Search

Stepwise drying is an effective technique that promotes energy saving without additional capital cost. The stepwise drying mode was investigated for energy consumption and dried product qualities using a coupled heat and mass transfer model associated with kinetics equations of volume shrinkage and degradation of β-carotene in carrot cubes. Simulations were performed using a finite element method with extension of a chemical species transport. Validation experiments were carried out under constant drying modes at 60 °C, 70 °C and 80 °C using a lab-scale convective hot air dryer. The verified models were subsequently employed to investigate the effects of two step-up drying modes (60 to 70 °C and 60 to −80 °C). The optimal drying condition was determined using the synthetic evaluation index (SI) with criteria of high specific moisture evaporation rate (SMER), low shrinkage ratio and β-carotene degradation. Simulated results showed comparable agreement with experimental data of moisture content, shrinkage ratio and β-carotene ratio. Step-up drying of 60 to 70 °C gave the highest SMER of 0.50 × 10−3 kg of water evaporated per kWh, while the operation at constant temperature of 80 °C gave the lowest value of 0.19 × 10−3 kg of water evaporated per kWh. Model-predicted results showed less shrinkage of carrot cubes, but higher degradation of β-carotene under step-up drying compared to single-stage drying under temperature of 60 °C. Based on the highest SI value (0.36), carrot cubes were optimally dried under step-up mode of 60 to 70 °C.

Made available in DSpace on 2022-04-28T19:46:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The water retention curve (WRC) of arable soils from the southeastern United States at different levels of compaction (no compaction, and 10 and 20% increases in soil bulk density) was estimated using the van Genuchten–Mualem (VG) model. The VG water retention parameters of the noncompacted soils were obtained first by fitting measured soil hydraulic data. To construct the WRC of the compacted soils, gravimetric values of the permanent wilting point (θgw, 1,500 kPa) and the residual (θgr) water content were assumed to remain unchanged with compaction. The VG parameter α and exponent η after compaction were estimated using two approaches. In Approach 1, α and η were estimated from saturation, the permanent wilting point, and the residual water content. In Approach 2, the value of η was assumed to remain unchanged with compaction, which allowed α to be estimated immediately from the VG equation. Approach 2 was found to give slightly better agreement with measured data than Approach 1. The effect of compaction on the saturated hydraulic conductivity (Ks) was predicted using semitheoretical approaches and the VG-WRC function. HYDRUS-1D was further used to simulate vertical infiltration into a single-layered soil profile to determine the impact of compaction on the infiltration characteristics of the soils used in our analyses. Results showed that a 10–20% increase in soil bulk density, due to compaction, reduced cumulative infiltration (Ic) at time T = Tfinal (steady-state) by 55–82%, and the available water storage capacity by 3–49%, depending upon soil type. Univ. of Southern Queensland Centre for Agricultural Engineering CSIRO Agriculture and Food Black Mountain Science and Innovation Precinct Dep. of Earth Sciences Utrecht Univ. Center for Environmental Studies São Paulo State Univ. Dep. of Agricultural and Biosystems Engineering Iowa State Univ. Engineering Dep. Harper Adams Univ. Center for Environmental Studies São Paulo State Univ.

Methods to measure shrinkage curves typically either disturb natural aggregate structure or include difficult or slow volume measurement techniques. Additionally, most shrinkage curves are obtained by serial measurement of a few samples. We obtained shrinkage curves by collecting rapid, one-off measurements of volume and moisture content for each of 200 undisturbed peds extracted from a field soil, taking measurements as peds slowly dried in the laboratory. The large sample size increased robustness of the shrinkage curve parameter estimates to noise generated by this rapid measurement technique, but a much smaller sample would have resulted in similar parameter estimates. Accepted version

Sediment resuspension may play a major role in sediment-water exchange of nutrients, matter and energy in coastal areas where waves and currents dominate sediment transport. Biogeochemical sediment properties regulate sediment erodibility, but there is only limited knowledge of how temporal variability in environmental variables is reflected in the resuspension potential, especially for subtidal habitats. Further, the significance of resuspension on nutrient fluxes in coastal environments has remained unclear as contradicting results have been reported. Here we quantified the temporal variation in resuspension potential metrics (erosion threshold (τc; N m−2) and erosion constant (me; g N−1 s−1)) and associated nutrient fluxes from three sites in the Hanko archipelago (Finland) using a core-based erosion device (EROMES). The sites were sampled bi-monthly from April to December. We also quantified the temporal variation in biogeochemical sediment properties at each site. The τc exhibited the clearest temporal pattern in muddy sediment, where the coefficient of variation (= 67) was two to three times higher than the mixed (= 29) and sandy (= 16) sediments. Dry bulk density was the best predictor for sediment erodibility at all sites explaining 26–46% of the temporal variation in τc despite its limited variability at sandier sites. In addition, temporal variations in the macrofaunal community were important predictors of muddy sediment erodibility and therefore community dynamics need to be considered in sediment transport studies. All sites were potential nutrient sources, yet the overall role of sediment resuspension on nutrient release from the sediments was small.

Soils with high stone content represent a challenge to root development, as each stone is an obstacle to root growth. A high stone content also affects soil properties such as temperature or water content, which in turn affects root growth. We investigated the effects of all soil properties combined on root development in the field using both experiments and modeling. Field experiments were carried out in rhizotron facilities during two consecutive growing seasons (wheat [Triticum aestivum L.] and maize [Zea mays L.]) in silty loam soils with high (>50%) and low (

Key message Rut depth in fine-grained boreal soils induced by an 8-wheeled forwarder is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Context Forest machines are today very heavy and will cause serious damage to soil and prevent future growth if forest operations are carried out at the wrong time of the year. Forest operations performed during the wettest season should therefore be directed at coarse-grained soils that are not as prone to soil damage. Aims The study aimed at investigating the significance of the most important soil characteristics on rutting and developing models that can be utilized in predicting rutting prior to forest operations. Methods A set of wheeling tests on two fine-grained mineral soil stands in Southern Finland were performed. The wheeling experiments were conducted in three different periods of autumn in order to get the largest possible variation in moisture content. The test drives were carried out with an 8-wheeled forwarder. Results Soil moisture content is the most important factor affecting rut depth. Rut depth of an 8-wheeled forwarder in fine-grained boreal soil is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Conclusion The results emphasize the importance of moisture content on the risk of rutting in fine-grained mineral soils, especially with high moisture content values when soil saturation reaches 80%. The results indicate that it is of high importance that soil type and soil wetness can be predicted prior to forest operations.

