, filter cake and vinasse) and evaluated for 112 days of incubation. Mineralization was quantified by the weekly evolution of 14CO2, and the extracted, bound residues and the formation of metabolites of aminocyclopyrachlor were quantified. The mineralization was lower than 45% in all treatments. The degradation half-life (DT50) is being 187 days for unamended soil and > 240 days for soils amended with organic materials. For 90% of the herbicide to be degraded (DT90), between 622 and 921 days was required in all soils. Bound residues were formed in the soil (30% of the total applied in all treatments). No metabolites were formed during the whole incubation period, regardless of the treatment. The presence of organic materials in the soil increased the persistence of aminocyclopyrachlor in the soil, so that persistence of the herbicide may promote a residual effect on weeds and carryover in subsequent crops.

Sorption-desorption isotherms and biodegradation of glyphosate in two tropical soils aged with eucalyptus biochar

ABSTRACT The objective of this study was to evaluate the sorption-desorption process and biodegradation of glyphosate in two tropical soils aged with biochar derived from eucalyptus. The biochar aging period was 30 d. There was little difference between the amounts of sorbed glyphosate in Ultisol (96.8, 96.8 and 96.4%) and Alfisol (97.1, 97.5 and 97.4%) soils that were unamended or amended with biochar aged for 0 or 30 d, respectively. Similar amounts of desorbed herbicide occurred in Ultisol (3.3, 3.3 and 3.4%) and Alfisol (4.1, 4.2 and 3.9%) soils, respectively. The degradation time half-life (DT50) of glyphosate in Ultisol unamended and initial amended were higher (38 and 36 d, respectively) than DT50 in the amended soil with 30 d of biochar aging (27 d); and in the Alfisol DT50 was higher in unamended soil (38 d), and similar in soil unamended at 0 and 30 d of biochar aging (21 and 26 d, respectively). The addition of biochar to two tropical soils or its aging did not have any effect on the sorption and desorption of glyphosate and its biodegradation in relation to the unamended soils, and it can did not affect the transport and persistence of this herbicide in soil.

Formation of Sesame Productivity under the Influence of Agricultural Techniques under Dry Steps of Ukraine

Formation of Sesame Productivity under the Influence of Agricultural Techniques under Dry Steps of Ukraine

Effectiveness of herbicides against weeds and their residual effect on soil and carrot (Daucus carota)

An experiment was conducted to study the efficacy of different herbicides for weed control in carrot (Daucus carota L.) and their residual effect on soil as well as on crop, at Research Farm of CCS Haryana Agricultural University, Hisar (2012–13 and 2013–14). Thirteen treatments includes pre-emergence application of three herbicides, viz. oxyfluorfen and oxadiargyl (80, 100, 120 g/ha and 100 g/ha + HW), and pendimethalin (1.0 kg/ha and 1.0 kg/ha + HW), two weedings at 30 and 60 DAS, weed free and weedy check (control) are replicated three times in Randomized Block Design. Residues of these herbicides were estimated in soil and root samples, using GC-MS/MS. Based on two years pooled data it was concluded that pre-emergence application of oxadiargyl 100 g/ha, oxyfluorfen 100 g/ha and pendimethalin 1.0 kg/ha integrated with one hand weeding at 30 DAS resulted in effective weed control (70–72%) in carrot without any phytotoxicity on crop and gave 79.5, 77.2 and 76.4% higher root yield over weedy check, respectively. The residues of these herbicides in soil, carrot root as well as in foliage were found below detectable level at the time of harvest.

Covalent immobilization of ionic liquid-based porous polymer onto poly(ether ether ketone) for stir bar sorptive extraction and its application in analysis of chlorophenoxy acid herbicides in soil

The application of stir bar sorptive extraction (SBSE) for polar compounds has been restricted because of less choice of suitable sorbents. In this study, an ionic liquid-based organic polymer with desired anionic exchange ability and porous structure was used for extraction of polar analytes with high extraction efficiency and capacity. For improving the workability of stir bar, the polymer was immobilized onto chemically resistant poly(ether ether ketone) (PEEK) tube by covalent modification method which including a skillful functionalization process. Afterwards, a facile detachable dumbbell-shaped structure with modified PEEK tube as jacket was constructed. Due to the excellent chemical and physical strength of PEEK material and dumbbell-shaped structure, the stir bar performed remarkable stability in the SBSE process. In addition, the detachable structure allowed the elution can be accomplished directly in the insert tube of autosampler vial with small amounts of solution, which significantly enhanced the enrichment factor and simplified the operation. After coupling with HPLC-MS/MS, the prepared organic polymer modified stir bar was applied for the analysis of three chlorophenoxy acid herbicides and showed favorable extraction efficiency with enrichment factors between 198 and 206 folds. For quantitative analysis of three chlorophenoxy acid herbicides, the method has wide linear range (0.003–10 ng/mL), good linearity (R2 ≥ 0.9958) and good reproducibility (intra-day relative standard deviation ≤ 6.16%). Furthermore, the proposed method was applied to determine chlorophenoxy acid herbicides in soil samples, the recoveries ranged from 79.4% to 97.4%, with relative standard deviation ≤ 9.3%.

