THE ADSORPTION OF UREA AND SOME OF ITS DERIVATIVES BY A VARIETY OF SOILS

Summary. The absorption of urea and a number of its derivatives by different soils was investigated using a slurry-type procedure. The materials could be listed in the following order of increasing tendancy to be adsorbed: urea, fenuron, methylurea, phenylurea, monuron, monolinuron, diuron. linuron, neburon and chloroxuron. Both N -aryl and N -alkyl substituents appeared to play a part in adsorption. Increasing chain length in the alkyl substituents and chloro- and chlorophenoxy substitution in the aryl substituent increased adsorption. There was no relationship between adsorption and water solubility.
Organic matter content was the only soil property that could be related to adsorptive capacity. The evidence of Langmuir isothermal equilibrium plots suggests that only a fraction of the total soil surface is available for the adsorption of substituted ureas.
L'adsorption Je l'uré de ses dérivés sur dfférents sols     

RESIDUAL ACTIVITY OF PARAQUAT IN SOILS II. ADSORPTION AND DESORPTION

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%.     

DEGRADATION, ADSORPTION AND VOLATILITY OF DI-ALLATE AND TRI-ALLATE IN PRAIRIE SOILS

Summary. Electron-capture gas chromatography was used to detect di-allate and tri-allate in two soils at different moisture levels. At rates equivalent to 2 25-2 - 50 lb/ac, 50% of the di-allate applied was degraded in Weyburn loam in 4 weeks at moisture levels in excess of the wilting point. Losses in Regina heavy clay were slightly lower. In both soils little degradation was observed at moisture levels below the wilting points and negligible losses occurred in sterile soils, indicating that microbial degradation can be an important factor contributing to di-allate breakdown. Breakdown of tri-allate in both soils was slower than for di-allate. At 2·0 lb/ac di-allate was leached more from Weyburn loam than from Regina heavy clay. Tri-allate underwent almost complete adsorption by four soils from aqueous solution, whereas di-allate was adsorbed to a lesser extent. Soil volatility of tri-allate appears to be negligible even on heating to 50°C for 28 days. Vapour losses of di-allate from treated soils are dependent on soil type and temperature. In field plots 15–20% of the applied tri-allate was found in the top 5 cm soil after one growing season. Less than 5% of the initial di-allate remained. Negligible residues of either chemical were found at the 5–10 cm level. Dégradation, adsorption et volatilité du di-allate et du tri-allate dans des sols de prairies Résumé. La capture d'électrons dans la chionnatographie en phase gazeuse a été utilisée pour déceler le di-allate et le tri-allate dans deux sols, à deux taux différents d'humidité. A des doses d'environ 2,52 à 2,80 kg/ha, 50% du di-allate appliqueé dans un limon de Weyburn fut dégradé en 4 semaines, à des taux d'humidité supérieurs au point de fiétris-sement. Les pertes furent légèrement inférieures dans un sol argileux lourd de Regina. Dans les deux sols, une faible dégradation fut observése à des taux d'humiditi inférieurs au point de flétrissement et les pertes furent négligeables dans les sols stéiles; ceci montre que l'activité microhienne peut etre un facteur important dans la degradation du di-allate. La degradation du tri-allate dans les deux sols fut moins rapide que celle du di-allate. A la dose de 2,2 kg/ha, le lessivage du diallate fut plus important dans le limon de Weyburn que dans le sol argileux lourd de Regina. Le tri-allate fut presque compléte-ment adsorbé par quatre sols, à partir d'une solution aqueuse, alors que le di-allate ne fut adsorbé que dans une proportion moindre. La volatilityé du tri-allate dans le sol apparut négligeable, meme en chauffant à50°C pendant 28 jours. Les pertes du diallate par évaporation à partir de sols traités sont sous la dependance du type de sol et de la température. Dans les parcelles au champ 15 à 20% du tri-allate appliqué fut rctrouvé dans les 5 premiers centimétres du sol aprés une saison de culture, alors qu'il ne subsista que moins de 5% de la quantité initiale de di-allate. Des résidus négligeables de I'un ou l'autre des deux produits furent retrouves au niveau 5 à 10 cm. Abbau, Adsorption undFluchtigkeit von Diallat und Triallat in Prairieböden Zusammenfassung. Elektroneneinfatig-Gaschromatographie wurde zur Bestimmung von Diallat und Triallat in zwei Böden bei verschiedenen Feuchtigkeitsstufen verwendet. Bei Atifwandmengen von 2,52-2,80 kg/ha, wurden 50% des ausgebrachten Diallats bei einem Feuehtigkeitsgehalt, der über dem Welkepunkt lag, innerhalb von vier Wochen abgebaut. In schwerem Regina-Ton waren die Verluste etwas geringer. In beiden Boden vnirde bei Feuchtigkeitsstufen unterhalb des Wclkepunktes wenig Abbau beobachtet. Vernachlässigbarc Verluste traten in sterilen Böden auf, was darauf hinweist, dass Mikro-organismen eine wichtigc Roile beim Abbau von Diallat spielen. Der Abbau von Triallat verlief in heiden Boden langsatner als der von Diallat. Bei 2,24 kg/ha wurde Diallat aus Weyburn Lehmboden stärker ausgewaschen als aus schwerem Regina-Tonboden. Triallat wurde aus einer wässrigen Lösung in vier Böden nahczu vollständig adsorbiert, wäirend Diallat in einem geringeren Ausmass adsorbiert wurde. Verdampfung von Triallat aus dem Boden scheint selbst bei 28-tägiger Erhitzung des Bodens auf 50°C gering zu sein. Verdampfungsverluste von Diallat aus behandelten Boden hängen vom Bodentyp und der Temperatur ab. In Feldversuchen wurden nach einer Vegetationsperiode 15–20% des ausgebrachten Triallats wiedergefunden. Weniger als 5% der ursprunglichen Diallatmcnge war dort verblieben. Nur vernachlassigbare Rückstandsmengen wurden bei beiden Herbiziden in Bodentiefen von 5–10 cm gefunden.     

