ALBERT

Notizen: The effect of haze in vertical daylight air photography for various solar altitudes is considered. If appreciable haze is present the density of negatives exposed when the solar rays are inclined to the vertical at angles less than the lens field semi-angle may vary over the field to such an extent that the photographs will be unsuitable for survey purposes. A theoretical investigation is made and practical results analysed. Methods by which the phenomena may be avoided are suggested. The effect on negative density of the variation in shadow length across the picture is also discussed.

Notizen: In Part I the visual processes involved in depth perception are briefly described and discussed, while in Part II their application in stereo plotting and allied observations is considered. Reference is made to the visual axis, the need for and nature of eye movements, the conception of the horopter space within which fusion of the binocular images occurs and objects are seen in three-dimensions, and the tolerances for fusion implied by the existence of Panum's areas. Monocular clues make an important contribution to the perception of depth, and the apparent location of an object in space is determined by the factors of retinal disparity, convergence, angular size, perspective, motion parallax, elevation, aerial haze, etc. The following problems are then discussed: The significance of the horopter in relation to the general contour in a stereo photograph; the fusion of the images in a stereo plotting machine; the arguments for and against some convergence of the eyepiece axes; the special problems of spectacle wearers; the functions of field stop. An analysis of the visual task in contour plotting is attempted, but a more complete analysis would be possible if records were available of the observer's eye movements while plotting. Finally, chromatic aberration in relation to the Multiplex system is considered, and also in connection with the stereoscopic effect observed with differently coloured objects lying in a plane.

Notizen: The object of this paper is to provoke discussion and not to present a finished study. It deals briefly with quantitative analysis of drainage patterns in geomorphological studies and refers to methods that have recently received some attention in the United States. It points to the value of aerial photographs in such studies and asks for discussion of two important points: firstly, whether the mathematical approach is soundly based; and, secondly, whether the analytical method is likely to give useful practical results.

Notizen: Abstract. Brownfield sites often require a geochemical survey to assess the extent of contamination that is present as a result of previous industrial activities. These measurements are subsequently assessed to ascertain whether the site presents the possibility of causing significant harm to those who may use the site for specified purposes. The measurement process comprises both field sampling and chemical analysis, with sampling being of crucial importance, since previous studies have repeatedly shown that it is the sampling phase that generates the highest component of uncertainty. A variety of methods are currently available for sampling brownfield sites, such as different sampling patterns and the choice of depth and mass recovered. An investigator may also choose to employ more innovative sampling methods, such as in situ measurement strategies that can significantly reduce the overall time taken to complete the survey. The general aim of a sampling strategy is to take representative samples for chemical analysis, although this is rarely achieved due to the inherent heterogeneity of contaminants within any given site. Since it is practically impossible to sample an entire site, and thus achieve a truly representative sample, it is becoming increasingly understood that the uncertainty of the measurements should be estimated, to provide a more reliable interpretation of the survey. Various methods are currently available to estimate the measurement uncertainty that arises from both sampling and analysis, which vary in terms of complexity and cost. The level of uncertainty estimated during a site investigation should also be judged on its fitness-for-purpose (i.e. whether subsequent decisions based upon it are acceptable). The ‘optimized contaminated land investigation’ (OCLI) method is a new approach that can be used to balance the site-specific variables of any given investigation, such as the measurement costs against the level of uncertainty and costs that may arise from misclassification. This provides an objective and traceable judgement of whether the measurements are fit-for-purpose.

Notizen: Abstract. Nuclear weapons' testing, mineral extraction industries and nuclear power generation are among the activities which have led to radioactively contaminated land. In the United Kingdom (UK), current activities such as the decommissioning of nuclear licensed sites and the sale of Ministry of Defence land require that the legislation, remediation and management of radioactively contaminated land be addressed. With an emphasis on the UK, this paper reviews potential management/remediation strategies for radioactively contaminated land, including consideration of the environmental mobility of potentially important radionuclides.

Notizen: Abstract. Methods that can be used to determine the distribution of metal species in soil solution are critically reviewed and assessed. They are divided into two groups: those that can provide free ion activity, and those that measure labile species in solution. Ion selective electrodes have long been regarded as a promising technique, but there are practical problems in performing accurate measurements and only the Cu electrode has been used routinely. The Donnan membrane technique is capable of measuring the free ion activity of many metals, but adequate sensitivity can be a problem. Although resin competition methods are versatile, care must be exercised to avoid perturbing the solution excessively. Anodic stripping voltammetry (ASV) measures labile species, so the approximation involved in interpretation as simple inorganic species, from which free ion activities can be derived, should be recognized. Diffusive gradients in thin-films also measures labile species, but it is applicable to a much wider range of metals than ASV. It requires larger volumes of solution, but it can be used directly on the whole soil where it also measures the metal that can be rapidly supplied to solution. Other techniques such as permeable liquid membranes have yet to be used for measurements on soil solution. All of these methods have strength and weaknesses, and measure different aspects of speciation. Knowledge of the availability of the metals to biota is likely to be best advanced by the critical use of one or more of these speciation methods with a thorough understanding of exactly what is being measured.

Notizen: Abstract. Effective use and recycling of manures together with occasional and judicious use of supplementary fertilizing materials forms the basis for management of phosphorus (P) and potassium (K) within organic farming systems. Replicated field trials were established at three sites across the UK to compare the supply of P and K to grass–clover swards cut for silage from a range of fertilizing materials, and to assess the usefulness of routine soil tests for P and K in organic farming systems. None of the fertilizing materials (farmyard manure, rock phosphate, Kali vinasse, volcanic tuff) significantly increased silage yields, nor was P offtake increased. However, farmyard manure and Kali vinasse proved effective sources of K to grass and clover in the short to medium term. Available P (measured as Olsen-P) showed no clear relationship with crop P offtake in these trials. In contrast, available K (measured by ammonium nitrate extraction) proved a useful measurement to predict K availability to crops and support K management decisions.

Notizen: Abstract. Sodic and saline–sodic soils are characterized by the occurrence of sodium (Na+) at levels that result in poor physical properties and fertility problems, adversely affecting the growth and yield of most crops. These soils can be brought back to a highly productive state by providing a soluble source of calcium (Ca2+) to replace excess Na+ on the cation exchange complex. Many sodic and saline–sodic soils contain inherent or precipitated sources of Ca2+, typically calcite (CaCO3), at varying depths within the profile. Unlike other Ca2+ sources used in the amelioration of sodic and saline-sodic soils, calcite is not sufficiently soluble to effect the displacement of Na+ from the cation exchange complex. In recent years, phytoremediation has shown promise for the amelioration of calcareous sodic and saline–sodic soils. It also provides financial or other benefits to the farmer from the crops grown during the amelioration process. In contrast to phytoremediation of soils contaminated by heavy metals, phytoremediation of sodic and saline–sodic soils is achieved by the ability of plant roots to increase the dissolution rate of calcite, resulting in enhanced levels of Ca2+ in soil solution to replace Na+ from the cation exchange complex. Research has shown that this process is driven by the partial pressure of CO2 (PCO2) within the root zone, the generation of protons (H+) released by roots of certain plant species, and to a much smaller extent the enhanced Na+ uptake by plants and its subsequent removal from the field at harvest. Enhanced levels of PCO2 and H+ assist in increasing the dissolution rate of calcite. This results in the added benefit of improved physical properties within the root zone, enhancing the hydraulic conductivity and allowing the leaching of Na+ below the effective rooting depth. This review explores these driving forces and evaluates their relative contribution to the phytoremediation process. This will assist researchers and farm advisors in choosing appropriate crops and management practices to achieve maximum benefit during the amelioration process.

