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The aim of this work was to study the effect of the application of a solid waste from olive oil production (alperujo) on the movement and persistence of the herbicide terbuthylazine (N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine). An experimental olive grove was divided in two plots: (i) Plot without organic amendment (blank) and (ii) Plot treated with alperujo during 3 years at a rate of 17920 kg of alperujo ha- 1. Terbuthylazine was applied to both plots at a rate of 2 kg ha- 1 a.i. Triplicates from each plot were sampled at 3 depths (0-10, 10-20 and 20-30 cm), air-dried, remains of olive leaves, grass roots, and stones removed and sieved through a 5 mm mesh sieve. Terbuthylazine was extracted with methanol 1:2 weight:volume ratio, the extracts were evaporated to dryness, resuspended in 2 mL of methanol, filtered and anylized by high performance liquid chromatography (HPLC). Higher amounts of terbuthylazine were detected at each sampling depth in plots treated with alperujo. The increase in soil organic matter content upon amendment with alperujo slightly increased sorption, suggesting that other factors beside sorption affect terbuthylazine degradation rate in organic amended soils. [ABSTRACT FROM AUTHOR]

Diuron [3-(3,4-dichlorophenyl)- = 1,1-dimethylurea] and simazine (6-chloro-N2, N4-diethyl-1,3,5-triazine-2,4-diamine) are soil-applied herbicides used in olive crops. The objective of this study is to investigate the combined effect of these herbicides and the amendment of soil with an organic waste (OW) from the olive oil production industry on the growth and photosynthetic apparatus of adult olive trees and to compare the results with those obtained by Redondo-Gómez et al.[1] for two-year-old trees. For this purpose, growth rate, gas exchange and chlorophyll fluorescence parameters were measured in 38-year-old olive trees, after one and two months of soil herbicide treatment and/or OW amendment. Soil co-application of OW and herbicide increases the quantum efficiency of Photosystem II (PSII) and the assimilation of CO2 in olive trees, which led to a higher relative growth rate of the branches and leaves in length. Herbicide treatment reduced the photosynthetic efficiency in olive trees after two months of soil application, while this reduction is evident from week one in younger trees. [ABSTRACT FROM AUTHOR]

Diuron (3-(3,4-dichlorophenyl)- = 1,1-dimethylurea) and simazine (6-chloro-N2, N4-diethyl-1,3,5-triazine-2,4-diamine) are soil-applied herbicides used in olive crops. The objective of this study is to investigate the effect of these herbicides on Photosystem II photochemistry of Olea europaea L., and whether the amendment of soil with an organic waste (OW) from olive oil production industry modifies this effect. For this purpose, herbicide soil adsorption studies, with unamended and OW-amended soil, and chlorophyll fluorescence measurements in adult olive leaves, after one, two and three weeks of soil herbicide treatment and/or OW amendment, were performed. Soil application of these herbicides reduced the efficiency of Photosystem II photochemistry of olive trees due to chronic photoinhibition, and this effect is counterbalanced by the addition of OW to the soil. OW reduces herbicide uptake by the plant due to an increase in herbicide adsorption. [ABSTRACT FROM AUTHOR]

New designs of pesticide formulations based on organoclays are receiving increasing attention in reducing offsite movement of pesticides in the environment and in prolonging the efficacy of soil-applied pesticides. In the present article, we report the results of laboratory and field experiments conducted to evaluate the influence of the saturating cation, the sorbent  :  herbicide ratio, and the type of preparation on the controlled release properties of organoclay-based formulations of the herbicide hexazinone. Two organoclays with different affinities for hexazinone (hexadecyltrimethylammonium-exchanged Arizona montmorillonite, HDTMA-SA, and phenyltrimethylammonium-exchanged Arizona montmorillonite, PTMA-SA), two herbicide loadings (10% and 20% AI), and three types of preparation were assayed. Laboratory experiments showed that hexazinone formulations based on HDTMA-SA displayed slow-release properties in water, retarded herbicide leaching through soil columns, and maintained a herbicidal efficacy similar to that of the currently available commercial hexazinone formulation (wettable powder). In contrast, PTMA-SA formulations released the herbicide instantaneously and did not display slow-release properties. High organoclay-herbicide ratios and the use of organic solvent made the interaction between HDTMA-SA and the herbicide more intimate and reduced the release rate of hexazinone, suggesting that a range of release and leaching behaviours can be achieved by selecting the type of preparation and the herbicide loading in the formulations. A field experiment confirmed the usefulness of HDTMA-SA formulations of hexazinone to reduce herbicide leaching while maintaining weed-control efficacy. [ABSTRACT FROM AUTHOR]

