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Six sunflower herbicides were tested at two application rates (1N and 2N) on three locations (with different soil types) within three years (2015-2017). Efficacy of the tested herbicides on Chenopodium album increased with an increasing cation exchange capacity (CEC) of the soil. Efficacy of pendimethalin was 95%, flurochloridone and aclonifen 94%, dimethenamid-P 72%, pethoxamid 49% and S-metolachlor 47%. All tested herbicides injured sunflower on sandy soil (Regosol) which had the lowest CEC, especially in wet conditions (phytotoxicity 27% after 1N application rate). The highest phytotoxicity was recorded after the application of dimethenamid-P (19% at 1N and 45% at 2N application rate). Main symptoms of phytotoxicity were leaf deformations and necroses and the damage of growing tips, which led to destruction of some plants. Aclonifen, pethoxamid and S-metolachlor at 1N did not injure sunflower on the soil with the highest CEC (Chernozem) in any of the experimental years. Persistence of tested herbicides was significantly longer in Fluvisol (medium CEC) compared to Regosol and Chernozem. Dimethenamid-P showed the shortest persistence in Regosol and Chernozem. The majority of herbicides was detected in the soil layer 0-5 cm in all tested soils. Vertical transport of herbicides in soil was affected by the herbicide used, soil type and weather conditions. The highest vertical transport was recorded for dimethenamid-P and pethoxamid (4, resp. 6% of applied rate) in Regosol in the growing season with high precipitation.

Metazachlor and pendimethalin are the most used herbicides in kohlrabi. The main objectives of the present study were to evaluate the residual activity of herbicides pendimethalin and metazachlor in kohlrabi and soil under different irrigation regimes and to evaluate the effect of soil adjuvants on the residual activity of tested herbicides. Pendimethalin dissipation half-life (17.3-38.3 days) was higher than metazachlor dissipation half-life (12.1-16.8 days). The pendimethalin half-life was not affected by an adjuvant, irrigation, and an experimental year. Pendimethalin mobility in the soil was affected more by natural precipitation than by irrigation. The use of adjuvant did not affect pendimethalin leaching in dry weather conditions. In wetter natural conditions, a higher pendimetha-lin leaching was found at early-irrigated plots treated by an adjuvant (9.39% of the applied dose was detected in the soil layer 5-10 cm). Metazachlor dissipation half-life was not affected both by an adjuvant and by irrigation. In the soil layer 5-10 cm, metazachlor was detected only in 2016 on intensively irrigated plots without the use of adjuvant (0.072 µg/g). A concentration of pendimethalin in kohlrabi tubers ranged between 2 and 7 µg/kg. The highest concentration of pendimethalin was detected in tubers, which were intensively irrigated shortly after the application of herbicides without an adjuvant, especially when natural precipitation was high. Metazachlor was not detected in any of the tested kohlrabi samples.

The leakage of pharmaceuticals present in soils towards groundwater is largely controlled by sorption of those compounds in soils. In some soils, soil aggregates are covered by coatings, which may have considerably different composition in comparison to that in an inner part of the aggregates. The aim of this study was to evaluate the sorption of three pharmaceuticals, which were applied in single or all compounds solutions, onto soil samples taken from the Bt horizon of a Haplic Luvisol. Analyses were performed on three types of disturbed soil samples: (1) entire aggregates, (2) aggregates from which coatings were removed, and (3) clay-organic coatings. Sorption of atenolol onto material from coatings was slightly higher than that onto material from the inner parts of the aggregates. On the other hand, sorption of sulfamethoxazole onto material from the coatings was lower than that from the aggregate interior. Both associates with a dominant fraction of clay particles (that are mostly negatively charged) in the coatings in comparison to soil composition in interiors and thus larger cation exchange capacity, which increased sorption of the positively charged atenolol and decreased sorption of the negatively charged sulfamethoxazole. Sorption of carbamazepine, which was in neutral form, did not substantially differ. The sorption of all three compounds did not decrease due to the competition between these compounds for the same sorption sites when applied simultaneously. Atenolol sorption was similar for both applications. Sorption of sulfamethoxazole increased when applied in solution with the other two compounds in comparison to its negligible sorption measured for the single compound solution likely due to sorption of the positively charged molecules of atenolol onto the negatively charged surface of soil components and reduction of repulsion between the soil components and the negatively charged molecules of sulfamethoxazole. Carbamazepine sorption also increased probably due to ionization of molecules due to dipole - induced dipole interaction between non-polar and polar molecules in solution.

