bluuebunny/crossref_metadata_2025_split huggingface dataset:
CHANGES IN THE PHYSICAL AND CHEMICAL PROPERTIES OF A MINERAL TOPSOIL UNDER THE INFLUENCE OF PEAT DEBRIS
Authors: COYLE E. , COLLINS J. F. 
Published: July 2006

SummaryChanges are reported of particle size distribution, organic carbon and nitrogen values, cation exchange capacity and exchangeable cation populations, and in iron and aluminium patterns as a result of adding varying rates of acid peat debris to a mineral topsoil. Up to 3 cm of peat had beneficial effects on soil chemical and physical properties but 5 to 8 cm was sufficient to cause considerable acidification, release of Fe and other ions from primary minerals and the development of an iron seam (or pan) which contains up to 7 per cent free iron. Greater thickness of peat (up to 30 cm) caused soil reaction to drop to pH 4 or less and produced so much humic acids as to inhibit iron precipitation and to facilitate its removal from the profiles. The effects of soil moisture on the pattern of peat humification in the deeper additions (20–30 cm) are also outlined.
ANALYSIS OF THE POTENTIOMETRIC TITRATION OF NATURAL AND SYNTHETIC POLYCARBOXYLATES
Authors: YOUNG S. D. , BACHE B. W. , WELCH D. , ANDERSON H. A. 
Published: July 2006

SummaryPotentiomctric titrations of a variety of natural and synthetic poly‐COOH's varying in molecular weight and COOH density gave pKm values varying from 3.5 to 5.2. The pattern of carboxylic acid group dissociation is discussed in terms of purely electrostatic assumptions and of COOH group clustering. Synthetic polymaleic acid showed many of the characteristics of both fulvic and humic acids, and therefore seems to be a reasonable representation of an average, hypothetical soil organic matter polycarboxylic acid.
FORMATION OF MICROBIAL BIOMASS DURING THE DECOMPOSITION OF 14C LABELLED RYEGRASS IN SOIL
Authors: CERRI C. C. , JENKINSON D. S. 
Published: July 2006

SummaryRyegrass uniformly labelled with I4C was incubated aerobically at 25°C for 62 days in two contrasting soils, a near‐neutral (pH 6.8) palcudalf from England and a strongly acid (pH 3.6) haplorthox from Brazil. Decomposition of the labelled plant material was faster in the near‐neutral soil throughout the whole of the incubation period. In neither soil did the addition of fresh plant material significantly accelerate the evolution of CO2 from organic matter already in the soil, i.e. there was no priming action.In the near‐neutral soil there was a rapid build up of labelled microbial biomass in the first 6 days, followed by a much slower increase that continued throughout the whole incubation period. After 62 days 22.5% of the labelled C remaining in the near‐neutral soil was in the biomass. The yield coefficient (the fraction of the incoming plant C converted to microbial C) of this stabilized or ‘resting’ biomass was 0.15.Much less labelled microbial biomass was formed in the acid soil than in the near‐neutral soil. By the end of 62 days only 6.2% of the labelled carbon remaining in the acid soil was in the biomass. Biomass C measurements in strongly acid soils must however be treated with caution as the technique used has not yet been adequately validated for such soils.
OPTIMAL INTERPOLATION AND ISARITHMIC MAPPING OF SOIL PROPERTIES. IV SAMPLING STRATEGY
Authors: BURGESS T. M. , WEBSTER R. , McBRATNEY A. B. 
Published: July 2006

SummaryA sampling strategy is presented for soil survey in which an individual soil property is of interest and can be measured. It depends on first determining accurately the semi‐variogram for the property, and this must be done in a prior reconnaissance stage of a survey. Then from the semi‐variogram estimation variances can be found for any combination of block size and sampling density by the methods of kriging. Alternatively for a given block size the sampling density needed to achieve a predetermined precision (maximum estimation variance) can be determined. The strategy is optimal in the sense that the sampling effort is the least possible to achieve the precision desired. An equilateral triangular configuration of sampling points is best where variation is isotropic, but a square grid at the same density is very nearly as good, and will usually be preferred for convenience. Where there is simple anisotropic variation optimal sampling is achieved by choosing a rectangular grid with sides in the same proportion to one another as the slopes of the semi‐variogram in the directions of maximum and minimum variation.
Variation in soil temperature with microrelief and soil depth in a newly planted forest
Authors: BOCOCK K. L. , BAILEY A. D. , HORNUNG M. 
Published: July 2006