The effect of organic amendments (OA) on imidacloprid sorption and dissipation in soil was investigated. A sandy soil was treated at a rate of 10% w/w with three OA: one liquid (Liquid Fertiormont, LF) and two solid (Solid Fertiormont, SF, and Alperujo, A). Sorption was measured using a batch equilibration method. Dissipation studies in the dark were performed by incubating pesticide-treated soils at moisture content of - 0.33 KPa and 20 ± 2°C for 28 days, whereas imidacloprid photolysis studies in soils were performed by irradiation of treated soils at water holding capacity in a Suntest apparatus with a xenon lamp for 32 h. In both cases, soils were sampled periodically and extracted for their imidacloprid content. Solid OA (SF and A) increased imidacloprid sorption by soils, whereas similar sorption was observed in soil amended with LF. Imidacloprid half-lives obtained from incubation studies in the dark remained unaffected upon amendment, whereas OA decreased the photolysis rate of imidacloprid in soils. However, no relation was observed between increase in sorption and decrease in the photodegradation rate of imidacloprid. [ABSTRACT FROM AUTHOR]

The sorption capacity and possible mechanisms of sorption of two new sulfonylaminocarbonyltriazolinone herbicides, methyl 2-[[[(4,5-dihydro-4-methyl-5-oxo-3-propoxy-1H-1,2,4-triazol-l-yl)carbonyl]amino]sulfonyl]benzoate (MKH 6561) and (4,5-dihydro-3-methoxy-4-methyl-5-oxo-N-[[2-(trilluoromethoxy)phenyl]sulfonyl]-1H-1,2,4-triazole-1-carboxamide) (MKH 6562), and their potential metabolites, 2,4-dihydro-4-methyl-5propoxy-3H-1,2,4-triazol-3-one (triazole) and 2-trifluoromethoxybenzenesulfonamide (phenylsulfonamide) on octadecyl (C18) and dioctadecyldimethylammonium (DOD) saturated and Fe&sup3+; and Na[sup+] saturated smectites has been investigated. Sorption of M K H 6561 on inorganic clays and C18 organoclays was much higher than for MKH 6562, but was similar on DOD saturated clays. For C18 saturated clays, sorption of both parent compounds increased with decreasing layer charge of the organosmectite. Sorption of triazole metabolite, which was much lower than for its parent compound MKH 6561, was higher on inorganic and CI8 saturated clays than on DOD saturated clays or inorganic clays. Phenylsulfonamide metabolic sorption, which was also lower than the corresponding parent compound MKH 6562, wets higher on DOD saturated clays than on C18 or inorganic saturated clays. These differences in sorption behaviour are related to the diverse relative contribution of hydrophobic and polar interactions for the various compound-clay systems. [ABSTRACT FROM AUTHOR]

An approach for minimizing the risk of ground water contamination for highly mobile pesticides is to enhance the soil sorption process through the application of the pesticide together with a sorbent which limits the amount of pesticide immediately available for undesirable leaching losses. In this work, a number of clays exchanged with different inorganic and organic cations were assayed as sorbents of the acidic herbicide picloram (4-amino-3,5,6-trichloropyridine-2-carboxylic acid) and the ability of three selected clays to retard the release of picloram into water and to reduce picloram leaching through a soil column was investigated. For the selected clays, Fe[sup31]-saturated Wyoming montmorillonite (Fe-SW), octadecylammonium-treated Arizona montmorillonite (ODA-SA[sub1]) and hexadecyltrimethylammonium-saturated Arizona montomorillonite (HDTMA-SA[sub2]), two types of clay picloram complexes (a physical mixture, PM, and a strongly-sorbed complex, SC) were prepared. All clay picloram complexes yielded slow release of the herbicide and retarded its vertical movement through soil columns compared to the free technical compound, showing that clay pesticide complexes prepared from selectively-modified clays may be useful in reducing rapid leaching of highly mobile pesticides such as picloram. [ABSTRACT FROM AUTHOR]

A laboratory study with a 1×3 factorial design has been conducted to assess the effect of the addition of 10% and 20% w/w of an organic amendment [26% organic carbon (C)] in sorption, degradation and leaching of simazine in a sandy soil (0.66% organic C, 75% sand, 16% clay). Sorption studies have been performed following a batch equilibration procedure and sorption isotherms fitted to Freundlich equation. The Kf increased by a factor of 2.5 and 1.8 with high and low amendment dose, respectively. Simazine treated soils were incubated at ‐33 KPa moisture content and 20°C for 28 days (d). Soils were sampled periodically and simazine residues extracted with methanol. No changes in simazine residues with incubation time were observed for the original unamended soil, whereas calculated half‐lives obtained by fitting simazine dissipation curves in the amended soils to first order kinetics were 123 d for the lower dose and 69 d for the high dose. Mobility was studied in handpacked soil columns under fluctuating saturated/ unsaturated flow conditions. Breakthrough curves were consistent with an inverse relationship between leaching and sorption, with greater mobility of simazine in the untreated sandy soil than in the amended soils. Recoveries of initially applied simazine in leachates after the application of 750 mL of water were 93% for the original soil, 88% for soil amended with the low dose of humic amendment, and 53% for the high dose, which is also consistent with degradation studies. These results indicate that the humic amendment reduces herbicide leaching by promoting sorption and degradation processes. [ABSTRACT FROM PUBLISHER]