The concentration and distribution of organochlorine pesticides (OCPs) were studied in sierozem-meadow soils around a buried obsolete chemicals stock in Mirzaabad district of Syrdarya region of Uzbekistan. 23 soil samples were collected from the topsoil (0-30 cm of soil depth) and 15 samples were collected from three soil profiles (down to 125 cm of soil depth) located in nearby vicinity of the stock. They were extracted using an automated Soxhlet extractor and analyses were done by gas chromatography-mass spectrometry. The detected OCPs were DDTs, HCHs, aldrin, dieldrin, endrin, chlorpyrifos, and endosulfans. The concentration of HCH was detected only as α-HCH in the range of 0-3.159 μg/kg. Only two isomers of DDT: p,p'-DDE and p,p'-DDD were found to be dominant, with the range of their values of 0.068-4.941 and 0-13.63 μg/kg, respectively. The concentrations of aldrin, dieldrin, endrin and chlorpyrifos in the samples collected around the source were in the range of 0-0.504, 0-1.117, 2.414-20.87 μg/kg and 0-3.819 μg/kg. β-endosulfan varied from a non-detectable amount to 74.56 μg/kg. According to results, the sum of DDTs was observed to be higher in the upper horizons, especially at depths of 0-10 and 10-50 cm, with the values 543.15 and 212.22 μg/kg, respectively, which can be a cause of concern. Due to their ability to migrate in the environment, accumulate in the food chain and be harmful to human health, monitoring the level of residues of organochlorine pesticides in soil is of vital importance.

The aim of this work was to compare the efficacy, selectivity to sunflower and dissipation of three pre-emergent herbicides. Flurochloridone, linuron and oxyfluorfen were applied individually and each herbicide was also applied in a tank mix with two different adjuvants (a silicon-based adjuvant and paraffin oil). Small-plot field trials were carried out with sunflower in Central Bohemia in 2012 and 2015. Around 25-35% of the active ingredients in the applied herbicides were detected in soil 60 days after application in both years, except for oxyfluorfen in 2012, whose residual concentration was 60%. The tested soil adjuvants did not affect the dissipation of any of the tested herbicide in soil in either experimental year. Oxyfluorfen exhibited the highest mobility and caused the greatest degree of sunflower injury (18%), especially in the year with high rainfall shortly after application. None of the tested adjuvants significantly affected sunflower injury by any tested herbicide. The efficacy of flurochloridone and linuron on Fallopia convolvulus was strongly affected by weather conditions shortly after application. The efficacy of oxyfluorfen was around 85% and was not affected by weather conditions. The effect of adjuvant on herbicide efficacy was positive only in dry conditions, where the efficacy of flurochloridone on F. convolvulus was positively affected by the silicon-based adjuvant.

Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2, 6-dinitrobenzenamine] is a herbicide used worldwide to control most annual grasses and common weeds in cereals, fruit, and vegetables. Its degradation in Haplic Chernozem under controlled greenhouse conditions was studied in this paper. The effect of recommended and doubled pendimethalin doses, as well as the effect of the biopreparate EM-EKO ProBio Plus on pendimethalin degradation in soil and on soil microorganisms was investigated. Pendimethalin half-life ranged from 24.4 to 34.4 days and the double dose did not increase the pendimethalin half-life. Thirty-eight days after pendimethalin application there was no statistical difference between the pendimethalin concentration in soil when applied at the recommended and doubled dose. No effect of pendimethalin on the amount or the activity of soil microorganisms was observed. The effect of EM-EKO ProBio Plus was apparent only on the first sampling of double-dose pendimethalin, however, this bio-preparate had no significant effect on the half-life of pendimethalin, as observed at the end of the experiment.

The chlorotoluron transport in the soil profiles was studied under field conditions on three different soil types of the Czech Republic. The herbicide was applied on 21. 4. 2005 on a four-square meter plot using an application rate of 2 kg/ha. Soil samples were taken on days 35 and 150 from the herbicide application to study the remaining chlorotoluron distributions in the soil profiles. The chlorotoluron distributions in the monitored soils were very similar 35 days after the herbicide application. The major part of chlorotoluron was detected in the top layer of the soil profile (0-8 cm). The highest concentration was obtained in the top 2 cm layer and it decreased gradually with the depth. The percentages of the remaining chlorotoluron 35 days after the herbicide application were similar in Haplic Luvisol (29.97%) and Greyic Phaeozem (30.78%), and slightly higher in Haplic Cambisol (38.58%). The chlorotoluron distributions in the monitored soils differed considerably 150 days after the herbicide application. Chlorotoluron was detected in the entire monitored soils profiles (0-50 cm). The highest concentration was found in all cases in the top 2 cm layer and it decreased gradually with the depth to the depth of approximately 10 cm. Below this level, the herbicide contents were low and the values oscillated randomly. The percentages of the remaining chlorotoluron 150 days after the herbicide application were in the increasing order: Greyic Phaeozem < (5.45%) < Haplic Luvisol (11.7%) < Haplic Cambisol (17.48%). The BPS mathematical model connected with the soil database was used to simulate the chlorotoluron distribution 35 and 150 days after the herbicide application. The comparison of the measured and simulated data indicated probably varying chlorotoluron half-life during the experiment. The results showed that, if the chlorotoluron half-life is estimated based on the remaining chlorotoluron content in the soil profile on the 150th day after the herbicide application, the simulated herbicide content on the 35th day is twice as high as the measured one. On the other hand, if the half-life degradation of chlorotoluron is estimated based on the remaining chlorotoluron content in the soil profile on the 35th day, the herbicide is almost totally degraded on the 150th day of the model simulation.