Nowadays, screw feeders are popular equipment in the pharmaceutical industry. However, despite the increasing research in the last decade in the manufacturing of powder-based products, there is still a lack of knowledge on the physics governing the dynamic behavior of these systems. As a result, data-driven models have often been used to address process design, optimization, and control applications. In this paper, a methodology for the modeling of twin screw feeders has been suggested. A first order plus dead time model has been developed, where a hybrid mechanistic-empirical approach has been used. Different powders and two screw feeder geometries have been investigated. The model predictions are in good agreement with the experimental measurements when the 35 mm diameter screws are employed. When the 20 mm diameter screws are used, the validity range of the model is limited for the least cohesive powders, suggesting that their screw speed-dependent resistance to flow in small screws requires further investigations.

Organic waste fertilizers have previously been observed to significantly affect soil organic carbon (SOC) content and soil structure. However, the effect of organic waste fertilizers on colloid dispersibility and leaching of colloids from topsoil has not yet been studied extensively. We investigated how the repeated application of different types of agricultural (liquid cattle slurry and solid cattle manure) and urban waste fertilizers (sewage sludge and composted organic household waste) affected soil physical properties, colloid dispersion from aggregates, tracer transport, and colloid leaching from intact soil cores. Total porosity was positively correlated with SOC content. Yearly applications of sewage sludge increased absolute microporosity (pores30 μm) and decreased relative macroporosity (pores30 μm) compared with the unfertilized control, whereas organic household waste compost fertilization increased both total porosity and the absolute porosity in all pore size classes (though not significant for 100-600 μm). Treatments receiving large amounts of organic fertilizers exhibited significantly lower levels of dispersible colloids compared with an unfertilized control and a treatment that had received moderate applications of cattle slurry. The content of water-dispersible colloids could not be explained by a single factor, but differences in SOC content, electrical conductivity, and sodium adsorption ratio were important factors. Moreover, we found that the fertilizer treatments did not significantly affect the solute transport properties of the topsoil. Finally, we found that the leaching of soil colloids was significantly decreased in treatments that had received large amounts of organic waste fertilizers, and we ascribe this primarily to treatment-induced differences in effluent electrical conductivity during leaching.

ISI Document Delivery No.: IY4KR Times Cited: 0 Cited Reference Count: 55 Soltani, I. Fouad, Y. Michot, D. Pichelin, P. Cudennec, C. Tunisian Republic The EFELE field experiment forms part of the SOERE-PRO (network of long-term experiments dedicated to the study of impacts of organic waste product recycling). It is certified by ALLENVI (Alliance Nationale de Recherche pour l'Environnement) and integrated as a service of the "Investment d'Avenir" infrastructure AnaEE-France, overseen by the French National Research Agency (ANR-11-INBS-0001). The authors are grateful to T. Morvan for providing access to the EFELE site and to F. Gaillard for assistance with fieldwork. The authors also appreciate the help provided by Ms. P. Breger and Mr. R. Dubois during sample collection, measurements of soil retention properties and spectral acquisition in the laboratory. The first author is supported by a Ph.D. grant from the Tunisian Republic. 0 Elsevier Amsterdam 1879-3444; International audience; Agricultural practices are expected to have significant effects on soil physical properties, such as soil structure and soil water retention (SWR) properties are among the relevant properties that can be used to assess these effects. Ex-situ measurements are costly and time-consuming. Visible (vis) and near infrared (NIR) spectroscopy has been widely used as a rapid, cost-effective and nondestructive technique to predict many soil properties, including soil water content (SWC). In this study, we explored the ability of vis-NIR to assess the effects of soil tillage and fertilization on SWR. The study was performed on silty soil samples with 10.4 g kg(-1) of organic carbon content and a pH of 5-6.5. Undisturbed soil blocks were collected from an experimental station located in Brittany, France. In 2012, the field was designed as two separate experiments, each with a different tillage system (conventional tillage (CT) and shallow tillage (ST)). For each experiment, two fertilizer types were considered (mineral and organic). Six undisturbed soil blocks were sampled at each of two depths (0-15 cm and 15-25 cm) and from each agricultural practice. Soil was sampled on two dates: before starting the treatment (2012) and after 5 years of agricultural practices (2017). From each soil block, four aggregates 3-4 cm wide and 5-6 cm long were collected. The whole aggregates were set at a number of matric potentials, from saturation to the permanent wilting point (pF = 4.2). At a given pressure head, soil samples were scanned in triplicate to acquire reflectance spectra from 400 to 2500 rim using a handheld spectrometer (ASD Fieldspeca (R)). We focused on the absorption band near 1920 nm and used a new NIR spectral index based on the band's full width at half maximum, called SWSI. Our results showed a linear relation between SWSI and SWC (R-2 > 0.99). Moreover, the slope and intercept of this linear relation were significantly correlated with water holding capacity (WHC) and soil quality. Using these parameters, we found that SWR and soil physical quality under CT were significantly greater under cattle manure (CTC) than under mineral fertilizer (CTM) or at TO. This significant effect was more pronounced at 15-25 cm. In ST treatments, SWR properties and soil quality were significantly lower than at TO. More importantly, our results show that the slope and intercept of the linear relation offer a way to summarize and assess the effects of agricultural practices on SWR properties and soil structural quality.

