bluuebunny/crossref_metadata_2025 huggingface dataset:
Factorial kriging analysis: a useful tool for exploring the structure of multivariate spatial soil information
Authors: GOOVAERTS P.
Published: July 2006

Most studies of relations between soil properties fail to take account of their regionalized nature because of the lack of appropriate methods. This paper describes a geostatistical technique, factorial kriging analysis, that bridges the gap between classical multivariate analysis and a univariate geostatistical approach. The basic feature of the method is the fitting of a linear model of coregionalization, i.e. all experimental simple and cross‐variograms are modelled with a linear combination of basic variogram functions. A particular variance‐covariance matrix, the coregionalization matrix, can then be associated with each spatial scale defined by the range of the basic variogram function. Each coregionalization matrix describes relationships between variables at a given spatial scale. A principal component analysis of these matrices produces a set of components, the regionalized factors, that reflect the main features of the multivariate information for each spatial scale and whose scores are estimated by cokriging.

The technique is described and illustrated with three case studies based on a simulated data set and soil survey data. The results are compared with those of the principal component analysis of the variance‐covariance matrix and the variogram matrices.
Measuring phosphorus fluxes through the root zone of a layered sandy soil: comparisons between lysimeter and suction cell solution
Authors: MAGID J. , CHRISTENSEN N. , NIELSEN H.
Published: July 2006

Chemical and physical processes govern the extent to which phosphorus dissolved from the plough layer is retained by or leached from the subsoil. The adsorption capacity of deeper layers, the velocity of solution flux and the amount of soil volume in contact with the leaching soil solution are important determining factors.

Soil solution from 90‐cm depth of a layered sandy soil, sampled over a 3‐year period with teflon suction cells, was systematically lower in P content than soil solution sampled with free drainage lysimeters from the same depth. On average 4.6 times as much inorganic P and twice as much organic P was found in lysimeter solutions.

Determination of apparent equilibrium solution concentrations of phosphate was performed by means of a series of batch experiments with soil and soil solution of varying initial P content. The results indicated that the suction‐cell solution was close to equilibrium with soil from the 90‐cm layer.

Rhodamine dye was applied, and flow paths of soil solution observed. Preferential flow was initiated from layers of finer texture overlying layers of coarser texture.

On the basis of these observations it is concluded that suction cells give the best representation of stagnant soil solution, whereas lysimeters give a better representation of mobile soil solution.
The Burns leaching equation
Authors: SCOTTER D. R. , WHITE R. E. , DYSON J. S.
Published: July 2006

The simplicity and utility of Burns' leaching equation make it worthy of study. The equation may be written as
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where X is the fraction of initially surface‐resident fertilizer leached below depth z by net rainfall I, in soil with a volumetric water content at ‘field capacity’ of θ. The equation is analysed using transfer functions. The analysis shows that Burns' equation is consistent with an ‘independent flow tube’ soil leaching model, rather than the soil solution being well‐mixed at each soil depth as Burns suggested. The flux and resident soil solution soil concentration profiles are shown to be quite different. An alternative definition of θ is suggested. The behaviour of ‘a Burns soil’ for different initial and boundary conditions is discussed.
Comparisons of methods for measuring the leaching of mineral nitrogen from arable land
Authors: WEBSTER C. P. , SHEPHERD M. A. , GOULDING K. W. T. , LORD E.
Published: July 2006

Comparisons were made between 1988 and 1991 to evaluate three methods of estimating the leaching of mineral nitrogen (N) from unstructured freely draining sandy loam and loamy sand soils. The studies compared the drainage patterns and quantities of N (almost exclusively nitrate) leached from monolith lysimeters with those estimated from ceramic suction cups and soil core extracts. The latter two methods gave direct measurements of the mineral N concentrations in drainage, but required an estimate of the drainage volume calculated from meteorological observations and evapotranspiration equations to give total N leached. A bromide tracer was also used to confirm conclusions from nitrate leaching studies. There was a delay in the onset of drainage from free draining lysimeters because they lack the subsoil matric potential of field soils. However, total annual drainage measured by lysimeters or calculated from meteorological observations was similar, providing that return to field capacity was correctly identified in the field soil. During the first year there were discrepancies between methods which were attributed to soil disturbance during lysimeter and/or ceramic cup installation. In the second and third years of the experiment, estimates of N leaching losses using the lysimeters and ceramic cups were in good agreement. Nitrate concentrations in soil solution at a depth of 130 cm measured from soil core extracts were smaller than found by the other methods during the second year and the peak concentrations were significantly different (P<0.05). However, total overwinter N leached was not significantly different. Thus, while lysimeters and cups can be used to quantify leaching losses on unstructured, free draining soils if used correctly, the use of soil core extracts is questionable.
Cation exchange capacities of organo‐mineral particle‐size fractions in soils from long‐term experiments
Authors: LEINWEBER P. , REUTER G. , BROZIO K.
Published: July 2006

Soils with and without organic manuring from 10 long‐term manurial experiments in East Germany were fractionated into organo‐mineral particle‐size separates by ultrasonic disaggregation and sedimentation/decantation. The cation exchange capacities (CECs) buffered at pH 8.1 were determined for the size fractions fine+medium clay, coarse clay, fine, medium and coarse silt, sand, and for the total soil samples.

In the samples from nine field experiments the CECs decreased with increased equivalent diameters (fine+medium clay: 489–8 13 mmolc kg−1, coarse clay: 367–749 mmolc kg−1, fine silt: 202–587 mmolc kg−1. medium silt: 63–345 mmolc kg−1, coarse silt: 12–128 mmolc kg−1 and sand: 10–156 mmolc kg−1. The CECs varied with genetic soil type, mineralogical composition of the <6.3‐μm particles, and the C and N contents of the size fractions.

