bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fate of nitrogen in cattle slurry following surface application or injection to grassland
Authors: THOMPSON R. B. , RYDEN J. C. , LOCKYER D. R. 
Published: July 2006

SUMMARYTwo field experiments commencing in winter (December) and spring (April) were conducted to determine the fate of nitrogen (N) in cattle slurry following application to grassland. In each experiment three methods of application were used: surface application, and injection ± the nitrification inhibitor, nitrapyrin. Slurry was applied at 80t ha−1, (≡248 kg total N ha−1in the winter experiment, and 262 kg N ha−1in the spring experiment). From slurry applied to the surface, total losses of N through NH3volatilization, measured using a system of wind tunnels, were 77 and 53 kg N ha−1respectively for the winter and spring experiments. Injection reduced the total NH3volatilization loss to ∼2 kg N ha−1. Following surface application, loss by denitrification, measured using an adaptation of the acetylene‐inhibition technique, was 30 and 5 kg N ha−1for the two experiments. Larger denitrification losses were observed for the injected treatments; in the winter experiment the loss from the injected slurry without nitrapyrin was 53 kgN ha−1, and with nitrapyrin 23 kgN ha−1. Total denitrification losses for the corresponding injected treatments in the spring experiment were 18 and 14 kg N ha−1. Apparent recoveries of N in grass herbage in both experiments broadly reflected the differences between treatments in total gaseous loss.
Factors affecting formation of methyl nitrite in soils
Authors: MAGALHÃES A. M. T. , CHALK P. M. 
Published: July 2006

SUMMARYThe formation of CH3ONO in 11 soils treated with HNO2or NaNO2in a closed system, was studied by measuring the concentration in the gas space above the soil and by absorbing CH3ONO in HI. The gaseous concentration of CH3ONO increased and then decreased following additions of HNO2or NaNO2, and the production of CH3ONO increased with increasing concentrations of HNO2or NaNO2added to soils.The amounts of CH3ONO trapped in HI were 13.5 to 20.4 times higher than those determined by integrating under the net production curves. The evolved CH3ONO amounted to 0.4 to 3.5% of added NO2−, and 4.2 to 50% of the gaseous forms of N absorbed by acidic KMnO4solution. The CH3ONO evolved from soils was positively correlated with the methoxy content of the soils, and inversely related to soil pH, with negligible amounts being evolved from alkaline soils. The results show that CH3ONO is a product of NO2−decomposition in soils, and indicate that small concentrations of the gas may be produced in N–fertilized soils in which NO2−accumulates.
Modelling water movement in drained clay soil. II. Application of the model in Evesham series clay soil
Authors: JARVIS N. J. , LEEDS‐HARRISON P. B. 
Published: July 2006

SUMMARYA two‐domain model of water movement, storage and drainage in a cracked clay soil has been applied and tested in the field by irrigating an instrumented lysimeter constructed around a 2.0 m length of mole drain. Measurements of drain outflow rates and of increases in soil water content were compared with model predictions. The model predicted satisfactorily the peak drain outflow rate and subsequent drain recession although there was a tendency for the model to underestimate the time to the start of drainage. Good agreement with the measured recharge profile was generally found.
The estimation of mineralization, immobilization and nitrification in nitrogen‐15 field experiments using computer simulation
Authors: BARRACLOUGH D. , SMITH M. J. 
Published: July 2006

SUMMARYA combination of mathematical analysis and computer simulation, using parameters readily measured in a nitrogen‐15 field experiment, is employed to determine rates of mineralization, immobilization and nitrification under a growing crop. The procedure also yields the proportion of crop nitrogen uptake occurring as ammonium and nitrate.When applied to ‐results from grass lysimeters receiving 250 or 900 kg N ha–1 a–1 as ammonium nitrate, the analysis suggested that at 250 kgN ha–1 a–1 64–66% of crop nitrogen uptake was as ammonium; at 900 kg N ha–1 a–1 the figure was 43–49%. Nitrification at 250kgNha–1 was only 13–19kgN ha–1 over 160d while at 900 kg N ha–1 between 191 and 232 kg N ha–1 were nitrified.The results suggested that the apparent inhibition of nitrification in grassland soils may simply reflect poor substrate competition by nitrifying bacteria. Finally, there was a suggestion that mineralization/immobilization was lower at the high fertilizer rate.
Distribution coefficients of Cd, Co, Ni, and Zn in soils
Authors: ANDERSON P. R. , CHRISTENSEN T. H. 
Published: July 2006