© 2019 The Author(s). Roots are known to use biopores as preferential growth pathways to overcome hard soil layers and access subsoil water resources. This study evaluates root- biopore interactions at the root-system scale under different soil physical and environmental conditions using a mechanistic simulation model and extensive experimental field data. In a field experiment, spring wheat (Triticum aestivum L.) was grown on silt loam with a large biopore density. X-ray computed tomography scans of soil columns from the field site were used to provide a realistic biopore network as input for the three-dimensional numerical R-SWMS model, which was then applied to simulate root architecture as well as water flow in the root-biopore-soil continuum. The model was calibrated against observed root length densities in both the bulk soil and biopores by optimizing root growth model input parameters. By implementing known interactions between root growth and soil penetration resistance into our model, we could simulate root systems whose response to biopores in the soil corresponded well to experimental observations described in the literature, such as increased total root length and increased rooting depth. For all considered soil physical (soil texture and bulk density) and environmental conditions (years of varying dryness), we found biopores to substantially mitigate transpiration deficits in times of drought by allowing roots to take up water from wetter and deeper soil layers. This was even the case when assuming reduced root water uptake in biopores due to limited root-soil contact. The beneficial impact of biopores on root water uptake was larger for more compact and less conductive soils. ispartof: VADOSE ZONE JOURNAL vol:18 issue:1 status: published

Most dielectric mixing models have been developed for mineral soils without extensive consideration of organic matter (OM). In addition, when used for in situ measurement, most of these models focus only on the real part of the effective dielectric constant without the corresponding imaginary part. Organic matter fractions in soils are found globally (57%), with an especially significant amount in the boreal region (17%). Without proper consideration of OM in dielectric mixing models and subsequent microwave radiative transfer modeling, brightness temperature (TB) calculations may be erroneous. This would lead to uncertainties in the estimation of higher level products, such as soil moisture retrievals from portable soil moisture sensors (e.g., time-domain reflectometers) or passive microwave sensors onboard the Soil Moisture Active Passive (SMAP), Soil Moisture and Ocean Salinity (SMOS), and Advanced Microwave Scanning Radiometer (AMSR2) satellites. We incorporated OM into a dielectric mixing model by adjusting the wilting point and porosity according to the OM content, i.e., the effective soil dielectric constant decreases with higher OM due to a decrease in the fraction of free water and an increase in bound water. With the proposed soil parameters in the dielectric mixing model, high levels of OM increase the TB for a specific soil moisture by decreasing the microwave effective dielectric constant. The simulated TB better reproduced SMAP-observed TB (11% in RMSE) through the improvement of the effective dielectric constant (40% reduction in RMSE). We anticipate that the application of our approach can improve microwave-based surface soil moisture retrievals in areas with high OM.

The Indian State of Andhra Pradesh is in the process of designing and constructing a planned capital city on the southern banks of the Krishna River at Amaravati. This region will see a significant increase in urban land cover and impervious surface area (ISA) under the 2050 draft perspective plan from the Andhra Pradesh Capital Region Development Authority. As the city central zone sits on the former floodplain of the Krishna River and is subject to concentrated rainfall during monsoon seasons-this increase in ISA risks increasing flood risk through preventing infiltration of storm water and causing increased peak storm water flow (NRSC 2014). The State has announced plans for a "zero-flooding city" through implementation of technologies including green roofs, porous pavement, and detention ponds (ADC 2017). This study aims to facilitate these efforts through mapping of present and future land usage, regional flood risk, and environmental services utilizing open-source data in order to maximize efficiency of installed green infrastructure and minimize future flood damages. A map of relative soil infiltration capacity was created through fuzzy overlay of sand percentage, clay percentage, and bulk density at several depths. Relative flood risk maps for both present-day land cover and a 2050 scenario were developed using several factors: elevation, flow accumulation, surface runoff, and soil properties. A novel Relative Environmental Services Provided Index is proposed here to in order to encourage cost-effective and ecologically sound development through composite visualization of carbon storage, greenery, runoff coefficients, and soil flood prevention.

Over the past three decades, pedotransfer functions (PTFs) have been widely used by soil scientists to estimate soils properties in temperate regions in response to the lack of soil data for these regions. Several authors indicated that little effort has been dedicated to the prediction of soil properties in the humid tropics, where the need for soil property information is of even greater priority. The aim of this paper is to provide an up-to-date repository of past and recently published articles as well as papers from proceedings of events dealing with water-retention PTFs for soils of the humid tropics. Of the 35 publications found in the literature on PTFs for prediction of water retention of soils of the humid tropics, 91 % of the PTFs are based on an empirical approach, and only 9 % are based on a semi-physical approach. Of the empirical PTFs, 97 % are continuous, and 3 % (one) is a class PTF; of the empirical PTFs, 97 % are based on multiple linear and polynomial regression of n th order techniques, and 3 % (one) is based on the k-Nearest Neighbor approach; 84 % of the continuous PTFs are point-based, and 16 % are parameter-based; 97 % of the continuous PTFs are equation-based PTFs, and 3 % (one) is based on pattern recognition. Additionally, it was found that 26 % of the tropical water-retention PTFs were developed for soils in Brazil, 26 % for soils in India, 11 % for soils in other countries in America, and 11 % for soils in other countries in Africa. Durante as últimas três décadas, as funções de pedotransferência (FPTs) foram amplamente utilizadas pelos cientistas para estimar propriedades de solos em regiões temperadas para responder à falta de banco de dados deles. Diferentes autores indicaram que poucos esforços foram dedicados à estimação de propriedades de solo nos trópicos úmidos, onde a necessidade de informações sobre as propriedades dos solos é ainda mais prioritária. Este artigo buscou proporcionar um inventário atualizado dos artigos, assim como trabalhos publicados recentemente em anais de congressos sobre FPTs com retenção de água para solos nos trópicos úmidos. Entre 35 publicações encontradas na literatura sobre as FPTs para a estimação da retenção de água dos solos nos trópicos úmidos, 91 % dos FPTs estão com base num enfoque empírico e somente 9 %, num enfoque semifísico. Das FPTs empíricas, 97 % são contínuas e 3 % (uma) é uma classe. Das FPTs empíricas, 97 % são com base em regressão multilinear e polinomial de n técnicas de ordenamento e 3 % (uma), no método k-NN; 84 % das FPTs contínuas são com base em pontos e 16 %, em parâmetros; 97 % das FPTs contínuas são baseadas em equação e 3 % (uma), no reconhecimento padrão. Adicionalmente, foi encontrado que 26 % das FPTs da retenção de água "tropical" foram desenvolvidas para solos no Brasil; 26 % , na Índia; 11 %, em outros países na América; e 11 %, em outros países na África.