In a pot experiment examining the role of various organic materials in the early stages of soil formation, the clay‐size fractions had the largest CECs (85–392 mmolc kg−1), followed by the medium‐silt (1 9‐222 mmolc kg−1) and fine‐silt fractions (23–192 mmolc kg−1). The effect of organic amendments on CEC was in general: compost>fresh farmyard manure = straw + mineral fertilizer = mineral fertilizer.
Complexometric gel permeation chromatography of soluble humic substances using Sephadex G‐25
Authors: KUITERS A. T. , MULDER W.
Published: July 2006

Sephadex G‐25 was used with 0.01 m sodium acetate containing a concentration of 3×10−5m Cu(II) as eluent to establish the molecular‐size distribution (MSD) and the Cu complexation of molecular‐weight fractions of organic solutes. The appropriateness of this modified gel permeation method for complexometric measurements on soluble humic Substances was investigated employing various types of soil solutions.

The presence of Cu in the eluent had an effect on the MSD obtained by elimination of electrostatic repulsion between gel and solutes. No evidence was found that the presence of Cu in the chromatographic system induced aggregation of the organic substances. The Cu‐binding capacity of the samples as obtained with this gel permeation method was found to increase linearly over a wide sample concentration range varying from 40–2000 mg C dm−3. No interference was observed between the Cu‐complexation by exclusion and inclusion peaks in the chromatograms. The analyses revealed that the fraction apparently low in molecular weight makes a large contribution to the complexation potential of forest soil solutions.
Sulphur cycling in New Zealand hill country pastures. II. The fate of fertilizer sulphur
Authors: SAKADEVAN K. , MACKAY A. D. , HEDLEY M. J.
Published: July 2006

The fate of fertilizer sulphur (S) applied as single superphosphate (SSP) to grazed pasture was examined in a field experiment for a period of 18 months using 35S‐labelled SSP. Four sites were selected on the basis of contrasting fertilizer history and land slope. The fertilizer histories since 1981 for the sites were 125 (LF) and 375 (HF) kg ha‐1 a‐1 SSP and the slope gradients were low (LS, 0‐12°) and medium (MS, 13–26°).

The amount of fertilizer S taken up by pasture as a fraction of total applied was greater at the LF (12%) than the HF (6%) site, suggesting that pasture at the LF site depended more on fertilizer than pasture at the HF site. At the LF site, fertilizer application did not significantly increase leaching losses of S (13 and 8.6 kg S ha‐1 for fertilized and unfertilized plots, respectively). At the HF site, fertilizer application significantly increased leaching losses of S (38 and 21 kg S ha‐1 for fertilized and unfertilized plots, respectively). The amount of fertilizer S lost by leaching as a fraction of total applied was greater at the HF (20%) than the LF site (7.6%). Most fertilizer S remained as soil organic matter. Plant uptake and leaching losses of fertilizer S were greater in the first year after application. The amount of N lost by leaching was very small in terms of N cycled through soil‐plant system (1 to 6 kg N ha‐1). The majority (> 80%) of the S and N taken up by pasture and lost by leaching was derived from the mineralization of soil organic matter and not from freshly applied fertilizer.
Phosphate sorption by natural hematites
Authors: TORRENT J. , SCHWERTMANN U. , BARRÓN V.
Published: July 2006

Iron (hydr)oxides are active phosphate sorbents in soils and sediments, but no information exists on phosphate (P) sorption by natural hematites. In this study, we characterized the chemical, mineralogical and P‐sorption properties of 14 hematite‐rich natural materials of different origins. Phosphate sorption was described by a modified Freundlich equation including a time term. Phosphate sorbed at 1d at an equilibrium concentration of 1 mg P dm−3 ranged widely (0.2–1.7 μmol m−2). After 1 d, hematites showed a marked slow sorption. At 75 d, and an equilibrium concentration of 6mg P dm−3, the total amount of P sorbed ranged between 0.8 and 4.1 μmol mp−2. Phosphate‐sorption capacity was influenced by the morphology of the coherently scattering domains: the shorter the domains in the crystallographic c relative to the a direction, the lower the P‐sorption capacity. This has been observed by other authors in synthetic hematites and agrees with the idea that the prismatic faces, which have singly co‐ordinated Fe‐OH groups, are more active in P‐sorption than other faces. The average P sorption capacity of hematites was similar to that of natural goethites (2.6 μmol P m−2) but, in contrast to these, variability among samples was high. In comparison with goethites, hematites show slower sorption and lower affinity for phosphate.
Scale‐dependent correlation between topsoil copper and cobalt concentrations in Scotland
Authors: GOOVAERTS P. , WEBSTER R.
Published: July 2006

The soil of south‐east Scotland is locally deficient in copper and cobalt. Measurements from nearly 3000 fields for which the soil association is known were analysed to study the coregionalization of the two elements and to assess the influence of parent material on the metals' concentrations. The experimental auto‐ and cross‐variograms revealed distinct local (1.5 km) and regional (20 km) scales of spatial variation. A combination of indicator variograms of the soil associations had the same spatial structures, suggesting that parent material influences the concentrations of the metals.