THE INFLUENCE OF SIMAZINE ON SHOOT AND ROOT GROWTH OF APPLES AND PLUMS

Summary. In loamy soil with a low humus content (0·8% organic carbon) simazine at a concentration of 2'5 ppm reduced growth of shoots, roots and trunk diameter in 1-year-old scions of five apple varieties on M IX rootstock. The most susceptible was Cox's Orange Pippin; 5 ppm was lethal for this variety only. In experiments with vertically divided pots, where one part of the root system developed in soil with simazine (2–5 ppm and 5–0 ppm for apple and 5·0 ppm for plum) and the other part in simazine-free soil, there was less effect on shoot growth and less leaf damage than where all the soil contained simazine. Growth of that part of the root system in soil containing simazine was stimulated.     

THE PERSISTENCE AND PENETRATION OF LARGE DOSES OF SIMAZINE IN UNCROPPED SOIL

Summary. The residues remaining in the soil from repeated annual application of simazine at 2–8, 5–6, and 22–4 kg/ha to uncropped plots on a loam soil were measured by chemical or bioassay methods at various intervals after treatment.
The total simazine residue present 12 months after the last of three treatments with 2–8 kg/ha and 8 months after the last of five treatments with 5–6 kg/ha was less than 10% of the annual dose. This rapid decomposition is considered consistent with the soil and climatic conditions. In contrast a much larger residue (a mean value of 1·7 kg/ha) was found on plots sampled 21/2 years after the last of two annual applications of simazine at 22·4 kg/ha and the reduction in the amount of residue during the next 12 months was only of the order of 25%.
In all treatments the highest concentration of simazine was found in the surface layers of the soil but measurable residues were detected to 60 cm depth, 31/2 years after the last 22·4 kg/ha application.
There was considerable variation in the total residues recovered between replicate plots and between different positions on the same plots in all treatments regardless of the depth of the sample. The possible causes of this variation are discussed.
Persistance et pénétration de fortes doses de simazine dans un sol non cultivé     

