bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term changes in the acidity of forest soils in North‐East Scotland
Authors: Billett M.F. , FitzPatrick E.A. , Cresser M.S.
Published: February 2007

Abstract. Fifteen soil profiles in the Alltcailleach Forest in NE Scotland have been resampled after almost 40 years. The pH, in 0.01 M CaCl2, of the soil has decreased by 0.07 to 1.28 units in 80% of the surface organic horizons and by 0.16 to 0.54 units in 73% of the mineral horizons below 40 cm. The key factors governing increases and decreases in soil pH are changes in ground vegetation and tree canopy, although some effects of acid deposition cannot be ruled out.
Soil salinity measurements
Authors: Dasberg S. , Nadler A.
Published: February 2007

Abstract.The soil solution may contain both plant nutrients and toxic ions. The total salt concentration affects both osmotic pressure and plant water stress. This review describes the main methods of evaluating soil salinity. They are listed as extraction methods (saturation and other soil extracts, suction cups), displacement methods (pressure membrane, centrifugation) and electrical methods of total salinity measurement (salinity sensors, four‐electrode methods and time‐domain reflectometry). The methods are compared so that the reader may choose the one most suitable for his purpose, based on cost, on the inherent advantages or drawbacks of the methods themselves, on his need for single or repeated measurements and either estimates of total salinity or the concentration of selected ions.
Soil shear strength measurements and their relevance to windthrow in Sitka spruce
Authors: Anderson C.J. , Campbell D.J. , Ritchie R.M. , Smith D.L.O.
Published: February 2007

Abstract. The measurement of the shear strength of the root plate/soil interface beneath mature trees is described. Results from this method are given for a total of 77 sample trees from crops of Sitka spruce aged between 24 and 35 years growing on a peaty gley, a deep peat and a brown earth. Shear strength was much higher for the brown earth than for either the peaty gley or the deep peat, mainly because there was a less clear‐cut boundary to the rooting depth compared with the rooting boundary caused by the high water table on the peat sites. There was a slightly higher shear strength for the peaty gley than for the deep peat, but no apparent difference in shear strength between the peat and the underlying mineral soil in the peaty gley. The shear strength measurements were consistent with observed differences in tree stability and the method of measuring shear strength aids the assessment of susceptibility of trees to windthrow.
Soil erosion and its control in the loess plateau of China
Authors: Fu Bojie
Published: February 2007

Abstract. The loess plateau in China is the most developed region of loess in the world in terms of extent, thickness and depositional sequence. It is also the region with the most serious soil erosion in the world. This paper reviews the factors and reasons for soil erosion in this area. The loess is prone to vertical cleavage and its surface soils are soft and loose. Rainstorms are frequent with intense rain concentrated during the summer. Irrational land use and exploitive management have been carried out for thousands of years and express themselves through the loss of grassland and natural forests. Finally, some soil conservation schemes for use in the loess plateau are suggested.
The quality of topsoil
Authors: Bradshaw A.D.
Published: February 2007

Abstract. The topsoil widely bought and sold for landscaping and similar schemes is intended to cover poor substrates and to provide improved growing conditions for plants. Two extensive surveys have shown that top soils at present being used are of very poor quality and rarely meet this requirement. Many of the substrates that the topsoils cover out‐perform them, or can readily be improved to do so if modern land reclamation techniques are used.

From this it follows that there could, and should, be (i) much more discretion in the use of topsoil, (ii) more attention paid to the improvement of existing substrates, (iii) more consideration given to the use of other materials as topsoil substitutes, and (iv) more care taken in the choice of top soil materials where these have to be used.

It is suggested that the present British Standard for topsoil is inadequate and that is should be replaced by a three‐tier system in which there would be separate specifications for; (i) high grade topsoil, (ii) lower grade topsoil, (iii) materials which can act as topsoil substitutes. In this way it should be possible to obtain a better and more reliable performance in landscaping schemes and lower costs.
Soil microbial activity in opencast coal mine restorations
Authors: Harris J.A. , Birch P.
Published: February 2007

Abstract.A number of restored areas, a soil store and undisturbed areas on opencast coal mine sites, all of similar soil type, were sampled. The microbiological activity (dehydrogenase assay), nitrogen mineralization and nitrifying potentials and physico‐chemical characteristics of the soils were determined. Dehydrogenase activities ranged from 140 to 580 μg TPF g‐124 h‐1in undisturbed control soils, whereas the disturbed soils had activities of 10 to 220 μg g‐124 h‐1, with the smallest activities being recorded in the stored and most recently reinstated soil, indicating that disturbance has depressed microbial activity. Nitrogen mineralization potential was significantly affected by disturbance, with a value of 18 to 26 μg inorganic N g‐121 d‐1in the soil store and 38 μg‐121 d‐1in a soil reinstated for six months, although the values were less than this in soils reinstated for up to six years. Nitrifying potential was not significantly less in the stored soils, being within the range of 60 to 135 μg nitrate N formed g‐1soil 21 d‐1, which was similar to that found in the undisturbed control soil.

