http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Thu, 11 Apr 2013 15:08:24 +0000 http://www.hindawi.com/journals/aess/2013/891534/ The availability of light detection and ranging data (LiDAR) has resulted in a new era of landscape analysis. For example, improvements in LiDAR data resolution may make it possible to accurately model microtopography over a large geographic area; however, data resolution and processing costs versus resulting accuracy may be too costly. We examined two LiDAR datasets of differing resolutions, a low point density (0.714 points/m2 spacing) 1 m DEM available statewide in Pennsylvania and a high point density (10.28 points/m2 spacing) 1 m DEM research-grade DEM, and compared the calculated roughness between both resulting DEMs using standard deviation of slope, standard deviation of curvature, a pit fill index, and the difference between a smoothed splined surface and the original DEM. These results were then compared to field-surveyed plots and transects of microterrain. Using both datasets, patterns of roughness were identified, which were associated with different landforms derived from hydrogeomorphic features such as stream channels, gullies, and depressions. Lowland areas tended to have the highest roughness values for all methods, with other areas showing distinctive patterns of roughness values across metrics. However, our results suggest that the high-resolution research-grade LiDAR did not improve roughness modeling in comparison to the coarser statewide LiDAR. We conclude that resolution and initial point density may not be as important as the algorithm and methodology used to generate a LiDAR-derived DEM for roughness modeling purposes. Kristen M. Brubaker, Wayne L. Myers, Patrick J. Drohan, Douglas A. Miller, and Elizabeth W. Boyer Copyright © 2013 Kristen M. Brubaker et al. All rights reserved. Wed, 20 Mar 2013 15:14:33 +0000 http://www.hindawi.com/journals/aess/2013/616578/ Sabine Chabrillat, Eyal Ben-Dor, Raphael A. Viscarra Rossel, and José A. M. Demattê Copyright © 2013 Sabine Chabrillat et al. All rights reserved. Mon, 25 Feb 2013 10:43:26 +0000 http://www.hindawi.com/journals/aess/2013/206758/ Terrestrial carbon (C) sequestration through optimizing land use and management is widely considered a realistic option to mitigate the global greenhouse effect. But how the responses of individual ecosystems to changes in land use and management are related to baseline soil organic C (SOC) levels still needs to be evaluated at various scales. In this study, we modeled SOC dynamics within both natural and managed ecosystems in North Dakota of the United States and found that the average SOC stock in the top 20 cm depth of soil lost at a rate of 450 kg C ha−1 yr−1 in cropland and 110 kg C ha−1 yr−1 in grassland between 1971 and 1998. Since 1998, the study area had become a SOC sink at a rate of 44 kg C ha−1 yr−1. The annual rate of SOC change in all types of lands substantially depends on the magnitude of initial SOC contents, but such dependency varies more with climatic variables within natural ecosystems and with management practices within managed ecosystems. Additionally, soils with high baseline SOC stocks tend to be C sources following any land surface disturbances, whereas soils having low baseline C contents likely become C sinks following conservation management. Zhengxi Tan and Shuguang Liu Copyright © 2013 Zhengxi Tan and Shuguang Liu. All rights reserved. Sun, 24 Feb 2013 09:35:20 +0000 http://www.hindawi.com/journals/aess/2013/617504/ The 24-year study was conducted in southern Illinois (USA) on land similar to that being removed from Conservation Reserve Program (CRP) to evaluate the effects of conservation tillage systems on: (1) amount and rates of soil organic carbon (SOC) storage and retention, (2) the long-term corn and soybean yields, and (3) maintenance and restoration of soil productivity of previously eroded soils. The no-till (NT) plots did store and retain 7.8 Mg C ha−1 more and chisel plow (CP) −1.6 Mg C ha−1 less SOC in the soil than moldboard plow (MP) during the 24 years. However, no SOC sequestration occurred in the sloping and eroding NT, CP, and MP plots since the SOC level of the plot area was greater at the start of the experiment than at the end. The NT plots actually lost a total of −1.2 Mg C ha−1, the CP lost −9.9 Mg C ha−1, and the MP lost −8.2 Mg C ha−1 during the 24-year study. The long-term productivity of NT compared favorably with that of MP and CP systems. Kenneth R. Olson, Stephen A. Ebelhar, and James M. Lang Copyright © 2013 Kenneth R. Olson et al. All rights reserved. Mon, 31 Dec 2012 18:51:23 +0000 http://www.hindawi.com/journals/aess/2012/619548/ Fernando José Garbuio, Jeffrey L. Howard, and Larissa Macedo dos Santos Copyright © 2012 Fernando José Garbuio et al. All rights reserved. Wed, 21 Nov 2012 16:08:37 +0000 http://www.hindawi.com/journals/aess/2012/294121/ Subsetting of samples is a promising avenue of research for the continued improvement of prediction models for soil properties with diffuse reflectance spectroscopy. This study examined the effects of subsetting by soil total carbon () content, soil order, and spectral classification with k-means cluster analysis on