Notizen: Abstract. Large nitrogen (N) inputs to outdoor pig farms in the UK can lead to high nitrate leaching losses and accumulation of surplus N in soil. We investigated the residual effects of three contrasting outdoor pig systems as compared to an arable control on nitrate leaching and soil N supply for subsequent spring cereal crops grown on a sandy loam soil during 1997/98 and 1998/99 harvest seasons. Previously, the pig systems had been stocked for 2 years from October 1995 and were designated current commercial practice (CCP, 25 sows ha−1 on stubble), improved management practice (IMP, 18 sows ha−1 on undersown stubble) and best management practice (BMP, 12 sows ha−1 on established grass). Estimated soil N surpluses by the end of stocking in September 1997 were 576, 398, 265 and 27 kg ha−1 N for the CCP, IMP, BMP and continuous arable control, respectively. Nitrate leaching losses in the first winter were 235, 198, 137 and 38 kg ha−1 N from the former CCP, IMP and BMP systems and the arable control, respectively. These losses from the former pig systems were equivalent to 41–52% of the estimated soil N surpluses. Leaching losses were much smaller in the second winter at 21, 14, 23 and 19 kg ha−1 N, respectively. Cultivation timing had no effect (P〉0.05) on leaching losses in year 1, but cultivation in October compared with December increased nitrate leaching by a mean of 14 kg ha−1 N across all treatments in year 2. Leaching losses over the two winters were correlated (P〈0.001) with autumn soil mineral N (SMN) contents. In both seasons, spring SMN, grain yields and N offtakes at harvest were similar (P〉0.05) for the three previous pig systems and the arable control, and cultivation timing had no effect (P〉0.05) on grain yields and crop N offtake. This systems study has shown that nitrate leaching losses during the first winter after outdoor pig farming can be large, with no residual available N benefits to following cereal crops unless that first winter is much drier than average.

Notizen: Abstract. Soil organic carbon stocks to 1 m for Brazil, calculated using an updated Soil and Terrain (SOTER) database and simulation of phenoforms, are 65.9–67.5 Pg C, of which 65% is in the Amazonian region of Brazil. Other researchers have obtained similar gross results, despite very different spatial patterns mapped due to use of different methods.

Notizen: Abstract. The effects of rice-straw management (incorporation, burning or removal) on soil organic carbon content and physical and hydraulic properties were determined after five years of rice–wheat cropping in a sandy loam soil in northwest India. Soil organic carbon content was greater with straw incorporation and straw burning than with straw removal, and aggregation status, total porosity, pore-size distribution, bulk density, dispersion ratio and soil strength were correspondingly improved. The treatment effects were confined mainly to the 0–5 cm depth. Water retention was less with straw burning than straw removal, owing to increased water repellency of the soil surfaces. Cumulative infiltration and its rate after five hours were greater with straw incorporation than straw burning or removal. Air entry values were unaffected by straw management; however, the values were greater after rice harvest than after wheat harvest.

Notizen: Abstract. A field study was conducted to assess the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), applied at a rate of 1 kg ha−1, on nitrous oxide (N2O) emissions, forage production and N extraction from a grassland soil after cattle slurry applications in autumn and spring. Nitrous oxide emissions were measured daily or weekly using the closed chamber technique. DMPP efficiency after slurry application was lower in spring (16.7 °C mean soil temperature) than in autumn (11.4 °C mean soil temperature). Thus, DMPP was able to maintain soil mineral N in the ammonium form for 22 days and reduce cumulative N2O emissions by 69% in autumn, while in spring its effect on soil mineral N lasted for 7–14 days, reducing cumulative N2O losses by 48%. Furthermore, application of DMPP after slurry did not decrease biomass yield or N uptake.

Notizen: Abstract. Nutrient losses from arable land are important contributors to eutrophication of surface waters, and phosphorus (P) and nitrogen (N) usually act together to regulate production of Cyanobacteria. Concentrations and losses of both nutrients in drainage water from pipe drains were studied and compared in 15 crop rotations on a clay soil in southwest Sweden. Special emphasis was placed on P and it was possible to evaluate critical components of the crop rotations by flow-proportional water sampling. Total P concentrations in drainage water were generally small (0.04–0.18 mg L−1), but during two wetter years out of six, high P concentrations were measured following certain management practices, including ploughing-in lucerne (Medicago sativa L.) and fertilizing in advance without incorporation into the soil to meet the needs of several subsequent crops. This resulted in average flow-weighted concentrations of total P between 0.3 and 0.7 mg L−1. In crop rotations containing green manures, green fallow or leguminous leys, there was also a risk for increased P losses after these crops were ploughed in. The losses increased in the order: cash crops 〈 dairy with grass 〈 dairy with lucerne 〈 monoculture with barley 〈 organic farming with cattle slurry 〈 stockless organic farming with green manure. P balances varied between −9 and +8 kg P ha−1 and N balances between +4 and +35 kg N ha−1. The balances were not related to actual leaching losses. Phosphorus losses in drainage from set-aside were 67–82% of those from cash crops grown in ploughed and P-fertilized soil at the same site, indicating a high background P loss from this clay soil.

Notizen: Abstract. Changes in surface soil properties of a savanna Alfisol under cultivation with applications of manure and inorganic NPK fertilizer were evaluated after 45 years of annual cropping. Soils from treatments with fertilizer only, fertilizer in combination with farmyard manure (FYM) at both high and low rates were compared to soil from a control receiving neither fertilizer nor manure. The high rate of FYM and fertilizer significantly improved soil aggregation, increased C, N and P status, while reducing soil penetration resistance. The results showed that there is a need to use both manure and inorganic fertilizer to maintain soil fertility in savanna soils under continuous cultivation.

Notizen: Abstract. Vertisols are among the most common, high-potential soils in the central highlands of Ethiopia, where over 88% of human and 77% of the livestock population are located. Productivity from these soils is constrained by severe waterlogging due to their physical properties and intensive rainfall in summer. Traditionally, farmers plant late in the season to avoid the waterlogging, which results in harvest yields that are far below optimal. To bridge this yield gap, the broad-bed and furrow system for surface drainage has been introduced. Despite reported yields of various crops, little is known of the on-site and off-site impacts of this system. Consequently, four land preparation methods viz. (i) broad-bed and furrow (BBF), (ii) green manure (GM), (iii) the traditional system of ridge and furrow (RF) and (iv) reduced tillage (RT) were compared on standard runoff plots for 5 years (1998–2002) at Caffee Doonsaa in the central Highlands of Ethiopia. Runoff, sediment, organic carbon and nutrient (organic nitrogen and available phosphorus) losses were determined during the last two years (2001 and 2002). Over 50% of the seasonal rainfall was lost as runoff, regardless of the treatment, with significantly more of the excess water running off BBF and RT treatments in both years. The BBF system drained 67% and 54% of rainfall as runoff in 2001 and 2002, respectively, compared with 61% and 53% from the RT system during the measurement period. Although not statistically significant, the largest sediment and total nutrient losses tended to be from the BBF. The effect of the treatments on total nutrient loss and enrichment ratio was inconsistent. The nutrient concentration in the eroded sediment was greater than that of the originating surface soil but was strongly correlated. The effect of the land preparation methods was significant and varied with crops. Recommended options for best crop productivity are BBF for lentil and RT for wheat and tef.

Notizen: Abstract. Soil organic matter (SOM) controls the physical, chemical and biological properties of soil and is a key factor in soil productivity. Data on SOM quantity and quality are therefore important for agricultural sustainability. In 1990, an experiment was set up at Saria, Burkina Faso on a sandy loam Lixisol to evaluate long-term effects of tillage (hand hoeing or oxen ploughing) with or without 10 t ha−1 yr−1 of manure and fallowing on SOM and N concentrations and their distribution in particle size fractions. The field was sown annually to sorghum (Sorghum bicolor [L.] Moench). Ten years later, total organic C and total N, SOM fractions and their N concentrations, and sorghum yield were determined. Continuous sorghum cultivation without organic inputs caused significant losses of C and N in the hoed and ploughed plots. However, addition of manure to hoed plots was effective in maintaining similar levels of C and N to fallow plots. Without manure, SOM was mainly stored in the size-fraction 〈0.053 mm (fine organic matter, FOM). SOM was mainly stored in the size-fraction between 0.053 and 2 mm (particulate organic matter, POM). In plots with manure and in fallow plots, the addition of manure more than doubled POM concentrations, with levels in tilled plots exceeding those of the fallow plots, and the highest levels in manually hoed plots. Nitrogen associated with POM (POM-N) followed a similar trend to POM. Hoeing and ploughing led to a decline in sorghum grain yield. Manure application increased yields by 56% in the hoed plots and 70% in the ploughed plots. Grain yield was not correlated with total SOM but was positively correlated with total POM. This study indicated that POM was greatly affected by long-term soil management options.