Sintering is a process in sinter machine for agglomeration of iron ore and other raw material fines into a compact porous mass, i.e., sinter, used in Blast Furnaces as an iron bearing input charge material for hot metal production. ‘Permeability’ of sinter-bed on sinter machine i.e., the porosity in sinter-bed of charged materials, facilitates atmospheric air passes from the top to bottom across the depth of sinter-bed, when suction created from the bottom of the bed, for efficient heat carry over from top to bottom of the bed for complete burning of charged materials for effective sintering process controls the productivity of the sinter machine. The level of ‘permeability’ in sinter-bed is depending upon the effectiveness of ‘charging chute’ in size-wise ‘segregation’ of charge materials across the depth in sinter-bed, achieved due to differences in the sliding velocities of particles during charging into the moving sinter-bed. The permeability achieved by the earlier conventional ‘charging chute’ was limited due to its design and positional constraints in sinter machine. Improving the productivity of sinter machine, through increased permeability of sinter bed is successfully achieved through implementation of an innovatively designed and developed, “Magnetic Charging Chute” at Sinter Plant no. 2 of Rourkela Steel Plant. The induced magnetic force on the charged materials while the charge materials dropping down through the charge chute has improved the permeability of sinter bed through an unique method of segregating the para-magnetic materials and the finer materials of the charge materials to top layer of sinter bed along with improved size-wise segregation of charge materials. This has increased the productivity of the sinter machine by 3% and also reduced the solid fuel consumption i.e., coke breeze in input charge materials by 1 kg/t of sinter.

Article en open access. ---------- Cet article a été le support d’une communication lors de la séance de l’Académie d’agriculture de France du 10 juin 2009 intitulée « Développement des techniques de cultures sans labour (TCSL) : implications agronomiques et environnementales ».; In this paper, we present a review of the literature on the effects of no-ploughing on soil structure, porosity and stability. In the second part, we discuss the consequences on soil erosion in a temperate environment. The effect of reduced tillage on soil physical properties has firstly to be evaluated on soil structure. If carbon accumulation on the soil surface improves aggregate stability, no-ploughing also greatly affects soil porosity. Not only does it decrease during the period following adoption of no-ploughing, but it also changes in nature and connectivity due to weathering, roots and biological activity. However, the efficiency of these factors is site-dependent and varies with the duration of no-ploughing and the crop sequence. Under tropical climates, reduced tillage systems have been proposed to prevent soil erosion while in temperate areas the present increase of no-till is motivated firstly by the decrease of production and mechanization costs. However, the efficiency of the numerous no-plough tillage systems on erosion control is not systematic. The soil must be sufficiently covered by crop residues and the infiltration rate has to remain high enough. This note critically assesses the available results on these two aspects of the effect of reduced tillage on soil physics.

Data of soil hydraulic properties forms often a limiting factor in unsaturated zone modelling, especially at the larger scales. Investigations for the hydraulic characterization of soils are time-consuming and costly, and the accuracy of the results obtained by the different methodologies is still debated. However, we may wonder how the uncertainty in soil hydraulic parameters relates to the uncertainty of the selected modelling approach. We performed an intensive monitoring study during the cropping season of a 10 ha maize field in Northern Italy. The data were used to: i) compare different methods for determining soil hydraulic parameters and ii) evaluate the effect of the uncertainty in these parameters on different variables (i.e. evapotranspiration, average water content in the root zone, flux at the bottom boundary of the root zone) simulated by two hydrological models of different complexity: SWAP, a widely used model of soil moisture dynamics in unsaturated soils based on Richards equation, and ALHyMUS, a conceptual model of the same dynamics based on a reservoir cascade scheme. We employed five direct and indirect methods to determine soil hydraulic parameters for each horizon of the experimental profile. Two methods were based on a parameter optimization of: a) laboratory measured retention and hydraulic conductivity data and b) field measured retention and hydraulic conductivity data. The remaining three methods were based on the application of widely used Pedo-Transfer Functions: c) Rawls and Brakensiek, d) HYPRES, and e) ROSETTA. Simulations were performed using meteorological, irrigation and crop data measured at the experimental site during the period June – October 2006. Results showed a wide range of soil hydraulic parameter values generated with the different methods, especially for the saturated hydraulic conductivity Ksat and the shape parameter α of the van Genuchten curve. This is reflected in a variability of the modeling results which is, as expected, different for each model and each variable analysed. The variability of the simulated water content in the root zone and of the bottom flux for different soil hydraulic parameter sets is found to be often larger than the difference between modeling results of the two models using the same soil hydraulic parameter set. Also we found that a good agreement in simulated soil moisture patterns may occur even if evapotranspiration and percolation fluxes are significantly different. Therefore multiple output variables should be considered to test the performances of methods and models.