The coregionalization between copper and cobalt was modelled as a linear combination of three spatial structures. The resulting structural correlation coefficients showed the two elements to be fairly strongly positively correlated at the regional scale. Kriging allowed determination and mapping of each spatial component; these maps were then compared with the spatial distribution of soil associations in the region. An analysis of variance was performed before and after filtering out the nugget and short‐range spatial components. Classification by soil association (parent material) accounted for a large proportion of the variance at the regional scale, suggesting that the parent material contributes substantially more to the trace element content of the soil than had been thought earlier.
Determination of DTNB‐reactive sulphhydryl groups in soil humic acids: their enrichment in humic acids from volcanic acid soils
Authors: TAKAMATSU T.
Published: July 2006

Thirteen acid soils were collected from typical volcanic regions in Japan (S content: 0.9–4.1, mean = 2.2g kg−1; pH (H2O): 2.81–3.93, mean = 3.33), as well as nine reference soils (S: 0.6–1.7, mean= 1.1 gkg−1; pH(H2O): 4.10–4.74, mean = 4.47). Humic acids were extracted from the soils separately with 0.1 M NaOH and precipitated by acidification (pH = 2, HCl). After purification, the humic acids were subjected to colorimetric analysis using a DTNB reagent [5,5′‐dithiobis(2–nitrobenzoic acid] for the active ‐SH group. Since humic acids have significant absorption at 4I2 nm, the coloured compound (5–mercapto‐2–nitrobenzoic acid) was separated from the humic acids by ultrafiltration or solvent extraction prior to the colorimetric measurement. Humic acids also caused discoloration of the coloured compound when they coexisted in the reaction solutions. Thus, the reproducible determination of ‐SH was accomplished by employing a standard addition technique (‐SH standard: cysteine). Although ‐SH contents obtained by the ultrafiltration method were considerably higher than those by the solvent‐extraction method, probably due to the denaturation of humic acids by the higher buffer concentration used in the ultrafiltration method, they correlated well with each other. The humic acids from acid soils contained apparently higher concentrations of ‐SH (120–510, mean = 270mg S kg−1 by the ultrafiltration method; 8–110, mean = 38mg S kg−1 by the solvent‐extraction method) compared to those from reference soils [20–260, mean = 90mg S kg−1 by the former; not detectable (<5)‐34, mean = 11 mg S kg−1 by the latter]. This ‐SH enrichment in the humic acids from acid soils may result from the degradation and subsequent humification of S‐rich debris of plants and micro‐organisms and/or direct incorporation of volcanic acid gas (H2S) into the humic acids.
Physical and chemical properties of a sandy loam receiving animal manure, mineral fertilizer or no fertilizer for 90 years
Authors: SCHJØNNING P. , CHRISTENSEN B.T. , CARSTENSEN B.
Published: July 2006

Ninety years after the start of the Askov long‐term fertilization experiment on sandy loam, bulk soil was taken from the 0–20 cm and 30–35 cm depths of unfertilized (UNF), animal‐manure (FYM) treated and mineral‐fertilized (NPK) plots and analysed for textural composition, carbon content, pH, CEC, particle density and plasticity limits. Undisturbed soil cores (100 cm3) from the 8–12 cm layer were brought to six different matric potentials and subjected to confined uniaxial compression, drop‐cone penetration and annulus shear tests. Water‐retention curves based on seven matric potentials were produced for undisturbed cores from the 8–12 and 30–35 cm layers. In the field, in situ shear strength of plough‐layer soil was determined by a vane shear tester and a torsional shear box.

FYM and NPK treatments increased the soil organic carbon content by 23 and 11% of the amount in UNF, respectively. Corresponding increases observed in CEC were 17 and 11%. The water content at the lower and upper plastic limits both decreased from FYM to NPK to UNF. Soil bulk density in the 0‐20 cm layer was reduced in FYM and NPK treatments relative to UNF, whereas the volume of soil pores larger than 30 μm was unaffected by past fertilization.

Soil receiving animal manure showed the greatest soil strength when exposed to annulus shear, drop‐cone penetration and confined uniaxial compression tests, Shear strength measurements indicated that the UNF sandy loam soil reacted like a sand, the increase in soil strength upon drying primarily being due to increased internal friction. In contrast, soil from FYM and NPK treatments showed reactions typical of a loamy soil, the increase in soil strength during drying being caused by increased cohesion in the soil matrix. The field tests employed were unable to detect the management‐induced differences in soil physical parameters found in the laboratory tests.

This study shows that physical soil properties related to conditions for tillage and traffic, to crop development and erosion are significantly influenced by differences in soil organic matter levels resulting from contrasting methods of fertilizer management. Exhausting a loamy soil by long‐term lack of fertilizer application severely affects the physical properties of the soil.
Slaking characteristics of some Australian and British soils
Authors: CHAN K.Y. , MULLINS C.E.
Published: July 2006

Aggregates (9.5–12.7 mm) from ten soils were equilibrated at a range of matric suctions (Ψa) between 1 kPa and 100 MPa before immersion in water or wetting on a porous plate at zero suction. The soils were from cultivated and grassland sites and included hardsetting and non‐hardsetting Australian and British soils as well as a Vertisol. The initial rate of wetting of each aggregate, and the composition and size distribution of the slaked fragments were measured. There was a significant inverse linear relation between the amount of slaking produced by plate wetting air‐dry soil (Ψa=100 MPa) and its organic carbon content (r= 0.82***). The three cultivated hardsetting soils shared several common features. Their slaking was the most pronounced after plate wetting and occurred at the smallest Ψa(10 kPa). Their slaking also increased linearly with rate of wetting and the particle‐size distribution of their slaked fragments varied significantly and considerably with Ψa. This last observation demonstrates that it is not always helpful to call the fragments produced by slaking, microaggregates.

