bluuebunny/crossref_metadata_2025 huggingface dataset:
Resin extraction of labile, soil organic phosphorus
Authors: RUBAEK G. H. , SIBBESEN E.
Published: July 2006

In order to develop a method for estimating labile, soil organic phosphorus (Po), macroporous anion‐exchange and adsorbent (XAD) resins were tested for their ability to extract Po from a permanent pasture soil. Experimental variables included: ionic form, soil‐water resin ratio, addition of cation‐exchange resin, extraction time, extraction temperature, continuous and stepwise extraction and soil pretreatment (chloroform and microwaves).

The amounts of extracted Po and Pi (inorganic phosphorus) showed little variation between the anion‐exchange resins, when used in the bicarbonate form. In the chloride form, the amounts extracted were less and more variable. XAD resins extracted much less Po and very little Pi. The macroporous anion‐exchange resin, Lewatit MP500A in the bicarbonate form, was chosen for further studies. It extracted 21 mg Po kg−1 from air‐dried soil and 8 mg Po kg−1 from moist, incubated soil.

The specific amounts of Po and Pi extracted were little affected by variations in the ratio between soil, water and resin, but increased with extraction time and temperature. Chloroform pretreatment of the soil mainly increased extracted Pi, whereas microwave pretreatment only increased extracted Po. The magnitude of these increases was approximately constant irrespective of extraction temperature, indicating that the increases came from killed micro organisms.
Root‐induced release of interlayer potassium and vermiculitization of phlogopite as related to potassium depletion in the rhizosphere of ryegrass
Authors: HINSINGER P. , JAILLARD B.
Published: July 2006

The ability of roots to weather phlogopite as shown by the release of interlayer‐K and by the concomitant vermiculitization of the mica was investigated in the rhizosphere of Italian ryegrass (Lolium multiflorum), grown for 1 to 32 d on 2–105 μm mica as sole source of both K and Mg. The K‐balance showed that ryegrass was able to induce a significant release of interlayer‐K from phlogopite after 8 d of cropping. After 32 d, this root‐induced release of K amounted to 191 g Kg−1 of total‐K and contributed a major part of plant nutrition. Concurrently, the concentration of K in solution decreased markedly in the rhizosphere and X‐ray diffractometry showed a strong vermiculitization of the phlogopite. The transformation of phlogopite into vermiculite was detected when the K‐concentration in the rhizosphere decreased below a threshold of about 80 μmol dm−3. That suggests that the roots act by depleting the rhizosphere‐K, and thus shifting the exchange equilibrium, so as to release interlayer‐K and expand the interlayer space of the phyllosilicate leading to the transformation of the phlogopite into vermiculite.
On the relation between number‐size distributions and the fractal dimension of aggregates
Authors: CRAWFORD J. W. , SLEEMANt B. D. , YOUNG I. M.
Published: July 2006

Number‐size distributions (i.e. particle‐ and aggregate‐size distributions) have historically been used as indicators of soil structure, and recent work has aimed to quantify this link using fractals to model the soil fabric. This interpretation of number‐size distributions is evaluated, and it is shown that a number‐size relation described by a power law does not in itself imply fractal structure as suggested, and a counter example is presented. Where fractal structure is assumed, it is shown that the power‐law exponent, φ, describing the number‐size distribution cannot be interpreted as the mass‐fractal dimension, DM, of the aggregate. If the probability of fragmentation is independent of fragment diameter, then the exponent may be identified with the boundary dimension, DB, of the original matrix. If, however, as is likely, this probability is scale‐dependent, then φ may over‐ or under‐estimate the boundary dimension depending on whether the fragmentation probability increases or decreases with fragment size. The significance of these conclusions is discussed in terms of the interpretation of number‐size distributions, and alternative methods for quantifying and interpreting soil structure are evaluated.
An amended functional leaching model applicable to structured soils. I. Model description
Authors: HALL D. G. M.
Published: July 2006

A functional model designed to simulate the transport of non‐interactive solutes through macroporous soil is described. The concept of mobile and immobile water is used but the pore volume available for mobile water is partitioned to allow for flow through smaller water‐filled pores and rapid preferential flow through larger macropores and fissures. The general performance of the model under steady infiltration following an injection of solute is presented. The sensitivity of the output to variations in the model parameters is also discussed. A second paper compares the model with bromide and chloride leaching data on two texturally contrasting soils.
An amended functional leaching model applicable to structured soils. II. Model application
Authors: HALL D. G. M. , WEBSTER C. P.
Published: July 2006

The performance of a functional leaching model (Hall, 1993) is compared with leaching data from two lysimeter experiments with soils of contrasting texture using sodium bromide and potassium chloride as the non‐reactive solutes. The model parameters are optimized using the solute elution curves as standards and compared with the physical properties of the soil. A good match with the measured discharge of both water and solute was achieved for both soils using the moisture release characteristics to define the pore volume available for mobile and immobile water. The results indicate that preferential flow takes place through even coarse‐textured soils but that there is negligible diffusive exchange of solute between water passing through the macropores and the rest of the soil.
Interference by organic complexation of Fe and A1 on the SO2‐4 adsorption in Spodic B horizons in Sweden
Authors: KARLTUN E. , GUSTAFSSON J. P.
Published: July 2006