visible/near-infrared and mid-infrared partial least squares models for prediction. Our sample set was composed of various Hawaiian soils from primarily agricultural lands with contents from <1% to 56%. Slight improvements in the coefficient of determination () and other standard model quality parameters were observed in the models for the subset of the high activity clay soil orders compared to the models of the full sample set. The other subset models explored did not exhibit improvement across all parameters. Models created from subsets consisting of only low samples (e.g., < 10%) showed improvement in the root mean squared error (RMSE) and percent error of prediction for low soil samples. These results provide a basis for future study of practical subsetting strategies for soil prediction. Meryl L. McDowell, Gregory L. Bruland, Jonathan L. Deenik, and Sabine Grunwald Copyright © 2012 Meryl L. McDowell et al. All rights reserved. Mon, 19 Nov 2012 18:40:31 +0000 http://www.hindawi.com/journals/aess/2012/265783/ Silvana I. Torri, Rodrigo Studart Corrêa, Giancarlo Renella, Alejandro Valdecantos, and Leonid Perelomov Copyright © 2012 Silvana I. Torri et al. All rights reserved. Mon, 22 Oct 2012 14:53:07 +0000 http://www.hindawi.com/journals/aess/2012/535646/ The ability of thermal and shortwave infrared spectroscopy to characterise composition and texture was evaluated using both particle size separated soil samples and natural soils. Particle size analysis and separation into clay, silt, and sand-sized soil fractions was undertaken to examine possible relationships between quartz and clay mineral spectral signatures and soil texture. Spectral indices, based on thermal infrared specular and volume scattering features, were found to discriminate clay mineral-rich soil from mostly coarser quartz-rich sandy soil and to a lesser extent from the silty quartz-rich soil. Further investigations were undertaken using spectra and information on 51 USDA and other soils within the ASTER spectral library to test the application of shortwave, mid- and thermal infrared spectral indices for the derivation of clay mineral, quartz, and organic carbon content. A nonlinear correlation between quartz content and a TIR spectral index based on the 8.62 μm was observed. Preliminary efforts at deriving a spectral index for the soil organic carbon content, based on 3.4–3.5 μm fundamental H–C stretching vibration bands, were also undertaken with limited results. Robert D. Hewson, Thomas J. Cudahy, Malcolm Jones, and Matilda Thomas Copyright © 2012 Robert D. Hewson et al. All rights reserved. Wed, 17 Oct 2012 08:35:15 +0000 http://www.hindawi.com/journals/aess/2012/850739/ Philip J. White, John W. Crawford, María Cruz Díaz Álvarez, and Rosario García Moreno Copyright © 2012 Philip J. White et al. All rights reserved. Sun, 14 Oct 2012 17:13:48 +0000 http://www.hindawi.com/journals/aess/2012/130941/ Surveys of soil properties related to soil functioning for many regions of Kyrgyzstan are limited. This study established ranges of chemical (soil organic matter (SOM), pH and total N (TN)), physical (soil texture), and biochemical (six enzyme activities of C, N, P, and S cycling) characteristics for nine profiles from the Kukart watershed of Jalal-Abad region in Kyrgyzstan. These profiles represent different soil orders (Inceptisols, Alfisols, and Mollisols) and land uses (cultivated, nut-fruit forests, and pasture). The Sierozem (Inceptisols) soils had the highest pH and contained the lowest SOM and TN contents compared to the Brown, Black-brown, and Meadow-steppe soils (Alfisols and Mollisols). Enzymatic activities within surface horizons (0–18 cm) typically decreased in the following order: forest > pasture > cultivated. Enzyme activity trends due to land use were present regardless of elevation, climate, and soil types although subtle differences among soil types within land use were observed. The significant reductions in measured soil enzyme activities involved in C, N, P, and S nutrient transformations under cultivation compared to pasture and forest ecosystems and lower values under Inceptisols can serve as soil quality indicators for land use decisions in the watershed. Zulfiia Sakbaeva, Veronica Acosta-Martínez, Jennifer Moore-Kucera, Wayne Hudnall, and Karabaev Nuridin Copyright © 2012 Zulfiia Sakbaeva et al. All rights reserved. Thu, 11 Oct 2012 15:47:42 +0000 http://www.hindawi.com/journals/aess/2012/274903/ Laboratory imaging spectroscopy can be used to explore physical and chemical variations in soil profiles on a submillimetre scale. We used a hyperspectral scanner in the 400 to 1000 nm spectral range mounted in a laboratory frame to record images of two soil cores. Samples from these cores were chemically analyzed, and spectra of the sampled regions were used to train chemometric PLS regression models. With these models detailed maps of the elemental concentrations in the soil cores could be produced. Eight different spectral pretreatments were applied to the sample spectra and to the resulting images in order to explore the influence of these pre-treatments on the estimation of elemental concentrations. We found that spectral preprocessing has a minor influence on chemometry results when powerful regression