Possible explanations for our results and their agricultural implications are discussed.
The effects of soil structure on protozoa in a clay‐loam soil
Authors: GRIFFITHS R.S. , YOUNG I.M.
Published: July 2006

Physical disruption of a clay‐loam soil by slaking, grinding and compaction was used to determine the specific effects of soil structure on soil protozoa. Individual air‐dry aggregates (1–2 cm diameter) were wetted slowly, or had their structure disrupted by slaking or grinding. They were then moistened with nutrient solution and incubated, at a matric potential of −10 kPa. The nutrient solution had to supply at least 400 μg C g−1 dry soil before protozoan populations increased measurably. Numbers of ciliate protozoa were enhanced by grinding, regardless of the amount of nutrient added. The moisture content and, therefore, the final nutrient concentration of the disrupted aggregates, changed markedly and could account for the observed increase in protozoan biomass from slowly wet to slaked to ground aggregates. There were no differences in protozoan biomass when the applied nutrient concentration was adjusted so that all treatments contained the same amount of nutrient. Soil cores were prepared from sieved (2–4 mm diameter), ground and ground/compacted soil. Thin sections revealed that the pore space accessible to protozoa decreased in these three treatments from 24% to 13% to 9%, respectively. Protozoan biomass was unaffected by grinding but showed a greater than 30‐fold decrease following compaction that could not be accounted for solely by the reduced pore space. Grinding and compacting could have favoured anaerobic conditions in the core which would have reduced protozoan activity. Soil structure had no measurable direct effect on protozoan populations, but it had a much greater indirect effect through its influence on moisture content and aeration status.
Quantitative determination of plant opal content in soils, using a combined method of heavy liquid separation and alkali dissolution
Authors: HERBAUTS J. , DEHALU F.‐A. , GRUBER W.
Published: July 2006

The aim of this study was to improve the quantitative determination of the plant opal content (i.e. phytoliths) in soils.

The proposed method is based on: (i) the separation of plant opal from the silt and sand fractions of the soil, using heavy liquid flotation (aqueous solution of ZnBr2, density = 1.92 g cm−3); (ii) the subsequent determination of alkali‐soluble silicon by atomic absorption spectrometry. Extraction and analytical procedures were tested on a broad sample of temperate and tropical soils with very different phytolith contents.

Our investigations lead to the following conclusions: (i) a selective dissolution of opal in alkaline solutions (e.g. hot 0.5 m NaOH as proposed by Jones, 1969) is inaccurate so that a sink‐float method must be used before any dissolution procedure; (ii) to dissolve opal completely, a 0.5 M NaOH dissolution treatment at 150°C can be easily and successfully carried out in steel PTFE‐lined pressure vessels; (iii) the reproducibility of the determination is satisfactory for a step‐by‐step procedure (mean coefficient of variation = 13.4%).

The comparison of this new method of quantitative assessment of soil opal with two other methods (gravimetric and phytolith‐counting methods), shows very highly significant correlations (P<0.001). Therefore, this procedure is a useful tool in studies connected with pedological and environmental history.
Differences between soil solutions obtained from rhizosphere and non‐rhizosphere soils by water displacement and soil centrifugation
Authors: LORENZ S.E. , HAMON R.E. , McGRATH S.P.
Published: July 2006

Soil solution was obtained from potted rhizosphere or non‐rhizosphere soils by water displacement or soil centrifugation. The pH of the displaced solutions was lower than that of bulk soils when solutions were obtained from non‐rhizosphere soil, although it increased as plants grew. This increase probably reflected true changes in rhizosphere pH, generated by the uptake by plants of N03‐N. In contrast, the pH of soil centrifugates was usually close to that of the bulk soils, implying that buffering by colloids had occurred during sampling. Concentrations of elements in solutions from non‐rhizosphere soil were similar for both methods when soils were incubated at ambient pCO2. However, when non‐rhizosphere soils were incubated at elevated pCO2, displacement solutions had lower pH values, and much larger concentrations of elements, compared to soil centrifugates.

Comparison of mass flow of elements versus actual plant uptake showed that Ca and Mg accumulated, while K, Zn and Cd were depleted from the rhizosphere. Displacement solutions showed this accumulation or depletion of the elements more clearly than soil centrifugates. These differences were attributed to the fact that, at constant soil moisture, the rhizosphere developed mainly in larger pores, which were sampled by displacement. With centrifugation, a mixture of pore sizes was sampled, so that rhizosphere solution was only obtained when all of the soil had become rhizosphere.

Soil centrifugates obtained after 22 days of growth also contained higher concentrations of organic carbon than displacement solutions, indicating contamination due to the disruption of roots and/or micro‐organisms. We conclude that water displacement is suitable for sampling solution from light to medium textured rhizosphere or non‐rhizosphere soils and that soil centrifugation is only of limited suitability.
Lysimeter study of the fate of nitrogen in animal urine returns to irrigated pasture
Authors: FRASE P.M. , CAMERON K.C. , SHERLOCK R.R.
Published: July 2006

The fate of 15N‐labelled synthetic urine (50 g N m−2) applied to an irrigated pasture soil was studied using large undisturbed monolith lysimeters (800 mm diameter × 1200 mm deep). Over a period of 1 year, the pasture plants recovered the largest fraction of the applied 15N (43%) and approximately 20% of the applied 15N still remained in the soil, the majority of which was found in the topsoil (0–20 cm). Although the experiment was conducted under relatively intense rainfall and irrigation conditions, only 8% of the applied 15N was found to have leached below 1200 mm after 1 year. During this time, the average peak concentration of nitrate in the leachate reached 42 mg NO3−‐N dm−3. The amount of nitrogen (N) lost by the process of denitrification was calculated as 28% of the applied 15N. This large loss of N to the atmosphere was attributed to the wet soil conditions which prevailed.
Land‐use effects on the composition of organic matter in particle‐size separates of soil: I. Lignin and carbohydrate signature
Authors: GUGGENBERGER G. , CHRISTENSEN B.T. , ZECH W.
Published: July 2006

Soil from Eutrochrept A horizons under long‐term spruce forest (Sf), mixed deciduous forest (Df), permanent grassland (Gp) and arable rotation (Ar) was fractionated according to particle size and analysed for contents of C, N, lignin‐derived phenols and carbohydrates.

Whole soil from Sf, Df, Gp and Ar contained 84, 59, 73 and 25 g C kg−1 soil, respectively. For all sites, the C content declined and C/N ratio increased in the order: clay (<2 μm), silt (2–20 μm), sand (20–2000 μm). Clay and silt were significantly lower in C in Ar than in Sf, Df and Gp, C associated with sand being substantially lower under arable rotation.

The yield of lignin‐derived phenols decreased and carboxyl functionality and methoxyl demethylation of lignin derivatives increased with decreasing particle size, indicating a progressive lignin alteration. Whole soil from Sf and Gp was substantially higher in vanillyl (V), syringyl (S) and cinnamyl (C) units (VSC) than soil from Df and Ar. Compared to whole soil, clay was depleted and sand enriched in VSC. Only sand appeared to be affected significantly by land use. Sand from Ar and Df was more enriched in VSC than sand from Gp and Sf.

Whole soil carbohydrates decreased in the order: Gp>Ar>Df>Sf. Sand‐ and clay‐sized separates were enriched in carbohydrates compared to silt. Carbohydrates in sand were mainly of plant origin whereas microbially‐derived sugars accounted for a larger proportion in the clay. Compared to Sf, Df and Gp, clay from Ar was enriched and sand depleted in microbial sugars.

Lignin and carbohydrate distribution patterns indicate that organic matter was in a more advanced stage of decomposition in the sand separates from forest than from agricultural A horizons. The forest soils also show a higher degree of oxidative changes in lignin associated with clay. In contrast, differences between silt from the four A horizons were small.
The role of tillage in soil redistribution on hillslopes
Authors: GOVERS G. , VANDAELE K. , DESMET P. , POESEN J. , BUNTE K.
Published: July 2006

Soil tillage is usually considered as a process having only an indirect influence on soil erosion. This paper describes the results of field experiments carried out with a mouldboard and a chisel plough showing that an important net downslope soil movement can be associated with soil tillage. Available experimental evidence suggests that the soil redistribution by tillage can be described by a diffusion‐type equation, which allows the intensity of the process to be characterized by a single number, which may be called the diffusion constant. The experimentally determined values of the diffusion constant vary between 100 and 400 kg m−1 a−1. This implies that erosion and sedimentation rates associated with tillage may be more important than those associated with water erosion on much of the hilly arable land in western Europe. A comparison of recent hillslope evolution with model simulation results corroborates this conclusion. Therefore, tillage should be considered as a soil degradation process per se, rather than a process which makes the soil more sensitive to erosion.
A STUDY OF THE COMPETITION BETWEEN BARLEY AND OATS AS INFLUENCED BY BARLEY SEEDRATE, NITROGEN LEVEL AND BARBAN TREATMENT
Authors: PFEIFFER R. K. , HOLMES H. M.
Published: July 2006

Summary. The object of the work described in this paper was to obtain information on the relationship between the effects of crop competition and barban treatment on oats growing in another cereal. The work was carried out on barley cross‐drilled with cultivated oats. Variation in crop competition was obtained by using different barley seed‐rates and nitrogen levels. Increasing the seedrate of barley without applying barban resulted in a reduction of the initial oat population. This reduction applied to weight of individual shoots, number of shoots and panicles per unit area and number of spikelets per panicle. The application of barban at selective rates gave an independent reduction of oats of the order of 80%. This value proved almost constant at each seedrate of barley. Crop competition and barban accordingly seem to art independently and their effects appear to be simply additive. The barley fresh weights per unit area increased substantially when oat competition was reduced by barban treatment. The highest increase occurred on the plots with the lowest barley seedrate in spite of the fact that these plots still appeared infested with oats at harvest time. Nitrogen application stimulated the growth of barley and oats to a similar degree and did not in consequence lead to a selective suppression of oats.

Etude de l'influence de la densité du Semis, du taux de fertilisation azotée et du traitement au barbane, sur la concurrence entre une Orge et une Avoine
UNTERSUCHUNGEN ÜBER DIE GEGENSEITIGE BEEINFLUSSUNG VON KULTURPFLANZEN UND UNKRÄUTERN IN WASSERKULTUR
Authors: RADEMACHER B. , KOLB F. , BÖRNER H.
Published: July 2006

Zusammenfassung. Es wurden Untersuchungen über die gegenseitige Beeinflussung von Kulurpflanzen und Uukräutern in Wasserkultur durchgeführt. Hierbei wurde eine Methodik verwendet, die es gestattete, die Ursachen einer gegenseitigen Beeinflussung auf den Wurzelbereich zu beschränken und gleichzeitig die Wirkung einiger Konkurrenz‐faktoren (z.B. Licht, Raum) ausz.uschalten. Von insgesamt 57 untersuchten Pflanzen‐kombinationen (Ergebnisse s. Tab. 1‐4) zeigten etwa ein Drittel keine gesicherten Symptome einer gegenseitigen Beeinflussung. Bei allen anderen Versuchen war ein mehr oder weniger ausgeprágter Hemm‐ bzw. Förderungseffekt festzustellen. Die Ursache dieser Erscheinung konnte in einigen Fallen als Náhrstoffkonkurrenz (Nr. 5, 6, 7, 23, 44d. Tabellen) erkannt werden, wáhrend bei anderen Versuchen (Nr. 12, 13, 15, 18, 23, 45, 46) mit der Beteiligung allelopathischer Faktoren (Abgabe organischer Verbin‐dungen aus lebenden und abgestorbenen Wurzelzellen) gerechnet werden muss. Die Wachstumshemmung bzw.‐ förderung war in einigen Fällen dann besonders deutlich (Nr. 46, 47, 51), wenn dem einen Partner durch Vorkultur ein gewisser Entwicklungs‐vorsprung gegeben wurde. Obwohl einige der vorliegenden Ergebnisse mit Befunden aus der Praxis gut übereinstimmen (Nr. 12, 13, 18), kann man aus naheliegenden Gründen (Abbau von Wurzelstoffen durch Mikroorganismen, Absorptionsverhältnisse im Boden usw.) die in Wasserkultur erzielten Resultate nicht unmittelbar auf die natürlichen Verhältnisse übertragen, Um jedoch den möglichen Ursachen einer gegenseitigen Beeinflussung von Kulturpflanzen und Unkräutern überhaupt einmal náher zu kommen, ist cine getrennte Untersuchung der in Frage kommenden Faktoren unumgánglich.

Experiments on the interaction between cultivated plants and weeds in water‐culture
CONTROLLED INTERFERENCE WITH NATURAL POPULATIONS OF PLANTAGO LANCEOLATA, P. MAJOR AND P. MEDIA
Authors: SAGAR G. R. , HARPER JOHN L.
Published: July 2006

Summary. An experiment was made to determine the effect of the removal of grasses on the behaviour of populations of Plantago lanceolata, P. media and P. major in three grassland habitats. Treatments included the addition of seed of all three species to the existing vegetation. The grasses were removed by treatment with 2,2‐dichloropropionic acid (dalapon), a herbicide selective against the Gramineae. The chemical appears to be slightly toxic to the Plantago species at the dose used (12 Ib/ac a.e.). The removal of the grasses was followed by a marked increase in the plantain populations shown both in counts of the numbers of plants and seedlings and in increased seed output per unit area. Deliberate sowing of seed into the habitats in autumn resulted in increased numbers of seedlings in the following spring, particularly in those plots where the grasses had been removed. Species of Plantago not occurring naturally in the communities were frequently established by sowing seed, if the grasses had been removed, but not otherwise. The overall results of the experiment suggest that in two of the communities the grasses played an important role in determining the presence or absence of particular Plantagn species and also in controlling the size of the existing plantain populations. The experiment is discussed in the wider context of population control in plants.

Tentative de modification de populations naturelles de Plantago lanceolata, P. major et P. media.
UNTERSCHEIDUNG VON UNKRAUTKEIMPFLANZEN DURCH VORHERIGE MARKIERUNG DER SAMEN MIT SCHWEFEL‐35
Authors: RADEMACHER B. , BÖRNER H. , MORGENSTERN W. , RENTSCHLER W.
Published: July 2006

Zusammenfassung. Samen von Sinapis arvensis (Ackerscnf) und Avena fatua (Fiughafer) wurden indirekt liber die Wurzeln in Wasserkultur aufwachsender Pflanzen mil S‐35 markiert. Die spezilische Aktivität der Nährlösung betrug für Sinapis 0,75 μ C.cm−3 und für Avena 1,0 μ C.cm−3. Die Sinapis‐Samen besassen bei der Ernte (0,88 Halbwertzeiten nach der Markierung) einc Aktivitat von 0,11 μC pro Einzelsame und 59,4 μC pro Gramm Samen. Die entsprechenden Werte für Avena waren nach 0,91 HWZ 0,24 μC und 21,2 μC. Die aus den markierten Samen aufwachsenden Keimpflanzen konnten ohne vorherige Präparation unter einem dünuwandigen Endfensterzählrohr von nicht markierten Keimpflanzen eindeutig unterschieden werden. Dabei betrug die Aktivität der Keimblätter von Sinapis nach einer HWZ ca. 1000 Imp./min., diejenige von Avena noch nach mehr als 4 HWZ 60‐80 Imp./min. Em sicherer Nachweis (doppelter Nulleffekt) von S‐35 in den unpräparierlen Keimblättern ist bei Sinapis für einen Zeitraum von 5 HWZ, für Avena von 4 HWZ nach der Markierung möglich. Die beschriebene Markierungs‐methode eignet sich daher auch für Samen mit längerer Keimruhe, wie am Beispiel von A. fatua gezeigt werden konnte. Um die Brauchbarkeit der markierungsmethode auch unter Feldbedingungen prüfen zu können, wurden im Herbst 1960 auf 4 Parzellen von je 2 m2 Grösse eincs abgeernteten Gerstenfeldes jeweils 2000 markierte Samcn von Sinapis arvensis, die kurz vorher im Gewächshaus zur Reife gelangt waren, eingesät. Die einzelnen Parzellen wurden anschliessend einer verschiedenen Bodenbearbeitung unlerworfen und danach die aufgehenden markierten Keimpflanzen zu verschiedenen Zeitpunkten ausgezählt. Dabei ergaben sich folgende Keimprozente: Unbearbeitete Parzelle: 11,8%; Schälpflug: 4,7%; schwere Egge: 48,7%; Scheibenegge: 31,1%. Auch bei diesen Versuchen war es mit Sicherheit möglich, eine Unterscheidung der aus unmarkierten und markierten Samen aufwachsenden Keimpflanzen vorzunehmen.
THE CONTROL OF WEEDS IN SPRING CEREALS WITH MCPA, MCPB AND 2,4‐DB
Authors: EVANS S. A.
Published: July 2006

Summary. Eighteen experiments were carried out over a period of 4 years jointly by the National Agricultural Advisory Service and the Agricultural Research Council Unit of Experimental Agronomy to compare the effects of spraying spring cereals with MCPA, MCPB, 2,4‐DB and mixtures of MCPA and MCPB, at two different times. The first applications was made before the cereal crop had reached the five‐leaf stage and when it was judged that most of the weeds had germinated. The second application was after the crop had reached the five‐leaf stage, which is the time normally recommended in Britain for the application of MCPA to spring wheat or spring barley. The earlier applications produced better crop yields and gave a better control of weeds except where conditions for spraying were unsatisfactory or where a considerable number of weeds germinated subsequently. Mild deformity of the ears of the crop occurred in some experiments following early applications of MCPA, otherwise there were no marked differences in the effect on the crop of the different herbicides at the doses used; the dose of MCPA was less than that of the other herbicides. In view of these results and the lower cost of MCPA, it is concluded that MCPA applied early is the most efficient of the treatments tested except where the risk of malformed ears occurring is not acceptable.

Le désherbage dans les céréales de printemps avec le MCPA, le MCPB, et le 2,4‐DB
HEMMUNG DER HILLREAKTION DURCH HERBIZIDE*
Authors: EXER B.
Published: July 2006

Zusammenfassung. In dieser Arbeit haben wir den Einfluss des Herbizides Simazin auf die Hillreaktion untersucht, wobei DPN (Diphosphopyridinnukleotid) und Janusgrün als Wasserstoffakzeptoren verwendet wurden. Die Hemmung der Hillreaktion durch Simazin ist bei verschiedener Lichitiniensität, sowie bei verschiedenen Chloroplasten‐ und Wasserstoffakzeptorkonzentrationen studiert worden. Die Hemmung der Hillreaktion durch Simazin ist von der eingesetzten DPN‐Menge unabhängig. Durch Erhöhung der Lichtintensität wird die Hemmwirkung von Simazin auf die DPN‐Reduktion abgeschwächt; im gleichen Sinne wirkt auch eine Erhöhung der Chloroplastenkonzentration. Die Bildung von Safranin durch reduktive Spaltung von Janusgrün durch belichtete Chloroplasten ist von der Menge des eingesetzten Janusgrüns abhängig, wobei ein Optimum auftritt. Je höher die Janusgrünkonzentration gewählt wird, um so stärker wird die Hillreaktion durch Simazin gehemmt. Dieser Effekt ist darauf zurückzuführen, dass sowohl Janusgrün, als auch Safranin bei höheren Konzentrationen selbst als Inhibitoren wirken, was mit der DPN‐Methode gezeigt werden konnte. Auf Grund dieser Ergebnisse haben wir die Methodik zur Messung der Hillreaktion mit DPN oder Janusgrün als Wasserstoffakzeptoren soweit ausgearbeitet, dass sie sich zur vergleichenden Messung der Hemmwirkung verschiedener Herbizide eignet. Wird die prozentuale Hemmung der Hillreaktion durch eine Substanz gegen den Antilogarithmus ihrer Konzentration aufgetragen, so erhält man eine Gerade im Bereich zwischen 15 und 90%; die Konzentration für eine 50%ige Hemmung lässt sich somit leicht interpolieren.

Inhibition of the Hill‐reaction by a herbicide
AN ASSEMBLY FOR THE CONTINUOUS RECORDING OF CO2 EXCHANGE AND TRANSPIRATION OF WHOLE PLANTS
Authors: VAN OORSCHOT J. L. P. , BELKSMA M.
Published: July 2006

Summary. Photosynthesis, respiration and transpiration of whole platns are continuously recorded with the assembly described. An infra‐red gas analyser is used for photosynthesis and respiration measurements, while for transpiration data psychrometers are employed, Air and leaf temperatures as well as light intensity are recorded. The assimilation chamber is constructed in such a way that whole platns of various plant species can be investigated under constant conditions of CO2 content of the air and air humidity. Some experiments with simazine and monuron are described.

Un appareil pour enregistrer continuellement l'échange de CO2 et la transpiration des plantes entiéres
THE MOVEMENT OF LABELLED 2,4‐D IN YOUNG BARLEY PLANTS
Authors: VAN DER ZWEEP W.
Published: July 2006

Summary. After the 4‐ or 5‐leaf stage in young barley plants, there is a decrease in the translocation of 2,4‐D from the leaves to the root system. It is shown that there is no relation between this phenomenon and ear initiation, which occurs at this stage of development. Movement of 2,4‐D out of leaves of the tiller in the axils of the 1st and 2nd leaves was also shown to be very small. There is some evidence for a‘block’in the movement of 2,4‐D in established grass plants.

La migration du 2,4‐D marqué dans l'orge
ACTION DE QUELQUES HERBICIDES SUR LA MORPHOGENESE DU RAY‐GRASS D'ITALIE
Authors: LEROUX R. , FAIVRE‐DUPAIGRE R. , LONGCHAMP R.
Published: July 2006

Résumé. Le Ray‐grass d'Italic (Lolium italicum A. Braun.), variété‘Mayenne’, traité au stade du tallage par des produits à basc de 2,4‐D, MCPA et MCPB, présente toute une série de modifications des tiges et des épis, lorsquc ces herbicides soni appliqués à des concentrations de l à 10 kg à l'hectare (exprimées en acidc libre). Les tiges deviennent rameuses par suite d'un tallage aberrant et certains nœuds et entre‐nœuds sont courbes, les courbures des entre‐nœuds étant inverses de celles des nœuds. Les altérations des épis concernent le rachis et les épillets. Le rachis peut être bifurqué ou trifurqué, sinucux, allongé ou raccourci, helicoidal, courbc enfin parce que retenu dans la gainc de la dernière feuille. Les épillets anormaux touchent le rachis par une face, sont attachés au même niveau ou au même point, sont encore pédicellés, composés, réduits, voire stériles. Ces différents types d'anomalies. notés séparément ou simultanément sur la même plante, la même tige, parfois sur le méme épi, sont rapprochés des modifications observées chez d'autres graminées fourragères et des résultats classiques obtenus sur les céréales, á la suite de traitements réalisés avec des désherbants de, nature identique.

Der Einfluss einiger Herbizide auf die morphologische Formbildung von Italienischem Raygras
THE INFLUENCE OF IRRIGATION, FERTILIZING AND MCPA ON THE COMPETITION BETWEEN SPRING CEREALS AND WEEDS
Authors: SUOMELA H. , PAATELA J.
Published: July 2006

Summary. The average air‐dry yield of weeds on fallow plots was about four times as large (2660 kg/ha) as the yield of weeds which developed among spring cereal crops (740 kg/ha). Application of fertilizers increased the number of weeds and their average weight on both irrigated and non‐irrigated plots. Treatment with MCPA reduced the weed yield to 36% on fallow plots and to 26% on weedy cereal plots. It was more effective on fertilized plots than on unfertilized plots, but irrigation made little difference to its effectiveness. The space left by the destroyed weeds was mainly occupied by Agropyron repens. Oats were better able to compete with weeds than were wheat and barley. On unfertilized and non‐irrigated plots spraying with MCPA (1‐26 kg/ha) at the beginning of shooting significantly reduced the yields of weed‐free barley. The yields of sprayed oats and wheat were also below the yields from the unsprayed although the reductions were not significant at the 5% level. However, on a number of fertilized and irrigated plots, both weedy and hand‐weeded, on which the plants had better growing conditions, MCPA resulted in a significant increase in the grain yield of barley and oats.

Influence de l'irrigation, de la fertilisation et du MCPA sur la compétition entre céréales de printemps et mauvaises herbes
FURTHER INVESTIGATIONS INTO THE FIELD USE OF A MIXTURE OF ENDOTHAL AND PROPHAM FOR PRE‐EMERGENCE APPLICATION TO SUGAR BEET
Authors: CALDICOTT J. J. B.
Published: July 2006

Summary. Pre‐emergence applications on a wide range of mineral soil types with a proprietary formulation of an endothal/propham mixture established a relationship between the amounts of coarse sand and clay in a soil and the rate of use of the chemical required for optimum results. The effectiveness of a given dose for any one soil type was found to be dependent on adequate rainfall between time of application and weed emergence. The minimum rainfall required varied with the date of the application. A wide range of seedling weeds was adequately controlled and treated areas which exhibited a good control of weeds at emergence were found to be still weed‐free as long as 14 weeks after treatment.

Etudes sur l'application en pré‐émergence aux betteraves d'un mélange endothal/propham
SOME ASPECTS OF THE USE OF BARBAN FOR WILD OAT CONTROL IN WINTER WHEAT
Authors: HOLMES H. M. , PFEIFFER R. K.
Published: July 2006

Summary. A study of the emergence and development of Avena fatua in winter wheat showed that after the mild winter of 1960/61 autumn‐germinated wild oats constituted a far more serious weed problem than spring‐germinated plants. It was concluded that the application of barban should be timed in relation to these autumn‐germinated plants. As an extension of their work on spring cereals, the authors investigated the effect of barban on the yield ratio of winter wheat and cultivated winter oats grown as a mixture. A reduction in the oats fraction as a result of barban treatment was accompanied by an increase in wheat giving a total yield which was almost the same as untreated. Experimental data are also presented on the occurrence, and significance of an interesting variation in crop tolerance during the winter. No obvious correlation was found between increased crop sensitivity and development stage or temperature. The capacity of the crop to recover was found to be high.

Quelques données sur l'utilisation du barbane dans la lutte contre la folle avoine dans le blé d'hiver
UUBER DEN ZUSAMMENHANG ZWISCHEN KONSTITUTION UND HERBIZIDER WIRKSAMKEIT BEI CYCLOALIPHATISCHEN HARNSTOFFVERBINDUNGEN*
Authors: SCHEUERER G. , FISCHER A.
Published: July 2006

Zusammenfassung. Substituierte N‐Cycloalkylharnstoffverbindungen wurden auf ihre Verwendung zur Bekämpfung unerwünschten Pflanzenwuchses untersucht. Die Herbizidwirksamkeit ist abhängig von der Grösse des Cycloalkylringes und der Art der Ringsubstituenten, sowie von deren Stellung und sterischen Anordnung am Ring. Das Wirkungsoptimum liegt bei 8 Ringkohlenstoffatomen. Die wirksamen Vertreter dieser Klasse eignen sich zur Bekämpfung von Unkrautwuchs in Hackfrucht‐ und Sonderkulturen.

Relationship between the structure and herbicidal properties of N‐cyclo‐alkyl‐urea
THE CONTROL OF WEEDS IN POTATOES BY PREEMERGENCE APPLICATION OF HERBICIDES
Authors: STEPHENS R. J.
Published: July 2006

Summary. Trials in 1959, 1960 and 1961 failed to show significant differences in yield between potatoes (Solanum tuberosum L.) of three varieties receiving from seven to nine separate tractnr cultivations and similar potatoes in which the weeds were well controlled by pre‐emergence applications of a mixture of dinoseb(6.0 lb/ac)*and dalapon (2.5‐5.0 lb/ac), With less effective herbicide treatments. including simazinc and 2,4‐DES, there were significant reductions in yield.

Preliminary taint tests in 1959 on cooked tubers suggested that slight tainting might have been caused by one of the treatments, but tests on potato crisps made from the 1959 and 1960 crops were completely inconclusive. Tubers from all the treatments in the 1959 and 1960 trials sprouted normally in the spring after harvest.

Le désherbage des pommes de terre par des herbicides de pré‐émergence