EFFECT OF ELECTROLYTES ON THE SOLUBILITY OF SOME 1,3,5-TRIAZlNES AND SUBSTITUTED UREAS AND THEIR ADSORPTION ON SOIL*

Summary. The solubilities of three isopropylamino, ethylamino-triazines (chloro-, methoxy- and methylthio-) and three, N′-phenyl-. NN-dimethylureas (0, 1 and 2 chlorine substitutions on the phenyl group) were determined in water and in solutions of chloride salts of NH⁺₄, K⁺ and Ca⁺⁺ at ionic strengths of 0·3 and 0·6. Adsorption of these compounds by soil from the same chloride solutions at ionic strengths of 0·3 was measured. As expected, the solubilities were depressed by increasing ionic strength but the type of cation exerted a small, though significant, effect. Adsorption of the test compounds increased in the presence of the various salts. The possible import of these findings in relation to joint fertilizer and herbicide use and soil drying following herbicide application is commented on. Effets des électrolytes sur la solubilité et l'adsorption par le sol de quelques 1,3,5-triazines et urées substituées Résumé. Les solubilités de trois isopropylamino, éthylamino-triazines (Chloro-, méthoxy-et méthylthio-), et de trois N′-phényl-NN-diméthylurées (0, 1 et 2 chlores substitutés sur le groupe phényle) ont été déterminées dans l'eau et dans des solutions de sels de chlorure de NH₄⁺, K⁺ et Ca⁺⁺à des forces ioniques de 0,3 et 0,6. L'adsorption de ces composés par le sol à partir de ces mêmes solutions à la force ionique de 0,3 a été mesurée. Comme il était attendu, les solubilités furent diniinuées par l'accroissement de la force ionique mais la nature du cation exerça une influence faible mais néanmoins significative. L'adsorption des composés essayé fut accrue en présence des différents sels. La signification possible de ces réultats, en relation avec l'utilisation simultanée des engrais et des herbicides ainsi qu'avec le déssèchement du sol aprés um traitement herbicide fait l'objet de commentaires. Einfluss von Elektrolyten auf die Löslichkeit einiger 1,3,5-Triazine und Harnstoffderivate und auf ihre Adsorption an Boden Zusammenfassung. Die Löslichkeit von drei Isopropylamino-äthylamino-triazinen (Chlor-, Methoxy- und Methylthio-) sowie drei N′-Phenyl-NN-diniethyl-harnstoffen (0, 1 und 2 Chlorsubstitutionen an der Phenylgruppe) wurden in Wasser und in Lösungen von NH₄Cl, KCl und CaCl₂ bei Ionenstärken von 0,3 und 0,6 bestimmt. Die Adsorption dieser Verbindungen an Boden aus Lösungen derselben Saize wurde bei der Ionenstarke von 0,3 gemessen. Wie erwartet wurde die Löslichkeit mit zunehmender Ionenstärke erniedrigt, wobei die Art des Rations einen kleinen, jedoch signifikanten Effekt zeigte. Die Adsorption der untersuchten Verbindungen nahm in Gegenwart der verschiedenen Salze zu. Es wird darauf hingewiesen, dass diese Befunde für die kombinierte Anwendung von Düngesalzen und Herbiziden wichtig sein können. Ebenso können sie wichtig sein für eine mögliche Austrocknung des Bodens nach Herbizideinsatz.     

THE ADSORPTION OF LINURON, ATRAZINE AND EPTC BY MODEL ALIPHATIC ADSORBENTS AND SOIL ORGANIC PREPARATIONS

Summary. Model adsorbents were prepared by treating cellulose phosphate powder with a series of alkyltrimethylammonium compounds in which the size of the alkyl group was varied from C₈to C₁₈. The adsorption of linuron, atrazine and EPTC by these materials was found to increase logarithmically with increasing chain length. The extent of the adsorption was large compared with the adsorption of these herbicides by a humic acid and by a preparation made by removing the bulk of the inorganic constituents of a peat soil with a mixture of HCl and HF. Since soil organic matter is thought to contain alkyl groups, it is concluded that the possible influence of such groups should be considered in any discussion of the mechanisms involved in the adsorption of organic molecules by soils.
Adsorption du linuron, de I'atrazine de l'EPTC par des adsorbants de la série aliphatique et des préparations organiques de sol     