Purpose – For measuring the effect of crop root content on soil water retention curves (SWRC), a simulation approach (multi-gene genetic programming (MGGP)), which develops the model structure and its coefficients automatically can be applied. However, it does not perform well due to two vital issues related to its generalization: inappropriate formulation procedure of the multi-gene model and the difficulty in model selection. The purpose of this paper is to propose a heuristic-based-MGGP (N-MGGP) to formulate the functional relationship between the water content and two input parameters (soil suction and volumetric crop root content). Design/methodology/approach – A new simulation approach (heuristic-based-MGGP (N-MGGP)), was proposed to formulate the functional relationship between the water content and two input parameters (soil suction and volumetric crop root content). The proposed approach makes use of a statistical approach of stepwise regression and classification methods (Bayes naïve and artificial neural network (ANN)) to tackle the two issues. Simulated data obtained from the models was evaluated against the experimental data. Findings – The performance of proposed approach was found to better than that of standardized MGGP. Sensitivity and parametric analysis conducted validates the robustness of model by unveiling dominant input parameters and hidden non-linear relationships. Originality/value – To the best of authors’ knowledge, an empirical model is developed that measures the effect of crop root content on the SWRCs. The authors also proposed a new genetic programming approach in simulating the crop root content dependent SWRCs.

The benefi ts of particle size reduction and mechanical densifi cation of biomass feedstock for storage, transportation, and handling must be assessed in relation to the systemic costs and energy consumption incurred due to these operations. The goal of this work was to determine the optimal levels of size reduction and densifi cation through a combination of modeling and experimen- tal studies. Size reduction and densifi cation data for Miscanthus and switchgrass were generated using a two-stage grinding process and the energy requirement and bulk densities for the particle sizes between 1 mm and 25.4 mm were determined. Increase in bulk density through compression by a pressure of 1.2 MPa was also measured. These data were used within BioFeed, a system-level optimization model, to simulate scenarios capturing the possibilities of performing size reduction and densifi cation at various stages of the supply chain. Simulation results assuming size reduction at farms showed that the optimal particle size range for both Miscanthus and switchgrass was 4-6 mm, with the optimal costs of $54.65 Mg -1 and $60.77 Mg -1 for Miscanthus and switchgrass, respectively. Higher hammer mill throughput and lower storage costs strongly impacted the total costs for different particle sizes. Size reduction and densifi cation of biomass at the county-specifi c centralized storage and pre-processing facilities could reduce the costs by as much as $6.34 Mg -1 for Miscanthus and $20.13 Mg -1 for switchgrass over the base case. These differences provided the upper bound on the investments that could be made to set-up and operate such systems. © 2014 Society of Chemical Industry and John Wiley & Sons, Ltd Supporting information may be found in the online version of this article.

Nonparametric approaches such as the k-nearest neighbor (k-NN) approach are considered attractive for pedotransfer modeling in hydrology; however, they have not been applied to predict water retention of highly weathered soils in the humid tropics. Therefore, the objectives of this study were: to apply the k-NN approach to predict soil water retention in a humid tropical region; to test its ability to predict soil water content at eight different matric potentials; to test the benefit of using more input attributes than most previous studies and their combinations; to discuss the importance of particular input attributes in the prediction of soil water retention at low, intermediate, and high matric potentials; and to compare this approach with two published tropical pedotransfer functions (PTFs) based on multiple linear regression (MLR). The overall estimation error ranges generated by the k-NN approach were statistically different but comparable to the two examined MLR PTFs. When the best combination of input variables (sand + silt + clay + bulk density + cation exchange capacity) was used, the overall error was remarkably low: 0.0360 to 0.0390 m 3 m −3 in the dry and very wet ranges and 0.0490 to 0.0510 m 3 m −3 in the intermediate range (i.e., −3 to −50 kPa) of the soil water retention curve. This k-NN variant can be considered as a competitive alternative to more classical, equation-based PTFs due to the accuracy of the water retention estimation and, as an added benefit, its flexibility to incorporate new data without the need to redevelop new equations. This is highly beneficial in developing countries where soil databases for agricultural planning are at present sparse, though slowly developing. Abbreviations: ANN, artificial neural network; BD, bulk density; CEC, cation exchange capacity; IGBP-DIS, International Geosphere–Biosphere Programme Data and Information System; k-NN, k-nearest neighbor; MD, mean difference; MLR, multiple linear regression; OC, organic carbon; OM, organic matter; PTF pedotransfer function; RMSD, root mean square difference; SSC, sand, silt, and clay; SWRC, soil water retention curve.

Soil information, particularly water storage capacity, is of utmost importance for assessing and managing land resources for sustainable land management. We investigated using digital soil mapping (DSM) and digital soil functional mapping (DSFM) procedures to predict available water capacity (AWC) of soils in Nigeria using three published Pedotransfer functions (PTFs). Soil information, particularly water storage capacity, is of utmost importance for assessing and managing land resources for sustainable land management. We used digital soil mapping (DSM) and digital soil functional mapping (DSFM) procedures to predict available water capacity (AWC) of soils in Nigeria based on three published Pedotransfer functions (PTFs). We followed the specifications of the GlobalSoilMap.net project to produce predictions at a grid resolution of 100 m using regression tree models applied to a compiled soil point database together with auxiliary environmental predictors. Mean AWC (cm cm-1) estimates for Nigeria using methods published by Hodnett and Tomasella (PTF-HT), Zacharias and Wessolek (PTF-ZW), and Minasny and Hartemink (PTF-MH) PTFs were 0.08, 0.21, and 0.12 cm cm-1 for the 0- to 5-cm depth interval and 0.16, 0.08, and 0.08 for the cumulative depth (0–200 cm). The AWC estimates from the PTFs and from the literature for a number of discrete points and locations generally compared well. Comparison of AWC estimated from predicted soil properties (AWPp) against those estimated directly from profile observations (AWPd) for a number of discrete point locations showed a significant relationship only for PTF-HT (R2 = 0.24, p