The water‐holding capacity was less in the stored soil than the undisturbed controls, and was significantly less in soil reinstated for 1.5 to 2.5 years, being only 65% of the undisturbed value (0.66 g water g‐1soil). Ammonium content of the soil store was one hundred fold larger in the soil store than in the controls (0.6 to 1.7 μg ammonium N g‐1). The carbon contents in the control soils ranged from 4.5 to 7.2%, whereas the stored and reinstated soils had generally less amounts ranging from 1.6 to 5.8%. There was a significant and positive correlation between water‐holding capacity and nitrifying potential.

The implications for long‐term restoration are discussed.
Response of linseed (Linum usitatissimumL.) to fertilizer nitrogen, phosphorus and sulphur, and their effect on the removal of soil sulphur
Authors: Aulakh M.S. , Pasricha N.S. , Azad A.S. , Ahuja K.L.
Published: February 2007

Abstract.Between 1981 and 1987 field experiments were made on loam and sandy loam soils to test the effects of nitrogen, phosphorus and sulphur fertilizers on the yield and quality of linseed, and the uptake of S by the crop. In one experiment, all through the six years, the application of fertilizers up to 60 kg N, 40 kg P2O5and 30 kg S ha‐1increased yields. In the second experiment, the same combination of N, P and S maximized crop yield, uptake of P and S, % oil and oil production. These balanced and optimum rates of fertilizers decreased the percentage of stearic, oleic and linoleic acids but increased that of linolenic acid by accelerating the metabolic pathway of linolenic acid synthesis. Applying P decreased the removal of native S in the soil but when more S was applied, more native S was taken up. Large dressings of P diminished crop yield and quality as well as the availability of native soil S.
Effect of urease inhibitors on nitrification in soil
Authors: Zhengping Wang , van Cleemput O. , Baert L.
Published: February 2007

Abstract. This paper describes experiments on the inhibitory effects of hydroquinone (HQ), phenylphos‐phorodiamidate (PPDA) and N‐butyl phosphorothioic triamide (NBPT) on the nitrification in soil. Incubations were carried out at 2/3 field capacity at 25°C of soil samples to which either ammonium or nitrite was added together with inhibitors. Addition of PPDA or NBPT did not influence the oxidation of ammonium. HQ. however, retarded the process significantly, and also the accumulation of nitrite. This was confirmed in experiments whereby added nitrite was followed. Some of the differences could be explained by changes in the soil pH. During incubation the evolution of the total mineral nitrogen was not importantly altered by addition of the inhibitors.
Effects of exotic tree plantations of teak (Tectona grandis) and gmelina (Gmelina arborea) on a forest soil in south‐western Nigeria
Authors: Aborisade K.D. , Aweto A.O.
Published: February 2007

Abstract. The properties of soil under 15‐year‐old plantations of gmelina (Gmelina arborea) and teak (Tectona grandis) were compared with logged forest soil in south‐western Nigeria. The soil was significantly denser in the 0–10 cm layer of plantation soil and total porosity less than that of forest soil. Organic carbon was significantly greater in the 0–10 cm layer of forest soil. Similarly, the concentrations of total N, exchangeable Ca, Mg and K were greater under forest soil, but the concentrations of available P were similar under all three ecosystems. The smaller organic carbon and nutrient content of plantation soil is mainly due to its more open organic matter and nutrient cycles and nutrient immobilization in the fast‐growing exotics.
Effect of tree species and species mixtures on soil properties at Gisburn Forest, Yorkshire
Authors: Moffat A.J. , Boswell R.C.
Published: February 2007

Abstract. The soil has been investigated at a long‐term experiment examining the silvicultural and site‐related effects of four tree species (Scots pine, Norway spruce, oak, common alder), planted pure or in mixtures. The experiment is located in Gisburn Forest, Yorkshire, and commenced in 1955. After 32 years, small significant differences were found for soil properties relating to soil organic matter accumulation and incorporation; the soil under the conifers and alder was slightly more acid than that under oak and grass control plots, and the conifers had thicker F and H but thinner A horizons. There was also some evidence that the conifers and alder has retarded the formation of a grey iron‐deficient B horizon. Some mixed plots were differentiated from pure ones by canonical variate analysis. Soil pH has declined under all plots since 1954; the effect of mixing species on this property is discussed.
Assessment and improvement of nitrogen fixation in tropical Phaseolus vulgaris L.
Authors: Giller K.E.
Published: February 2007

Abstract. The methods available for measurement of nitrogen fixation by field grown Phaseolus vulgaris are reviewed. Phaseolus is generally considered to have little ability to fix nitrogen. This is discussed in the light of research on host genotypes and Rhizobium strains, and the influences of environment on these in isolation and in symbiosis.
Morphological and hydraulic properties of a silt loam soil in New Zealand as affected by cropping history
Authors: Francis G.S. , Kemp R.A.
Published: February 2007

Abstract. A rotation trial of four years’ pasture followed by two years’ arable was used to study the effect of cropping on the morphological and hydraulic properties of soil. An adjacent paddock in grass for the past 35 years was included as a permanent pasture reference. Initial infiltration and field saturated hydraulic conductivity (Kfs) were least for cultivated soil and increased with increasing time under pasture. This could be explained by the contrasting porosities of resin‐impregnated blocks of undisturbed soil which had been infiltrated with methylene blue dye. Small Kfs values for cultivated soil resulted mainly from a thin surface crust, although pore discontinuity at the depth of the cultivation pan (130 mm) could also have contributed. Greater Kfs values under short‐term pasture resulted primarily from water flowing through biogenic pores connected to the surface. The greatest Kfs values were in soil that had been under pasture for 35 years (P35). This was attributed to flow through biogenic pores and fissures associated with the strongly‐developed subangular blocky structure. The amount of water that infiltrated the two‐ and four‐year pasture soils (P2 and P4) under ponding was 2.5 and 5 times greater, respectively, than the soil that had been cultivated for two years (C2).