Notizen: Abstract. The impact of different tropical farming systems on soil quality was examined using a systematic sampling strategy. Total organic C, pH, extractable P, exchangeable K, bulk density, water stable aggregates, microbial biomass C, cation exchange capacity, soil depth, and clay content were determined. An assessment framework, including a minimum data set, linear scoring functions and weighted additive indices, was used to evaluate the soil quality of a tropical farm growing various crops in Hainan, China. Soil quality was evaluated according to four functions: water availability, nutrient availability, rooting suitability, and erosion resistance. Our results showed that soils were intrinsically lacking in nutrients and vulnerable to degradation, and that these problems were exacerbated by inappropriate management. There was strong evidence that long-term rubber farming caused soil acidification, soil compaction, and depletion of organic matter and nutrients. By contrast, conservation practices in coffee plantations protected or improved organic matter concentration and soil structure, resulting in higher soil quality indices.

Notizen: Abstract. The practice of large phosphorus (P) additions to agricultural land has resulted in an increased depletion of limited mineable rock phosphate resources, P accumulation in soils with an increased risk for P losses, and intensified eutrophication and deterioration of water quality in recipient water bodies. A number of measures have been used to reach balance between P inputs and outputs in agricultural systems, with the goal of achieving improved P use efficiency, sustained high crop yields and reduced P losses. This paper discusses how this goal may be achieved. Results from a Swedish long-term fertility experiment combined with results of a P leaching study using a selection of soils from the fertility experiment are used to evaluate the effects of a balanced P system on yields, soil P levels and P leaching. Three P fertilizer application strategies are compared (zero P, replacement P, and a treatment where surplus P fertilization was used to achieve a rapid increase in the soil P status). The replacement P strategy appeared to be the most sustainable system but P fixation in this system must be accounted for. When surplus P rates were applied, increased crop yields were counterbalanced by poorer use efficiency and P accumulation in soil. Topsoil P content was a poor predictor of P leaching. Instead, balancing P inputs and outputs represents a first step in the management of P losses, but additional, site-specific measures are required to counteract site-specific factors responsible for P losses.

Notizen: Abstract. The regulatory regime for contaminated soils and groundwater in the UK is risk based. Indeed, the definition of contaminated land in UK law requires the presence, or likelihood, of significant pollution or harm before affected land meets the statutory test of being contaminated land. In dealing with contamination, a risk management approach is used that also requires the consideration of wider land-use planning priorities, the costs and benefits of remedial action, and the goal of achieving sustainable development. A parallel risk-based framework is adopted for polluted groundwater. The risk assessment process adopted for contaminated groundwater in the UK follows a tiered structure. A simple conceptual model is developed from desk study and site reconnaissance. This model is then used as the basis for designing a site investigation programme, the sampling being undertaken to test assumptions within the model as well as to develop it further. The Environment Agency (England & Wales) has developed a package of tools to aid this tiered approach. This paper describes the integrated risk assessment and risk management processes for contaminated groundwater in the UK, with emphasis on the tools and methods developed. It explains the importance of a conceptual understanding (or model) to all tiers of risk assessment and subsequent risk management.

Notizen: Abstract. Sustainable management of nutrients in agricultural systems is critical for sufficient production of nutritious foods and to minimize environmental pollution. In this overview, we discuss some of the most important factors influencing nutrient cycling, and how practices for sustainable nutrient management can be optimized. In most cases, problems are associated with excessive use of nutrients (manures, other organic amendments, and inorganic fertilizers). Options for dealing with such problems at the farm level include: reducing nutrient inputs to balance exports, increasing the land area on which manures are applied, and export of excess nutrients from the farm in the form of value-added products. These strategies can be used singly, or in combination. Nutrients in the human food chain are often not recycled back to primary crop production. To manage such issues, and avoid regional nutrient accumulations, we need to develop a better understanding of large-scale nutrient flows, and develop policies to manage them. We stress the importance of scale when considering nutrient management in the future.

Notizen: Abstract. The practice of large phosphorus (P) additions to agricultural land has resulted in an increased depletion of limited mineable rock phosphate resources, P accumulation in soils with an increased risk for P losses, and intensified eutrophication and deterioration of water quality in recipient water bodies. A number of measures have been used to reach balance between P inputs and outputs in agricultural systems, with the goal of achieving improved P use efficiency, sustained high crop yields and reduced P losses. This paper discusses how this goal may be achieved. Results from a Swedish long-term fertility experiment combined with results of a P leaching study using a selection of soils from the fertility experiment are used to evaluate the effects of a balanced P system on yields, soil P levels and P leaching. Three P fertilizer application strategies are compared (zero P, replacement P, and a treatment where surplus P fertilization was used to achieve a rapid increase in the soil P status). The replacement P strategy appeared to be the most sustainable system but P fixation in this system must be accounted for. When surplus P rates were applied, increased crop yields were counterbalanced by poorer use efficiency and P accumulation in soil. Topsoil P content was a poor predictor of P leaching. Instead, balancing P inputs and outputs represents a first step in the management of P losses, but additional, site-specific measures are required to counteract site-specific factors responsible for P losses.

Notizen: Abstract. Sustainable nutrient management includes economizing on finite natural resources such as fossil energy and limited phosphorus (P) resources. Arable farms with exclusively crop production are characterized by large nutrient export in farm products. In the long term, nutrient export from soils and losses must be balanced by adequate inputs of fertilizers, biological N2 fixation or recycled products from the human food system. Critical issues associated in particular with arable systems discussed in this paper include organic matter depletion and lack of synchronization between nitrogen (N) release from organic N pools (such as plant residues and green manures) and crop demand, leading to N losses and/or N deficiency. Further critical issues identified include efficient use of indigenous soil P and applied P fertilizers and, especially in organic systems, risk of depletion of P and K, which if realized reduce soil fertility and limit production. The risk of enrichment of trace elements to levels toxic to soil microbes, plants, animals or man is also discussed. Suggested measures for managing these critical issues include choice of crop rotation, residue and green manure management.

Notizen: Abstract. The intensity of animal production around the world has increased substantially during the last half-century, which has led to large problems with the disposal of manures and waste waters. The focus of this paper is on the development of national policies to improve the nutrient management of concentrated animal feeding operations (CAFOs), where nutrients are invariably in surplus. To create proper nutrient management strategies for CAFOs, and to avoid environmental problems when surplus nutrients enter air, soil and water, we need to know the number of animals/birds in the unit, the quantity of manure/slurry produced, how this material is stored and handled and how much land is available for manure spreading. In this paper, we discuss the development of nutrient management strategies for CAFOs in Europe and North America, and the voluntary measures and environmental regulations related to this. For the planning of nutrient management to be comprehensive and efficient, we need expertise from several disciplines. This planning includes development of: animal diets that reduce the amounts of excreted nutrients; efficient storage and land application technologies; land application programmes to optimize yields and reduce nutrient losses; and strategies for use of excess manure outside the farm. Also, large-scale efforts involving many stakeholders (farmers, governments and private industry) are needed to solve problems with nutrient imbalances over the long term. Efforts along these lines include manure relocation, alternative uses of manures, nutrient trading, and a general extensification of animal agriculture. The overall guiding principle for policies and planning should be a balance of nutrients, on farms as well as at larger scales.

Notizen: Abstract. To establish strategies for sustainable nutrient management, the priority of each identified element for different user groups and the issue of data transferability from one scale to the next need to be addressed. This is important to avoid developing policies and strategies using inaccurate data. This paper provides a thorough background on such issues and provides data from specific case studies to reflect the impact of scale on the usability and transferability of data. These data show that using information obtained in a laboratory setting for larger scales can generate major errors. Data are also provided regarding the spatial variability in total N and total P measured at different sub-watersheds within a large watershed. Results from this case study indicate that there is a definite spatial variability in N and P loadings, which makes it difficult to transfer and extrapolate from data measured at one sub-watershed to the entire watershed. Therefore, it can be concluded that using either measured or simulated data obtained at a small scale to respond to questions for larger scales may be erroneous. Such difficulty may be due to the inherent spatial variability in soils, nutrients, biology and other features of the landscape.