The relations between pH, different fractions of Fe and A1 and Na4P2O7‐soluble C and the amount of adsorbed SO2‐4 were assessed by analysing 63 soil samples from 14 podsolized soils in Sweden. The amount of adsorbed SO2‐4 was significantly better correlated with the calculated amount of the inorganic fraction of Fe and A1 oxides obtained by subtracting Na4P2O7‐soluble Fe and A1 from oxalate‐soluble Fe and Al than with the oxalate extraction alone. There was a close correlation between C and organically‐bound S in the Na4P2O7 extract which shows that the C:S ratio of the extracted fulvic acids is about constant in the soils studied. It was found that, as the proportion of organically‐complexed Fe and Al increases, the ability of the soil to adsorb SO2‐4 decreases. The amount of adsorbed SO2‐4 expressed on the basis of the amounts of oxalate‐soluble Fe and Al was generally smaller in areas with low S deposition (< 60 mmol m‐2 a‐1). The ratio between pyrophosphate‐soluble C and oxalate‐extractable Fe and Al was negatively correlated with pH in water. It was concluded that Fe and Al associated with organic matter cannot adsorb SO2‐4 and that the degree of this association is pH dependent. These observations have important implications regarding the effects of anthropogenic acidification.
Simple determination of nitrate in soils by second‐derivative spectroscopy
Authors: SEMPERE A. , OLIVER J. , RAMOS C.
Published: July 2006

A new and simple method for nitrate analysis in soil extracts and soil solution is described. The method uses the second derivative of the direct ultra‐violet (UV) spectrum, available from most microprocessor‐controlled spectrophotometers with a UV source. Results with the proposed method were similar to those obtained by the cadmium‐reduction column and ion‐chromatographic methods. The main advantages of the proposed technique are that it is simple, rapid, accurate and requires no sample pre‐treatment, making it useful for routine analysis of large numbers of samples.
Fragipan formation in argillic brown earths (Fragiudalfs) of the Milfield Plain, north‐east England. III. Micromorphological, SEM and EDXRA studies of fragipan degradation and the development of glossic features
Authors: PAYTON R. W.
Published: July 2006

The micromorphology of eluvial and glossic areas with weak soi1, strength from the upper fragipan, and the upper parts of grey polygonal zones, in some argillic brown earths (Glossic Fragiudalfs) from north‐east England shows unstable void walls stripped of clay with remnants of ferri‐argillans, pale grey grainy clay coatings and darker grainy coatings. These occur alongside loose surface residues of skeleton grains and thin grey fine silt coatings of quartz and muscovite. SEM and EDAX studies of coating surfaces, and optical microscopy, SEM and EDXRA of very thin polished sections, show that some grainy clay coatings form as alteration rims of ferri‐argillans through localized waterlogging, iron oxide loss and micro‐erosion leading to micropitting and disoriented fabrics. The inclusion of coarse clay to fine silt‐sized quartz, feldspar and muscovite in other grainy coatings suggests either alteration of impure ferri‐argillans or accumulation of degradational products derived from elsewhere on void walls. This is more certainly the case for dark grainy coatings in layered compound illuviation coatings adjacent to glossic areas. These fragipans are degrading from the top downwards by processes which are partly a consequence of the effects that the fragipan has on water percolation and root penetration. The destabilization of void walls, the degradation of ferri‐argillans and the remobilization of clay to form glossic features did not begin until seasonal waterlogging in parts of the upper pan was sufficient to mobilize iron.
Measurement of soil gas diffusivity in situ
Authors: BALL B.C. , GLASBEY C.A. , ROBERTSON E.A.G.
Published: July 2006

Assessment of gas diffusivity in situ gives a direct measure of the ability of soils to exchange gas with minimal soil disturbance. A versatile, readily portable probe for measuring the diffusion of a tracer gas through soil in situ is described. The radioactive tracer 85Kr is injected into a cell located at the end of the probe. The change in activity within the cell as the gas diffuses out is measured by a Geiger‐Muller tube in the cell. The probe can be used by insertion either directly into an auger hole (buried‐probe mode) or into a chamber pushed into the soil surface. A method to simulate diffusion numerically using Fick's equation for both methods of insertion is presented. In the tests reported, diffusivity was estimated by expanding or contracting the time axis of the simulation until it matched the observed count rates. A goodness‐of‐fit was attached to each diffusivity estimate. The probe was generally effective, giving diffusivities comparable to those measured in the laboratory on cores taken near the cell (buried‐probe mode) or linked to the surface chamber. Poor fits were found for some diffusivities measured in the buried‐probe mode on coarsely structured soils. These were attributed to non‐uniform distribution of porosity and possible upward leakage of tracer when used at shallow depths in the buried‐probe mode. However, thein situ diffusivities may be more representative than those measured in cores in the laboratory because of the greater sample volume. We show how the probe can be used to detect soil layers that restrict gas diffusivity and differences in aeration status between tillage treatments.
Structural collapse and strength of some Australian soils in relation to hard setting: I. Structural collapse on wetting and draining
Authors: GUSLI S. , CASS A. , MACLEOD D.A. , BLACKWELL P.S.
Published: July 2006

The surface structure of many Australian red and red‐brown earths frequently collapses (slakes) when dry, disturbed aggregates are wetted by rain or irrigation. The resulting fine matrix sets, on drying, to a strong, cohesive layer of up to 200 mm thick (hard setting). We investigated the mechanism of collapse and the extent to which the structure of aggregate beds Iron hard setting and non‐hard setting soils collapsed when wetted by quick flooding or slowly with water at a suction of 200 mm, then drained in sequential steps of increasing suction and finally dried at 40°C. After flood wetting, but before draining, no collapse was observed due to the small effective stress prevalent in the flooded beds.

After suction wetting, some collapse was measured owing to the effective stress (approximately 1.4 kPa) from the applied suction. On draining, flood‐wetted beds collapsed extensively (volume strain >0.20), largely due to the disappearance of large pores (>75 μm diameter). Suction‐wetted beds collapsed less (volume strain <0.16) and retained more large pores. Hard setting soils collapsed more following both flood and suction wetting (volume strain >0.20 and 0.10, respectively), while non‐hard setting soils did not collapse as extensively (volume strain <0.16 and 0.09, respectively). Results indicate that the mechanism causing collapse was independent of wetting method and involved two steps: (i) slaking of aggregates on wetting, and (ii) collapse of the aggregate bed on draining as a result of development of effective stress within the beds.
Effect on Colwell soil‐test P of storing air‐dry soil samples at room temperature for up to seventeen years
Authors: BOLLAND M.D.A. , DHALIWAL J. , BOWDEN J.W. , ALLEN D.G.
Published: July 2006

We wished to determine whether soil‐test P was affected by storing air‐dry soil samples at room temperature. The soil samples had been collected from field experiments and air‐dried (<40°C) before measuring soil‐test P (bicarbonate‐extractable P). The samples were from field plots that had been treated with different applications of fertilizer P (superphosphate, rock phosphate) one or more years previously. Soil‐test P was measured on two different sub samples of the same sample: either A, in the year the sample was collected; or B, after the sample had been stored at fluctuating room temperatures either from 2 to 8 years (four field experiments) or 17 years (59 field experiments). The room temperature ranged from 10 to 30°C, and averaged 17°C. The aim was to test whether soil‐test P was systematically and consistently different between sub samples A and B.

Differences between A and B were mostly small, and there were no consistent or systematic differences. For the Colwell soil test, applied to a range of south‐western Australian soils, possible decreases in soil‐test P due to continued reaction with the soil could not be detected using bicarbonate‐extractable soil P, and storage of air‐dry samples at room temperature did not significantly affect soil‐test P measured up to 17 years later. We conclude that, provided fertilizer P has had time to react with soil in the field, no further changes in Colwell soil‐test P occur during air‐dry storage for up to 17 years at room temperature.
Evidence of biogenic greigite (ferrimagnetic Fe3S4) in soil
Authors: STANJEK H. , FASSBINDER J. W. E. , VALI H. , WÄGELE H. , GRAF W.
Published: July 2006

The occurrence of greigite (Fe3S4) in soils is reported for the first time. It forms irregularly‐shaped aggregations within plant cells in the Gr2 horizon of a gley soil developed from colluvial material. Greigite was identified by X‐ray diffraction and magnetic measurements and was investigated by optical and transmission electron microscopy. Biogenic formation is proposed, based on the elongated shape of single greigite crystals, and sulphur isotope analyses, which showed a depletion in 34S relative to the soil‐water sulphate. The cell‐edge length of 0.98639±0.00003 nm is significantly smaller than values reported for sedimentary greigite. The mean coherence length of 27 nm agrees with TEM observations and indicates that the single greigite crystals lie in the superparamagnetic region. However, the fine aggregates show magnetically single‐domain behaviour. Greigite is the only carrier of a stable magnetic remanence in the soil profile studied.
The effect of energy peak drift on the calibration of a high resolution gamma‐ray soil density gauge
Authors: HENSHALL J.K.
Published: July 2006

High spatial resolution is obtained from a gamma‐ray transmission density gauge by restricting the measured counts to a narrow band of the energy spectrum, close to the emission energy peak. The effect on measurement accuracy of any movement of this measurement window relative to the energy peak was investigated. The findings were related to anticipated energy peak movements in a proposed LED‐based gain‐stabilization system.

Movements of the energy peaks during recording of unstabilized spectra prevented direct comparisons of spectra at different positions. A simulation procedure was, therefore, developed in which movements of the measurement window relative to sets of stable calibration spectra were examined.

When analysing spectra, recorded using a gauge with a different gain‐stabilization system, accuracy was found to be unaffected by simulated peak movements of up to 0.03 MeV in the direction of increasing energy. However, movements of stabilized spectra in the direction of decreasing energy, and of unstabilized spectra in either direction, increased measurement errors to twice the level of inherent measurement errors within 0.02 MeV, with errors in bulk density of up to 0.7 Mg m−3 for movements of 0.1 MeV. The spectra of the new LED‐based stabilization system are expected to behave in a manner similar to the unstabilized system, therefore requiring regular monitoring of the peak position.
Applications of fertilizer cations affect cadmium and zinc concentrations in soil solutions and uptake by plants
Authors: LORENZ S.E. , HAMON R. E. , McGRATH S.P. , HOLM P.E. , CHRISTENSEN T.H.
Published: July 2006

A pot experiment was conducted to study changes over time of Cd and Zn in soil solution and in plants. Radish was grown in a soil which had been contaminated with heavy metals prior to 1961. Constant amounts of a fertilizer solution (NH4NO3, KNO3) were added daily. Soil solution was obtained at intervals by displacement with water.

The cumulative additions of small amounts of fertilizers were made equal to the plants' requirements at the final harvest but were found to exceed them during most of the experiment. Excess fertilizers caused substantial increases of major (K, Ca, Mg) and heavy‐metal (Cd, Zn) ions in soil solutions and a decrease in soil pH, probably due to ion‐exchange mechanisms and the dissolution of carbonates.

Uptake of Cd and Zn into leaves was correlated with the mass flow of Cd (adjusted r2= 0.798) and Zn (adjusted r2= 0.859). Uptake of K, Ca and Mg by the plants was independent of their concentrations in solution.

It is concluded that, in order to study effects of plants on heavy‐metal availability and obtain soil solution that has not been altered by fertilizer ions, nutrients must be added according to the needs and growth of the plants. This could be achieved by linking fertilizer additions to the rate of transpiration, as nutrient uptake and transpiration were closely correlated in this experiment.
Calculating the annual input of organic matter to soil from measurements of total organic carbon and radiocarbon
Authors: JENKINSON D.S. , COLEMAN K.
Published: July 2006

Measurements of total organic C, δ13C and δ14C are given for topsoils taken from six experimental sites in southern England. At each site, some of the samples were collected before and some after the thermonuclear tests of the early 1960s, so that pre‐ and post‐bomb samples could be compared for radiocarbon content. The current Rothamsted model for the turnover of organic C in soil gave an acceptable fit to the data from five of the sites, apart from one aberrant radiocarbon measurement. The annual input of C to the topsoil was calculated for the five sites from these fits; the values obtained were: 0.15 t C ha−1 a−l for a site on silty clay loam, kept bare by hand weeding since 1870; 0.2 for unmanured spring barley growing on a sandy loam; 2.95 for a fertilized all‐arable rotation on a loamy sand; 1.9 for the same fertilized all‐arable rotation on a silty loam and 2.5 from this rotation on a calcareous silty loam. The corresponding values for Net Primary Production at the five sites were 0.15, 0.76, 5.16, 5.71 and 5.46 t C ha−1 a−l. In fitting the model to the radiocarbon data it was necessary to postulate that all these sites contained substantial quantities of biologically‐inert organic matter, ranging from 2.2 to 10.0 t C ha−1.
Incorporation of natural monoacids from plant residues into an hydromorphic forest podzol
Authors: AMBLÈS A. , JAMBU P. , PARLANTI E. , JOFFRE J. , RIFFE C.
Published: July 2006

The monoacid part of soil lipids was studied in a hydromorphic sandy podzol under pine trees (Pinus maritima sp.). The undecomposed forest‐litter layer (L), the fragmented mycelium‐invaded litter layer (F) and the A1 soil horizon were sampled, and analysed for total lipid and total monoacid contents. Total monoacids were separated into straight‐chain components and terpenic components.

Straight‐chain monoacids were determined as free acids and esters of fatty alcohols and of glycerol. Among these components, branched alkanoic acids occurred in the A1 soil horizon. Alkenoic acids were mainly determined as glycerides. Free n‐alkanoic acids were mainly produced in soil from terminal oxidation of plant n‐alkanes and plant n‐alkanols. Free alkanoic acids with the longest carbon chains and alkanoic acids esterified as glycerides were concentrated in the A1 soil horizon.

Terpenic monoacids were mainly diterpenic components from pine resin. Their concentration decreased markedly during the decomposition of plant debris.
The effect of spruce (Picea abies Karst.) on soil development: an analytical and experimental approach
Authors: RANGER J. , NYS C.
Published: July 2006

Changes in soil and biogeochemical processes following the replacement, 60 years ago, of part of a deciduous forest by a coniferous stand were evaluated by (i) a balance‐sheet approach using soil and biomass element content analyses and the mineral flux, and (ii) the inclusion of test‐mineral and resin bags in an integrative experimental approach.

The comparison of soils under different stands shows that the change to spruce is inducing physical, chemical and biological modifications in soil properties. Changes in the humus layers lead to a reduction in mineralization and the mobilization of active organic acids in the system. Under spruce, the soil structural stability is reduced as fine clay is dispersed. Soil acidification is increased, linked to a decrease in soil pH and desaturation of the soil exchange complex. Soil mineralogy also indicates this tendency, particularly with an increase in the stability of Al intergrades. The biogeochemical cycle is modified especially for N, S and Al. with large changes in the internal fluxes between the ecosystem components, but the modification of the input‐output balance due to spruce introduction is large only for S.

The acidification is partly due to a change in litter quality, which inhibits biological activity, and partly because, during the dormant season, evergreen species intercept ‘dry and occult’ depositions from the atmosphere containing acidic or potentially acidic components.

Use of test‐mineral bags improves understanding and interpretation of the current soil mechanisms. The test mineral, a vermiculite, introduced into the soil or placed in the lysimeter flux very quickly undergoes measurable transformation characterized by desaturation and fixation of non‐exchangeable Al in the interlayer zone, easily identified by Al speciation. The acidifying effect of spruce is clearly demonstrated by the experimental approach used, including the characterization of soil solutions by resin bags.

All the techniques are complementary and could be used together or individually, depending on the aim of the study.
Choosing models for soil chronofunctions and fitting them to data
Authors: SCHAETZL R.J. , BARRETT L.R. , WINKLER J.A.
Published: July 2006

The effectiveness and utility of soil chronofunctions is examined in the light of existing pedogenic theory. Statistical treatments applied in chronofunction research are reviewed, including linear transformations of raw data, which may improve the utility of the chronofunction. We advocate using a particular statistical model only if it can be justified based on our current understanding of the functioning of the pedologic system. We emphasize the potential difficulties of using linear chronofunction methods; simple linear and logarithmic functions are not always the best option for chronofunctions. Hyperbolic, polynomial or nonlinear functions might improve not only the fit of the chronofunction but also advance our understanding of the pedologic system.

When the chronofunction explaining the most variance is not best suited to a process‐based understanding of pedogenic theory, other functions with slightly smaller r2 values that have been judged suitable by a priori reasoning or theory might better reflect the functioning of the pedologic system. We justify limited extrapolation of some chronofunctions to time zero and discuss how this can be useful in the identification of pedogenic thresholds and ‘step functions’. Interpretation of the Y‐intercept of chronofunctions can, at times, aid our understanding of the soil system near time zero and be useful in the identification of the existence and timing of thresholds.
Conservation of mineral nitrogen in restored soils at opencast coal mine sites: I. Results from field studies of nitrogen transformations following restoration
Authors: JOHNSON D. B. , WILLIAMSON J. C.
Published: July 2006

One of the characteristics of soils located within the cores of stockpile storage mounds at opencast mine sites is their accumulation of ammonium‐nitrogen. Two areas of restored land were constructed from soil stockpiled for 3 years; one consisted of mound‐surface (‘aerobic zone’) soil, and the other of deeply buried (‘anaerobic zone’) soil. In that constructed from mound‐surface soil, concentrations of both ammonium‐ and nitrate‐nitrogen remained fairly stable throughout the first 6 months of restoration at about 12–20 μg g−1, but in the site constructed from deeply buried soil, concentrations of ammonium‐N decreased from an initial high of 160 to 14 μg N g−1 soil after 14 weeks, and increased again to 42 μg N g−1 soil by week 29. In contrast, concentrations of nitrate‐nitrogen at the latter site increased from an initial 9 μg to a maximum recorded level of 77 μg N g−1 soil by week 14, before subsiding to 9 μg N g−1 soil by week 29. Nitrate was considered to have been lost from the restored soils by a combination of leaching and denitrification, as no vegetation was established at these sites. After a short‐term stimulation following restoration, soil microbial biomass levels remained fairly constant, though soils (up to 3 years after restoration) were characterized by a very small ratio of biomass C: organic C.
Identification of free amino acids in peat by gas chromatography and mass spectrometry
Authors: KUNNAS A.V. , ERONEN M.
Published: July 2006

The qualitative and quantitative composition of free amino acids in a typical Finnish peat bog at various depths down to 5.3 m below the surface was studied using capillary gas chromatography and mass spectrometry.

Sixteen amino acids were identified at each depth: α‐alanine, β‐alanine, glycine, valine, leucine, proline, isoleucine, serine, threonine, glutamic acid, aspartic acid, phenylalanine, tyrosine, γ‐aminobutyric acid, ornithine and lysine. Their amounts decreased markedly at a depth of 40–100 cm. The total amount of amino acids varied between 0.6 and 5.6 g kg−1 dry matter (i.e. 0.06–0.56%) depending on the depth. The proportion of neutral amino acids was greatest at all depths studied, except at the surface layer where it ranged between 41 and 72% by mass. The acidic amino acids decreased with depth from 56 to 23% of the total. The proportion of aromatic amino acids was very small, 3.2–5.5% by mass.

In samples from aerobic conditions, where the microbial production of free amino acids was the greatest, α‐ala, gly, glu and asp were most abundant. In peat from anaerobic conditions, where the microbiological activity was low, the proportion of the most chemically stable amino acid was exceptionally high. This may have been because glycine was a degradation product of other amino acids or peptides.

Peat type and degree of decomposition had a strong influence on the total amount of free amino acids and their qualitative composition.
Identification of pyromorphite in mine‐waste contaminated soils by ATEM and EXAFS
Authors: COTTER‐HOWELLS J.D. , CHAMPNESS P.E. , CHARNOCKY J.M. , PATTRICK R.A.D.
Published: July 2006

Calcium‐rich pyromorphite [Pb5(PO4)3Cl] has been positively identified as the major lead‐bearing phase in mine‐waste soils from the South Pennine Orefield, UK, by a combination of EXAFS spectroscopy, ATEM and XRD. Evidence for a pyromorphite‐like structure was provided by electron diffraction of individual Ca‐rich, lead chlorophosphate grains in the soil using ATEM. Approximate unit‐cell parameters derived from electron diffraction were used to identify peaks on the powder XRD trace obtained from the soil sample, allowing the cell parameters to be refined. The unit‐cell parameters derived for the Ca‐rich pyromorphite [a= 0.9789(7), c= 0.726(1) nm] are smaller than those reported for pure end‐member pyromorphite (a= 0.998, c= 0.733 nm; Baker, 1966) and are sufficiently different to prevent positive identification by conventional XRD analysis. Lead absorption spectra and interatomic distances obtained from EXAFS performed on bulk soils confirmed the predominance of pyromorphite‐like structure. EXAFS is shown to be a useful tool in the identification of soil minerals. It gives information about the local environment of one specific element in solids, be they crystalline or amorphous, and is unaffected by the limited chemical substitution of Ca for Pb.

The identification of impure Pb minerals in soil by techniques other than XRD suggests that previous studies, based on XRD, may have underestimated the amount of soil Pb present as discrete Pb compounds.
Characterization of phosphate species in urban sewage sludges by high‐resolution solid‐state 31P NMR
Authors: FROSSARD E. , TEKELY P. , GRIMAL J.Y.
Published: July 2006

The mineral forms of phosphorus in three urban sewage sludges were characterized using high‐resolution solid‐state phosphorus‐31 nuclear magnetic resonance (NMR) coupled to a sequential extraction. The sludges studied were an anaerobically‐digested and heat‐treated sludge (Paris‐Achères), an activated sludge (Briare) and an anaerobically‐digested sludge (Nancy). NMR observations were conducted using both single‐pulse and cross‐polarization sequences in order to distinguish between 31P nuclei far from 1H nuclei, and 31P located within a fraction of a nanometre of 1H. This approach showed that a complex mixture of P species was present in these sludges. A mixture of hydrogenated octocalcium phosphates and apatites was observed in the three samples. Monetite was present in the anaerobically‐digested sludge and brushite in the activated sludge. Dehydrogenated condensed calcium phosphates (compounds with a Ca:P ratio higher than 1.0 such as fluorapatite or tricalcium phosphate) and dehydrogenated pyrophosphates were also probably present in the anaerobically‐digested sludge. A poorly‐ordered wavellite was observed in the three sludges after the HCl extraction. However, results were inconclusive as to whether this mineral was present in the three sludges, or had been precipitated during the sequential extraction.
A REVIEW OF EXPERIMENTAL WORK WITH DIQUAT AND RELATED COMPOUNDS
Authors: CRONSHEY J. F. H.
Published: July 2006

Summary. Published literature on diquat (9,10‐dihydro‐8a, 10a‐diazonia phenanthrene dibromide; 1,1′‐ethylene‐2,2′‐dipyridylium dibromide) and related dipyridyl herbicides is reviewed. Their activity is probably connected with the formation of stable free radicals on reduction and both photosynthetic and respiratory processes may be associated with free radical formation in the plants. These herbicides are rapid‐acting translocated desiccants and kill the aerial parts of most plants, but are safe as soon as they touch the ground, having no residual effect through the soil. Possible uses are as desiccants, in place of cultivation to clear fallows and seedbeds before sowing, in pre‐emergence weedkilling, for weeding round trees and bushes and, with directed spraying, for inter‐row weeding in row crops.

Revue des essais effectués avec le Diquat et des composés apparentés
UNTERSUCHUNGEN ÜBER DAS VERHALTEN VON SIMAZIN IM BODEN
Authors: BURSCHEL P.
Published: July 2006

Zusammenfassung. Zur Untersuchung des Abbaus von Simazin im Boden wurden Versuche angestellt. Die quantitative Bestimmung des Herbizids geschah nach der Methode von Delley (1958). Es können folgende Feststellungen gemachten werden: (1) Der Abbau von Simazin im Boden erfolgt als Reaktion I. Ordnung. Das bedeutet, dass — unter sonst gleichen Bedingungen — zu einem gegebenen Zeitpunkt der gleiche Prozentsatz der Ausgangsdosierung im Boden nachweisbar ist, unabhängig davon, wie hoch diese gewählt worden war. (2) Der Abbau ist in starkem Masse temperaturabhängig. Eine Verringerung der Temperatur von 25°C auf 8,5°C verlangsamte die Abbaugeschwindigkeit um das 7fache. (3) Der Abbau von Simazin im Boden ist vom Vorhandensein von Humussubstanz abhängig. Fehlt sie, findet kein Abbau statt; mit zunehmendem Anteil wird der Abbau beschleunigt. Daraus wird der Schluss gezogen, dass die Vorgänge durch Mikroorganismen bewirkt werden. (4) In schweren Böden bleibt Simazin auch nach erheblichen Niederschlägen in den oberen 0–4 cm des Bodens. Mit zunehmendem Sandanteil steigt die Wahrscheinlichkeit, dass geringe Mengen des Mittels auch in tiefere Schichten eindringen. (5) Die Beobachtung des Abbaus von zwei Dosierungen des Präparates unter Feldbedingungen bestätigte die Ergebnisse der Laborversuche.

Experiments on the breakdown of simazine in the soil
MOVEMENT OF 2,6‐DICHLOROBENZONITRILE IN SOILS AND IN PLANTS IN RELATION TO ITS PHYSICAL PROPERTIES
Authors: MASSINI P.
Published: July 2006

Summary. The movement of the herbicide H133 (2,6‐dichlorobenzonitrile) in soils and in plants is shown to be governed mainly by its relatively high volatility, its low solubility in water and its strong adsorption on lignin, on humic matter and on lipid material. Some evidence for a transformation of H133 in plants is presented.

Les déplacemcnts du 2,6‐dichlorobenzonitrile dans les sols et dans les plantes et leurs relations avec les proriétés physiques
THE FATE OF N'‐(4‐CHLOROPHENOXY)‐PHENYL‐NN‐ DIMETHYLUREA (C‐1983) IN SOILS AND PLANTS*
Authors: GEISSBÜHLER H. , HASELBACH C. , AEBI H. , EBNER L.
Published: July 2006

Summary. Seedlings of Galinsoga parviflora and Polygonum convolvulus were cultured in nutrient solution and soil with C‐1983‐14C. Uptake and translocation of herbicide was followed by measuring radioactivity in roots, stems and leaves as a function of time. The capacity of the two plants to take up C‐1983 from nutrient solution and to translocate it into stems and leaves was found to be strikingly different. The difference in herbicidal effect of C‐1983 on the two species parallels the concentration of radioactivity translocated into leaves. Uptake of C‐1983 from nutrient solution as well as subsequent translocation to top parts by lowering temperature increasing humidity and transfering the plants from light to darkness.

In soil cultures, the two plants were found to take up and to translocate smaller quantities of C‐1983 than was to be expected from the calculated soil solution concentration.

The mechanisms regulating the rate of uptake C‐1983 from nutrient cultures and soils are discussed. The strong adsorption of C‐1983 in tissues appears to be a decisive factor in controlling movement of the herbicide in plants.

Le comportement de la N'‐(4‐chlorophenoxy)‐phenyl‐NN‐dimethyluric (C‐1983) dans les terres et dans les plantes II. Absorption et migration dans les plantes
ON THE REGENERATION OF ROOT FRAGMENTS OF LEAFY SPURGE (EUPHORBIA ESULA L.)
Authors: RAJU M. V. S. , STEEVES T. A. , COUPLAND R. T.
Published: July 2006

Summary. The roots of leafy spurge (Euphorbia esula L.) normally produce shoot buds abundantly near the soil surface but with decreasing frequency at increasing depths. By placing Fragments of roots collected from various depths in the soil in shallow flats in a glasshouse, it was demonstrated that root Fragments from all depths down to 2–8 m do not differ appreciably in rcgenerative capacity and this capacity is not dependent upon the presence of performed shoot buds. By collecting root fragments from the same stand throughout the growing season it was shown that regenerative capacity is lowest in June at the time of maximum flowering. The implications of these findings arc discussed in relation to the control of this species.

Sur la régénération des fragments de racines de Euphorbia esula L.
CHEMICAL AND BIOLOGICAL PROPERTIES OF TWO NEW HERBICIDES—IOXYNIL AND BROMOXYNIL
Authors: CARPENTER K. , COTTRELL HELEN J. , DE SILVA W. H. , HEYWOOD B. J. , LEEDS W. G. , RIVETT K. F. , SOUNDY MARGERY L.
Published: July 2006

Summary. The preparation of ioxynil, bromoxynil, and their salts is described, and information on solubilities and stability to storage is summarized. Although the toxicology of the herbicides is to be reported in greater detail, a preliminary statement is made here. Evidence of herbicidat activity under glasshouse conditions is indicated briefly, and supports the conclusion that both compounds are effective when applied to the foliage of a wide range of dicotyledon weed species. Seedlings of some weed species resistant to the phenoxy alkanoic acids are controlled under glasshouse conditions at doses as low as 0.125 lb/ac, and ioxynil has a wider range of activity than bromoxynil at these low doses. Graminaceous species tolerate 4–8 lb/ac of both herbicides without injury, and certain leguminous crops tolerate one or other herbicide at doses of 0.5–0.75 lb/ac. The contact action of the herbicides is rapid, there are also slower systemic effects, and seed germination is inhibited. In susceptible species the level of post‐emergence activity is shown to be influenced by the growth stage of the weed, the distribution of herbicide on the foliage, and environmental factors of which light intensity appears to be most important.

Propriétés chimiques et biologiques de deux nouveaux herbicides: ioxynil et bromoxynil
A STUDY OF THE COMPETITIVE ABILITY OF CHENOPODIUM ALBUM L.
Authors: WILLIAMS T.
Published: July 2006

Summary. Experiments arc reported that demonstrate that there is mutual interference between kale and Chenopodium album when grown in association. As the plants grow, those at high density, whether in mixtures or in pure stands, interfere with each other and individual plant weight and leaf area are reduced. By changing the time:of Introduction of one of the species into a mixture it was shown that kale suffered heavy mortality when C. album had an initial advantage. When kale was introduced before C. album the weed remained stunted but there was no mortality. The weed exerted an early effect of kale. The ability of C. album to interfere with kale, seems to be related to its plasticity. It is able to grow rapidly, to trap light effectively and even under adverse conditions to set seed.

Etude sur le pouvoir de compétition de Chenopodium album L. I. Recherches sur la compétition enire les choux et C. album
THE ADSORPTION OF UREA AND SOME OF ITS DERIVATIVES BY A VARIETY OF SOILS
Authors: HANCE R. J.
Published: July 2006

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
SEED POLYMORPHISM AND GERMINATION
Authors: WILLIAMS J. T. , HARPER J. L.
Published: July 2006

Summary. Achenes of Chenopodium album are polymorphic; four categories can be recognized visually, brown‐smooth, brown‐reticulate, black‐smooth and black‐reticulate. All four types may be borne by one plant. The polymorphic seeds differ in germination requirements, responding differently to chilling and nitrate application.

Dormant seeds contain at least one extractable germination inhibitor. The inhibitor fails to act in the presence of added nitrate.

Nitrate is replaceable by some other nitrogen compounds and by chlorate. Nitrate application stimulates germination of C. album in soil.

The ecological significance of seed polymorphism and the relevance of polymorphism to the interpretation of germination tests are briefly discussed.
AN IMPROVED METHOD OF CONTROL OF PASPALUM CONJUGATUM WITH AMITROLE‐T AND PARAQUAT
Authors: HEADFORD D. W. R.
Published: July 2006

Summary. Paraquat, amitrole‐T and disodiumn methylarsonate (DMA) were evaluated for the control of the stoloniferous grass Paspalum conjugatum in young rubber plantations in Malaya. The herbicides were tested alone, in mixtures and in split applications. Paraquat at 0–5 lb/ac gave good initial desiccation but regeneration was extremely rapid and repeated sprays of 0–25 lb/ac were required for a long period of suppression. Amitrole‐T at 15 lb/ac was very slow to act but gave complete kill after 10 weeks. DMA at 8–12 lb/ac gave marked suppression, but regeneration rapidly developed after 8 weeks. Mixtures of either amitrole‐T or DMA with paraquat gave less than the expected additive effects of the components, indicating an antagonistic action. Sub‐lethal rates of amitrole‐T or DMA applied to regenerating shoots after paraquat treatment gave results inferior to those from higher rates of the herbicides alone.

When paraquat was applied 2 weeks after an initial sub‐lethal dose (0.375 lb/ac) of amitrole‐T, desiccation was rapid and complete eradication was achieved; this did not occur when a low rate of DMA was used as the first spray. In terms of both speed of kill and final effect, a split application of a low rate of amitrole‐T followed by paraquat was the most effective treatment. A possible explanation of the apparent synergism between amitrole‐T and paraquat applied in this way is advanced and suggestions for further work outlined.

Une méthode améliorée pour la lutte centre Paspalum conjugatum avoc l'amitrole‐T et le paraquat
THE SPEED OF ATTAINMENT OF SORPTION EQUILIBRIA IN SOME SYSTEMS INVOLVING HERBICIDES
Authors: HANCE R. J.
Published: July 2006

Summary. Measurements were made of the time taken for equilibrium to be established during adsorption and desorption under aqueous slurry conditions using monuron, linuron, atrazine and chlorpropham with a variety of adsorbents. An appreciable time was taken for equilibria to be established in adsorption processes, although with one exception, this period was 24 hr or less. Desorption processes were generally rather slower and in seven cases out of eighteen equilibrium was apparently not established in 72 hr. However, in all but two cases it seemed likely that the sorption process was reversible or nearly so.

Possible explanations for differences of equilibrium times are discussed together with implications the results might have on the interpretation of leaching phenomena.

Vitesse à laquelle est atteint I'équilibre d'adsorption et de désorption dans certains systèmes impliquant des herbicides
THE INFLUENCE OF SIMAZINE ON SHOOT AND ROOT GROWTH OF APPLES AND PLUMS
Authors: DVORCÅK J.
Published: July 2006

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.
EFFECT OF PARAQUAT ON MICROBIAL ACTIVITIES IN SOILS*
Authors: TU C. M. , BOLLEN W. B.
Published: July 2006

Summary. When paraquat was added to four different soils, nitrification was not appreciably affected but ammonification of soil organic‐matter nitrogen was slightly retarded. Carbon dioxide evolution as well as oxygen consumption was used as an index of metabolic activity of soil micro‐organisms and paraquat had a stimulatory effect at higher concentrations. Oxidation of added sulphur was slightly depressed. Paraquat decreased both the total mould and bacterial populations in Chehalis silt loam. After 30 days incubation the percentages of Streptomyces and Penicillia were markedly increased by most treatments but were little affected in Chehalis silt clay and Woodburn soils. Except for the temporary suppression of nitrification, paraquat had no significant influence on general microbial activities of importance to soil fertility. Some bimodal effects or toxicity inversions were observed with intermediate concentrations.

Effet du paraquat sur les activités microbiennes dans les sols
RATE OF DETOXIFICATION OF 4‐AMINO‐3,5,6‐TRICHLOROPICOLINIC ACID IN SOIL
Authors: HAMAKER J. W. , YOUNGSON C. R. , GORING C. A. I.
Published: July 2006

Summary. 4‐Aniino‐3,5,6‐trichloropicolinic acid was incubated at 70° F in thirteen different soils for periods of up to 2 years at a concentration range of 0–023–24 ppm. Losses varied from complete to non‐measurable by the bioassay technique employed. The percentage decomposed was generally greater for lower initial concentrations. The results were mathematically analysed in terms of zero‐order, half‐order, first‐order and Michaclis‐Menten kinetics. Half‐order and Mirhaelis‐Menten were found to be the kinetic expressions that most satisfactorily described the detoxification of the herbicide in soil.

Taux de deloxification de l'acide 4‐amino‐3,5,6‐trichloropicolinique dans le sol