As irrigation duration cannot be varied under the border‐dyking system used on the Canterbury Plains, the interval between irrigations must be varied if the same total amount of water is to be applied to each of these soils through the season. The interval should be less for the cultivated soil than for those under pasture, and should increase with increasing time under pasture (i.e. P35 > P4 > P2 > C2).
Interactions between mycorrhizae and diseases caused by soil‐borne fungi
Authors: Perrin R.
Published: February 2007

Abstract . There are many records of mycorrhizae, particularly ectomycorrhizae, protecting roots against soil‐borne plant pathogens, though fungal or viral diseases of the green parts are usually more severe in mycorrhizal plants. There are various mechanisms by which mycorrhizae protect themselves against soil‐borne diseases. The occurrence and ecological significance of these mechanisms are discussed in relation to environmental factors. Mycorrhizae will probably become a very effective means of biological control once we have learned how to manage them.
Prediction of nitrate leaching losses from arable land under different fertilization intensities using the SOIL‐SOILN models
Authors: Bergström L. , Jarvis N.J.
Published: February 2007

Abstract. The ability of the SOIL‐SOILN models to predict nitrate leaching rates from arable land under different fertilizer inputs is tested. The SOIL model predicts water and temperature conditions in a layered soil profile and provides driving variables for the SOILN model which describes nitrogen inputs, transformations and losses. SOILN model predictions were compared with measurements of nitrate leaching at application rates of zero, 100 and 200 kg N per hectare (NO, N100 and N200) in a long‐term field experiment in south‐west Sweden. Large discrepancies between model predictions and measurements of nitrate leaching were found in some years (up to 100%) and were attributed to important soil processes which are either not included in the model (macropore How) or are difficult to model satisfactorily (partitioning between surface runoff and infiltration during snowmelt periods, crop nitrogen uptake). Nevertheless, long‐term mean yearly leaching losses at the different nitrogen application rates (3, 6 and 46 kg per hectare at NO, N100 and N200, respectively) were reasonably well estimated by the model.
Simulation of solute leaching in soils of differing permeabilities
Authors: Addiscott T.M. , Whitmore A.P.
Published: February 2007

Abstract. The model described divides the soil into layers and considers two categories of water, mobile and immobile, in each layer. It has two main parameters, one a measure of the soil's capacity to hold water and thence to retain solutes against leaching, and the other a measure of the ease with which water can pass through the soil and carry solutes with it. These are, in effect, capacity and rate parameters, and the model is unusual in having both. They can be estimated from the percentages of clay and other soil components. The rate parameter varied appreciably between plots in the field but in a consistent manner. The model has been validated against field experiments following the vertical movement of solute applied to the soil surface and allowed to leach, and the paper includes one such test.
An analysis of the leaching of chloride tracer applied to pipe‐drained plots using a coupled unsaturated‐saturated zone model of solute transport
Authors: Vinten A.J.A. , Vivian B. , Redman M.H.
Published: February 2007

Abstract. The modelling of leaching of nitrate and other solutes in artificially drained soils is complicated by the need to consider both unsaturated and saturated components of the system. This work is an attempt to couple together an unsaturated zone transport model (Addiscott & Whitmore, 1991) with a steady state travel‐ time model (Ernst, 1973) for the saturated zone. The model was tested using chloride leaching data from eight hydrologically isolated plots on a pipe‐drained clay loam soil. Approaches to parameter estimation are discussed. Results were variable, for on some plots saturated zone travel time could be virtually neglected, whereas on other plots this component was apparently important.
Biological aspects of soil protection
Authors: Wood M.
Published: February 2007

Abstract.Soil provides an environment for all forms of life, from viruses and bacteria to trees, and these soil inhabitants play many important roles in soil development and in the maintenance of soil fertility. Policies for protection of soil should therefore include criteria for the biological quality of soil. The establishment of such criteria can only be based on an understanding of the function of the different groups of soil organisms, including the interactions between these groups which give rise to such processes as mineralization of organic matter. However, we are only beginning to understand this most complex of ecosystems. Current information is reviewed and the problems of establishing biological standards for soil are considered. Much of the discussion on assessment of pesticide side effects is relevant to this topic, and the future need to quantify risk associated with the introduction of genetically‐engineered organisms into soils is likely to stimulate further debate on this topic.
Soil protection as a component of gravel raising
Authors: Bransden B.E.
Published: February 2007