Notizen: Abstract. This paper describes the development and application of a simple empirical model describing differences in water movement through a cracking clay soil at Brimstone Farm, Wiltshire, UK. An extended data set comprising readings of soil water tension has been collected from an area of 9 m2 instrumented with 4 nests each of 3 tensiometers. The cracks are responsible for considerable differences both in water pathway and flow magnitude. Variations in water flow suggested by changes in soil-water tension are described by a model developed using ‘ModelMaker’ and applied separately to each profile nest. The model envisages water flow to occur through three soil layers, and to be partitioned into matrix and macropore flow components. Water is lost via drainage to clay tile drains at 60 cm depth. Water flow between layers is described as a function of the hydraulic gradient using Darcy's Law, with additional drainage from structural voids within the soil. Differences in the effective hydraulic conductivity describing slow and rapid flow components equate to macro and matrix flow for each tensiometer profile. The results illustrate heterogeneous patterns of flow through a soil block and demonstrate that a comparatively simple model is able to represent satisfactorily water flow dynamics through a cracking clay soil.

Notizen: Abstract. To evaluate the effect of sea salmon sludge on soil and ryegrass yield and quality, five treatments were tested (30, 60 and 90 t ha−1 of sludge, inorganic fertilizer and control). The sludge contained 16% dry matter (DM), 0.13% total N and 1.6% P. The sludge increased ryegrass DM yield, P and Na content, but decreased K concentrations in soil and plants. Sludge can be applied successfully on to land, but its addition should be complemented with inorganic nutrients (N, K). The high Na content of the sludge may limit repeated application, but the main benefit is its P content.

Notizen: Abstract. Soils contaminated with organic chemicals are now widespread in industrialized and developing countries, and the risk assessment and remediation of such contaminated sites is a priority. However, containment and remediation strategies are complicated in many cases by the range of contaminants present and the historical nature of the contamination. Research has increased our understanding of the behaviour of organic contaminants in soil and the factors that control their behaviour. There is a fundamental need to understand and, where possible, quantify the bioavailable fraction as well as the total concentration of contaminant present in soil: the bioavailable fraction is key to toxicity or biodegradation. To quantify these fractions, a large number of techniques have been employed, ranging from organic and aqueous based solvent extractions to the use of biota. Many studies have been carried out investigating the use of chemical techniques to describe bioavailability, which could be used in the assessment and remediation of contaminated land. The aim of this review is to consider the behaviour of organic contaminants in soil, highlighting issues of bioavailability, and then to discuss the relevance of the various methods for assessing risk and potential remediation of organic contaminants in soil.

Notizen: Abstract. Fertilizer and manure application rate and timing are often based on the optimal nitrogen rate and not on potassium (K) requirements. This can lead to excess or shortage of K depending on the crop and rotation. In grass-dominated agricultural production, including many organic farming systems, K has become a critical element, especially in areas dominated by coarse-textured or organic soils. In this paper we review K management in relation to long-term sustainability of both the soil resource and the production of crops of high yield and quality. One question for the future is whether we can adopt management options that favour efficient use of K and secure a sustainable future for global K reserves. For example, is it possible to enhance the release rate of K from soil mineral sources so that we require less fertilizer K from K-bearing salt deposits? A reduction in external K inputs requires improved on-farm recycling of K in order to reduce losses. We also need a better understanding of soil processes and soil-plant interactions and decision-support tools to predict the potential K release from mineral weathering. Certain areas dominated by young, clay-rich soils can potentially supply enough K, whereas other areas with coarse sandy or organic soils have a very low weathering potential and would thus need external inputs of K.

Notizen: Abstract. Changes in agricultural subsidies in Europe and the ready availability of fertilizers have allowed a spatial decoupling of livestock and crop production. This has increased the flow of nutrients that occurs between farms compared to within individual farms. In terms of nutrient cycling, mixed farms provide the opportunity to re-integrate aspects of agricultural production. The degree of integration between crop and livestock production is denned by the reliance on the use of home-produced feed compared to imported feed, and is independent of intensity. Management of inputs and/or internal flows offers the scope to improve nutrient use efficiency (NUE) on mixed farms. Greatest uncertainties in calculating NUE are associated with variation in yield and composition of home-produced feed, and consequent manure composition. Three key areas are addressed to highlight the interchange of nutrients (and risks for losses) between crop and livestock production; (i) the role of livestock diet in manipulating the amount and availability of manure nutrients; (ii) the impact of manure management on nutrient losses; and (iii) nutrient management through the integration of crops and livestock in rotations. While not all the associated issues are unique to mixed farming, these three areas all influence NUE.

Notizen: Abstract. This paper highlights the principal problems related to the recycling of municipal wastes to arable land and outlines future solutions. History reveals that transport of sewage with water was introduced early (2500 bc), but only some Asian societies, which did not utilize sewage flushing, redistributed toilet wastes to arable land effectively. Nutrient flow analyses in developed countries indicate a withdrawal of 20 kg N and 3kgP ha−1 yr−1 from arable land because of non-return of organic human wastes. Limited reuse of municipal organic wastes in agriculture in several European countries is often seen as a question of waste quality. However, we believe that despite acceptable quality levels only minor progress in recycling has been achieved. Higher water contents in organic wastes than in harvested crops and, consequently, high costs for drying or transportation of wastes, often in combination with non-optimal plant nutrient composition, will remain the bottleneck which restricts the recycling of nutrients in wastes. One solution is to extract nutrients out of organic wastes and thereby derive concentrated compounds similar to those in inorganic fertilizers that can be redistributed and applied to soil. The challenge for modern sewage treatment systems is to shift perspective from removal to recovery of nutrients.

Notizen: Abstract. The Pan-European Soil Erosion Risk Assessment (pesera) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha−1 yr−1 with a maximum error of 1.49 t ha−1 yr−1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7-month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over-riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha−1 yr−1, compared to a soil erosion rate of 0.04 t ha−1 yr−1, which can be tolerated for protecting the area for the sea turtle.

Notizen: Abstract. The compilation of a database of soil carbon and land use is described, from which models of soil carbon dioxide emissions across the United Kingdom (UK) can be run. The database gives soil organic carbon, sand, silt and clay contents and bulk densities weighted to reference layers from 0 to 30 cm and from 30 to 100 cm depths. The data are interpolated from information on soil types and land use on a 1 km grid across the UK and are used to estimate soil carbon stocks. For 1990, the baseline year for the Kyoto Protocol on carbon emissions, the estimate is 4562 Tg soil organic carbon in the top 1 m of soil across the UK, with an average density of 18 kg m−2. The data can be reported by layer (e.g. 54% in topsoils) and country (e.g. 48% in Scotland) as well as by soil and land type.

Notizen: Abstract. We examined the use of soil quality (SQ) assessment to predict soil productivity and stability as a component of site potential for rangelands. Two minimum sets of data were compared for the SQ assessment within an area of relatively uniform climate. Data set 1 consisted of total soil N, topsoil depth, effective profile depth (EPD), and grade of structure, thus incorporating only soil chemical and physical properties. Data set 2 included exchangeable soil potassium, EPD, soil water retention capacity at wilting point, a soil slake test, and a nutrient cycling index. The interrelationships between soil properties and plant growth characteristics (i.e. total and herbage yield) were investigated and interpreted by statistical analysis and expert knowledge. By performing multiple regressions for each data set against the plant growth characteristics, we identified the contribution of each data set variable to the variability in plant characteristics and, thus, the predictive potential of each variable and data set. Within data set 1, EPD was important and in data set 2 the nutrient cycling index, which is a landscape function index derived from soil surface attributes, played the most important role in predicting potential. Principal component analysis was used to provide weighting factors for each indicator. We then transformed and combined observed indicator values for each data set using weighting factors and scoring functions into an additive soil quality index (SQI) varying in value from 0 to 1. The SQIs, with values greater than 0.8, provide optimum conditions for high yield.

Notizen: Abstract. Saprolite is formed from bedrock weathered in situ that retains the structure and fabric of the parent rock. Landscaping in hilly and rugged topography with unavoidable land levelling exposes saprolites, which are often associated with poor growth of trees and shrubs. In Malaysia, the suitability of saprolites derived from basalt, granite and schists for growing trees and palms was assessed from their physical and chemical properties. Following FAO guidelines all the saprolites were adjudged to be unsuitable due to wetness, shallowness and low chemical fertility as the main limitations.