Persistence of imazapyr+imazapic in irrigated rice area and effect on soybean due to soil moisture and phytoremediation in the off-season

ABSTRACT The residue of imidazolinone herbicides in soil can be detrimental to soybean cultivation in rotation with Clearfield® rice. Thus, this research aimed to evaluate the ryegrass phytoremediation capacity on the imazapyr+imazapic residue in the soil in two soil moisture conditions in the off-season, and the effect on soybean growth in the next growing season. Two experiments were conducted between 2016 and 2017 in Santa Maria, Rio Grande do Sul state, Brazil. It was used the randomized block design in a 3 × 2 factorial. The first factor being the residue in the soil of 0, 210 and 420 g c.p.·ha–1 of the formulated mixture of the herbicides imazapyr+imazapic(525 + 175 g a.i.·kg–1) applied to rice in the 2015/2016 growing season, and the second factor being the presence or absence of ryegrass in the off-season. One experiment was conducted under soil moisture above 70% of field capacity in the off-season, and the other under ambient condition of soil moisture. The soil residue of the application of 420 g c.p.·ha–1 of the imazapyr+imazapic herbicides performed129 days before planting caused phytotoxicity and reduced dry matter of ryegrass under high soil moisture condition in the off-season in irrigated rice areas. Soybean, when planted 359 days after application, has its initial root and shoot growth affected by the residue of 210 and 420 g c.p.·ha–1 rates in high soil moisture condition in the off-season, regardless of ryegrass cultivation during the same period. However, grain yield is not affected.

Mobility of 2,4-Dichlorophenoxyacetic Acid, Glyphosate, and Metribuzine Herbicides in Terra Rossa-Amended Soil: Multiple Approaches with Experimental and Mathematical Modeling Studies

2,4-Dichlorophenoxyl acetic acid (2,4-D), glyphosate, and metribuzine are used extensively as an herbicide in the vicinity of Antalya, Turkey. The objective of this study was to investigate the mobility of such herbicides in terra rossa-amended soil by multiple approaches with batch, miscible-displacement, and mathematical modeling studies. The results indicated that the sorption isotherms exhibited predominantly linear behavior over a wide range (0–100 mg/L) of selected herbicides. The average distribution coefficient (Kd) obtained from linear sorption isotherm was 0.95, 1.20, and 44.15 L/kg for 2,4-D, metribuzine, and glyphosate, respectively. After hydrogen peroxide treatment for eliminating organic carbon content in the soil, the average distribution coefficient (Kd) obtained from the linear sorption isotherm was 0.096, 0.118, and 4.37 L/kg for 2,4-D, metribuzine, and glyphosate, respectively. Miscible-displacement experiments also showed that the sorption of 2,4-D, metribuzine, and glyphosate was described by linear and rate-limited processes in the soil. Transport of metribuzine and 2,4-D was slightly but glyphosate was extensively delayed compared to non-reactive tracer experiments in the soil. Hydrogen peroxide treatment experiments also indicated that the organic carbon content was responsible for the non-ideal sorption behavior of such herbicides. The rapid desorption can be attributed to soft carbon fraction (humic/fluvic acid and lipids), whereas slower desorption can be responsible by hard carbon fraction (black carbon, kerogen) of soils that led to chemically non-ideal behavior. Two-site transport modeling analyses, including linear sorption and rate-limited sorption–desorption, provided a reasonably good match to the herbicide breakthrough curves indicating mathematical modeling results were generally consistent with the results obtained from the batch and column experiments. As a result, sorption of 2,4-D and metribuzine onto terra rossa-amended soil was low which could lead to contamination risk of karstic groundwater resources overlying the Antalya travertine plateau in the region. On the other hand, glyphosate exhibits much more sorption affinity in the soil and leaching risk is limited as with more delay. As a result, investigating the mobility of such herbicides in top soils overlying the karstic aquifer systems in Antalya would be very important to identify the contamination risk of groundwater resources. The results from the present study would also help in the design of effective herbicide management strategies in Antalya, Turkey.

CONTROL OF QUANTITY OF WEEDS IN SOWING OF CORN

It was established that in the agrophytocenosis of corn on the control variant (without introducing herbicides) a mixed type of debris was formed, in which a group of late spring weeds prevailed. After the introduction of the soil herbicide Adengo 465 (0.5 l / ha) on the sowing of maize weeds were 92% less compared to the contamination of the control experiment, where the chemical method was not used. The combination of the use of the soil herbicide Adengo 465 (0.35 l / ha) and the insurance herbicide Master Power (1.25 l / ha in the 4-5 leaf phase of the crop) in the agrophytocenosis of corn provided the qualitative control of the main weed species. At the time of harvesting in corn crops there were 97% less weeds compared with the control variant. The combined use of these herbicides has provided a high increase in the yield of corn grain - 4.8 t / ha.