Abstract. The methods of soil handling used by Greenham Construction Materials Ltd (Greenham) have been designed to avoid damage to restored soils and the need for subsequent curative work. The systems used to plan restoration, move soil and install drainage are described. The quality of restored land and its cropping potential are described with reference to Greenham's Laleham Farm site at Shepperton Pit in Middlesex. Materials Ltd, to avoid soil damage in the course of extract‐
International standardization of soil quality measurement procedures for the purpose of soil protection
Authors: Hortensius D. , Nortcliff S.
Published: February 2007

Abstract. The paper introduces the need for soil protection policies and the importance of standardized soil analytical and descriptive procedures, using examples from The Netherlands and the international Labex programme. The structure and concerns of the International Organization for Standardization Technical Committee on Soil Quality (TC 190) are outlined.
How geostatistics can help you
Authors: Oliver M. A. , Webster R.
Published: February 2007

Abstract. Geostatistics is basically a technology for estimating the local values of properties that vary in space from sample data. Research and development in the last 15 years has shown it to be eminently suited for soil and ripe for application in soil survey and land management. The basic technique, ordinary kriging, provides unbiased estimates with minimum and known variance. Data for related variables can be incorporated to improve estimates using cokriging. By more elaborate analysis using disjunctive kriging the probabilities of deficiency and excess can be estimated to aid decision.

The variogram is crucial in all geostatistics; it must be estimated reliably from sufficient data at a sensible scale and modelled properly. Once obtained it can be used not only in the estimation itself but also to choose additional sampling sites, improve a monitoring network or design an optimal sampling scheme for a survey. It may also be used to control a multivariate classification so that the resulting classes are not too fragmented spatially to manage.
The effects of straw disposal and depth of cultivation on the growth, nutrient uptake and yield of winter wheat on a clay and a silt soil
Authors: Christian D. G. , Bacon E. T. G.
Published: February 2007

Abstract. Experiments were conducted for one year on two different soil types. On a clay soil straw was either (a) burnt, (b) baled leaving the stubble, or (c) chopped and spread. The soil was tine cultivated to depths of 5, 10 or 15 cm or ploughed to 20 or 30 cm before winter wheat was sown conventionally. In addition, a direct‐drilled crop was sown after each straw treatment. On a silt loam soil the direct‐drilled, tine cultivated to 15 cm and ploughed to 30 cm treatments following burning or chopping and spreading straw were repeated.

Tine cultivation incorporated less straw than ploughing, decreased plant establishment and early growth but did not decrease yield. Direct‐drilling through chopped straw decreased yield on the silt loam but not on the clay soil. Short straw (< 5 cm) was easier to incorporate than longer straw. Ploughing was the most efficient method of straw incorporation because it inverts soil. Early effects on crop growth and nutrient uptake following straw incorporation were transient and associated with large amounts of straw in the seeded layer of soil.
Recent trends in soil pH and nutrient status in England and Wales
Authors: Skinner R. J. , Church B. M. , Kershaw C. D.
Published: February 2007

Abstract. Results of the Representative Soil Sampling Scheme between 1978 and 1988 show that soil acidity remains widespread, particularly in Wales, and suggest that the proportions of grassland with low pH increased during this period in the traditional grassland areas of England and Wales.

Average soil nutrient levels changed little over the decade. However, at least one in five grassland fields are likely to suffer yield restrictions because of shortage of soil P or K (index 0). One in four arable fields were found to be at index 1 for K, indicating that many crops are being grown at potassium levels which can be described as borderline. On the other hand, 22% of arable crops were grown at phosphate index levels in excess of 3, so phosphate savings could be made on many crops. Texture and calcium carbonate levels and their relationships with nutrient levels are also examined.
Bypass flow and leaching of nitrogen in a Kenyan Vertisol at the onset of the growing season
Authors: Smaling E. M. A. , Bouma J.
Published: February 2007

Abstract.Bypass flow and concurrent leaching of nitrogen were studied on a Vertisol in south‐western Kenya under rangeland and bare, manually tilled cropland. Showers of 30 mm/hr were simulated, causing bypass flow of 47–62% in rangeland topsoils and 19–49% in cropland topsoils. Volumetric water contents after experimentation increased from 28 to 35% and from 24 to 38%, respectively, for the two land‐use types.

In rangeland samples up to 3.4 kg N/ha was found in the leachate of unfertilized soil. With a fertilizer application of 50 kg N/ha, up to 5.7 kg N/ha was lost from a pre‐wetted soil, and more than 20 kg N/ha from dry soil. In cropland topsoils up to 2.2 kg N/ha was lost from unfertilized soil, and only up to 2.9 kg N/ha from both dry and prewetted fertilized soil. Although Vertisols are often linked with excess water, the phenomenon of bypass flow can cause water stress to crops in their early growth stages. Nitrogen leaching losses were large from dry grassland, but prewetting helped to decrease them. On intensively cultivated cropland there was little nitrogen leaching; the tilled topsoil was able to retain most of the supplied nitrogen.
Implications of spatial averaging weather and soil moisture data for broad scale modelling activities
Authors: De Jong R. , Dumanski J. , Bootsma A.
Published: February 2007