Notizen: Abstract Diverter berms are used to control soil erosion along restored pipeline corridors between the time the pipe is installed and the establishment of a vegetation cover. Current practice, based on standard design procedures, is often inadequate in areas of steep slopes and erosive rainfall because the resulting berm channels are too steeply graded and too widely spaced, and insufficient attention is given to their outlets. The Universal Soil Loss Equation provides a more flexible procedure for determining the spacing required to achieve a specified erosion target for given conditions of rainfall, soils and slopes. Where the required spacings are not feasible because they are too close, spacings should be based on ensuring that flow velocity does not exceed 80% of the maximum non-eroding velocity, and additional supporting erosion-control measures should be provided. Channels should be graded at 0.4% and the grade should never exceed 2%. The choice of type of outlet should be determined by the erodibility of the soil, the steepness of the slope, vegetation cover and whether the outlet slope is on undisturbed or made-up ground. Broad-based berms should be used as an alternative to narrow-based ones where there is a risk of damage from vehicles.

Notizen: Abstract. Different types of contaminants such as polycyclic aromatic hydrocarbons (PAHs) and metals coexist in different chemical forms in soil. Although bioremediation of organics has been widely studied, little attention has been paid to changes in metal behaviour during the bioremediation process. In this study, the diffusion gradient in thin-film (DGT) technique was used to assess changes in potentially bioavailable Cd and Cr fluxes in soil during the bioremediation of phenanthrene. Fluxes of Cd were low (〈 0.2pgcm−2 s−1) and increased to 0.4–0.9 pg cm−2 s−1, while Cr(III) fluxes showed an approximately tenfold increase. Results showed that there was increased mobilization of metals associated with the fungal reduction of phenanthrene concentrations by Penicillium frequentans.

Notizen: Abstract. The rate and extent to which cattle or pig slurry infiltrates into soil after application is one of the important factors determining the rate and extent of subsequent ammonia (NH3) volatilization. Better characterization of the infiltration process is required to improve predictive models of NH3 losses after land spreading. This paper describes a laboratory system using time domain reflectometry to measure slurry infiltration into soil columns. This system enabled semi-continuous, non-destructive infiltration measurements to be made, assessing the influence of slurry type, dry matter (DM) content, soil type and soil water tension. Differences were noted in the infiltration behaviour of cattle and pig slurries. For cattle slurry, DM content (range 1.7–7.1%) was the main influencing factor. Infiltration rate rapidly decreased with increasing DM content and there was no influence of soil type or water tension. For pig slurry, all of the slurry infiltrated into a sandy clay loam soil within the first hour, regardless of DM content (range 1.5–4.7%), whereas only 60% infiltrated into a clay loam soil over the same time period (slurry DM content 2.1%).

Notizen: Abstract. Manures can supply nitrogen (N) beyond the year of application, producing residual effects that are are not fully expressed in short-term experiments. From 1997 to 2003 we conducted a field experiment on a sandy soil in the Netherlands to quantify the residual N effect. Treatments comprised different time series of cattle slurry applied at rates ranging from 0 to 220 kg total-N ha−1 yr−1, while compensating for differences in available potassium and phosphorus. Dry matter and N yields of silage maize responded positively (P〈0.05) to both current cattle slurry applications and applications in previous years. N yields could be satisfactorily predicted with a simple N model by adopting an annual relative decomposition rate (RDR) of the organic N in cattle slurry of 25–33%. Subsequent model calculations indicated that the relative N fertilizer value (RNFV) of cattle slurry rises from approximately 55–60% when manure is first applied to approximately 80% after 6 and 8 years for RDRs of 33% and 25%, respectively. Given the long manuring history of most agricultural systems, rethinking the fertilizer value of manure seems justified.

Notizen: Abstract. Flooding of abandoned coal mines often causes discharges of iron-rich drainage water into the environment. Treatment of these discharges results in the formation of ochre (hydrous iron oxides) for which no end-use has been identified. Ochre effectively adsorbs phosphate from solution and thus could be used for remediation of waste waters. The resulting P-enriched ochre could then potentially be recycled as a P fertilizer. Pot and field experiments were set up to assess performance and environmental acceptability of ochre in this role, using grass and barley as test crops, as well as birch and spruce tree seedlings. Soils and plant materials were analysed for total and available P, total metals and pH. Results showed that P-saturated ochre functioned as a slow-release P fertilizer, and in the short term was as effective as conventional P fertilizer in maintaining crop yields. It also raised soil pH, and did not pose any significant problem through introduction of potentially toxic trace metals into the soil.

Notizen: Abstract. Knowledge of the stocks and the potential range of soil organic carbon (SOC) in various land–soil combinations is an important precursor to policies aimed at linking, for example, management of SOC to greenhouse gas emission controls. To investigate the factors controlling the percentage of SOC (%SOC) of soils in England and Wales, we made a multiple regression analysis of data for the 2448 arable and ley-arable sites in the 1980 England and Wales National Soil Inventory (NSI). Clay content, average annual precipitation and depth of topsoil explained 25.5% of the variation in %SOC, when calcareous and peaty soils and those susceptible to flooding were excluded. Using ‘robust’ statistics, ‘indicative SOC management ranges’ were estimated for different physiotopes, that is, landscape units for which the environmental factors governing %SOC are similar, namely soil clay content and precipitation. These ranges describe the expected %SOC range for an arable soil in a given physiotope. They have potential to support approximate targets for the %SOC of arable soils and for estimating upper and lower limits for sequestered soil carbon in arable systems.

Notizen: Abstract. Soil associated with Northampton Sand within the area of the Borough Council of Wellingborough has elevated levels of arsenic. Arsenic in such soil at a private dwelling was analysed to determine the arsenic oral bioavailability and uptake by fruit and vegetables grown at the site. This information was used to assess the risk to a present occupant with 22 years' exposure, and to a 0–6-year-old girl, the critical receptor in the standard residential land use as stated in UK policy. The exposure pathways comprised soil and dust ingestion, consumption of home-grown vegetables and ingestion of soil attached to home-grown fruit and vegetables. The soil guideline value (SGV) for arsenic in residential land use with plant uptake derived using the Contaminated Land Exposure Assessment (CLEA) model was deemed inappropriate for use at this site, since the SGV does not include the consumption of home-grown fruit, potentially a major pathway in this site for the current occupant, and also assumes 100% arsenic bioavailability. Hence, it was necessary to derive site-specific assessment criteria for arsenic, for which we used the first edition of the Scotland and Northern Ireland Forum for Environmental Research (SNIFFER) framework, modified to reflect guidance in Contaminated Land Research (CLR) Reports CLR 9 and 10, and to incorporate the consumption of home-grown fruit. The incorporation of site-specific data on arsenic bioavailability and vegetable: soil arsenic concentration factor for the 0–6-year-old receptor gave a site-specific assessment criterion (SSAC) of 139 mg kg−1 soil. For the adult female receptor, incorporating the site-specific data on arsenic bioavailability, the vegetable: soil and the fruit: soil concentration factors gave a SSAC of 251 mg kg−1 soil. In both cases, the vegetable consumption pathway drives the risk. None of the 19 soil sample results for arsenic exceeded the site-specific assessment criteria derived for the current occupiers, but 13 of the soil samples slightly exceeded the site-specific assessment criteria for the putative 0–6-year-old girl. Given the degree of conservatism in the selection of input values for the exposure parameters in the SNIFFER framework, this exceedance was not considered to warrant further regulatory action at the time.

Notizen: Abstract. Terrestrial ecosystem risk assessment remains in its infancy by comparison with the aquatic discipline, yet it is advancing quickly in response to increasing concerns surrounding soil quality and the sustainable use of soil. Several international frameworks have been developed during the last decade to aid decision-makers as the need for scientifically derived tools for determining ecological risk from land contamination has been recognized. From the regulatory viewpoint, the priority is establishing what to protect in order to prevent ecological harm. This is a complex issue requiring clear objectives in a risk assessment context. The most important factor in assessing ecological harm is whether or not ecosystem function is altered as a result of land contamination and, if it is, judging the significance. A consensus is developing that ecological risk assessment should aim to protect populations rather than individuals. This paper critically reviews recent developments in risk assessment for terrestrial ecosystems and land contamination in the UK, with emphasis on deriving a measure of ecological harm to assess ecosystem function. We seek to further justify the use of earthworms as a favoured indicator species for protecting ecological function. Guidance on how to measure harm in relation to ecological function is, however, still lacking.