SummarySpatial variability in exponential mean soil temperature for a full year in a newly planted forest in northern England was examined using the sucrose inversion method of temperature measurement. The exponential mean temperature decreased significantly with soil depth (P < 0.001). The rate of this decrease varied significantly between different areas of the forest with slightly different soil profiles (0.001 < P < 0.01). Exponential means for 30–50cm depth in the forest and comparable arithmetic means for the nearest meteorological stations were similar. Exponential mean temperatures at 5 cm soil depth were, on average, 1.5° higher in the ridges than in the adjacent flat areas (P < 0.001). The exponential mean for the flat areas was, on average, 0.3° higher to the south‐west of the ridge than to the north‐east (0.001 < P < 0.01). It was also 0.9°C lower than the mean at 5 cm depth in the neighbouring rides (0.001 < P < 0.01).
Distribution of carbon, nitrogen, phosphorus, sulphur, and acidity in two molecular weight fractions of organic matter in soil chronosequences
Authors: GOH K. M. , WILLIAMS MARY R. 
Published: July 2006

SummaryTen different topsoils from three soil chronosequences were pretreated with 0.1 m HCl and 0.1 m HCl: 0.3 m HF, then extracted with neutral 0.1 m Na4P207, followed by 0.5 m NaOH. Pretreatments and extracts were purified and fractionated into two nominal molecular weight (MW) fractions (> 50000 and < 50000) using gel filtration. The distribution between the two MW fractions of total carbon (C), nitrogen (N), phosphorus (P), sulphur (S), total acidity, and carboxyl (COOH) acidity and their ratios relative to C were determined. Organic matter in the > 50000 MW fraction contained lower N, P, S and acidity ratios relative to C than those of the < 50000 MW fraction. The chemical nature ofthe > 50000 MW fraction remained unaffected by soil development or vegetation, whereas that of the < 50000 MW fraction changed with soil age and appeared to be influenced by vegetation. The results strongly suggest that two chemically different extractable fractions of organic matter can be isolated from most soils, represented by the active fraction (< 50000 MW) and the relatively large (> 50000 MW) and less active (passive) fraction. A three‐phase system of organic matter is proposed comprising the two extractable fractions and the non‐extractable component.
Organic matter and water‐stable aggregates in soils
Authors: TISDALL J. M. , OADES J. M. 
Published: July 2006

SummaryThe water‐stability of aggregates in many soils is shown to depend on organic materials. The organic binding agents have been classified into (a) transient, mainly polysaccharides, (b), temporary, roots and fungal hyphae, and (c) persistent, resistant aromatic components associated with polyvalent metal cations, and strongly sorbed polymers. The effectiveness of various binding agents at different stages in the structural organization of aggregates is described and forms the basis of a model which illustrates the architecture of an aggregate. Roots and hyphae stabilize macro‐aggregates, defined as > 250 μm diameter; consequently, macroaggregation is controlled by soil management (i.e. crop rotations), as management influences the growth of plant roots, and the oxidation of organic carbon. The water‐stability of micro‐aggregates depends on the persistent organic binding agents and appears to be a characteristic of the soil, independent of management.
Simplification of a model for ion adsorption on oxide surfaces
Authors: POSNER A. M. , BARROW N. J. 
Published: July 2006

SummaryThe adsorption equation of Bowden et al. (I 977) was modified so that adsorption at a constant pH could be described by three parameters. One of these parameters represents the maximum adsorption. The second is the product of three characteristics. These are the binding constant for the adsorbing ion; the proportion of the adsorbate present as that ion; and the electrostatic potential in the plane of adsorption before adsorption had started. The third parameter indicates the rate at which the electrostatic potential in the plane of adsorption changes as adsorption increases. With these modifications, the adsorption equation may be linearized and graphs used to estimate the parameters. This simplification may be of value either when there is no data for the charge characteristics of the surface, or when there is insufficient computer expertise to fit more complex models.
A qualitative field test for locating zones of anoxic soil
Authors: BATEY T. , CHILDS C. W. 
Published: July 2006

SummaryA field test for ferrous ions, based on the formation of a red complex between Fe2+ and α, α′‐dipyridyl, is shown to be useful in identifying anoxic zones in a cultivated soil. The test can be used in two ways—either a pinch of soil is added to a vial containing reagent or the reagent can be sprayed directly on to a freshly exposed soil surface. The latter way allows the location, size, and pattern of anoxic zones to be observed in situ. Soil in which Fe2+ ions were detected had higher ammoniacal‐N and lower nitrate‐N concentrations than soil which gave a negative reaction to the Fe2+test.
Comparative rates of leaching of chloride, nitrate and tritiated water under field conditions
Authors: CAMERON K. C. , WILD A. 
Published: July 2006

SummaryThe rate of leaching of 36Cl‐, 15NO‐3 and HTO were measured in two experiments under field conditions following the application of irrigation water (40mm and 80 mm) and under winter rainfall (71 mm and 156 mm excess over evaporation). Nitrate and chloride leached at about the same rate, which was on average 23 per cent faster than that of HTO, but with a smaller difference under winter rainfall. It is concluded that although HTO is not an accurate marker for nitrate leaching, ‘bomb’ tritium gives a rough guide to the dating of nitrate pulses in porous rock.
Some observations on the desorption and distribution behaviour of copper with soil components
Authors: McLAREN R. G. , WILLIAMS J. G. , SWIFT R. S. 
Published: July 2006

SummaryThe ability of copper adsorbed by soil components to desorb back into solution was studied by means of experiments using radioactive 64Cu. It was demonstrated that the amounts of copper which can be readily desorbed from soil components are very small.A dialysis equilibration technique was used to examine the distribution of adsorbed copper between individual materials in a multi‐component system. Where only adsorption of copper was involved, the distribution of copper between soil materials was found to agree with predictions based on adsorption studies with individual materials. However, where desorption was involved, as in the experiments on the redistribution of copper between components after an initial adsorption, the results were strongly governed by the poor reversibility of copper adsorption.It is clear that desorption or lack of desorption is very important in affecting plant availability of indigenous or added soil copper and in controlling the distribution of copper added to soils.
The influence of iron oxides on phosphate adsorption by soil
Authors: BORGGAARD O. K. 
Published: July 2006

SummarySoils from Denmark and Tanzania were extracted with ammonium acetate (controls), EDTA to dissolve amorphous iron oxides, and dithionite‐EDTA (DE) to dissolve crystalline iron oxides. The phosphate adsorption capacities of the extracted soils were taken as the maximum quantity of phosphate adsorbed computed from the Langmuir equation. The decreases in the phosphate adsorption capacity following EDTA extraction and DE extraction were attributed to the removal of iron oxides. Close correlations (P<0.001) were found (i) between EDTA‐extractable iron (amorphous iron oxides) and the decrease in phosphate adsorption capacity following EDTA extraction, and (ii) between the difference between DE‐extractable iron and EDTA‐extractable iron (crystalline iron oxides) and the further decrease in phosphate adsorption capacity following DE extraction.The phosphate adsorption capacity, estimated to be approximately 2.5 μmol P m−2, was in good agreement with the capacity of various synthetic iron oxides. The calculated phosphate adsorption capacity of soil iron oxides, obtained from the contents and specific surfaces of amorphous and crystalline iron oxides together with the phosphate adsorption capacity per m2 for synthetic iron oxides, compared favourably with the measured phosphate adsorption capacity.
Denitrification loss from a grassland soil in the field receiving different rates of nitrogen as ammonium nitrate
Authors: RYDEN J.C. 
Published: July 2006

SummaryDenitrification loss from a loam under a cut ryegrass sward receiving 0, 250 and 500 kg N ha−1 a−1 in four equal amounts was measured during 14 months using the acetylene‐inhibition technique. The rate of denitrification responded rapidly to changes in soil water content as affected by rain. Mean rates of denitrification exceeded 0.2 kg N ha−1 day−1 only when the soil water content was >20% (w/w) and nitrate was >5μ N g−1 in the upper 20 cm of the profile and when soil temperature at 2 cm was >5–8°C. When the soil dried to a water content <20%, denitrification decreased to <0.05 kg N ha−1 day−1. Highest rates (up to 2.0 kg N ha−1 day−1) were observed following application of fertilizer to soil at a water content of about 30% (w/w) in early spring. Denitrification in the control plot during this period was generally about a hundredth of that in plots treated with ammonium nitrate. High rates of N2O loss (up to 0.30 kg N ha−1 day‐1) were invariably associated with high rates of denitrification (> 0.2 kg N ha−1 day−1). However, within 2–3 weeks following application of fertilizer to the plot receiving 250 kg N ha−1 a−1 the soil acted as a sink for atmospheric N2O when its water content was >20% and its temperature >5–8°C. Annual N losses arising from denitrification were 1.6, 11.1 and 29.1 kg N ha−1 for the plots receiving 0, 250 and 500 kg N ha−1 a−1, respectively. More than 60% of the annual loss occurred during a period of 8 weeks when fertilizer was applied to soil with a water content >20%.
Mercury intrusion porosimetry of some New Zealand soils in relation to clay mineralogy and texture
Authors: CHURCHMAN G. J. , PAYNE D. 
Published: July 2006

SummaryPore size distributions in the 10/104 nm e.c.d. range in aggregates from three New Zealand soils with largely monomineralic clay fractions, were determined by mercury porosimetry after oven drying and also after critical point drying following methanol and then CO2 exchange from a range of water contents.A soil containing halloysite showed considerable porosity in the fine pores (10–30 nm) regardless of the method of drying. A smectitic soil showed virtually no porosity in the 102–104 nm range when oven dry. A soil containing allophane was dominated by large pores (> 103 nm). The change from a fine (clayey) to a coarser (clay loam) texture within the profile of one soil was reflected in an increase in large pores.
Multiscale sources of spatial variation in soil. II. A non‐Brownian fractal model and its application in soil survey
Authors: BURROUGH P. A. 
Published: July 2006

SummaryStochastic fractals (for example, the fractional Brownian noises) model the often observed power law relation between the variance of a soil property and the length of transect sampled, but fail to account for abrupt changes of the mean (i.e. soil boundaries), for second‐order stationarity and for the non self‐similarity of variations at different scales that are observed in real data. This paper proposes a non‐Brownian, nested model to account for situations where differences of soil have been caused by superimposed, independently acting soil‐forming processes having different weights and acting at separate, discrete scales. The model is explained and theoretical examples of the semivariograms and confidence limits that arise from it are given. The model is applied to three sets of experimental data and is found to give a remarkably good fit where lateral mixing of soil has been negligible and soil boundaries are sharp. The implications for efficient mapping in situations where the soil results from a number of superimposed, independent causes are discussed.
Variation in yield between two similar sandy loam soils. I. Description of soils and measurement of yield differences
Authors: COSTIGAN P. A. , GREENWOOD D. J. , McBURNEY T. 
Published: July 2006

SummaryYields of seven different vegetable crops on one site were always much less than those on another nearby site despite the soils on both sites being of the same soil series and the incorporation of large quantities of fertilizer immediately before drilling.Severe restriction of growth on the poorer site always occurred when the plants were small. Experimental evidence showed that this restriction could not be attributed to a worse aerial environment or a poorer supply of soil nitrogen. Although there were differences in soil physical conditions these seemed unlikely to be sufficient to reduce the growth of young plants.Plants on the poorer site had much lower potassium and slightly lower phosphorus and water contents than plants on the other site.It is argued that restricted growth results from the inability of the poorer site to supply sufficient potassium and possibly phosphorus to the crop in the early stages of growth. It was also shown that these nutrient stresses could not be significantly relieved by incorporating fertilizer in any quantity, in the usual way, before drilling.
The variability in soil particle size test results by various subsampling techniques
Authors: SMITH R. B. , PRATT D. N. 
Published: July 2006

SUMMARYAnalysis of the results of 104 personnel who determined the particle size distribution of 16 different soil‐size materials indicated that there was an effect of subsample preparation. Subsamples prepared using a chute splitter tended to be coarser than those prepared by coning and channelling. This effect was observed for material retained on 425 μm and 75 μm sieves from a variety of soil types. The results confirm those obtained on artificially prepared mixes. The conclusion is that the chute splitter is a more reliable method for obtaining the test portion than coning and channelling.
Influence of iron oxides on the non‐specific anion (chloride) adsorption by soil
Authors: BORGGAARD O. K. 
Published: July 2006

SUMMARYSoils from Denmark and Tanzania were extracted with ammonium acetate (controls), EDTA to dissolve amorphous iron oxides, and dithionite‐EDTA (DE) to dissolve crystalline iron oxides. The amounts of chloride adsorbed by the extracted soils from 1 m NaCl at pH 5 and pH 7 were determined.The differences (ΔCl) between chloride adsorption at pH 5 and pH 7, attributed to variably charged groups, decreased when iron oxides were removed by EDTA and DE extraction. Close correlations (P>0.001), with negligible intercepts, were found (i)between EDTA‐extractable iron (amorphous iron oxides) and the decrease in ΔCl following EDTA extraction, and (ii) between the difference between DE‐extracted iron and EDTA‐extractable iron (crystalline iron oxides) and the further decrease in ΔCL following DE extraction.The difference between ΔCl for acetate‐extracted and DE‐extracted samples was calculated from the contents and specific surfaces of amorphous and crystalline iron oxides, together with ΔCl per m2 for synthetic iron oxides. Calculated and measured values were in very good agreement, indicating that soil iron oxides, in relation to chloride adsorption, may be treated as if they consist of only two fractions.
Iron oxyhydroxides in soils developed from Lower Palaeozoic sedimentary rocks in mid‐Wales and implications for some pedogenetic processes
Authors: ADAMS W. A. , KASSIM J. K. 
Published: July 2006

SUMMARYLepidocrocite and goethite are pedogenetic crystalline Fe oxyhydroxides in the soils of mid‐Wales. Lepidocrocite is more abundant and widespread, occurring in brown earths (Denbigh series) as well as morphological gleys. It is commonly dominant in horizons intermediate in depth. Goethite occurs in subsoils and was found to be dominant in the subsoil of surface water gleys (Cegin series). Apart from the Cegin series, a large proportion of the total free Fe occurs in non‐crystalline forms. This amounted to 50–80% of the free Fe in organic and eluvial horizons of podzols. Despite lower proportions of non‐crystalline Fe in Bs horizons, amounts were similar to those in eluvial horizons. Data on the distribution of crystalline and non‐crystalline free Fe together with correlations observed between Fe and C extracted by pyrophosphate suggest that transformation and translocation of Fe in the podzols examined are governed by its association with organic fractions.
The extraction of Fe and Al by 0.1 M pyrophosphate solutions: a comparison of some techniques
Authors: LOVELAND P. J. , DIGBY P. 
Published: July 2006

SUMMARYFe and Al were extracted by 0.1 M pyrophosphate solutions from six replicate samples of seven soils by different, widely‐used techniques, viz. those of the Soil Survey of England and Wales, the Canadian Soil Survey and the United States Soil Conservation Service. The effects of K‐ versus Na‐pyrophosphate solution, and of a difference in the pH of the latter were also investigated. All the techniques gave both different, and a wide spread of, values for Fe and Al in all soils. No one technique was consistently the least variable for both elements. Replicate determinations using each technique were so variable that comparison of results obtained by the different techniques cannot be made with confidence.
Soil water regimes of soils developed on Keuper Marl
Authors: McGOWAN M. 
Published: July 2006

SUMMARYThe deeper horizons of soils developed on Keuper Marl (Worcester Series) often remain unsaturated during the winter, with corresponding high tensions, even when the surface layers are waterlogged. Re‐wetting of the deeper layers is restricted because of the inherent low volume of coarse pores in the Bt horizon and because the small volume of desiccation cracks formed during the summer soon disappear on re‐swelling. It is suggested that this unexpected water regime may not be uncommon in soils developed on clay‐shale sediments and that the soil drainage (wetness) classes recognized in England and Wales may need to be modified.