Abstract. Spatial averaging of data before or after modelling has important implications for large area land evaluation studies. Two procedures are evaluated for the spatial averaging of weather and soil moisture data before and after modelling (procedures A and B, respectively). The Thiessen polygon weighting technique is applied to a network of weather stations to derive daily weather values for the period 1955 to 1985 for 12 selected Agroecological Resource Areas (ARAs) on the Canadian prairies. These values are used in the model for procedure A. The components of the soil moisture balance for spring wheat are estimated with a budgeting model, assuming wheat is grown continuously for 30 years on soils with available water‐holding capacities (AWCs) of 150 and 250 mm. In procedure B, the data from individual stations are used as input to the model and the same Thiessen polygon weighting coefficients are applied to the output variables. A comparison of the two procedures shows no significant difference for temperature‐related variables such as frost dates, harvest date and cumulative potential evapotranspiration. The differences for moisture‐related variables (soil moisture content at sowing, cumulative actual evapotranspiration, runoff and deep drainage) are often statistically significant, but the absolute differences are less than 10 mm at probability levels ranging from 10 to 90%. For many practical applications the two procedures give similar results.
A comparison of qualitative and quantitative physical land evaluations, using an assessment of the potential for sugar‐beet growth in the European Community
Authors: Van Lanen H. A. J. , Van Diepen C. A. , Reinds G. J. , De Koning G. H. J.
Published: February 2007

Abstract. Qualitative and quantitative physical land evaluations differ in their technical procedures, i.e. use of expert knowledge versus process‐orientated simulation models. This paper compares the results of both procedures using the growth potential for sugar‐beet in the European Community. Qualitative procedures give suitability expressions, such as land being well suited or moderately suited for a given land use. Less than 30% of EC land was found to be well suited or moderately suited under water‐limited conditions. No quantitative expressions for the crop yield potential are, however, produced. The quantitative procedure describes suitability in terms of average crop yield and its temporal variability. Water‐limited and potential dry matter yields of sugar‐beet were estimated to range from 3.5 to 20 t/ha, and from 6 to 25 t/ha, respectively.

Comparison of results of the qualitative and quantitative procedures for regions showed that the suitability classes obtained by the former can be characterized by different yield distributions derived from the latter. These yield assessments showed that results of qualitative land evaluation procedures aimed at assessing yield potential are meaningful only when they are linked to agroclimatic zones. The comparison also showed that some moderate restrictions, which often can be counteracted by adequate farm management, are not incorporated into the quantitative procedure.
MicroLEIS: A microcomputer‐based Mediterranean land evaluation information system
Authors: De la Rosa D. , Moreno J. A. , Garcia L. V. , Almorza J.
Published: February 2007

Abstract. A computer‐based land evaluation information system (MicroLEIS) was developed for optimal use of agricultural and forestry land systems under Mediterranean conditions. Through an interactive procedure several land capability, suitability and yield prediction methods may be applied. The system addresses land evaluation at reconnaissance, semi‐detailed and detailed scales in an interrelated manner. Biophysical land evaluation methods are incorporated using empirical, scale‐appropriate models, which range from purely qualitative (reconnaissance) through semi‐quantitative (semi‐detailed) to quantitative (detailed). This software is helpful for teaching, research and development, predicting appropriate agroforestry land uses. Its use is illustrated by an example.

MicroLEIS runs on IBM PC, XT, AT, or a compatible microcomputer with at least 128 kilobytes of RAM and a PC‐DOS or MS‐DOS version 2.0 or later operating system. The software package on double or high density diskettes can be obtained from the first author.
The amount of soil cover provided by a unit mass of guinea grass, banana leaf and palm leaf residues
Authors: Ozara N. A.
Published: February 2007

Abstract. The area covered per unit mass (Am) of a mulch material is an important factor for controlling erosion, especially in the humid tropics. Values of Am for mulching materials commonly available in S.E. Nigeria ‐ guinea grass, banana leaves and palm leaves ‐ were found to be 0.00035, 0.00038 and 0.00020 haAg, respectively. These values are within the range (0.0001–0.0007 ha/kg) reported for other mulching materials elsewhere. They can be fitted into existing equations to determine the amount of mulches required to achieve any predetermined ground cover percentage.
The adhesion to leaf surfaces of heavy metals from sewage sludge applied to grassland
Authors: Klessa D. A. , Desira‐Buttigieg A.
Published: February 2007

Abstract. When sewage sludge is surface‐applied to grassland, herbage may become contaminated with heavy metals from adhering solids, posing a risk to the health of grazing livestock and possibly increasing the entry of heavy metals into food products. A field trial examined factors influencing sludge adhesion to leaf surfaces and changes in the concentration of heavy metals in herbage over time. Metals differed in their persistence on leaves. The time required for metal concentrations in herbage to reach background levels depended on herbage growth, the dry solid content of sludges, their rate of application and the height of the grass when the sludge was applied. The implications of the results for the length of a safe no‐grazing period following sludge application are discussed in the context of UK and EC legislation governing sludge use on agricultural land.
Effects of ‘Agri‐SC’ soil conditioner on the erodibility of loamy sand soils in East Shropshire, UK: preliminary results
Authors: Fullen M. A. , Tye A. M. , Pritchard D. A. , Reynolds H. A.
Published: February 2007

Abstract. The effect of Agri‐SC’ soil conditioner on the erodibility of loamy sand soils has been investigated at the Hilton experimental site, Shropshire, since March 1988. Factors measured have included runoff and erosion, soil structure, crust strength, splash susceptibility, aggregate stability, soil micromorphological properties, response to compaction and penetrometer resistance.