Notizen: Abstract. Knowledge of changes in soil organic matter (SOM) fractions resulting from agricultural practice is important for decision-making at farm level because of the contrasting effects of different SOM fractions on soils. A long-term trial sited under Sudano-Sahelian conditions was used to assess the effect of organic and inorganic fertilization on SOM fractions and sorghum performance. Sorghum straw and kraal manure were applied annually at 10 t ha−1, with and without urea at 60 kg N ha−1. The other treatments included fallowing, a control (no fertilization), and inorganic fertilization only (urea, 60 kg N ha−1). Fallowing gave significantly larger soil organic carbon and nitrogen (N) levels than any other treatment. Total soil SOM and N concentrations increased in the following order: urea only 〈 straw 〈 control 〈 straw+urea 〈 manure with or without urea 〈 fallow. Farming had an adverse effect on SOM and N status; however, this mostly affected the fraction of SOM 〉0.053 mm (particulate organic matter, POM). The POM concentrations in the control, straw and urea-only treatments were about one-half of the POM concentrations in the fallow treatment. POM concentrations increased in the following order: urea only 〈 control 〈 straw with or without urea 〈 manure with or without urea 〈 fallow. The fraction of SOM 〈0.053 mm (fine organic matter, FOM) was greater than POM in all plots except in fallow and manure+urea plots. Total N concentration followed the same trend as SOM, but cultivation led to a decline in both POM-N and FOM-N. Crop yield was greatest in the manure plots and lowest in the straw, control and urea-only plots. Results indicate that under Sudano-Sahelian conditions, SOM, POM and FOM fractions and crop performance were better maintained using organic materials with a low C/N ratio (manure) than with organic material with a high C/N ratio (straw). Urea improved the effect of straw on crop yield and SOM concentration.

Notizen: Abstract. A number of organic farms in Flanders were sampled to investigate the general phosphorus (P) status and degree of P saturation (Psat) of the soils. Where possible, the soil P status was compared to that in conventional agriculture and related to farm characteristics: agricultural land use, soil texture, fertilization intensity and time since conversion. Generally, the P status of the organic farms was high, and similar to that of conventional farms in Flanders, which is due to the restricted time since conversion to organic farming on most farms. The average soil Psat was slightly lower (37%) than the average value for East Flanders (39%) taken over the soil profile to 90 cm. However, a large proportion of the field areas on organic farms still had a Psat greater than 30% (critical Psat value), which may be an indication that P saturation will continue to be a problem for these farms.

Notizen: Abstract Application of organic residues to soil is generally assumed to improve soil tilth. Only few studies have reported the long-term effects on the more subtle aspects of soil porosity, and no reports have considered the potential effects of organic amendments on the pore system in the subsoil. We sampled undisturbed soil cores (100 cm3 and 6280 cm3) using metal cylinders in differently fertilized plots in the long-term field experiment at Askov Experimental Station, Denmark. We selected the 0–60 cm soil layer of plots dressed for a century with either mineral fertilizers (labelled NPK) or animal manure (labelled AM) and unfertilized plots (UNF) as a reference. Both fertilization treatments were studied at two levels of nutrient application: ‘normal’ (labelled ‘1’) and 1.5 times ‘normal’ (labelled ‘1½’). Water retention, air permeability and air diffusivity were measured on the small cores, and we used the large cores for measuring near-saturated and saturated hydraulic conductivity. In the plough layer, the AM and NPK soils displayed identical pore volumes in size fractions that were larger as well as smaller than 30 μm, while the UNF soil had a significantly smaller volume of pores 〈 30 μm. No clear trends were found in treatment effects on pore organization as calculated from air diffusivity and air permeability measurements. No significant differences in hydraulic conductivity were found in the plough layer. For the subsoil below ploughing depth, significantly larger macropore volumes and near-saturated hydraulic conductivities were found for soil of plots receiving the larger (‘1½’) amount of nutrients compared with the ‘normally’ dressed soil. This effect was independent of fertilization system (AM or NPK). We attribute the larger volume of macropores to the improved root growth conditions in the soil with the higher nutrient level. We conclude that addition of animal manure at rates realistic in agriculture has only a modest effect on soil pore characteristics of the plough layer soil compared with the use of mineral fertilizers. For the subsoil below ploughing depth, a high level of nutrient application may increase soil macroporosity and near-saturated hydraulic conductivity, but the origin of nutrients is of no significance.

Notizen: Abstract In Galicia (northwest Spain) the application of organic wastes to agricultural land is a common practice, which may increase total and bioavailable metal contents in the soil. In this study, total metal concentrations were determined in acid soils under different use (pasture, cropland, woodland) in an agricultural area where agro-industrial sludges are frequently recycled as manure. The aim was to establish baseline metal levels which could be used to determine the capacity of soils to absorb organic wastes. The estimation of baseline metal concentrations was carried out by two methods, one based on the analysis of means and geometric deviations, and another based on a modal analysis. Results suggested that the modal analysis procedure might be preferable when analysing data sets with a heterogeneous frequency distribution. In general, there was no significant difference in total metal concentrations when comparing soils from different land uses. Baseline levels for each metal indicated that all soils were suitable for organic waste application under current European Union (EU) legislation. From 2015, more restrictive metal limit values have been proposed by the EU, potentially preventing the addition of metal-containing wastes to pasture, cropland and woodland soils. The dissolved metal values in each soil were also estimated by empirical equations relating total metal concentrations, pH and organic matter content. Results showed that only the pasture soils would be suitable for organic waste disposal under the proposed EU metal limits for 2015, due to liming and substantial organic matter content. Total metal concentrations were insufficient to discriminate environmental risk in acid soils of different land use. The determination of baseline levels in reference areas and the estimation of soil metal bioavailability are suggested to define permissible values in the developing legislation.

Notizen: Abstract. A daily multi-layered water balance (DAMUWAB) approach has been formulated with modest input data on daily climatic records, slope gradient, physical soil properties and basic crop characteristics, for predicting the water and oxygen availability in freely drained soils of semiarid as well as subhumid tropical cropping systems. In this study, a simple one-dimensional root extension model is coupled to a water-uptake model that differentiates the uptake capacity of roots according to their depth. It has an intermediate level of detail between functional, 10-day period single-layered water balance (DESIWAB) approaches for land evaluation purposes, and the descriptive, daily water balances used in many crop growth models. Modelling capacity, functionality and expandability of DAMUWAB surpass the performance of DESIWAB. Water and oxygen shortages occurring in each compartment were found to limit water uptake and transpiration. Sensitivity analysis and comparison of DAMLWAB with the worldwide operational DESIWAB approach proved successful for model validation in the tropics and subtropics.

Notizen: Abstract. A study was conducted to compare the performance of the PR1 capacitance probe (Delta-T Devices) in measuring soil volumetric moisture content (θ) with two established standard methods: the neutron probe (Didcot Instruments) and the gravimetric method. Over a two-year period, the three methods were used to measure θ in glasshouse plots containing crops of either oilseed rape (Brassica napus L.) or bambara groundnut (Vigna subterranea L.). The PR1 probe gave variable performance depending on the depth and soil profile where the measurements were made. In most cases, the PR1 probe significantly overestimated θ. In some cases, it significantly underestimated θ or gave similar values to the other methods. Despite this frequent overestimation of θ, the PR1 probe adequately registered the relative changes in θ Its measurements were linearly and positively related to those of the gravimetric and neutron-probe methods. However, the regression lines significantly deviated from the 1:l line. This paper discusses the possible reasons for the unsatisfactory performance of the PR1 probe and the practical problems associated with the installation of its access tubes.