SUMMARYBatch adsorption experiments were conducted with a mixture of solutes at low equilibrium concentrations of Cd (0.7‐12.6 μg1−1), Co (18‐118μg1−1, Ni (22‐330 μg 1−1), and Zn (40‐1480 μg1−1) in 38 different soils. Statistical correlations indicated that metal sorption onto the soils was influenced by the presence of clays and hydrous oxides of Fe and Mn. Based on calculated distribution coefficients for these metals, Co will generally exhibit the highest mobility in soils, but the mobility of Zn will increase faster with decreasing pH. Two types of empirical relationships are developed from these data to estimate values for the distribution coefficients.
Two mechanisms for age‐hardening of soil
Authors: DEXTER A. R. , HORN R. , KEMPER W. D. 
Published: July 2006

SUMMARYSoil samples from Germany, Israel and USA were moulded at water contents around the lower plastic limit and compacted with uniaxial pressures c. 20‐200 kPa. The samples were stored at constant water content. At intervals after moulding, the strengths of sub‐samples were measured with a small penetrometer.The soils showed increases in strength with time. Two types of behaviour were observed and explained by a simplified theory for soil strength. With the German and Israel soils, penetrometer strength increased by the same absolute amount irrespective of compaction pressure. This indicates that new particle‐particle bonds were being formed at a rate which was not affected by compaction. With the USA soils, the ratio of penetrometer strength/initial strength increased with time and was independent of compaction pressure. This indicates that existing particle‐particle bonds were being reinforced by a cementation mechanism. Evidence is presented which suggests that age‐hardening by this second mechanism may be inhibited by soil organic matter.
The effect of soil texture on the dissolution of North Carolina phosphate rock
Authors: KANABO I. A. K. , GILKES R. J. 
Published: July 2006

SUMMARYLaboratory investigations of the dissolution of North Carolina phosphate rock (PR) in soil, as affected by soil texture, were conducted using soils created by mixing various proportions of the <45 μm and >45 μm fractions of a lateritic soil. The dissolution of PR in soil, and the resulting changes in plant available P, were estimated by measuring increases in exchangeable Ca (ΔCa) and NaHCO3‐extractable P (ΔPb), respectively. The total fertilizer phosphate dissolved (ΔP) was calculated from δCa values based on the assumption that dissolution of PR released amounts of Ca and P in a constant ratio determined by the stoichiometry of the PR. δP increased with increasing content of <45 μm particles. APb also increased with the percentage of <45μ fraction, with about 20% of AP being recovered as APb. A smaller proportion of dissolved P was soluble in NaHCO3 for the soil comprising only the <45μ particles. The increase in δP with increased percentage of <45 μn soil was probably due inter alia to the greater P‐sorption, Ca‐sorption and the pH buffering capacity of the fine grained soil constituents.
Quantity/intensity and quantity/potential studies in Na–Ca exchange system in some salt‐affected soils
Authors: KOTUR S. C. , RAO T. SESHAGIRI 
Published: July 2006

SUMMARYThe Q/Icurves for Na in the Na–Ca system in some salt‐affected soils of Malaprabha and Ghataprabha river valleys lacked the curvature commonly seen in the Q/I curve for potassium. The Malaprabha soils showed lower AR0Na, NaL and BC0Na values and higher energies of replacement of calcium by sodium than the Ghataprabha soils; the latter showed a higher affinity for Na than Ca. Two distinct linear parts of the quantity/ potential curves, with different slopes, indicated that Na is held in these soils in two characteristic types of exchange sites having different affinities for sodium. The intersection of the two linear parts corresponded to ESP values in the range of 13 to 64%. The change in the affinity at such a high degree of Na saturation was attributed to the presence of chloritized smectitic clays and sodium‐selective zeolite, such as analcite, reported in these soils.
Correlations between extractable Na, K, Mg, Ca, P & N from fresh and dried samples of two Aquults
Authors: GILLIAM F. S. , RICHTER D. D. 
Published: July 2006