Treatment decreased runoff and erosion rates, bulk density, splash erosion, crust strength and penetrometer resistance, and increased pore space and aggregate stability. The effects on crust strength, aggregate stability and bulk density were statistically significant. The results suggest that applications of ‘Agri‐SC’ could have beneficial effects for soil conservation.
Effects of cropping system and rates of nitrogen in animal slurry and mineral fertilizer on nitrate leaching from a sandy loam
Authors: Thomsen I. K. , Hansen J. F. , Kjellerup V. , Christensen B. T.
Published: February 2007

Abstract. Leaching of nitrate from a sandy loam cropped with spring barley, winter wheat and grass was compared in a 4‐year lysimeter study. Crops were grown continuously or in a sequence including sugarbeet. Lysimeters were unfertilized or supplied with equivalent amounts of inorganic nitrogen in calcium ammonium nitrate (CAN) or animal slurry according to recommended rates (1N) or 50% above recommended rates (1.5N).

Compared with unfertilized crops, leaching of nitrate increased only slightly when 1N (CAN) was added. Successive annual additions of 1.5N (CAN) or 1N and 1.5N (animal slurry) caused the cumulative loss of nitrate to increase significantly. More nitrate was leached after application of slurry because organic nitrogen in the slurry‐was mineralized.

With 1N (CAN) the leaching losses of nitrate were in the following order: continuous spring barley undersown with Italian ryegrass < continuous ley of perennial ryegrass < spring barley in rotation and undersown with grass < perennial ryegrass grown in rotation = winter wheat grown in rotation < sugarbeet in rotation < continuous winter wheat < continuous barley < bare fallow.

At recommended levels of CAN (1N), cumulative nitrate losses over the four years were similar for the crops when grown in rotation or continuously. When crops received 1.5N (CAN) or animal slurry, nitrate losses from the crops grown continuously exceeded those from crops in rotation. Including a catch crop in the continuous cropping system eliminated the differences in nitrate leaching between the two cropping systems.
Preliminary investigations of soil patterns in large‐scale agricultural projects in Nigeria
Authors: Ekanade O.
Published: February 2007

Abstract. The effects of increasing periods of mechanical cultivation on soil properties under maize and cassava are compared with those under savanna in south‐western Nigeria. Bulk density is significantly greater under cultivation and total porosity, pH, organic matter and extractable nutrients are all significantly less than under savanna. However, the amounts of nitrate‐nitrogen and extractable nutrients do not show clear decreases with increasing mechanical cultivation. As the periods of mechanization increase, changes in most soil properties indicate increasing soil degradation. The implications of these results for agricultural policies in Nigeria arc discussed.
Nitrogen cycling and losses from dairy farms
Authors: Jarvis S. C.
Published: February 2007

Abstract. The concern over leakage of nitrate into waters and loss of other forms of N to the environment demands an appraisal of N flows within complete systems. The grassland N cycle is complex, with interactive controls over fluxes and transformations, and has the potential for considerable losses. Although there are data from experimental systems, a total comprehension of flows is not yet possible.

Intensive dairy farming has a number of opportunities for leaks. A ‘model’ system in SW England has an annual input of 25.6 tonnes of N: of this only 20% is transferred into protein or milk, a further 46% is lost to the wider environment, 34% is as yet unaccounted for and much is recycled. Recent research has provided new techniques to decrease losses. To meet the joint requirements of production and environmental concerns we need to consider N flows and supplies on an integrated, whole farm basis, and to take better account of mineral N in the soil profile in relation to current crop demand, local climate and past sward management.
Utilizing the nitrogen content of organic manures on farms—problems and practical solutions
Authors: Smith K. A. , Chambers B. J.
Published: February 2007

Abstract. Organic manures contain valuable quantities of nitrogen, phosphate and potash, but many farmers regard them as ‘waste materials’ rather than as sources of plant nutrients. Utilization of the plant‐available nitrogen content is poor at present because of manure management practices which lead to leaching and atmospheric losses. Experiments studying the effect of timing suggest that, in order to decrease nitrate leaching, applications of manures which contain much available nitrogen should not be made during the period September to December on freely draining grassland and arable soils. Spring top dressings of dilute pig or cattle slurries and poultry manures to growing cereal crops are generally more efficient than autumn applications, particularly on freely draining soils. Legislation requiring manures to be applied in an environmentally acceptable manner and the economic need for farmers to realize the nutrient value of organic manures are likely to change the farming industry's perception of manures as ‘waste materials’.
Influence of cattle trampling on preferential flow paths in alkaline soils
Authors: Dreccer M. F. , Lavado R. S.
Published: February 2007