International audience; Compaction of agricultural soils is a concern for many agricultural soil scientists and farmers since soil compaction, due to heavy field traffic, has resulted in yield reduction of most agronomic crops throughout the world. Soil compaction is a physical form of soil degradation that alters soil structure, limits water and air infiltration, and reduces root penetration in the soil. Consequences of soil compaction are still underestimated. A complete understanding of processes involved in soil compaction is necessary to meet the future global challenge of food security. We review here the advances in understanding, quantification, and prediction of the effects of soil compaction. We found the following major points: (1) When a soil is exposed to a vehicular traffic load, soil water contents, soil texture and structure, and soil organic matter are the three main factors which determine the degree of compactness in that soil. (2) Soil compaction has direct effects on soil physical properties such as bulk density, strength, and porosity; therefore, these parameters can be used to quantify the soil compactness. (3) Modified soil physical properties due to soil compaction can alter elements mobility and change nitrogen and carbon cycles in favour of more emissions of greenhouse gases under wet conditions. (4) Severe soil compaction induces root deformation, stunted shoot growth, late germination, low germination rate, and high mortality rate. (5) Soil compaction decreases soil biodiversity by decreasing microbial biomass, enzymatic activity, soil fauna, and ground flora. (6) Boussinesq equations and finite element method models, that predict the effects of the soil compaction, are restricted to elastic domain and do not consider existence of preferential paths of stress propagation and localization of deformation in compacted soils. (7) Recent advances in physics of granular media and soil mechanics relevant to soil compaction should be used to progress in modelling soil compaction.

In sloping vineyard soil is subjected to a series of degradation processes, among which compaction caused by tillage operation and vehicular traffic, that can influence soil physical and hydrological properties with effects on crop production and quality of environment (Lagacherie et al., 2006). Considering the significance of these impacts, soil compaction has been recognized as one of the threats related to land degradation identified by the European Soil Framework Directive (2006). The aim of the study was to assess the influence of soil management on compaction in hillside vineyard surface, in a long period of monitoring. The experimental trial has been conducted since 2004 and data of penetration resistance (PR) and bulk density (DB) have been collected from three plots of a Barbera vines with rows along the slope. Soil PR was measured by means of a recording penetrometer (Walczak et al., 1973) and BD by core method (Blake and Hartge, 1986). Changes in soil structure due to compaction by tractor traffic and different inter-row tillage (conventional tillage vs. reduced tillage vs. grass cover), analyzing spring and autumn sampling, are reflected in cone index (CI) of penetrometer and BD trend. Cone index was significantly higher with grass cover and reduced tillage than conventional tillage, with the opposite trend for BD where the grass cover appeared to have suffered to a lesser extent the effects of compaction due to vehicle traffic. In general Cl was higher in the tractor tracks than in the middle, and showed lower values during the spring following the recovery of soil compaction occurred after winter precipitation.

In sloping vineyard soil is subjected to a series of degradation processes, among which compaction caused by tillage operation and vehicular traffic, that can influence soil physical and hydrological properties with effects on crop production and quality of environment (Lagacherie et al., 2006). Considering the significance of these impacts, soil compaction has been recognized as one of the threats related to land degradation identified by the European Soil Framework Directive (2006). The aim of the study was to assess the influence of soil management on compaction in hillside vineyard surface, in a long period of monitoring. The experimental trial has been conducted since 2004 and data of penetration resistance (PR) and bulk density (DB) have been collected from three plots of a Barbera vines with rows along the slope. Soil PR was measured by means of a recording penetrometer (Walczak et al., 1973) and BD by core method (Blake and Hartge, 1986). Changes in soil structure due to compaction by tractor traffic and different inter-row tillage (conventional tillage vs. reduced tillage vs. grass cover), analyzing spring and autumn sampling, are reflected in cone index (CI) of penetrometer and BD trend. Cone index was significantly higher with grass cover and reduced tillage than conventional tillage, with the opposite trend for BD where the grass cover appeared to have suffered to a lesser extent the effects of compaction due to vehicle traffic. In general CI was higher in the tractor tracks than in the middle, and showed lower values during the spring following the recovery of soil compaction occurred after winter precipitation.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Background and Aims Root system development is affected by soil conditions. The effects of bulk density, water content and penetration resistance on root development processes were investigated in peach trees. Methods Peach tree rootstocks were grown in various soil conditions, combining two bulk densities (1.2 and 1.5 g soil. cm(-3)) and three water contents (0.14, 0.17 and 0.20 g.g(-1) soil). Root parameters (tip diameter, length of apical unbranched zone, branching density and diameters of main and lateral roots) and plant growth (leaves, branches, trunk, root dry mass) were measured. Root growth processes (elongation, branching) were studied using relationships between root parameters. Results The proportion of biomass allocated to each plant compartment was similar whatever the soil conditions. Variations in root development were best explained by the variation in penetration resistance, rather than other soil properties. Increased soil penetration resistance reduced the root elongation rate, especially for thick roots. In addition, the branching pattern was affected. In soil with a high penetration resistance, the root system shape differs from a typical herringbone pattern. Conclusions These results allow quantification of the root system plasticity, and improve our understanding of the interactions between root development and soil properties.

Context Nowadays, harvest operations are predominantly performed fully mechanized using heavy tractors or forestry machines. The resulting soil compaction may negatively affect the soil ecosystem. Aims We wanted to draw general conclusions concerning the impact of mechanized harvesting on forest soil bulk density and the influencing factors. Method Therefore, we combined the data of several studies using a meta-analysis approach. Results The impact decreased from the surface towards deeper soil layers. At 0–10 cm depth, the impact on clayey soils was highest although not significantly different from the impact on sandy soils. Higher initial bulk densities, i.e., on already compacted forest soils, generally led to smaller extra increases of bulk density after machine traffic. For sandy soils, the impact was also significantly smaller when machines were lighter. No significant relationship was observed between the compaction degree and traffic intensity. Conclusions We observed clear compaction on both clayey and sandy soils, especially in case of low initial soil compaction degrees and heavy machines. The compacted initial state of many forest soils, the long recovery period, and the generally high impact of the first passes that is frequently mentioned in literature all count in favour of designated skid trails and an adjustment of the machine type to the job.