algorithms like PLSR are used. Henning Buddenbaum and Markus Steffens Copyright © 2012 Henning Buddenbaum and Markus Steffens. All rights reserved. Wed, 10 Oct 2012 15:48:51 +0000 http://www.hindawi.com/journals/aess/2012/868090/ Information on soil clay and organic carbon content on a regional to local scale is vital for a multitude of reasons such as soil conservation, precision agriculture, and possibly also in the context of global environmental change. The objective of this study was to evaluate the potential of multi-annual hyperspectral images acquired with the HyMap sensor (450–2480 nm) during three flight campaigns in 2004, 2005, and 2008 for the prediction of clay and organic carbon content on croplands by means of partial least squares regression (PLSR). Supplementary, laboratory reflectance measurements were acquired under standardized conditions. Laboratory spectroscopy yielded prediction errors between 19.48 and 35.55 g kg−1 for clay and 1.92 and 2.46 g kg−1 for organic carbon. Estimation errors with HyMap image spectra ranged from 15.99 to 23.39 g kg−1 for clay and 1.61 to 2.13 g kg−1 for organic carbon. A comparison of parameter predictions from different years confirmed the predictive ability of the models. BRDF effects increased model errors in the overlap of neighboring flight strips up to 3 times, but an appropriated preprocessing method can mitigate these negative influences. Using multi-annual image data, soil parameter maps could be successively complemented. They are exemplarily shown providing field specific information on prediction accuracy and image data source. Heike Gerighausen, Gunter Menz, and Hermann Kaufmann Copyright © 2012 Heike Gerighausen et al. All rights reserved. Tue, 02 Oct 2012 11:44:08 +0000 http://www.hindawi.com/journals/aess/2012/593623/ Different plants are known to have different soil microbial communities associated with them. Agricultural management practices such as fertiliser and pesticide addition, crop rotation, and grazing animals can lead to different microbial communities in the associated agricultural soils. Soil dilution plates, most-probable-number (MPN), community level physiological profiling (CLPP), and buried slide technique as well as some measured soil physicochemical parameters were used to determine changes during the growing season in the ecosystem profile in wheat fields subjected to wheat monoculture or wheat in annual rotation with medic/clover pasture. Statistical analyses showed that soil moisture had an over-riding effect on seasonal fluctuations in soil physicochemical and microbial populations. While within season soil microbial activity could be differentiated between wheat fields under rotational and monoculture management, these differences were not significant. A. Marais, M. Hardy, M. Booyse, and A. Botha Copyright © 2012 A. Marais et al. All rights reserved. Wed, 26 Sep 2012 16:29:43 +0000 http://www.hindawi.com/journals/aess/2012/506302/ Below-ground residue of agroforestry trees is an important N source for associated crops. Several studies have shown that its isotopic signature (δ15N) may change after tree pruning, which makes it difficult to study below-ground N inputs from pruned trees by isotopic techniques. We studied how temporal variation of legume root residue δ15N could be explained by considering differential decomposition kinetics and 15N content of residue fractions. A mathematical model on the isotopic patterns of soil and a N recipient plant during root decomposition was developed and applied for testing assumptions about residue characteristics against two experimental datasets. Observed 15N patterns of the recipient plants could be satisfactorily simulated only when the residue was assumed to consist of at least two fractions with distinct δ15N and decomposition rates depending on their C : N ratio. Assuming δ15N of residue constant over time resulted in substantial underestimates of N derived from low-quality residue (%Ndfr) by the recipient plant when compared with experimental data. Results of this study suggest that residue fractionation can help improve estimation of %Ndfr in isotopic studies, as an alternative or complementary method to assuming or aiming at homogenous isotopic composition of N sources. Riina Jalonen and Jorge Sierra Copyright © 2012 Riina Jalonen and Jorge Sierra. All rights reserved. Mon, 17 Sep 2012 11:30:08 +0000 http://www.hindawi.com/journals/aess/2012/971252/ The accurate assessment of selected soil constituents can provide valuable indicators to identify and monitor land changes coupled with degradation which are frequent phenomena in semiarid regions. Two approaches for the quantification of soil organic carbon, iron oxides, and clay content based on field and laboratory spectroscopy of natural surfaces are tested. (1) A physical approach which is based on spectral absorption feature analysis is applied. For every soil constituent, a set of diagnostic spectral features is selected and linked with chemical reference data by multiple linear regression (MLR) techniques. (2) Partial least squares regression (PLS) as an exclusively statistical multivariate method is applied for comparison. Regression models are developed based on extensive ground