Abstract.Preferential flow paths (PFP) are important in water and solute movement through soils, especially in regions where vertical water movements predominate, such as the flooding Pampa (Argentina). The impact of grazing on PFP and its interactions with other properties were studied in three soils with natric horizons in the flooding Pampa using an iodide colouring technique. In the soil with a mollic horizon (Typic Natraquoll), % PFP was decreased by trampling but was later restored by shrink‐swell. In the Typic Natraqualf, the most alkaline of the studied soils, % PFP was very small under both grazed and ungrazed conditions. In a coarser textured soil (Mollic Natraqualf) trampling did not affect % PFP. The % PFP of the Ah horizons increased with increasing organic carbon and sand contents and decreased as clay content, pH and sodium adsorption ratio (SAR) increased. The Bt horizons had small % PFPs and were not affected by cattle trampling.
Soil losses under simulated rainfall in semi‐arid shrublands of the Ebro Valley, Spain
Authors: Navas A.
Published: February 2007

Abstract. Runoff and soil loss were measured using simulated rainfall at nine shrubland sites on gypsiferous soils in the Ebro Valley. The sites represented diverse physiographical situations, including three soil types, three slopes and different percentages of rock outcrop and vegetation cover. Soil type, slope and vegetation cover significantly affected runoff and soil losses. An average of 40% of the simulated rainfall (48 mm/h) appeared as runoff and amounts were positively correlated with soil losses. The greatest runoff and soil losses were from plots with the steepest slopes. Rock outcrops decreased soil losses.
Bioavailable potassium in river‐bed sediments and release of interlayer potassium in irrigated arid soils
Authors: Rahmatullah B.Z. Shaikh , Gill M.A. , Salim M.
Published: February 2007

Abstract. Crop responses to applied potassium fertilizers are erratic in many arid and semi‐arid soils. The potassium supplying potential of river‐bed sediments and release of interlayer potassium from eleven alkaline soils were measured in two separate experiments. Sediments from the Chenab and Ravi Rivers in Pakistan were exhausted of potassium by successively growing wheat, maize, mungbean, and wheat in them for a total of 200 days, using Hoagland solution to supply optimum amounts of other nutrients. Cumulative plant dry matter yield was significantly greater on the Chenab sediments. The quantities of potassium supplied to plants from the sediments of the two rivers were also significantly different.

Interlayer potassium was extracted for 1230 minutes from a Udic Haplustalf (Pindorian series) by twelve different solutions each with the same electrolyte content (100 cmol). The sodium adsorption ratios (SAR) of the solutions were adjusted to 5, 10, 25, and 50, each with Ca: Mg ratios of 25:75, 50: 50 or 75:25, using solutions of sodium, calcium and magnesium chloride. The potassium released from the soil was inversely related to solution SAR. Increasing proportions of magnesium relative to calcium in solution favoured the release of potassium, except in the SAR 50 solution. Significantly different quantities of potassium were extracted by various solutions. Maximum potassium (442 mg/kg) was extracted by SAR 5 solution with a Ca: Mg ratio of 25:75. Interlayer potassium subsequently removed by this solution from 11 alkaline soils ranged from 407 to 499 mg/kg. The potassium released from all but three of the soils was related to their clay content (r= 0.72; n= 8). The release of potassium from the soils followed the Elovich function. The intercept (X1) and slope (X2) estimated for the function was related to potassium released (y) by the equation:

y=−1.13 + 2.74X1−0.014X2 (r= 0.998; n= 8)

The results imply that river sediments treated with irrigation water containing magnesium and sodium ions can contribute substantial amounts of available potassium for plant growth.
Comparison of sulphur uptake by oilseed rape and the soil sulphur status of two adjacent fields with different soil series
Authors: Zhao F. , McGrath S.P.
Published: February 2007

Abstract. At Woburn Experimental Farm (SE central England) sulphur (S) deficiency symptoms occurred in a winter oilseed rape crop grown in Lansome field on soil of the Cottenham series, but not on the Blithe series soil in the adjacent Mill Dam Close field. At maturity, the two crops produced a similar amount of dry matter but seed yield and harvest index were significantly less in Lansome. Total S uptake of the crop in Lansome was less than half of that in Mill Dam Close, which was similar to the amount normally found in a S sufficient crop. Both soils are of light texture (loamy sand and sandy clay loam for the Cottenham and Blithe series, respectively), and there was little difference in the extractable S concentration in the topsoils between the two fields. However, more extractable S was found in the subsoil of Blithe series, because it contains more free Fe and Al oxides and has a lower pH. These results show that any evaluation of the soil S supply needs to take into account the pool of available S in the subsoil.
Mobilization of aluminium in soil by acid deposition and its uptake by grass cut for hay – a Chemical Time Bomb
Authors: Blake L. , Johnston A.E. , Goulding K.W.T.
Published: February 2007

Abstract. Analyses of soil and hay samples collected from the Park Grass Experiment at Rothamsted during the last 137 years indicate slow but significant increases in KCl‐ and EDTA‐extractable aluminium in soil and a sudden and very large recent increase in the concentration of aluminium in the herbage. The latter is associated with a sudden increase in the rate of acidification of the soil over the last 10–15 years and the mobilization of aluminium as the soil enters the aluminium buffer range ‐a Chemical Time Bomb. Such severe acidification from atmospheric inputs on a well‐buffered soil illustrates how quickly an apparently stable situation can change as a result of acid deposition. It highlights the need to protect soils and plants from the effects of acidification by decreasing acid inputs or by liming.
Nutrient depletion in Ferralsols under hybrid sisal cultivation in Tanzania
Authors: Hartemink A.E. , Van Kekem A.J.
Published: February 2007