International audience; Soil compaction is a major contributor to forest soil degradation. To make a decision on soil remediation, both the soil compactness after heavy traffic of forest machinery and the natural soil recovery rate must be estimated. We estimated the impact of heavy traffic on soil specific volume (V) and its recovery rate on two forest sites by yearly collecting steel cylinders close to field capacity, as currently recommended, at different depths (D) during 3 to 4 yr. Though collected at water contents (w) as homogeneous as possible, the comparison of sample volumes led to inconsistent results. Using w as covariate was necessary to quantify the initial compaction and the V recovery with time and D. Moreover, compared to the soil V and w determined with shrinkage analysis, some field values were very large, suggesting an artifact due to hammering the cylinder at large w. The surface layer (0-10 cm) of the less compacted site showed no residual compactness 3 yr after heavy traffic and the 10- to 20-cm layer compactness decreased significantly with time. The compactness of the second site decreased significantly only in the 0- to 10-cm layer, and the recovery was still ongoing after the third year of monitoring. This site had less swelling clays and larger clay content. The recovery of the soil volume was attributed to shrink-swell processes. Longer monitoring is required to validate these trends, and further research should evaluate the need for more accurate monitoring based on shrinkage analysis and the use of soil organic carbon (SOC) and clay content as covariates.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; This study was conducted to evaluate quality and structural changes in parallelepipedic pieces of pears during convective drying at different air temperatures (30-70 degrees C). Submitted to atmospheric O-2 conditions, ascorbic acid deterioration demonstrated first-order kinetic behaviour and was found to depend on air temperature and pear moisture content. Loss of ascorbic acid content increased with increasing air temperature. Possible explanation could be the irreversible oxidative reaction occurring during drying. Phenol content degradation fitted a pseudo first-order reaction and was significantly influenced by air temperature. Variations in bulk density, shrinkage and porosity essentially depended on changes in moisture content. Porosity exhibited a nonlinear variation with respect to moisture content. Volume change showed, as expected, a linear variation with moisture content. Drying temperature significantly induced the increase of a* and b* colorimetric parameters due to non-enzymatic browning reaction, which turned the samples more reddish and yellow when the temperature rose. (C) 2011 Published by Elsevier B.V. on behalf of The Institution of Chemical Engineers.

SUMMARYEstimates on soil organic carbon (SOC) and nitrogen (N) stocks in soils cannot be directly calculated from routine soil analyses, since these often lack measurements on soil bulk density (Bd). Hence, flexible pedotransfer functions are required that allow the calculation of SOC stocks from gravimetrically determined SOC contents. The present paper aimed to: (1) quantify SOC and N stocks in grassland topsoils for a Northern Dutch region dominated by dairy farming and (2) analyse the relationships between SOC and bulk density at the field level. As estimates of SOC and N stocks are potentially affected by soil compaction, the combined measurements on soil bulk density and soil organic matter (SOM) were also evaluated with respect to critical limits for soil compaction using soil density (Sd) for sandy soils and packing density (Pd) for clay soils. The SOC andBdmeasurements were done in the upper 0·1–0·2 m of grasslands at 18 dairy farms, distributed across sandy, clay and peat soils. Both farm data and grassland management data were collected. Non-linear regressions were used to analyse relationships betweenBdand SOM. Significant non-linear relationships were found between gravimetric SOC contents and bulk density for the 0–0·1 m layer (R2=0·80) and the 0·1–0·2 m layer (R2=0·86). None of the fields on sandy soils or clay soils indicated signs for limited rooting in the topsoil although some fields appear to approach the critical limit for compaction for the 0·1–0·2 m layer. Stocks of SOC in the top 0·2 m at farm level were highest in the peat soils (21·7 kg/m2) and lowest in the sandy soils (9·0 kg/m2). Similarly, N stocks were highest for farms on peat soil (1·30 kg/m2) and lowest for farms on sandy soil (0·60 kg/m2). For the sandy soils, the mean SOC stock was significantly higher in fields with shallow groundwater tables.

It is practically impossible to measure soil properties continuously at each location across the globe. Therefore, it is necessary to have robust systems that can predict soil properties at a given location. That is needed in many tropical countries where the dearth of soil property measurements is large. This paper reviews the use of pedotransfer functions (PTF) for predicting properties of soils in the tropics. First, the guiding principles of prediction and the type of predictors are discussed, including laboratory data, field description and soil morphology, electromagnetic spectrum, proximal and remote sensed data. In the subsequent section, PTFs are discussed for soil physical and chemical properties followed by infrared spectroscopy, proximal sensing and remote sensing. An analysis of ISRIC (mainly tropical) and USDA (mainly temperate) soil databases showed that soils in the tropics have higher clay content, lower cation exchange capacity, higher bulk density, lower water content at − 10 kPa and − 1500 kPa than soils in the temperate regions. Various methods developed in temperate regions can be applied for the soils in the tropical regions although calibration and careful selection of predictors remains necessary. It is concluded that PTFs are an important tool to overcome the dearth of soil data in many tropical countries.

The estimation of non available soil variables through the knowledge of other related measured variables can be achieved through pedotransfer functions (PTF) mainly saving time and reducing cost. Great differences among soils, however, can yield non desirable results when applying this method. This study discusses the application of developed PTFs by several authors using a variety of soils of different characteristics, to evaluate soil water contents of two Brazilian lowland soils. Comparisons are made between PTF evaluated data and field measured data, using statistical and geostatistical tools, like mean error, root mean square error, semivariogram, cross-validation, and regression coefficient. The eight tested PTFs to evaluate gravimetric soil water contents (Ug) at the tensions of 33 kPa and 1,500 kPa presented a tendency to overestimate Ug 33 kPa and underestimate Ug1,500 kPa. The PTFs were ranked according to their performance and also with respect to their potential in describing the structure of the spatial variability of the set of measured values. Although none of the PTFs have changed the distribution pattern of the data, all resulted in mean and variance statistically different from those observed for all measured values. The PTFs that presented the best predictive values of Ug33 kPa and Ug1,500 kPa were not the same that had the best performance to reproduce the structure of spatial variability of these variables.

An extensive field trial was set up in eight forest stands to examine the influence of soil texture (two stands on sand, four on loam to silt loam, two on clay), machine mass (light, heavy) and traffic intensity (one and five skidding cycles) (i.e. pass back and forth on the skid trail) on soil compaction after mechanized harvesting. Dry bulk density (BD), penetration resistance (PR), micro-topography and soil carbon dioxide (CO2) concentration were applied as response variables for soil compaction. Significant effects on BD were nearly absent ( In contrast with BD and PR, soil CO2 concentration, measured in a forest stand on sand, showed significant increases within and between wheel tracks, even after one skidding cycle. Although soil compaction degrees were small to negligible, machine passes apparently had a strong negative impact on pore continuity. CO2 concentration seems to be a more sensitive and thus better indicator for soil compaction.

Knowledge on soil pore geometry is important for understanding soil processes as it controls the movement and storage of fluids on various scales. With the advent of modern non-destructive tomography techniques there have been many attempts made to analyze pore space features mainly concentrating on the visualization Of Soil Structure. Multifractal formalism or the wavelet transform has been revealed as a useful tool in these cases where highly complex and heterogeneous media are studied. The field of 3D pore space analysis opens a challenging opportunity to develop techniques for quantifying and describing pore space properties. One of these quantifications can be the maximum depth pore network (MD), analogous as the quantification of the preferential flow paths. In this paper, a variation of the wavelet transform modulo maxima (WTMM) method used to compute multifractal behavior is presented. As a wavelet transform analysis (WTA), it allows us to focus on every scale which can be useful to select the range of scales where multifractal analysis (MFA) can be applied, revealing the MD global scaling patterns. In addition, the proposed method does not make any global estimate, so it can also be used to focus on local distribution of singularities. So, in the context of multiscaling structure analysis, the proposed wavelet-based method can complement box-counting analysis in order to statistically describe preferential flow path geometry and flow processes. The methodology is applied to determine the multifiractal behaviour of 3D images of soil samples with 45.1 mu m resolution (256 x 256 x 256 voxels) with closer porosities (ranging from 12% to 14%) and different spatial arrangements. (C) 2009 Elsevier B.V. All rights reserved. 2.178 JCR (2010) Q1, 5/32 Soil science UEM

Statistical methods were developed to assess required changes in the contents and pools of major nutrients and exchangeable base cations in the organic layer and the mineral soil of European forest soils, to derive significant differences. Furthermore a simple element retention model is described and applied to assess the variation time periods, as a function of site and soil characteristics and atmospheric inputs, that are needed before repeating soil surveys in order to assess significant differences in element pools. Time periods that are needed to assess a significant difference have been limited to N in the organic layer and base cations in the mineral layer, since those pools are liable to change caused by nitrogen or acid deposition. Results showed that a time interval of 10 years, which is generally considered for a repetition of the soil survey, might give a significant difference in N and exchangeable base cation pools for approximately 25% and 10% of the plots, only.

The soil formation process ripening can be used as a bioremediation technique for dredged sediments that are polluted with organic chemicals. Currently, data are lacking that quantify the effects of physical ripening on parameters that affect aerobic bioremediation. We quantified the effects of physical ripening on shrinkage, swelling, moisture retention, hydraulic conductivity, and oxygen diffusion for three freshly dredged sediments using specially designed pressure chambers. We also quantified the effect of physical ripening on structure development by measuring aggregate size distributions for four half-ripe and four ripe sediment samples that were collected from field sediment disposal sites. The course of physical ripening and the aerobic bioremediation process for sediments at above ground (upland) disposal sites can be predicted using the data and information developed in this study when using a combination of existing water and oxygen transport and ripening models.

This paper describes development of the soil-water characteristic curve (SWCC) of a silty soil by measuring its matric suction Psi(m), corresponding to different gravimetric water contents w. To achieve this, a field tensiometer and a dew point potentiameter (WP4) were employed. For this soil, the SWCC was determined indirectly using the estimation algorithms known as pedo-transfer functions (PTFs), which are based on volume-mass properties and the grain-size distribution characteristics, and are available in a commercial database SoilVision. In addition to this, experimental results were used for developing the SWCC of the soil, using various fitting functions cited in the literature and available in the database. An attempt has been made in this technical note to demonstrate the usefulness of these three methods for obtaining the SWCC of the silty soil. The study reveals that the PTFs developed previously to estimate SWCCs match very well with the experimental results.

Measurement of soil suction for developing soil-water characteristic curve, SWCC, is a laborious and time-consuming task. On the other hand, commercially available databases that employ empirical fitting functions or the estimation algorithms for establishing the SWCC are quite costly and hence, beyond the reach of many. In such a situation, application of two simple nonlinear curve-fitting procedures (viz., a spreadsheet based program, SBP, and Levenberg-Marquardt Algorithm, LMA) for developing the drying SWCC was investigated. The utility and efficiency of these fitting procedures have been demonstrated by comparing the results vis-A-vis those obtained from a dewpoint potentiameter, WP4, and a knowledge-based database, KBD. In addition to this, efforts were made to develop correlations between the parameters used in the SWCC fitting functions and the physical properties of the soil, which can be determined quite easily by conducting routine laboratory tests. It has been demonstrated that these correlations can be used very efficiently for indirect estimation of the SWCC of the fine-grained soil.