Notizen: Abstract. Nitrate leaching from crop rotations supporting organic grain production was investigated from 1997 to 2000 in a field experiment at three locations in Denmark on different soil types. Three experimental factors were included in the experiment in a factorial design: (1) proportion of N2-fixing crops in the rotation (crop rotation), (2) catch crop (with and without), and (3) manure (with and without). Three, four-course rotations were compared, two at each location. The nitrate leaching was measured using ceramic suction cells. Leaching losses from the crop rotation with grass–clover green manure and without catch crops were 104, 54 and 35 kg N ha−1 yr−1 on the coarse sand, the loamy sand, and the sandy loam, respectively. There was no effect of manure application or time of ploughing-in the grass–clover green manure crop on the accumulated nitrate leaching from the entire rotation. Catch crops reduced nitrate leaching significantly, by 30–38%, on the sandy soils. At all locations catch crops reduced the annual averaged nitrate concentration to meet drinking water quality standards in the crop rotation with green manure. On the coarse sand there was a time lag between the onset of drainage and the start of N-uptake by the catch crop.

Notizen: Abstract. Despite considerable investment, some UK bathing waters fail to comply with mandatory standards as defined by the EU Bathing Water Directive (76/160/EEC). Continued non-compliance has been associated with diffuse sources of faecal indicator organism (FIO) contamination, in particular those deriving from agricultural land. This paper examines concentrations of FIOs in surface, subsurface and instream water samples at field sites considered to pose a high potential risk of FIO contamination. Quality of samples was compared with FIO standards for bathing water compliance in the UK. FIO concentrations exceeding mandatory and guideline standards were recorded frequently at all sites. In freely draining soils, FIO mobilization by rainfall was predominantly via subsurface flow, with occasional surface water flow linked to intensive rainfall events. In slowly permeable soils, surface mobilization of FIOs predominated, with the occurrence of limited subsurface samples linked to seasonal desiccation cracking within the soil, and to intense rainfall events. Watercourse FIO concentrations were significantly increased as the stream passed-by fields with freely draining soils. The data imply a generally higher risk of FIO transfer from freely draining soils and occasional increased risk from less permeable soils due to temporal changes in soil structure and rainfall intensity.

Notizen: Abstract. A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand.

Notizen: Abstract. Low input grazing-based meat production is often practised on land where alternative land use is restricted and where high biodiversity warrants specific environmental payments. Although these systems are characterized by low external nutrient inputs, significant nutrient losses may occur per unit of produce, even though losses per unit area are low. If the aim is to have animal production without further eutrophication of watercourses, these losses should be minimized,. However, if nutrient-poor grasslands characterized by high biodiversity are the aim, some losses must be accepted to balance nutrient inputs by atmospheric deposition. The impact of grazing animals on nutrient dynamics in grasslands is reviewed in this paper, and options to further improve nutrient management are discussed. It is concluded that nutrient management should largely be addressed indirectly through management of animal behaviour in relation to grazing and supplemental feeding, as well as through optimization of the seasonal distribution of livestock size. A case study indicated that N losses from a cattle farm could be reduced considerably by these means, while animal production could actually be improved. Sustainability issues and trends in legislative and social pressures on low input grazing-based systems of animal production are discussed in relation to nutrient management and practical recommendations.

Notizen: Abstract. Changes in agricultural subsidies in Europe and the ready availability of fertilizers have allowed a spatial decoupling of livestock and crop production. This has increased the flow of nutrients that occurs between farms compared to within individual farms. In terms of nutrient cycling, mixed farms provide the opportunity to re-integrate aspects of agricultural production. The degree of integration between crop and livestock production is defined by the reliance on the use of home-produced feed compared to imported feed, and is independent of intensity. Management of inputs and/or internal flows offers the scope to improve nutrient use efficiency (NUE) on mixed farms. Greatest uncertainties in calculating NUE are associated with variation in yield and composition of home-produced feed, and consequent manure composition. Three key areas are addressed to highlight the interchange of nutrients (and risks for losses) between crop and livestock production; (i) the role of livestock diet in manipulating the amount and availability of manure nutrients; (ii) the impact of manure management on nutrient losses; and (iii) nutrient management through the integration of crops and livestock in rotations. While not all the associated issues are unique to mixed farming, these three areas all influence NUE.

Notizen: Abstract. We studied the effect of inoculation with three arbuscular-mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae ([Nicol & Gerd.] Gerd. & Trappe) and the addition of composted sewage sludge on root nitrate reductase (NR, EC 1.6.6.1.) activity, mycorrhizal colonization, plant growth and nutrient uptake in Retama sphaerocarpa L. seedlings afforested in a semiarid, degraded Mediterranean soil under well-watered and non-watered conditions. Six months after planting, the mycorrhizal inoculation and the irrigation of plants had a strong effect on the growth parameters. The effect on plant growth was a negative interaction between plant irrigation and mycorrhizal inoculation and a positive interaction between plant irrigation and composted sewage sludge addition. The latter treatment had a significant, but moderate, effect on the growth but conferred no additional benefit when combined with mycorrhizal inoculation. Mycorrhizal inoculation, composted sewage sludge and irrigation had a significant effect on NR activity in roots and on foliar nutrients. The irrigation significantly increased the positive effect of composted sewage sludge on NR activity and the concentrations of foliar N and K. The effect of mycorrhizal inoculation on NR activity did not depend on the water regime. The effectiveness of mycorrhizal inoculation on the establishment and growth of R. sphaerocarpa seedlings in these Mediterranean conditions was independent of water regime. The addition of composted sewage sludge was only effective when soil water was freely available. The combination of mycorrhizal inoculation and composted sewage sludge addition had no synergistic effect on plant growth.

Notizen: Abstract. The effects of nitrogen fertilizer and tillage systems on soil organic carbon (SOC) storage have been tested in many field experiments worldwide. The published results of this research are here compiled for evaluation of the impact of management practices on carbon sequestration. Paired data from 137 sites with varying nitrogen rates and 161 sites with contrasting tillage systems were included. Nitrogen fertilizer increased SOC but only when crop residues were returned to the soil; a multiple regression model accounted for just over half the variance (R2=0.56, P=0.001). The model included as independent variables: cumulative nitrogen fertilizer rate; rainfall; temperature; soil texture; and a cropping intensity index, calculated as a combination of the number of crops per year and percentage of corn in the rotation. Carbon sequestration increased as more nitrogen was applied to the system, and as rainfall or cropping intensity increased. At sites with higher mean temperatures and also in fine textured soils, carbon sequestration decreased. When the carbon costs of production, transportation and application of fertilizer are subtracted from the carbon sequestration predicted by the model, it appears that nitrogen fertilizer-use in tropical regions results in no additional carbon sequestration, whereas in temperate climates, it appears to promote net carbon sequestration. No differences in SOC were found between reduced till (chisel, disc, and sweep till) and no-till, whereas conventional tillage (mouldboard plough, disc plough) was associated with less SOC. The accumulation of SOC under conservation tillage (reduced and no till) was an S-shape time dependent process, which reached a steady state after 25–30 years, but this relationship only accounted for 26% of the variance. Averaging out SOC differences in all the experiments under conservation tillage, there was an increase of 2.1 t C ha−1 over ploughing. However, when only those cases that had apparently reached equilibrium were included (all no till vs. conventional tillage comparisons from temperate regions), mean SOC increased by approximately 12 t C ha−1. This estimate is larger than others previously reported. Carbon sequestration under conservation tillage was not significantly related to climate, soil texture or rotation.

Notizen: Abstract. Over the last three decades there has been a great increase in the production of waste from urban, industrial and agricultural activity that could be recycled as a source of plant nutrients, and used to enhance soil quality. The use of these materials could partially offset the need for mineral fertilizers, giving both economic and environmental benefits. An incubation experiment was carried out using different organic waste materials applied to a Cambic Arenosol. Air-dried soil was mixed with increasing amounts of composted solid municipal waste, secondary pulp-mill sludge, hornmeal, poultry manure, solid phase from pig slurry, and composted pig manure, resulting in applications equivalent to 0, 40, 80, 120, 160 and 200 kg ha−1 of Kjeldahl nitrogen. The samples were incubated for 244 days under a controlled environment of 24 °C and 60% water holding capacity of the soil. The increasing amounts of waste applied always led to a greater amount of potentially available nitrogen present in the soil/waste mixture. Based on the proportion of their active N fraction, wastes were ranked: poultry manure〉hornmeal〉solid phase from pig slurry〉composted pig manure〉secondary pulp-mill sludge〉composted municipal solid waste. The results were well described by a one-pool exponential mineralization model, and mineral N formation was proportional to the quantity of waste applied. Of the wastes tested, those from animal sources showed greater nitrogen mineralisation. Nitrification was rapid, and concentrations of ammonium nitrogen remained relatively small.