SUMMARYSignificant increases in extractable ions resulted from air‐drying and grinding samples of two infertile Aquults. Effects of the sample preparation differed markedly between ions and between the two soils. Regression equations were calculated to predict extractable ions in dried, ground samples from extractable ions in fresh, unground samples and the relationships were compared between the two soil series. Regressions were significantly different between soils for extractable PO34, Mg++, and K+, but not for Ca++ and Na+. Extractable NH +4 and NO‐3 in fresh, unground samples were not correlated with those in air‐dry, ground samples of either soil. Differences in response to preparation between soil types appeared to be related to the oxidative status of these soils in the field, wherein constituents of more poorly‐drained soils may be less stable to the oxidizing conditions of air‐drying and grinding. Such complexities suggest that effects of sample preparation should be considered when interpreting soil nutrient data for studies of forest nutrient cycling and forest soil fertility.
Gas diffusion, fluid flow and derived pore continuity indices in relation to vehicle traffic and tillage
Authors: BALL B. C. , O'SULLIVAN M. F. , HUNTER R. 
Published: July 2006

SUMMARYRelative gas diffusivity, air permeability and hydraulic conductivity were measured in undisturbed soil cores from tillage and traffic experiments. Continuity indices were taken as the quotient of relative diffusivity and air‐filled porosity, and of air permeability and air‐filled porosity (and the square of air‐filled porosity). These were applied to individual measurements or to treatment means. More general continuity indices were derived from the changes in flow or diffusion with porosity, where the variations in porosity were due to both field variability and applied changes of water potential. These indices were the exponent in the relationship between relative diffusivity and air‐filled porosity and the slope of log–log plots of air permeability and air‐filled porosity or hydraulic conductivity and degree of saturation. Some physical significance was attached to the exponents by comparison with models of soil porosity. Positive intercepts of the relative diffusivity or air permeability plots on the air‐filled porosity axes were taken as porosities blocked to gas movement.Continuity indices and flow measurements showed differences between tillage and traffic treatments which did not necessarily reflect differences in bulk density. Intrinsic permeability was better estimated from air permeability than from unsaturated hydraulic conductivity.
A micromorphometric method for estimating change in the volume of soil induced by weathering
Authors: MORAN C. J. , McBRATNEY A. B. , KOPPI A. J. 
Published: July 2006

SUMMARYA stereological and spatial‐statistically based method for the volumetric estimation of weathering of an in situ soil profile is described. The technique uses the distances between, and size of, zircon grains in undisturbed, horizontal, thin sections. Results are presented as volume attenuation indices, describing the decrease which occurs when a volume of soil material is developed from a given volume of parent material. The method allows computation of confidence intervals for the index and precursory quantities. A soil profile developed in granodiorite, near Bathurst in New South Wales, Australia, is examined to illustrate the technique. The results appear consistent with field description of the profile, with estimates using X‐ray fluorescence analysis (20–90 um sand fraction), and with sand grain counts of the non‐magnetic heavy mineral portion of the same fraction, although the latter methods are of unknown precision.
The influence of sward species composition on the rate of organic matter decomposition in grassland soil
Authors: HOPKINS D. W. , SHIEL R.S. , O'DONNELL A.G. 
Published: July 2006

SUMMARYTo examine the influence of different plant materials on the rate of organic matter (OM) decomposition in soil, respiration and N mineralization/immobilization were measured during incubation of a test soil to which the plant materials were added. Amendments consisted of sward material either from grassland plots with different amounts of OM accumulation, or material from plants associated with soils having markedly different OM contents. Evolution of CO2from the test soil plus herbage from an experimental plot showing OM accumulation was greater than that from the same soil amended with herbage from plots without accumulation. Apparently, grass species had no significant effect on OM turnover; differences in accumulation in grassland soils must be related to other environmental factors. Decomposition of youngCalluna vulgariswas, however, slower than that of young grass material and in this case species could affect organic matter accumulation.
Inhibition of nitrate accumulation in tropical grassland soils: effect of nitrogen fertilization and soil disturbance
Authors: SYLVESTER‐BRADLEY R. , MOSQUERA D. , MÉNDEZ J. E. 
Published: July 2006

