The Fate of Paraquat in Soils

Calderbank, A.; Tomlinson, T. E.

doi:10.1080/04345546909415313

Cited by 9 publications

(18 citation statements)

References 4 publications

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“…The phytotoxic symptoms exhibited by the seeds and seedlings in the various treatments show that inactivation on acid peat soil is not complete. This anomaly may be resolved by assuming either (a) that not all the applied chemical is sufficiently strongly held on the absorptive sites of this particular peat soil and a fraction is therefore available to plants (Calderbank & Tomlinson, 1968) or (b) that following an initial and complete adsorption phase some desorption takes place and the behaviour of the herbicide then follows an adsorption isotherm.…”

Section: Experiments 2 the Effect Of Herbicide Placement On The Germimentioning

confidence: 99%

“…In 1964 an investigation was begun to examine the evidence for phytotoxic residues of paraquat in soils. Since tlien, several authors have reported work of a similar nature but they have given particular attention to clays and have concentrated on the physical chemistry of the processes (Knight & Tomlinson, 1967;Calderbank & Tomlinson, 1968;Tomlinson et al, 1968;Weber, Ward & Weed, 1968;.…”

Section: Introductionmentioning

confidence: 99%

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Residual Activity of Paraquat in Soils I. Factors Affecting Persistence

Watkin¹,

Sagar

1971

Weed Research

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Section: Experiments 2 the Effect Of Herbicide Placement On The Germimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Residual Activity of Paraquat in Soils I. Factors Affecting Persistence

Watkin¹,

Sagar

1971

Weed Research

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“…Much work has been published on the inactivation of paraquat by adsorption on mineral soils and clays but knowledge of its behaviour in organic soils is limited (Taylor, 1964;Weber, Perry & Upchurch, 1965;Knight & Tomlinson, 1967;Weber & Weed, 1968;Galderbank, 1968;Calderbank & Tomlinson, 1968). In most mineral soils paraquat is completely and quickly adsorbed.…”

Section: Introductionmentioning

confidence: 99%

The Adsorption and Mobility of Paraquat on Different Soils and Soil Constituents*

et al. 1970

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Summary. The adsorption capacity for paraquat of the following materials was examined: three peat soils; two peaty layers below a turf; a commercial sphagnum peat; grass; Begbroke soil; Fullers’ earth; humic acids isolated from a peat soil; lignin isolated from hardwood sawdust; cellulose powder. The Strong Adsorption Capacity (SAC) of these adsorbents was examined first using a chemical method of analysis and then with the more sensitive Lemna bioassay. Peat soils had an appreciable SAC for paraquat even when measured with the bioassay (88–165 kg/ha 2–5 cm depth, 750–1000 ppm), > 10 times that of Begbroke soil (14 kg/ha, 50 ppm). Humic acids had a higher adsorption capacity (k = 42, 000) than lignin (k = 2600), while cellulose adsorbed very little paraquat (k = 64). The adsorption of paraquat decreased as the ratio of soil to water increased. Temperature appeared to have very small effects on adsorption in organic soils. Results were consistent with calcium competing for adsorption sites. Paraquat sprayed on the surface of a peat soil up to 36 kg/ha remained in the top 7 mm after leaching with 305 mm of natural rainfall over a period of 4 months. Paraquat adsorbed on commercial sphagnum peat could transfer to clays after incorporation and be inactivated. Adsorption et mobilité du paraquat sur diffétrents sols et constituents du sol Résumé , La capacityé d'adsorption du paraquat par les milieux suivants a étéétudiée: 3 sols tourbeux, 2 assises tourbeuses sous un gazon, une tourbe commerciale de sphagnum, une tourbe, un sol de Begbroke, une terre à foulon, un acide humique extrait d'un sol tourbeux, une lignine extraite d'une sciure de bois dur, de la poudre de cellulose. La capacityé brute d'adsorption (CBA) de ces adsorbants a été examinée, au moyen d'une méthode chimique d'analyse puis avec la méthode biologique plus sensible utilisant Lemna. Les sols tourbeux montrèrent une CBA appréciable pour le paraquat même lorsqu'elle fut mesurée par la voie biologique (88/165 kg/ha 2,5 cm de profondeur, 750–1000 ppm), plus de 10 fois celle du sol de Begbroke (14 kg/ha 50 ppm). Pour les acides humiques, la capacityé d'adsorption fut plus éievée (k = 42 000) que pour la lignine (k = 2600) alors que la cellulose n'adsorba que très peu de paraquat (k = 64). L'adsorption du paraquat diminua à mesure que le rapport sol/eau augmentait. La temperature n'eut que de très faibles effets sur l'adsorption dans les sols organiques. Les résultats furent en accord avec la concurrence du calcium pour les lieux d'adsorption. Le paraquat appliquéà la surfaee d'un sol tourbeux jusquà la dose de 36 kg/ha resta dans les 7 premiers millimètres après lessivage par 305 mm de pluie natureile péndant une période de 4 mois. Le paraquat adsorbé sur une tourbe commerciale de sphagnum put être transféréè des argiles aprtè avoir été incorporé et inactiveée. Adsorption und Beweglichkeit von Paraquat in verschiedenen Böden und Bodenbestandteilen Zusammenfassung. Die Adsorptionskapazität von Paraquat wurde für folgende Materialien untersucht: 3 Torfböde...

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“…When paraquat was applied at 2*24, 4-5 or 9 kg/ha it would appear that at the lowest concentration the surface area of soil covered by a spray droplet did not contain sufficient strong adsorption sites to inactivate the compound. Hence, some ofthe herbicide would only be weakly adsorbed (Galderbank & Tomlinson, 1968) and would remain available to seeds. At the two lowest doses the concentration of paraquat might apparently fail to saturate the available strong adsorption sites no matter what the volume rate.…”

Section: Experiments 2 the Effect Of Volume Of Application On Residuamentioning

confidence: 99%

Residual Activity of Paraquat in Soils Ii. Adsorption and Desorption

Watkin

Sagar

1971

Weed Research

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Summary Glasshouse studies showed that low doses of paraquat inhibited the germination of Lolium perenne L. broadcast directly onto the paraquat‐sprayed surfaces of a sphagnum and a peat soil, but that higher doses were necessary to produce phytotoxic symptoms on mineral soils, a compost and a loam. On all soils residual activity increased rapidly with increasing dose once the minimum phytotoxic dose was reached. On a sandy soil, residual activity increased almost linearly from the lowest to the highest dose applied. At 9·0, 4·5 and 2·24 kg/ha phytotoxicity on a compost was not affected by changes in the volume of application, but at 1·68 kg/ha and lower, reducing the volume from 562 1/ha to 281 and 112 1/ha resulted in increased phytotoxicity. Phytotoxic residues were eluted from paraquat‐treated compost surfaces by percolating de‐ionized water up soil columns but residual activity was not removed from the eluted surfaces. Surface irrigation of paraquat‐treated surfaces with water previously percolated through columns of untreated soil reduced residual activity by 45%.

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The Fate of Paraquat in Soils

Cited by 9 publications

References 4 publications

Residual Activity of Paraquat in Soils I. Factors Affecting Persistence

Residual Activity of Paraquat in Soils I. Factors Affecting Persistence

The Adsorption and Mobility of Paraquat on Different Soils and Soil Constituents*

Residual Activity of Paraquat in Soils Ii. Adsorption and Desorption

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