Abstract. Sisal production in Tanzania has declined sharply in the past two decades because of a decrease in the area grown and a decrease in yields. As sisal is cultivated without manuring, depletion of soil fertility is considered one of the main causes of the declining yields. This paper presents a balance of the macronutrients N, P, K, Ca and Mg for sisal grown in a plantation in NE Tanzania on deep, red clay soils (Ferralsols). Annual fibre yields declined from 2.5 t/ha in the 1960s to about 1 t/ha in the 1980s. Hybrid sisal is a demanding crop and in ten years, with a total fibre yield of 11 t/ha, about 260 kg of N, 40 kg of P, 385 kg of K, 890 kg of Ca and 330 kg of Mg are removed in the harvested leaves. A comparison of soils after two and three 10‐yr cycles of sisal production showed that in the third cycle the pH decreased by 0.5 units and that exchangeable bases were decreased by fifty per cent or more. The amounts of K, Ca and Mg removed from the soil were similar to those in leaves. However, soil analyses could not detect changes in total N and available P, possibly because of the large amount of total N in the soil and the lack of precision in the N and P analyses. In the Ferralsols, potassium is likely to become deficient first, followed by magnesium and calcium. The soil has little available P, and an increase in soil acidity may decrease it further and also create aluminium and manganese toxicities. In order to maintain sisal production, fertilization with P, K, Ca and Mg is necessary, and to improve yields N must also be applied.
Nitrate leaching in field lysimeters at an agricultural site in Zimbabwe
Authors: Kamukondiwa W. , Bergström L.
Published: February 2007

Abstract.Nitrate leaching in lysimeters containing a tropical sandy agricultural soil was studied over two summers with maize (Zea maysL.) and one winter season with wheat (Triticum aestivumL.). The treatments included two moisture regimes and two nitrogen sources, cattle manure and inorganic fertilizer‐N (either ammonium nitrate or ammonium sulphate) applied at 100 kg N/ha in the summers. Neither manure nor fertilizer‐N was applied in the intervening winter. Leachate volume from the manured lysimeters was mostly larger than from fertilized ones because of poor growth and less evapotranspiration. The largest seasonal nitrate loads (17–39 kg N/ha) were obtained in the wet summer immediately after installation of the lysimeters. Nitrate loads in winter (3.7–18.6 kg N/ha) were larger than those obtained in fertilized (0.6 and 9.3 kg N/ha) and manured (0.3 and 3.0 kg N/ha) lysimeters for the two moisture regimes in the second summer. The drier conditions in the second summer decreased N‐mineralization and leaching of manure.
Integration of biophysical and economic data using an expert system: results from a case study in northern Australia
Authors: Johnson A.K.L. , Cramb R.A. , McAlpine J.R.
Published: February 2007

Abstract. Biophysical and economic data from numerous sources are integrated using the ALES expert system. A systematic approach to data collection and evaluation procedure is presented. The collection of management data is emphasized if management and crop yield data are to be adequately correlated. Different land utilization types are evaluated for numerous land mapping units. The results show that direct comparison of land mapping units is possible both within and between different land utilization types. Use of the model enabled objective relationships to be developed between biophysical criteria, crop productivity and management, allowing economic measures of performance to be routinely determined for large databases. The study shows that land mapping units with the most favourable physical suitability class may not necessarily have the largest net return and that the best lands are determined not only by their ability to produce high yields but also their ability to achieve them at the least cost.
Water treatment sludge: a potential plant growth medium
Authors: Skene T.M. , Oades J.M. , Kilmore G.
Published: February 2007

Abstract. The disposal of water treatment sludge produced when turbid water is treated with flocculants (alum and polyDADMAC) and filtered for clarification is becoming increasingly expensive in South Australia. The physical and chemical properties of the sludge suggest that it might be used as a plant growth medium, and a glasshouse experiment compared the growth and elemental composition of broad beans in both alum and polyDADMAC sludge applied at different rates.

Dry matter production differed significantly between treatments. Poly + Fertilizer (F) and Poly 4%+ F produced the most dry matter. The Alum + F treatment produced significantly less dry matter than the Poly + F treatment but it was not significantly different from the control. The difference in plant growth between the pure poly and pure alum treatments resulted from increased availability of the fertilizer phosphorus in the poly sludge and the supply of some potassium and nitrogen by the poly sludge. Fertilizer was required for optimum plant growth. Greater rates of fertilizer may be required if alum sludge is to be used as a growth medium, than if poly sludge is used.

There was no evidence that aluminium toxicity would be a problem if water treatment sludges are used as growth media. The physical properties of the sludges (i.e. water holding capacity, drainage characteristics and structural stability) are probably more important than their inherent nutrient levels, although poly sludge does supply some nitrogen and does not fix phosphorus to the same extent as alum sludge.