SUMMARYIn acid soils in the Eastern Plains of Colombia, forage grasses planted on land prepared before the previous dry season produced 40–50% more dry matter than when land was prepared immediately before planting. Virtually no NO3− accumulated in surface (0–10 cm) soil from three native undisturbed savanna sites. Where land was ploughed before the dry season, NO3− levels increased gradually after a 2–3 month lag, and dropped at the beginning of the rains. In samples incubated for 4 weeks, more NO3− accumulated in the wet than the dry season. A similar 2–3‐month lag occurred when land was ploughed after the dry season. NH4+ levels were higher in ploughed than savanna soils, and rose in all soils at the beginning of the rains. More NO3− and NH4+ accumulated on incubation in pots than in soil cores. Forage grasses inhibited NO3− accumulation in the soil, relative to plant‐free plots, and legumes stimulated it. N fertilization overcame this inhibition except in the case of Brachiaria humidicola.
Analysis of cone resistance data with missing observations below stones
Authors: GLASBEY C. A. , O'SULLIVAN M. F. 
Published: July 2006

SUMMARYWhen stones prevent the measurement of cone resistance, and missing values below the stones are ignored, then averages can be seriously underestimated. Methods are considered for correcting this bias and an algorithm is proposed in which missing observations are replaced by their expected values. A numerical example gives results in close agreement with those obtained using the optimal, but computationally expensive, method of maximum likelihood estimation. It is recommended that data from incomplete penetrations should not be discarded but should be used, preferably with the proposed algorithm, to reduce the bias in estimates of mean values.
The macroporosity of artificial aggregates of varying texture
Authors: SHIEL R. S. , ADEY M. A. , SHANNON J. B. 
Published: July 2006

SUMMARYArtificial soil blocks were made by mixing either ballotini or natural sand with a suspension of silt and clay (fines). The soil was allowed to dry, shrinkage was measured, and from thin sections, the type, area and size of voids in the horizontal plane were observed. As the fines content increased, from 0 to 25%, packing voids (spaces caused by a lack of sufficient small particles to fill voids between sand grains) decreased and were partly replaced by fissures (caused by shrinkage of fines leading to isolated cracks within blocks). From 25% to 50% fines, aggregate shrinkage increased rapidly resulting in the development of large inter‐aggregate voids, but packing voids and fissures decreased. There was a transfer of porosity from within the block to the inter‐aggregate spaces as the fines content increased. Blocks containing coarse sand‐size particles had larger packing voids and fissures, a greater area of fissures, but similar shrinkage to blocks containing fine sand‐size particles.
Effects of sorbed orthophosphate on zinc status in three soils of eastern Canada
Authors: XIE R. J. , MACKENZIE A. F. 
Published: July 2006

SUMMARYP‐Zn interactions can affect fertilizer use and produce Zn deficiencies with certain crops. Phosphorus‐Zn sorption‐desorption reactions were studied in topsoil and subsoil samples from three Quebec soils. Soils were equilibrated with P solutions, then with Zn solutions, and finally with solutions containing no P or Zn. The first equilibration evaluated P sorption (Ps), the second evaluated Zn sorption (Zns) after P sorption (Ps), and the third evaluated Zn desorption (ZnD) as related to added P. Subsequently, Zn fractions were extracted sequentially with KNO3 (Znkno3), NaOH (ZnNaOH) solutions and concentrated HN03+ H202(ZnHNO,).One mmole sorbed P resulted in increases of 0.5 to 1.0 meq (mean = 0.72) increases in cation exchange capacity (CEC). Increased Zns with added P was equivalent to 4 to 5% of the increase in CEC induced by Ps in the Uplands (sand) and St. Bernard (loam) soils, and 0.4 to 0.9% in the Dalhousie (clay) soils, while one meq increase in CEC resulted in 1.5‐3.5% decrease in ZnD. There existed positive correlations between Ps and extractable soil Fe materials. Phosphate sorption enhanced associations between Zns, ZnD or Zn fractions and soil organic or crystalline Fe contents, confirming that P addition increased specific sorption of Zn on Fe components. Other mechanisms including precipitation, P‐induced negative charge and ‘bridge’ effects are also discussed.
Nitrogen mineralization in the field at various soil depths
Authors: HADAS A. , FEIGIN A. , FEIGENBAUM S. , PORTNOY R. 
Published: July 2006