Notizen: Abstract. Fertilizer and manure application rate and timing are often based on the optimal nitrogen rate and not on potassium (K) requirements. This can lead to excess or shortage of K depending on the crop and rotation. In grass-dominated agricultural production, including many organic farming systems, K has become a critical element, especially in areas dominated by coarse-textured or organic soils. In this paper we review K management in relation to long-term sustainability of both the soil resource and the production of crops of high yield and quality. One question for the future is whether we can adopt management options that favour efficient use of K and secure a sustainable future for global K reserves. For example, is it possible to enhance the release rate of K from soil mineral sources so that we require less fertilizer K from K-bearing salt deposits? A reduction in external K inputs requires improved on-farm recycling of K in order to reduce losses. We also need a better understanding of soil processes and soil–plant interactions and decision-support tools to predict the potential K release from mineral weathering. Certain areas dominated by young, clay-rich soils can potentially supply enough K, whereas other areas with coarse sandy or organic soils have a very low weathering potential and would thus need external inputs of K.

Notizen: Abstract. The intensity of animal production around the world has increased substantially during the last half-century, which has led to large problems with the disposal of manures and waste waters. The focus of this paper is on the development of national policies to improve the nutrient management of concentrated animal feeding operations (CAFOs), where nutrients are invariably in surplus. To create proper nutrient management strategies for CAFOs, and to avoid environmental problems when surplus nutrients enter air, soil and water, we need to know the number of animals/birds in the unit, the quantity of manure/slurry produced, how this material is stored and handled and how much land is available for manure spreading. In this paper, we discuss the development of nutrient management strategies for CAFOs in Europe and North America, and the voluntary measures and environmental regulations related to this. For the planning of nutrient management to be comprehensive and efficient, we need expertise from several disciplines. This planning includes development of: animal diets that reduce the amounts of excreted nutrients; efficient storage and land application technologies; land application programmes to optimize yields and reduce nutrient losses; and strategies for use of excess manure outside the farm. Also, large-scale efforts involving many stakeholders (farmers, governments and private industry) are needed to solve problems with nutrient imbalances over the long term. Efforts along these lines include manure relocation, alternative uses of manures, nutrient trading, and a general extensification of animal agriculture. The overall guiding principle for policies and planning should be a balance of nutrients, on farms as well as at larger scales.

Notizen: The findings of this paper may be summarized in a few paragraphs which, of course, omit all qualifications of the statistical data used.1. The best single measure of economic growth from the stock (rather than the flow) aspect now available is deflated durable reproducible tangible wealth per head,1excluding military tangible assets, subsoil assets, and civilian semi-durable and perishable assets.2. The average rate of growth of real R.T.W. per head for the entire period from 1805 to 1950 is 2 percent, with a range of about 1.8 to 2.2 percent. These figures should be regarded as minima because they do not make allowance for the probable overstatement of the effective rise in the price level involved in the process of deflation and because of the omission or understatement of some types of durable assets such as soil improvement.3. The rate of growth increased from approximately 2.2 percent in the first half of the nineteenth century to 2.5 percent in the second half. The highest decadal rate for periods of about ten years was apparently reached in the‘eighties with approximately 3.8 percent. From this peak it declined to approximately 1.6 percent for the period 1890 to 1922, but rallied to 2 percent in the‘twenties. From 1930 to 1945 R.T.W. per head not only failed to grow but declined slightly, an unprecendented phenomenon due to the Great Depression and to World War II.4. Since World War II the rate of growth of real R.T.W. per head has averaged fully 4 percent. This is higher than any decadal rate known; and probably higher too than that prevailing during any previous period of prosperity. The increase of 22 percent in the five years 1946–50 seems to be as high as that in any previous period of equal length. While part of this rapid increase may be regarded as making up for deficiencies in the ratio of R.T.W. to national product created in the preceding fifteen years; and while it is uncertain how long the recent rapid rise will continue, even if we disregard restrictions on civilian capital formation under the impact of rearmament, it may be that the downward trend in the rate of growth of R.T.W. per head in evidence since the late nineteenth century has been arrested.5. During the one hundred and fifty years for which data are available and which encompass virtually the entire economic history of the United States, the structure of R.T.W. has shown considerable changes, but also a degree of stability which may be regarded as astonishing in view of the extraordinary extension of the economic area of the United States and the radical changes in the nature of its economy. In particular, the proportion of R.T.W. represented by reproducible durable assets for consumers' direct use and for use in production has changed but little.6. Residential buildings and consumers' durable goods accounted for approximately two-fifths of total domestic R.T.W. (in current prices) throughout the period, although the ratio has shown a slight tendency to rise since the middle of the nineteenth century. Within consumers' R.T.W. residential buildings have lost slightly in importance at the expense of movable durable goods. The share of government (including non-profit institutions but excluding military assets) has risen from an insignificant fraction to approximately one-eighth of total R.T.W.’The proportion of R.T.W. represented by private enterprise (including farms) has declined moderately. Within total business R.T.W. changes, however, have been very substantial. The two outstanding trends are the relative decline of R.T.W. of agriculture (excluding farmers' residences and consumers' durables), and the increase in the share of non-farm business structures and equipment, particularly prior to 1880. Non-farm business inventories, on the other hand, seem to have maintained approximately the same proportion to total domestic R.T.W. throughout the period.7. Until World War I part of domestic R.T.W. must be regarded as being the property of foreign owners. The proportion of foreign investments to R.T.W. of the United States, however, declined rapidly throughout the nineteenth century from a proportion of over one-eighth at its start to only a few percent after World War I.Investments abroad have never been substantial compared to R.T.W. They have been almost insignificant throughout the nineteenth century. Even at their peak in 1929 they represented only 7 percent of domestic R.T.W., a proportion not yet regained by 1950.

Notizen: Abstract. Previous industrial and waste disposal activities and natural processes have led to elevated concentrations of harmful substances in soil. Risk-based land management requires the risk posed by such substances to be managed. Generic assessment criteria offer a simple and efficient but often over-cautious approach to human health risk assessment. Site-specific assessment criteria reduce over-conservatism but require extra time and effort to determine. Generic assessment criteria should represent contaminant concentrations below which there is no unacceptable risk to human health. Consistent definitions, application and interpretation are essential prerequisites for fostering and maintaining stakeholder confidence in risk-based land management.

Notizen: Abstract. The two approaches most commonly applied to characterizing the chemical form and ‘reactivity’ of metals in the soil solid phase are sequential extraction procedures (SEPs) and isotopic dilution (ID). The development and limitations of both approaches are described and their application to contaminated soils discussed. It may be argued that ID offers a better means of discriminating between ‘reactive’ and ‘inert’ forms of metal. However, the literature on SEPs is considerably larger, providing greater scope for comparative analysis of new data. Although ID methods are subject to operational constraints, the procedural dependency of SEPs is probably much greater. Thus greater effort has been expended to standardize and verify methodologies for SEPs. However, despite achieving a level of ‘political ratification’ at the procedural level, the use of SEPs within risk assessments for planning or development purposes is currently almost absent. The future for ID methods in this context may lie in site-specific risk assessments that include improved methods for the prediction of metal solubility and bioavailability.

Notizen: Abstract. Chemical analysis alone is inadequate for comprehensively assessing the impact of soil pollution on biota. The term bioavailability can only be applied in a context specific to a target biological receptor or a proven chemical surrogate. Integration of biological and chemical data can often yield significant advances in hazard assessment and act as a suitable baseline for making site-specific risk assessments. Here, the value of biological techniques is discussed and their application described. The relative merit of test selection is considered and the new direction being developed in sublethal assessments. Currently, however, one of the major limitations is the seeming lack of flexibility of many assays in that they are either applicable to agricultural systems or industrial scenarios, but rarely to both. As a consequence, few assays have internationally adopted protocols. The introduction of new methods and the continued improvement and refinement of assays make this area of soil science dynamic and responsive.

Notizen: Abstract. A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand.