bluuebunny/crossref_metadata_2025 huggingface dataset:
Composition of organic matter in particle‐size fractions of an agricultural soil
Authors: SCHULTEN H.‐R. , LEINWEBER P. , SORGE C.
Published: July 2006

The composition of organic matter was studied in clay (< 2 μm), fine silt (2‐6.3 μm), medium silt (6.3‐20 μm), coarse silt (20‐63 μm) and sand (63‐2000 μm) fractions of the Ap‐horizon of a clay loam (Orthic Humic Gleysol) from Bainsville (Ottawa, Canada) by organic C and total N analyses and pyrolysis‐field ionization mass spectrometry (Py‐FIMS).

The C and N contents were largest in fine silt and medium silt and smaller in coarse silt and sand. Differences in the contents of organic matter and absorbed water were significantly (r= 0.945***) reflected by the amounts of volatilized matter during Py‐FIMS. The Py‐FI therniograms and mass spectra showed clear differences in thermal stability and molecular composition of organic matter between the organo‐mineral size‐fractions. Abundances of carbohydrates, phenols and lignin monomers, alkylaromatics and N‐containing compounds decreased, whereas abundances of lignin dimers and lipids increased with increasing equivalent diameters. An exception was the sand fraction which was dominated by the characteristic features of plant residues. The six compound classes, calculated using signals of biomarkers, accounted for 35% to 60% of the recorded total ion intensity.

The thermal evolution of the selected compound classes, which are important constituents of soil organic matter (SOM), indicated the stability of humic and organo‐mineral bonds in particle‐size fractions, Moreover, the influence of mineral matrix on organic matter composition was shown by significant correlations between relative abundances of carbohydrates, N‐containing compounds, lipids, lignin dimers, and proportions of phyllosilicates.
The decomposition of straw in soil: use of Multiple Internal Reflectance Infrared Spectroscopy
Authors: CHESHIRE M. V. , RUSSELL J. D. , FRASER A. R.
Published: July 2006

Changes in the surface layers of wheat and barley straw internodes incubated in soil at 15°C for up to 448 d were analysed using multiple internal reflectance (MIR) infrared spectroscopy. Results were compared with chemical analyses of total C and N and polysaccharides in straw and soil‐straw mixtures. Detectable spectroscopic changes occurred only at the inner surface of the straw. There was progressive enhancement of lignin absorption bands relative to those of polysaccharide and enhanced acetyl absorption. There was a greater association of clay mineral matter with the inner surfaces of the wheat straw than with those of the barley.

Using the absorbance ratio of carbohydrate to lignin and assuming a negligible change in lignin content, it was estimated that for wheat straw about 75% of the carbohydrate in the surface layers was lost within the first 14 d of incubation. The barley straw showed no loss until 28 d, and 75% loss only after 112 d.

In the early phases, the pattern of decomposition of straw carbohydrate in soil as revealed by MIR resembled that in sheep's rumen, but the rate of decomposition was much slower.

Changes in the carbohydrate content of the soil‐straw mixtures measured chemically paralleled those observed spectroscopically, but only gross chemical changes were observable.

MIR infrared spectroscopy was shown to provide a sensitive measure of the early stages of plant tissue decomposition.
Field‐measured redox potentials in soils at the groundwater–surface‐water interface
Authors: NORRSTRÖM A.C.
Published: July 2006

At the groundwater–surface‐water interface the last modification of discharging groundwater takes place. In this study the redox potential was measured in situ in four groundwater discharge areas with a size of 3–4 m2. Three of them were the upper reaches of streams in coniferous forests and one was an alder fen. Measurements were made at different seasons, with 50 and 100 platinum micro‐electrodes respectively, in each area. Readings were taken in the upper 30 cm of the soil, at two depths.

A method study showed that the electrodes needed a longer equilibrium time than is usually reported. The main finding of this study was the large spatial variation within soils in the discharge zone; regions as small as 10 cm in diameter could have redox potentials covering several hundred mV. It was not possible to identify a seasonal variation due to the large spatial variation. Differences in the distribution of the redox potential with depth may be explained by the structure of the peat affecting flow patterns and the residence time of water.
Phosphate sorption by synthetic amorphous aluminium hydroxides: a 27Al and 31P solid‐state MAS NMR spectroscopy study
Authors: LOOKMAN R. , GROBET P. , MERCKX R. , VLASSAK K.
Published: July 2006

The sorption of phosphate on amorphous aluminium hydroxides was investigated using 27Al and 71P solid‐state magic‐angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, following the effect of different exposures to soluble phosphate. The spectra obtained were compared with the spectrum of amorphous aluminium phosphate. Aluminium in the unreacted hydroxide had a 100% octahedral co‐ordination. When dried at 200°C and exposed to soluble phosphate, very little (maximum 0.1%) amorphous aluminium hydroxide transformed to a tetrahedral co‐ordination (A1 bound by oxygen bridges to four P atoms), even after 120d. The tetrahedral co‐ordination exists in aluminium phosphate gel, although most of its A1 atoms exhibit an octahedral co‐ordination. For the aluminium hydroxide dried at 200°C, no formation of aluminium phosphate in which aluminium is in octahedral co‐ordination could be detected, not even when the aluminium hydroxide was exposed to a phosphate solution for 120 d. We concluded that the formation of aluminium phosphate is restricted to the surface of the hydroxide. Most of the phosphate which is bound to the aluminium oxide however may not have formed a ‘bulk solid’ aluminium phosphate, but is adsorbed on the internal and external surface of the oxide. The same amorphous aluminium hydroxide, dried at 70°C instead of 200°C, is converted much more rapidly to aluminium phosphate when exposed to soluble phosphate. We propose a P‐induced weathering mechanism to describe P sorption on amorphous aluminium hydroxides at high P concentrations. In addition to NMR, phosphate adsorption experiments conducted on aluminium hydroxides dried at different temperatures produced evidence that the porosity of the aluminium hydroxide aggregated particles can also be a factor controlling the rate of phosphate uptake from solution, if the aggregate is stable (is not resuspended) in solution.
Modelling soil distortion during compaction for cylindrical stress load paths
Authors: PETERSEN C. T.
Published: July 2006

A slightly modified critical‐state model was formulated in order to account for the volume‐change behaviour at yield and failure observed in triaxial tests on unsaturated soils. Model parameters were specified for two soils (a sandy loam and a loam), each at three different soil‐moisture contents. Maximum shear strain was integrated numerically for 36 cylindrical load paths with constant confining pressure (type I) or constant mean normal stress (type II). Predicted stress‐strain relationships for load paths bringing soils from a normally‐consolidated to a critical state were compared with stress‐strain relationships observed for identical load paths in triaxial tests of the lubricated ends variety.

The agreement between predicted and observed maximum shear strain depended on type of load path and soil‐moisture content. The model failed to predict maximum shear strain at stress states close to critical. The absolute difference between observed and predicted strain was on average ≤0.05 for deviatoric stresses smaller than 90% of the critical‐state values. The comparable maximum differences were 0.11 and 0.07 for load‐path types I and II, respectively. The largest differences were found for the largest soil‐moisture contents. The type of load path had a considerable effect on sample distortion, type I giving rise to larger (predicted and observed) maximum shear strain at common stress states.
Coregionalization of trace metals in the soil in the Swiss Jura
Authors: WEBSTER R. , ATTEIA O. , DUBOIS J.‐P.
Published: July 2006

The provenance of trace metals in soil, whether from the parent material or from pollution, is rarely known with certainty, and the metals' history must usually be pieced together from fragmentary statistical information. This is particularly true in the Swiss Jura where the concentrations of several heavy metals around La Chaux de Fonds exceed the statutory recommended thresholds for safety.

The topsoil of the 14.5‐km2 region was sampled on a square grid at 250‐m intervals with additional nesting with distances of 100 m, 40 m, 16 m and 6 m. The concentrations of seven potentially toxic metals, namely Cd, Co, Cr, Cu, Ni, Pb and Zn, were measured. Their coregionalization could be represented by a linear model consisting of a nugget component plus two spherical structures with ranges of 0.2 km and 1.3 km. The short‐range component dominated the variograms of Cd, Cr, Cu and Pb; the long‐range component dominated those of Co and Ni; the variogram of Zn combined the two in approximately equal proportions. The coregionalization matrices contain moderate correlation among the nugget and the short‐range components, notably between Cu and Pb, between Cd and Zn, and between Cr, Ni and Zn. The strongest correlations are at the long range between Co, Cr and Ni, and to a somewhat smaller degree between Zn and Co. Analysis of variance showed Co and Ni to be related to geology, and to the Argovian formation in particular. The indicator variogram of this formation has also a short‐range component. The analysis also showed Cr and Cu to be related to land use (in different ways). Copper and Pb are strongly correlated to one another and distinct from the five other metals. The long‐range structure is almost certainly a geological effect, whereas the one of short range probably results from both the geology and human activities.
Simulating soil deformation using a critical‐state model: I. Laboratory tests
Authors: KIRBY J.M.
Published: July 2006

The paper examines the ability of a critical‐state model to predict stresses and deformations of agricultural soil in a variety of laboratory shear and compression tests. The critical‐state model used is a simple extension to the well‐known Modified Cam Clay model. The extension provides a smoother transition from elastic to plastic behaviour and, amongst other things, introduces a capacity to model cyclic loading. The model is incorporated into a finite‐element program.

The model predictions are compared with: experimental observations of simple and direct shear tests with both constant normal stress and constant volume conditions; cyclic uniaxial compression tests; compaction tests in U‐shaped and V‐shaped boxes; and observations of some gross structural features caused by shear in direct‐shear boxes. Predictions are made for both the compressing, strain‐hardening and the expanding, strain‐softening regimes of behaviour. In all cases the material properties for the model were obtained from tests other than those being used for the comparisons.

The model predictions generally compare well with the various experimental results, although some numerical problems were encountered in strain‐softening conditions. This demonstrates the versatility of the critical‐state model for predicting fairly general stress and, deformation conditions in unsaturated soils using only five material‐property constants. It also demonstrates that common laboratory strength and compression tests are adequate to measure the material properties.
Long‐term changes in chemical weathering rates between 1949–50 and 1987 in forest soils from north‐east Scotland
Authors: ZULLA Y. , BILLETT M.F.
Published: July 2006

Long‐term changes in weathering rates in mineral soil horizons from the Alltcailleach Forest, north‐east Scotland, were estimated from a 3‐month leaching experiment conducted using archived soils sampled in 1949/50 and 1987. Data on changes in surface exchange chemistry, total element composition and mineralogy are also presented.

The most sensitive Group 1 sites were characterized by a decrease in weathering rate and exchangeable Ca and Mg with time. Sodium increased in the total, exchangeable and the weatherable pools. The more base‐rich Group 2 sites exhibited a slight increase in weathering rate between 1949/50 and 1987.

The results have implications for the use of weathering rates in the modelling of long‐term acidification of soils and water, and in the use of Na in weathering calculations as an element which is assumed not to accumulate in the soil‐plant system.
Diffusion from instantaneous sources of differing geometries
Authors: BIRD N.R.A. , DEXTER A.R.
Published: July 2006

The effects of geometry upon diffusion from instantaneous sources is considered. Although surface area is important initially, it is the square of the volume of the source which determines flux from the source at large times. This asymptotic shape independence is demonstrated for spherical and cuboidal sources.
EXPERIMENTS IN HAND‐WEEDING OF CONIFER SEEDBEDS IN FOREST NURSERIES
Authors: ALDHOUS J. R.
Published: July 2006

Summary. In 3 years and in three nurseries, experimental plots sown with conifer seed were weeded by hand at intervals from 1½ to 12 weeks. Assessments of the seedlings at the end of each year showed a reduction in numbers and height only on plots left for 12 weeks between successive weedings. The total time taken to weed plots during the growing season was least for plots weeded at intervals of 3‐4 weeks and greatest for plots weeded at the longest intervals. Data on the total weight of weeds, the total number of weeds, the species composition and the stage of weed growth at weeding are also given and discussed.

Essais de désherbage dans les pépinières
THE EFFECTS OF 4‐CHLOROPHENOXYACETIC ACID ON THE RHIZOME OF PTERIDIUM AQUILINUM (L.) KUHN
Authors: CONWAY E. , FORREST J. D.
Published: July 2006

Summary. Tests have been carried out on the effects induced by the growth‐regulating compound 4‐chlorophenoxyacetic acid (4‐CPA) on the rhizome of Pteridium aquilinum when the compound is applied to the leaves of the plant. Experiments, made on unit plants grown from sporelings or fragments of mature rhizomes, and on stands of field bracken, showed that 4‐CPA in various formulations entered the tissues of the fronds easily and was readily translocated to the growing points of the rhizome branches. Epinasty, with hardening of the tissues of stem apices and frond buds, was seen after treatment with the chemical at low concentration; at higher concentrations, irregular growth led to splitting of the outer apical tissues and resultant rotting. Such harmful effects after treatment were seen to a high degree at the apices of stem branches bearing treated fronds. Lesser effects were seen on branches that were without expanded fronds at the time of treatment. In the field, time of application affected markedly the degree to which harmful effects were induced at the growing points. Spraying young fronds at herbicidal concentrations caused much scorching and early death, but the effects on the apices of the underground stem branches were relatively light. Spraying older fronds resulted in less obvious foliar effects, but damage caused to the rhizome was much greater. This may have been due to the young leaf tissues being killed before translocation had taken place. Surveys of untreated field bracken in the West of Scotland have shown that the matted underground stem contains a varying, mainly high, proportion of secondary branches with developing stem tips and frond buds not directly linked to an expanded frond, and that the frond population of a unit area docs not reflect the extent of the frond bud reserve. Since such secondary branches are those to which translocation appears to be restricted, they are likely to suffer only partial damage from chemical treatment of expanded fronds; and in the years following spraying, they may be expected to form frond populations relative to the extent of the frond bud reserve.

Les effets de l'acide 4‐chlorophénoxyacétique sur le rhizome de Pteridium aquilinum (L.) Kuhn
FORMULATION OF DALAPON TO REDUCE SOIL CONTAMINATION
Authors: DAY BOYSIE E.
Published: July 2006

Summary. Two means of reducing soil contamination resulting from the leaching of spray residues of dalapon from plant foliage were tested: use of volatile forms of the herbicide, residues of which slowly evaporate from the foliage; and use of formulations that congeal to a solid film to retain the herbicide against leaching. Rates of evaporation from glass slides at 20° C for the ethyl ester, n butyl ester, acid, and diethyleneglycol bisester of dalapon were respectively 15, 1‐6, 0′27 and 0.01 mg/cm2. As foliar herbicides the ethyl and butyl esters were ineffective and the acid of limited effectiveness due to rapid evaporation. The glycol ester was as effective as the sodium salt. With its evaporation rate of approximately 1 kg/ha/hr at 20°C, application of dalapon in the form of the diethylrneglycol bis ester is considered promising as a means of limiting soil contamination. Mixtures of the diethyleneglycol bis ester of dalapon with polyvinylacctate emulsion dry to form films that greatly reduce leaching of the herbicide at the expense of minor reduction in herbindal activity. Such formulations afford a means of limiting soil contamination.

Formulation du dalapon pennettant de rédiuire la contamination du sol
EXPERIMENTS ON THE CONTROL OF WEEDS IN GROUNDNUTS IN TRIPOLITANIA
Authors: ORAM P. A.
Published: July 2006

Summary. Studies on weed control in groundnuts grown with summer irrigation in the sandy coastal plain of Tripolitania (Libya) are described. These conditions favour rapid vigorous weed growth which competes severely with the crop; nearly 10 tons/ac of herbage was gathered from unweeded plots, on which groundnut yields were under half those from land kept effectively weeded. Early planting is desirable but may aggravate weed problems, due to inadequate time for cultivation and labour for weeding, through conflicting demands of other crops. It was therefore decided to investigate the possibilities of chemical control. Herbicides applied pre‐emergence included TCA, PCP, monuron, propham and 2,4‐D‐esters. Control of the predominant annual dicotyledons (Portulaca oleracea, Thlaspi arvense and Amaranthus retroflexus) comparable to that from hand‐weeding during early growth was obtained from PCP (10 lb/ac), the crop was not damaged by rates up to 20 lb. and the highest groundnut population was consistently established on plots treated with this herbicide. Effective control was obtained from 2,4‐D‐ester at 0.5 and 1.5 lb/ac, but the higher rate severely checked the groundnuts. Crop damage also occurred from monuron (3 lb/ac) which destroyed all vegetation, TCA (24 lb/ac) which was effective only against Cynodon dactylon; and propham (up to 10 lb/ac) which failed to control weeds. Post‐emergence treatment with MCPB (1.8 lb/ac) and 2,4‐DB (2.5 lb/ac) controlled some 50% of broad‐leaved weeds, but was slow to act and also damaged the crop. A combined PCP + 2,4‐D spray applied pre‐emergence proved to be the best chemical treatment, but maximum persistence was only about 10 weeks; after this, perennial monocotyledons such as C. dactylon and Cyperus sp., not effectively checked by any of the selective herbicides, became a serious problem. Under these conditions good yields depend on weed suppression late into the growing season and excellent results were achieved when an efficient pre‐emergence herbicide was followed, as its persistence waned, by careful handweeding. Early cultivation often damaged the crop, and a comparison of plots where this was omitted and the initial weeding delayed over several weeks, with those hand‐weeded throughout growth, showed no significant advantage from the extra operation. If no pre‐ernergence herbicides can be applied it may therefore be better to postpone the first cultivation for 5–7 weeks after planting. Observations on varieties representing the four broad morphological groups of groundnuts suggest certain differences in susceptibility to herbicides; further studies are required on this subject.

Expériences sur le désherbage des Arachides en Tripolitaine
STUDIES ON THE BIOTYPES OF CYNODON DACTYLON (L.) PERS.
Authors: ROCHECOUSTE E.
Published: July 2006

Summary. Studies on clones of cynodon dactylon (L.) Pers. have revealed the existence of four biotypes of this species. The sole use of morphological characters to classify them was found unsatisfactory and other definite diagnostic characters have been introduced comprising hair group characteristics and leaf and stolon epidermal structures. Cytotogical studies showed that the biotypes differ in their chromosome number; tetraploid and triploid races have been distinguished. Phasic growth investigations have pointed out that thr biotypes have a similar growth behaviour but that the tetraploids are more vigorous plants than the triploids. Studies on the seasonal variation in available carbohydrates in rhizomes and roots have established that the seasonal trend of this reserve substance in these organs is related to rhizome growth.

Recherches sur des biotypes de Cynodon dactylon (L.) Pers.
PRELIMINARY STUDIES ON THE TRANSLOCATION OF 14C‐LABELLED HERBICIDES IN BRACKEN (PTERIDIUM AQUILINUM)
Authors: McINTYRE G. I.
Published: July 2006

Summary. The translocation of 14C‐labelled herbieides in field bracken has been sludied in some preliminary experiments by means of autoradiography. A detailed account is given of the methods employed. It is shown that when 2,4‐D is applied to fronds at different stages of development movement of the tracer into the rhizome is considerably greater from parts of the frond which are still immature. Trasnslocation within the frond is predominantly basipetal at all stages of development; within the rhizome the direction of movement appears to be determined primarily by the nature of the vascular connections with the treated pinna.

In a comparison between the translocation of 2,4‐D, 4‐CPA and dalapon no difference was apparent after 24 hours, but when the treatment period was extended to 96 hours there was evidence that 4‐CPA bad been translocated in a considerably greater amount than either of the other two herbicides.

Rechrches iréliminaires sur la migration des herbieides marqués am
14
C dans la fougrère algle (Pteridium aquilinum)
NOTE ON THE BIOASSAY OF CHLORPROPHAM IN SOIL
Authors: ROBERTS H. A. , WILSON B. J.
Published: July 2006

Summary. A method for the bioassay of chlorpropham in soil from field plots is described which involves the preparation of mixtures of treated soil with untreated soil and the determination of the dilution required to produce 50% inhibition of primary root growth in buckwheat (Fagopyrum esculentum Moench). Using this method, it was found that the period required for 90% disappearance of chlorpropham from a sandy foam ranged from 3 to 14 weeks, according to the prevailing temperature and soil moisture conditions. When applications of 1 and 2 lb/ac were compared, the percentages of chlorpropham remaining at any one time were similar.

Dosage biologique du chlorpropham dans le sol
STUDIES ON THE BIOTYPES OF CYNODON DACTYLON (L.) PERS.
Authors: ROCHECOUSTE E.
Published: July 2006

Summary. Results obtained on the growth response of biotypes of Cynodon dactylon to trichloroacetic acid (TCA) and 2,2‐dichloropropionic acid (dalapon), both formulated as the sodium salt, have indicated that the tetraploid biotypes are more resistant than the triploid, and that biotypes of the same chromosome number also differ in their response to these herbicides.

Investigations on the effects of adding non‐ionic, cationic and anionic wetting agents to aqueous Solutions of the herbicides in which the leaves of plants were immersed showed that, in general, the wetting agents did not significantly increase the phytotoxicity of either herbicide.

Studies on bud dormancy revealed that uptake of TCA and dalapon via the roots is through the transpiration stream and that in tetraploids the dormant period induced by the acids is shorter than in triploids.

Eludes sur les biotypes de Cynodon dactylon (L.) Pers. II. Les réactions aux acides trichloracétique et 2,2‐dichloropropionique
AN AUTORADIOGRAPHIC STUDY OF THE MOVEMENT OF 14C‐LABELLED ASSIMILATES IN THE DEVELOPING WHEAT PLANT
Authors: QUINLAN J. D. , SAGAR G. R.
Published: July 2006

Summary. 14CO2 together with autoradiographic techniques was used to stuy the movement of labelled carbon within wheat plants at different stages in their development. Movement of 14C about the plain was found to be extensive in the early stages, gradually bccoming more localized until at a stage after ear emergence there was little transference of labelled carbon between tillers within a 24‐hour period.

In the early stages of development 14C from leaves on the main shoot was transported throughout the plant but accumulated in greatest amounts in the meristematic regions. Assimilates produced by the leaves of newly formed tillers were distributed mainly to the meristematic regions of those tillers although labelled carbon was moved in into the rest of the plant. In the later stages of development of each tiller the labelled assimilate was restricted to the tiller itself and to any very young tillers associated with it. After car emergence the pattern of distribution of the labelled carbon from the youngest and second youngest leaves was found to differ. Movement was predominantly towards the ear from the flag leaf and towards the root system from the leaf below the flag.

It was noticed that mature leaves accumulated some labelled material and the possibility that this occurred via the transpiration stream following migration from phloem to xylem, as is the case with some of the case with some of the translocated herbicides, was investigated, but no indication of xylem transference was obtained.

The possible application of these studies to investigations into the relationship between the movement natural assimilates and of translocated herbicides is discussed.
PERSISTENCE OF PHYTOTOXIC RESIDUES OF TRIAZINE HERBICIDES IN SOIL
Authors: HOLLY K. , ROBERTS H. A.
Published: July 2006

Summary. A bioassay technique for the determination of phytotoxic residues of triazine herbicides and monuron in soil from field plots is described. The effect of a dilution series with untreated soil on shoot growth of Italian ryegrass (Lolium multiflorum Lam.) is compared with that in a corresponding assay at the lime of application of the herbicide. This method was used to compare the persistence of residues of simazine, propazine, prometon and monuron, and to compare persistence in 3 years and in three soil types. The time required for disappearance of 80% of the activity following application of 2 lb/ac of simazine varied from 7 to 27 weeks, according to the year. Prometon was the most persistent of the triazines tested.

Persistance de résidus phyloloxiques d'herbicides à base de triazines dans le sol
THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLE CROPS
Authors: WAY J. M.
Published: July 2006

Summary. The effects of sub‐lethal doses of MCPA‐sodium on the morphology, yield and marketability of cabbage, cauliflower and Brussels sprouts were studied in field and glasshouse experiments. The epinastic and formative effects in all three crops were similar. Cauliflower was the most susceptible and cabbage the least, but the marketability of these two crops was adversely affected at lower doses (less than 0.06 lb/ac a.e.) than that of Brussels sprouts (not below 0.1 Ib/ac a.e.), where the damage to the apex had less effect on the economically important portion of the plant. Brussels sprouts also produced lateral shoots on which normal sprouts developed even when the main stem above had been killed. In all three crops, characteristic galls were produced on the stems, and these, together with the effects on the stem apices, the leaves and the roots, are described and contrasted with abnormalities caused by other agencies.

Effets de doses sub‐létales de MCPA sur la morphologie et le rendement des cultures tégumières IL Choux, choux‐fleurs et choux de Bruxelles
ESSAIS DE DESTRUCTION DE LA FOLLE‐AVOINE (AVENA FATUA L.) DANS LES CULTURES D'ORGE DE PRINTEMPS
Authors: FAIVRE‐DUPAIGRE R.
Published: July 2006

Résumé. La folle‐avoine (Avena fatua L.) est en grande expansion dans les cultures d'orge de printemps, en France. Le barbane, le di‐allate, la triazine G 34361, le dichlobénil ont été expérimentés, pour détruire sélectivement cette adventice. Ces essais, réalisés en 1961, avaient pour but de déterminer l'action de ces produits sur la folle‐avoine, et quelques variétés d'orge, et d'en déduire les conditions pratiques d'emploi.

La dose de 0,7.5 kg/ha de barbane, permet de détruire 80–95% de la population de folle‐avoine, lorsqu'elle a 2–3 feuilles. Une bonne régularité de la leveé de l'adventice est un facteur essentiel de réussite des traitements. Les variétés: Rika, Piroline, Irma, Ingrid, Alouette, Wisa, Carlsberg II, peuvent être traitées à la dose précédente sans risque de diminuer leur rendement. La variété Aurore est apparue la plus sensible; des essais ultérieurs seront réalisés pour déterminer s'il est possible de la traiter avec le barbane.

Le di‐allate, utilisé avant le semis de l'orge, à la dose de 1 kg/ha, permet une bonne destruction de la folle‐avoine, sans nuire à la céréale, sauf dans certaines conditions de sol (terre sableuse). La dose de 2 kg/ha provoque généralement une diminution importante du rendement de l'orge.

La triazine G 34361, utilisée en post émergence et le dichlobénil utilisé en préémergence, n'ont pas une sélectivité suffisante pour detruire la folle‐avoine dans l'orge.

Versuche zur Flughaferbekämpfung in Sommergerste
THE RESPONSE TO VARIATIONS IN NITROGEN LEVEL OF SOME WEED SPECIES OF THE SUDAN
Authors: CHADWIGK M. J. , OBEID MOHAMMED
Published: July 2006

Summary. Five weed species, Argemone mexicana, Calotropis procera, Cynodon dactylon, Cyperus rotundus and Dactylocleniwn aegyptium, and two crop plants, Gossypium barbadense and Sorghum vulgare, were grown at five nitrogen levels (3, 9, 27, 81 and 243 ppm N) in sand‐culture. The response of the species was noted in terms of total dry‐weight yield, percentage dry‐weight and mm; shout ratio.

Cynodon dactylon and Calotropis procera both showed a strong linear relationship between dry‐weight yield and nitrogen level, yield increasing with increase in nitrogen concentration. This response was at a higher overall level and higher rate in the former species. Argemone mexicana, and the two crop plants, yielded best at 81 ppm, yield being depressed by the highest nitrogen level. Dactyloctenium aegyptium showed a somewhat similar response to Argemone mexicana. Cyperus rotundus exhibited yield peaks at 9 and 81 ppm N. Percentage dry‐weight values were highly variable but in most cases highest yield was accompanied by the highest shoot : root ratio.

The responses of the species are discussed in relation to the soil factors prevailing in the habitats in which they are usually found. Adaptation on the part of some weed species is suggested where the yield response is similar to that of some of the crop plants with which they are usually associated.

The ability to reproduce similar reactions to variations in nitrogen level on the part of three weed species, on two separate occasions, indicates that real and reliable responses can be demonstrated in work of this kind.

Réaction de quelques espèces de mauvaises herbes du Soudan à diverses concentrations d'azote
THE EFFECTS OF MCPA AND 2,3,6‐TBA ON GLASSHOUSE CUCUMBERS
Authors: KINGHAM H. G. , FLETCHER J. T.
Published: July 2006

Summary. The effect of sub‐lethal doses of MCPA‐sodium and 2,3,6‐TBA‐sodium on young cucumber plants was studied in three replicated experiments. The materials were applied either to the leaves of plants in pots or as a soil drench. Epinastic and formative effects were observed. Formative effects included leaf inrolling and blistering, stem and petiole proliferation, and root modification. The symptom pattern resulting from application of each material was described.

Les effets du MCPA et du 2,3,6‐TBA sur Us concombres cultivés en serre
FACTORS AFFECTING THE SELECTIVITY OF 2,3‐DICHLOROALLYLDIISOPROPYLTHIOLCARBAMATE (DI‐ALLATE) AGAINST AVENA SPP. IN WHEAT AND BARLEY
Authors: PARKER C.
Published: July 2006

Summary. A series of pot experiments has been undertaken to assess the selectivity of 2,3‐dichloroallyldiisopropylthiolcarbamate (di‐allate) against Avena spp. in wheat and barley. It is shown that depth of incorporation, depth of sowing, variety and temperature can all influence the degree of selectivity. When di‐allate is incorporated deeply before sowing, there is good selectivity against Avena fatua L. (wild oat) in barley, but the order can be influenced by the depth at germination of both crop and weed, since the susceptibility of both species increases with increasing depth. Wheat does not exhibit the same response to depth of sowing but variety and temperature are important; the variety ‘Svenno’ is particularly susceptible, and both ‘Svenno’and‘Atte’are much more susceptible at 20° C than at 10° C. As A. fatua is slightly more susceptible at 10° C than at 20° C, selectivity is greater at the lower temperature.

Shallow incorporation of di‐allate after sowing gives a much more general selectivity in both barley and wheat, but there is still some element of risk in wheat. Whereas for barley a layer of only 0.5 in. of untreated soil above the seed is adequate protection against damage by di‐allate, 1–1.5 in. of untreated soil may be required above the seed of wheat, depending on variety and temperature. The success of shallow incorporations is explained on the basis that the most sensitive region of the plant is the 10–15 mm above the coleoptile node, which includes the stem apex and developing leaf tissue. This region is moved up in the soil rapidly in Avena spp. by elongation of the ‘mesocotyl’, whereas in wheat and barley, the stem apex is only moved up considerably later by elongation of the internode above the coleoptile node.

2,3,3‐Trichloroallyldiisopropylthiolcarbamate (tri‐allate) as compared to di‐allate has a greater selectivity in barley when the compounds are incorporated deeply; also it has greater selectivity in both wheat and barley when shallowly incorporated after sowing.

Facteurs influençant la sélectivité du diisopropylthiolcarbamate de 2,3‐dichloroallyle (di‐allate) appliqué sur blé et sur orge contre Avena spp.
THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLE CROPS
Authors: WAY J. M.
Published: July 2006

Summary. The effects of sub‐lethal doses of MCPA‐sodium on the morphology, yield and maturity of French beans, and on the morphology of broad beans, were studied in field and glasshouse experiments. Epinasty in French beans developed at 0.002 lb/ac a.e., but formative effects were not seen at less than 0–1 lb/ac. With doses up to 0.4 lb/ac there was no significant reduction in yield or haulm weight, but at 1.0 lb/ac and above, yield was reduced and some of the plants sprayed at an early stage of growth were killed. There were characteristic modifications of the roots and stems and of those leaves which were at a susceptible stage of development when sprayed. Broad beans were only slightly injured by 0.2 lb/ac but were generally killed by 2.0 lb/ac. Abnormalities were noted in the germination of seed produced by affected plants.

Effets de doses sub‐léthales de MCPA sur la morphologic et le rendement des cultures légumières IV. Haricots verts et fèves
THE HERBICIDAL EFFECT OF SOME SUBSTITUTED ANILIDES
Authors: MATOLCSY G. , HAMRAN M.
Published: July 2006

Summary. The 3,4‐dichloroanilides of four herbicidally active and of four inactive or weakly active phenoxyalkanecarboxylic acids were synthesized and tested for herbicidal activity, in order to study the effect of compounds comprising the two characteristic groupings within one molecule. 4‐Chloro‐2‐methylphenoxyacetic acid, 2,4‐dichloro‐phenoxyacetic acid, 2,4,5‐trichlorophenoxyacetic acid and a‐[2,4,5‐trichlorophenoxy] propionic acid were selected as representatives of active compounds; and phenoxyacetic acid, 2‐methylphenoxyacetic acid, 3,5‐dichlorophenoxyacetic acid and 2,4,6‐trichloro‐phenoxyacetic acid as inactive or weakly active compounds.

The compounds were tested in the glasshouse on wheat and white mustard as pre‐and post‐emergence treatments. The synthesized 3,4‐dichloroanilides had no or little herbicidal activity, as compared with the high activity of the known herbicides 3,4‐dichloropropionanilide and 2,4‐dichlorophenoxyacetic acid. The conclusion can be drawn that the introduction of phenoxy groupings into the acid moiety of the active fatty acid‐3,4‐dichloroanilides as well as the introduction of the 3,4‐dichloroaniline group into the carboxylic group of the active phenoxyacetic acids decreases herbicidal activity. This last phenomenon is probably due to a decreased ability to be hydrolysed.

L'activité herbicide de quelques anilides substituées
FIELD INVESTIGATIONS CONCERNING THE SELECTIVE PHYTOTOXICITY OF DI‐ALLATE TO AVENA SPP. IN WHEAT AND BARLEY
Authors: HOLROYD J.
Published: July 2006

Summary. The following factors influencing the selectivity of di‐allate against Avena spp. in spring wheat and barley have been investigated in seven field experiments: (a) depth and degree to which the herbicide is mixed with the soil, (b) time of application of the herbicide relative to sowing the crop, (c) implement used to incorporate the herbicide with the soil, (d) depth of germination of the Avena spp.

Di‐allate and tri‐allate incorporated relatively deeply before drilling the crop controlled Avena spp, much more effectively than when incorporated shallowly by chain‐harrowing after drilling, but the pre‐drilling treatments were also more toxic to the crop.

In wheat, di‐allate incorporated shallowly after drilling was slightly more selective than when incorporated more deeply before drilling but in barley there was no evidence to favour either time of application. Pre‐drilling treatments incorporated by a rotary cultivator were a little more selective to both crops than those incorporated by springtine harrows.

Tri‐allate was more selective than di‐allate, in wheat, when incorporated before drilling the crop. There was no evidence regarding its selectivity as a post‐drilling treatment.

The initial distribution of the herbicide in the soil, after incorporation by: (a) spring‐tine harrowing once, (b) rotary cultivating once or twice, or (c) chain harrowing once, was measured in one experiment by a fluorescent tracer technique. The results showed that ordinary farm implements give a very uneven distribution (both vertical and lateral) of herbicide in the soil.

In the field, di‐allate and tri‐allate incorporated with the soil shallowly after drilling proved to be less selective and less active than similar treatments in the glasshouse. It is suggested that the reduced selectivity of these treatments in the field is due to loss of herbicide by vaporization and retention of the herbicide by the soil under dry conditions.

The importance of the various factors influencing the selectivity of di‐allate and triallate in the field is discussed in the light of the results of these experiments and those of other research workers (particularly Parker, 1963).

Essais de plein champ sur la phytotoxicité sélective du di‐allate envers les Avena spp. dans le blé et l'orge
THE USE OF NUCLEAR MAGNETIC RESONANCE IN DETERMINING THE STRUCTURE OF ISOCIL, 5‐BROMO‐6‐METHYL‐3‐ISOPROPYLURACIL*
Authors: MERKLE M. , DANTI A. , HALL R.
Published: July 2006

Summary. Nuclear magnetic resonance spectra have shown that isocil, 5‐bromo‐6‐methyl‐3‐isopropyluracil, exists almost entirely in the ‘keto’ form, i.e. that the hydrogen atom is attached to the nitrogen at position one in the ring rather than to the oxygen at position two. Spectra were obtained in deuterated chloroform to avoid solvent interference. This method may be of value in determining structures of other herbicides where‘keto’‐‘enol’equilibria arc believed to exist.

Utilisation de la résonance magnétique nucléaire pour la détermination de la structure de l'isocil (5‐bromo 6‐méthyl‐3‐isopropyluracile)
CHEMICAL WEED CONTROL IN MAIZE
Authors: EDDOWES M. , HARPUR R. L.
Published: July 2006

Summary. From 1959 to 1962 the effects of some triazine and growth regulator herbicides applied pre‐emergence and post‐emergence to maize grown for silage were studied in field experiments on light to medium loam soils at Harper Adams College, Shropshire.

Atrazine applied pre‐emergence at 1–1.5 lb/ac gave good control of annual weeds and was superior to simazine at equivalent rates. Soil moisture and rainfall after spraying were found to influence the activity of the triazines, but both were completely tolerated by maize. In 1960, 1961 and 1962 atrazine was much more effective against annual weeds than post‐emergence applications of MCPA and 2,4‐D. However MCPA and 2,4‐D gave adequate control of a range of annual and perennial weeds under favourable conditions in 1959 and 1960 but results were poor in the two following years due to the presence of resistant and late germinating weeds.

The effect of the herbicides on development and yield of ihe maize are discussed.

Le désherbage chimique dans le mais
COMPARATIVE TOLERANCE OF SOME DICOTYLEDONS TO CHLORPROPHAM
Authors: ROBERTS H. A.
Published: July 2006

Summary. The concentration of chlorpropham required to reduce primary root clongation by 50% was determined for more than 180 species of dicotyledons in laboratory tests and was found to vary from 0.01 ppm to more than 10 ppm. With certain exceptions, species within a family responded similarly; the Polygonaccae and Caryophyllaceae were the most susceptible and the Compositae were the most tolerant. There was a general correspondence between the test results and the relative susceptibility of species in the field. Tests with different varieties of Brassies oleracea and Daucus carota showed no significant differences in varietal response.

Tolérance comparée de quelques dicotylédones au chlorpropham
ZUR MORPHOLOGISCHEN DIFFERENZIERUNG VON KAMILLE‐ARTEN (GATTUNGEN ANTHEMIS UND MATRICARIA) IM ROSETTENSTADIUM
Authors: RUSCH R.
Published: July 2006

Zusammenfassung. Für die in Deutschland als Ackerunkräuter vorkommenden Kamillearten der Gattungen Anthemis und Matricaria wird ein Bestimmungsschlüssel gebracht, der die Differenzierung dieser Arten im Rosettenstadium ermöglicht.

Morphological difference between species of the genera Anthémis ami Matricaria (mayiveeds) at the rosette stage
SOIL PLACEMENT STUDIES WITH EPTC AND OTHER CARBAMATE HERBICIDES ON AVENA SATIVA*
Authors: APPLEBY A. P. , FURTICK W. R. , FANG S. C.
Published: July 2006

Summary. Studies were conducted to determine the effect of soil placement of EPTC, di‐allate and propham (IPC) on oats. A technique called the‘envelope method’was used to make possible the separate exposure of coleoptiles, seed and roots of emerging oat seedlings to the various herbicides. EPTC at 1.0 ppm, di‐allate at 2.0 ppm and propham at 3.0 ppm were all extremely toxic to oats through colcoptile uptake. Penetration of roots into treated soil, however, resulted in very little injury to the plant. Plants grew undamaged from seeds which had been allowed to imbibe for 36 hr in soil treated with EPTC at 1.0 ppm.

Studies using radioactive EPTC indicated that both roots and coleoptiles readily absorbed EPTC from soil and that measurable amounts translocated both upward and downward. Under certain circumstances, as much unmetabolized EPTC could accumulate in roots as in shoots, even though less toxicity was noted from root exposure. This would indicate, that the differential sensitivity between roots and shoots is not due to differences in uptake, translocation, or metabolic breakdown. Rather it appears that the shoot is the major site of lethal action of EPTC in oats.

Étude du placement de l'EPTC et d'autres carbamates dans le sol avec Avena saliva
STUDIES ON OXALIS PES‐CAPRAE L. IN AUSTRALIA
Authors: MICHAEL P. W.
Published: July 2006

Summary. Experiments are described in which appreciable reductions in bulbs of the widespread pentaploid variety of Oxalis pes‐caprae L. were obtained by two cultivations, one at the time of old bulb exhaustion (late May to mid June) and the other in late July or early August. The second cultivation was required to kill plants regenerated from the stems and crowns of plants injured at the first cultivation and was timed to take place before the appearance of new bulbs.

Where heavy infestations had been lowered by such cultivations, it proved possible to reduce bulbs still further to very low levels (140 or less kg/ha), acceptable for long‐term control, by spraying with fenoprop (2.2 kg/ha) in the following year. The use of fenoprop alone without previous cultivation and of cultivation alone without subsequent spraying was inadequate except on less severe infestations on light soils.

Études sur l'Oxalis pes‐caprae L. en Australie. II. Méthodes de lutte contre la variété pentaploïde
THE DEVELOPMENT OF HERBICIDES FOR POTATOES
Authors: COX T. I. , ELLIOTT J. G.
Published: July 2006

Summary. Since 1961 the Weed Research Organization has been testing and developing herbicides for weed control in potatoes. Inthe three experiments which are reported, herbicides were compared with other forms of weed control. The first experimentin 1961 was exploratory and compared yields following hand‐weeding versus no weed control versus several promising herbicides. The highest yield was produced by the hand‐weeded crop. Several herbicide treatments applied before crop emergence gave useful selective weed control.

Assuming weed control to be necessary, selected herbicides were then compared in 1962 and 1963 with conventional mechanical cultivations. In both years successful weed control by herbicide resulted in a higher yield of potatoes than did mechanical cultivation although the soil‐acting chemical used in 1962 caused some crop damage. The 1963 experiment included triangular planting patterns, at normal and high plant densities. Increases both in gross and marketable yield were obtained at normal plant density with the triangular arrangement as compared with the row crop. The high plant population resulted in the largest gross yield but a lower yield per plant and smaller average tuber size.
THE DEVELOPMENT OF SELECTIVE HERBICIDES FOR KALE IN THE UNITED KINGDOM
Authors: ELLIOTT J. G. , COX T. I.
Published: July 2006

Summary. The purpose of this paper is firstly to describe the background of an investigation started in 1961 to develop new herbicides for the control of weeds in agricultural kale, Brassica oleracea vars. acephala D.C. and fruticosa Metz, and secondly to present the results of four experiments concerned with the effects of weeds on the yield of kale. The results of the herbicide investigation are to be presented in subsequent papers.

Kale as grown in the United Kingdom is a valuable fodder crop and relatively easy to grow, but beset by weeds against which existing mechanical and chemical methods of control have not usually been successful. The effect of weed competition on the yield of four farmers’crops was investigated in 1961 and 1962. When grown entirely free of weeds, the crops provided yields in the range of 20.9–34.5 tons of green material per acre. Where no attempt was made to control the weeds, the yields were reduced by 9.4, 14.5 and 18.9 tons/ac, respectively, in three experiments. In no case did kale, hoed only between the rows, produce as high a yield as the weed‐free crop. Although variable in effect, uncontrolled weed growth early in the life of the crop always lowered the yield of kale.

Le développement de l'usage des herbicides selectifs pour le chou fourrager dans le Royaume‐Uni. La plante cultivée, les mauvaises herbes et le problème