SUMMARYThe accumulation of mineral nitrogen was measured in the field in five soil‐layers between 0 and 120 cm, in two plots of a long‐term experiment contrasting high and low fertilizer inputs. Soil temperature and moisture were also determined. The total quantity of mineral N that accumulated in the 0‐120 cm soil layer during 11 weeks in the summer was 138 and 78 kg ha−1, 25% and 45% of which were found below 60cm, in the high and the low fertility plots, respectively. Nitrogen mineralization in the field was predicted by a model which takes account of changes in temperature and moisture content of the soil. The potentially mineralizable N for this model was found from laboratory incubation experiments. The measured amount of mineralized N was 13 to 26% less than the predicted amount.
Diffusion of methyl bromide in soil
Authors: MIGNARD E. , BENET J. C. 
Published: July 2006

SUMMARYPhenomenological modelling is proposed for penetration by diffusion with aqueous dissolution of a gaseous constituent in non‐saturated soil when there is a thermodynamic imbalance between this gas phase constituent and the same constituent in solution. Non‐equilibrium experiments (Mignard & Benet, 1986) led to specifying the equation governing the kinetics of dissolution and measurement of the phenomenological coefficient for methyl bromide.The results of the model with dissolution imbalance are compared with those of models in the literature which assume immediate dissolution equilibrium in the treatment of soil with methyl bromide applied at the surface. The model developed gives profiles of concentration of substance in the soil in both liquid and gas phases, and makes it possible to judge the extent of the soil zone treated and to forecast what will be the behaviour of the substance.
Seasonal changes in the structure of clay soils in relation to soil management and crop type. I. Effects of crop rotation at Cruden Bay, NE Scotland
Authors: MACKIE‐DAWSON L. A. , MULLINS C. E. , FITZPATRICK E. A. , COURT M. N. 
Published: July 2006

SUMMARYChanges in soil structure and macroporosity were investigated using large thin sections and image analysis of photographs taken from fluorescent resin impregnated soil blocks. In this way porosity measurements were combined with visual assessment of the distribution and type of soil pores and aggregates. Three sites were chosen on a clay soil at Cruden Bay, Aberdeenshire, and sampled throughout two growing seasons in order to characterize various stages of a 7‐year rotation.The seasonal pattern of structural change depended on the crop. During a dry period in April and May 1980, a system of cracks developed on the grass site but not on sites sown to spring barley. The changes in structure on the grass sites could mainly be attributed to changes in water content, and the resulting cycle of shrinking and swelling.After cultivation, structural changes resulting from settling were evident. Earthworm activity, especially after manure spreading, also had a pronounced effect on structure. Since many of these processes are cyclic in this environment, the resulting structural states showed a pattern of cyclic recurrence.
A multiple ion uptake model
Authors: BOULDIN D. R. 
Published: July 2006

SUMMARYA model is developed which describes uptake of Ca, Mg, K, NO3, Cl, and SO4. The electrical neutrality of plant and soil are maintained through exchange of H or OH at the root‐soil interface, constant partial pressure of CO2 and non‐exchangeable H reaction with the soil cation exchange complex.An important innovation in this model is the inclusion of electrical neutrality as a condition for plant, soil and soil solution. The uptake of cations is a function of both concentration of anions in solution and the suite of exchangeable cations. The model emphasizes an important role for CO2 in soil chemistry and plant nutrition. Presently, the model is most useful for generating research hypotheses. Perhaps the most important hypothesis is that something about as complicated as the present model will be required to model multiple ion uptake and crop yields.
The soil solution chemistry of some Oxfordshire soils: temporal and spatial variability
Authors: CAMPBELL D. J. , KINNIBURGH D. G. , BECKETT P. H. T. 
Published: July 2006

SUMMARYThe immiscible liquid displacement method was used to displace soil solutions from a variety of Oxfordshire soils. These included grassland, arable, and woodland soils. The results of detailed chemical analyses demonstrated that for most solutes there were significant seasonal differences as well as differences both within and between soil series. The variation over time intervals of a few days or weeks appeared to be relatively small in relation to sampling errors. Median concentrations (in mmol m−3) for soil solutions derived from 21 grassland sites and six arable sites sampled six or seven times throughout 1 year were: pH 7.7, alkalinity 1810, Na 465, K 390, Mg 135, Ca 2120, Sr 1.9, Ba 0.16, Mn 0.52, Fe 3.4, Cu 0.25, TON 860, Cl 1590, S 327, P 64, Si 220, B 5.1, and DOC 4250. For many solutes, the individual soil solution concentrations spanned a range from approximately five‐times less than these median values to approximately five‐times more.