THE ADSORPTION OF FOUR HERBICIDES BY DIFFERENT TYPES OF ORGANIC MATTER AND A BENTONITE CLAY*

Summary. A bioassay was used to study, adsorption of prometryne, simazine, linuron and pyrazon by fibrous peat, sphagnum moss, muck soil and bentonite as 1 % mixtures with quartz sand. Of these bentonite caused least reduction in bioactivity, and sphagnum moss reduced it only slightly more. Fibrous peat and muck soil were the most adsorptive. Prometryne, simazine and pyrazon were more highly adsorbed by fibrous peat than by muck soil, while for linuron the opposite occurred. Fibrous peat was approximately three, seven, thirteen and three times more adsorptive than bentonite for pyrazon, linuron, prometryne and simazine, respectively, while for muck soil the corresponding values were two, fourteen, seven and two. Studies with prometryne and five different soils indicated that percentage organic matter, cation-exchange capacity and specific surface area were all highly correlated with adsorption.     

CONTROL OF WEEDS IN MARROWSTEM KALE BY EPTC AND SOME OTHER HERBICIDES

Summary. Two experiments on chemical weed control in marrowstem kale are reported. In the first of these three herbicides applied before sowing were compared; in the second experiment four herbicides were studied, one applied before sowing and the others applied after emergence. Of all the herbicides examined, EPTC, applied before sowing and incorporated into the seedbed, was the most satisfactory in terms of both weed control and yield of kale. Neither endothal + propham nor dinoseb + TCA proved satisfactory as pre-sowing treatments. The three herbicides applied post-emergence (all methylmercapto triazines) were ineffective for the control of Polygonum spp. and Poa annua , although fairly effective against Stellaria media and Chenopodium album . They caused considerable damage to the crop and reduced yields by at least 25%.
Le désherbage du chou moellier par l'EPTC et quelques autres herbicides     

CHLORTHAL DEGRADATION IN SOILS AND ITS UPTAKE BY PINE SEEDLINGS

Summary. Similar chlorthal (dimethyl 2,3,.5,6-tetrachloroterephthalate) degradation patterns were found in pot cultures of white pine and Monterey pine grown in a sandy soil and in fallow cultures of the same soil. After 120 days, the content of chlorthal plus its degradation products (as measured by ¹⁴C-activity) had decreased to 37% in the fallow and white pine cultures. A somewhat slower rate of degradation in soil (average 45%*C-activity remaining) was observed for the Monterey pine cultures. Thus in 120 days, 55–63% of the added chlorthal had been lost from the soil system. A negligible amount of this could be accounted for by plant uptake. After 60 days of growth the rate of degradation in soil was greatly curtailed suggesting that the accumulated degradation produces were able to inhibit the further degradation of the herbicide.
Analysis of *C-labelled extracts from the pine tissue showed that uptake of chlorthal varied from 0–25 to 1–2% of the total amount of the chemical added to the soil. Degraded, as well as intact chlorthal, were found in both Monterey and white pine tissue. Very limited mobility of chlorthal in the plant was observed and the concentration in the shoots was less than 10 pm. About 80% of the absorbed chlorthal remained in the root systems. Plant growth led to a rapid dilution of absorbed chlorthal. The growth of both species of pine was rapid and apparently healthy in chlorthal-treated soil and comparable to that of the control plants.     

THE PERSISTENCE AND MOVEMENT OF FLUORODIFEN IN SOILS AND PLANTS

Summary. Miller clay and Lufkin sandy loam soils were treated with fluorodifen (4-nitrophenyl 2-nitro-4-trifluoromethylphenyl ether) at 3–4 and 5 kg/ha. The disappearance was monitored using electron-capture gas chromatography. Less than 10% of the herbicide remained 6 months after application. Persistence was increased by incorporation in the loam but not in the clay soil. Little leaching was detected in either soil. Fluorodifen was applied to both roots and leaves of soybean (Glycine max (L.) Merr.), grain sorghum (Sorghum vulgare Pers.), peanut (Arachis hypogaea L.) and morning glory (Ipomoea purpurea L.). The herbicide was absorbed by the treated tissue, but limited trans-location into other plant parts was detected by gas chromatography, autoradiography and liquid scintillation spectrometry. Following root application, higher concentrations of fluorodifen were found in the lower stems of morning glory and grain sorghum than in other species. La persistance et la migration du fluorodifene dans divers sols et plantes Résumé. De I'argile de Miller et des sols sablo-limoneux de Lufkin ont été traités avec du fluorodiféne (4-nitrophényl 2-nitro-4-trifluorométhylphényl éther) à 3, 4 et 5 kg/ha. La degradation a été suivie en utilisant la chromatographic en phase gazcuse avec détecteur à capture d'électrons. Aprés 6 mois d'application il ne fut détecté que moins de 10% de l'herbicide. La persistance fut accrue par l'incorporation dans le sol limoneux mais non dans le sol argileux; il ne fut mis en évidence qu'un faible lessivage dans les deux sols. Le fluorodifene fut appliquéà la fois sur les racines et sur les feuilles du soja (Glycine max (L.) Merr.), le sorgho à grains (Sorghum vulgare Pers.), l'arachide (Arachis hypogaea L.) et le volubilis (Ipomoea purpurea L.). L'herbicide fut absorbs par les tissus traites, mais il ne fut décelé qu'une migration limitée dans les autres parties de la plante, au moyen de la chromatographie en phase gazeuse, de l'autoradiographie, et de la spectrométrie à scintillation liquide. A la suite d'application par les racines, les concentrations de fluorodifene constatées dans les tiges basses du volubilis et dans le sorgho à grain furent supérieures à celles trouvées dans les autres espéces. Persistenz und Translokation von Fluorodifen in Böden und Pflanzen Zusammenfassung. Miller-Ton und Lufkin-Lehmboden wurden mit 3,5 und 5 kg/ha Fluorodifen (4-NitrGphenyl 2-nitro-4-trifluoromethyIphenylather) behandelt. Der Verlust der Aktivsubstanz wurde mit Hilfe der Elektroneneinfang-Gaschromatographic bestimmt. Sechs Monate nach der Behandlung waren weniger als 10% der ursprünglich ausgebrachten Aktivsubstanz noch nachweisbar. Die Persistenz war im Lehmboden, nicht jedoch im Tonboden, durch Inkorporation erhöht; in keinem Boden war nennens-werte Einwaschung zu beobachten. Fluorodifen wurde bei Sojabohnen (Glycine max (L.) Merr.), Körner-Hirse (Sorghum vulgare Pers.), Erdnuss (Arachis hypogaea L.) und Ipomoea purpurea L. sowohl über das Blatt als auch über die Wurzel angewandt. Das Herbizid wurde in das brhandelte Gewebe aufgenommen. Es erfolgte jedoch nur cine geringe Translokation in andere Pflanzenteile, wie die Untersuchung mit Hilfe der Gaschromatographic, Autoradio-graphic und Flüssigkeits-Scintiliations-Spectrometrie ergab. Nach Wurzelapplikation wurden in den unteren Sprossteilen von Ipomoea purpurea und Sorghum vulgare grössere Fluorodifen-Konzentrationen gefunden als bei den anderen Arten.     

UPTAKE, TRANSLOCATION AND METABOLISM OF SIMAZINE IN NORWAY SPRUCE (PICEA ABIES)

Summary. Uptake, distribution and fate simazine (2-chioro-4,6-biserthylamino- s -triazine) in 4-year-old seedlings of Norway spruce ( Picea abies ) are discussed. Simazine was found to be readily absorbed and distributed in the spruce seedlings. A positive relationship between the amount of simazine absorbed and the growth intensities of the plants indicates an active mechanism of uptake. A fixation of simazine in roots and sterm was observed.
Simazine was degraded by roots and stem to hydroxysimazine and two other unknown metabolites. No simazine and only metabolites could be traced in the needles, indicating a very rapid rate of metabolism in the root system. The glucose derivative of benzoxazinone was extracted from all parts of the spruce seedlings and is probably responsible for the hydrolysis of simazine.
The results indicate a very slow degradation of the metabolites to CO₂ as one of the final products.     

绿洲吨粮田土肥因素的分析

分析论证绿洲吨粮田土肥因素,结果表明培肥提高地力任务之艰巨。同时,为了良田常在,永续利用,必须改变单一种植业结构,农、林、牧相结合,科学地轮作施肥管理,方可实现生态良性循环的持续农业。     

HERBICIDAL EFFECTS ON CERTAIN SOIL MICROBIAL ACTIVITIES IN SOME BROWN SOILS OF SASKATCHEWAN

Summary. Amitrole, 2,3,6-TBA, 2,4-DB and di-allate were applied at normal field rates to a loam soil in a preliminary study, The toxic effects, as measured by nitrification studies, persisted for 8 weeks after application. After a further 8 weeks this depressive effect was decreased.
Residual effects were assayed by measuring the nitrification rate of soils following the application of the same four herbicides at two rates to four different soils. The residual effects of amitrole, di-allate, 2,3,6-TBA and 2,4-DB were overcome 34, 28, 32 and 44 weeks respectively after treatment. Total microbial counts were also corelated with the nitrification rate of the soils. The trend of disappearance of the toxic effect of these chemicals was similar in all the soils in these laboratory investigations.
Under field conditions the residual effect of amitrole, 2,3,6-TBA and 2,4-DB had disappeared by the end of 52 weeks, as far as could be determined by studies of nitrate production, ammonification and total counts of microorganisms. A second application of the chemicals 56 weeks after the initial treatment affected nitrification in the laboratory for only half as long, indicating adaptation of' the microorganisms to the herbicides
Effels des herbicides sur certaines activités des microorganismes du sol     

SOME PHYSICO-CHEMICAL INTERACTIONS OF PARAQUAT WITH SOIL ORGANIC MATERIALS AND MODEL COMPOUNDS I. EFFECTS OF TEMPERATURE, TIME AND ADSORBATE DEGRADATION ON ARAQUAT ADSORPTION

Summary. Some investigations were carried out on the adsorption of paraquat by a range of organic materials which included an organic soil, various humic fractions from that soil, model polymers prepared by the oxidative coupling of benzoquinone, the ion exchange resins Zeo-Karb 216 and 226, and Amberlite XAD-2. The time required for the adsorption process to reach equilibrium ranged from about 3 h (for the soil and humic preparations) to about 48 h (for the more highly cross-linked materials). Adsorption by Amberlite XAD-2, a cross-linked polystyrene resin, was very small, presumably because it lacked ion-exchange sites.
The results suggested that particle diffusion control was operating and the different equilibrium times reflected different degrees of molecular complexity within the adsorbents.
Temperature, within the 20°–70°C range, did not affect the adsorption equilibrium, and this is indirect evidence for ion exchange as the primary adsorption mechanism. No evidence was found for decomposition of paraquat in the adsorption systems studied.
Quelques interactions physico-chimiques du paraquat avec des inatéaux de sol organique et des composes modéles I. Effets de la température, du temps et de la dégradation sur I'adsorption du paraquat     

GENETIC VARIATION IN SIMAZINE RESISTANCE IN WHEAT, RAPE AND MUSTARD

Summary. The resistance to simazine of a range of varieties of wheat ( Triticum aestivim L.), rape ( Brassica napus L.) and mustard ( Sinapis alba L.) was assessed in glasshouse tests Varietal differences in survival and final weight of survivors were found in all three crops Variability m the time for which individual plants survived was greatest in the two out-breeding crops, rape and mustard. The 1 % of mustard plants that survived 10 oz/a csimazine were allowed to produce seed in a polycross. These progenies showed a very marked increase m resistance over the unselected controls.
There is thus appreciable genetic variation in resistance to simazine both within and between varieties. This is readily available for selection, and could he valuable in extending the selectivity of herbicides.
Variation génétique de la resistance á la simazine chez le blé, le colza et la moutarde