reference data of 163 sampled sites collected in the Thicket Biome, South Africa, where land changes are observed due to intensive overgrazing. The approaches are assessed upon their prediction performance and significance in regard to a future quantification of soil constituents over large areas using imaging spectroscopy. Anita Bayer, Martin Bachmann, Andreas Müller, and Hermann Kaufmann Copyright © 2012 Anita Bayer et al. All rights reserved. Wed, 22 Aug 2012 14:55:23 +0000 http://www.hindawi.com/journals/aess/2012/439567/ We explored the effect of raindrop energy on both water infiltration into soil and the soil's NIR-SWIR spectral reflectance (1200–2400 nm). Seven soils with different physical and morphological properties from Israel and the US were subjected to an artificial rainstorm. The spectral properties of the crust formed on the soil surface were analyzed using an artificial neural network (ANN). Results were compared to a study with the same population in which partial least-squares (PLS) regression was applied. It was concluded that both models (PLS regression and ANN) are generic as they are based on properties that correlate with the physical crust, such as clay content, water content and organic matter. Nonetheless, better results for the connection between infiltration rate and spectral properties were achieved with the non-linear ANN technique in terms of statistical values (RMSE of 17.3% for PLS regression and 10% for ANN). Furthermore, although both models were run at the selected wavelengths and their accuracy was assessed with an independent external group of samples, no pre-processing procedure was applied to the reflectance data when using ANN. As the relationship between infiltration rate and soil reflectance is not linear, ANN methods have the advantage for examining this relationship when many soils are being analyzed. Naftali Goldshleger, Alexandra Chudnovsky, and Eyal Ben-Dor Copyright © 2012 Naftali Goldshleger et al. All rights reserved. Wed, 15 Aug 2012 12:52:07 +0000 http://www.hindawi.com/journals/aess/2012/539582/ This study presents soil system budgets of N, P and K in six contrasting cropping systems during 10 years of a long-term experiment in southeast Norway. The experiment included systems with arable cash-cropping and with mixed arable-dairy cropping (cash- and fodder crops), with organic and conventional management represented in both groups. All major nutrient inputs and outputs were measured or estimated. State of the art conventional cash-cropping appeared to be balanced in terms of N, whereas conventional mixed cropping had an N surplus. By contrast, less up to date conventional arable cash-cropping and all the organic systems showed indications of soil organic N depletion (negative N budgets). All the organic systems showed that mining of the soil P and K content occurs, whereas the conventional systems all had P and K surpluses. The results corresponded well with measured differences between systems in terms of ignition loss, P-AL, K-AL and K-HNO3 measured in 2009. This study shows that a fertile soil may be exposed to substantial mining of N, P and K over many years before it is detectable by traditional analyses, and that field nutrient budgeting is a feasible, but data-demanding, approach to detect such misbalances at an early stage. Audun Korsaeth Copyright © 2012 Audun Korsaeth. All rights reserved. Thu, 09 Aug 2012 10:24:49 +0000 http://www.hindawi.com/journals/aess/2012/241535/ Predicted global warming will be most pronounced in the Arctic and will severely affect permafrost environments. Due to its large spatial extent and large stocks of soil organic carbon, changes to organic matter decomposition rates and associated carbon fluxes in Arctic permafrost soils will significantly impact the global carbon cycle. We explore the potential of soil spectroscopy to estimate soil carbon properties and investigate the relation between soil properties and vegetation composition. Soil samples are collected in Siberia, and vegetation descriptions are made at each sample point. First, laboratory-determined soil properties are related to the spectral reflectance of wet and dried samples using partial least squares regression (PLSR) and stepwise multiple linear regression (SMLR). SMLR, using selected wavelengths related with C and N, yields high calibration accuracies for C and N. PLSR yields a good prediction model for K and a moderate model for pH. Using these models, soil properties are determined for a larger number of samples, and soil properties are related to plant species composition. This analysis shows that variation of soil properties is large within vegetation classes, but vegetation composition can be used for qualitative estimation of soil properties. Harm Bartholomeus, Gabriela Schaepman-Strub, Daan Blok, Roman Sofronov, and Sergey Udaltsov Copyright © 2012 Harm Bartholomeus et al. All rights reserved. Tue, 07 Aug 2012 11:41:14 +0000 http://www.hindawi.com/journals/aess/2012/817158/ The main aim of this study was to examine the influence of sewage sludge (SS) and stabilized SS application on Olsen-P and DTPA-extractable Cu and Zn in relation to soil type, sewage source, mixing rate and incubation time. Two different SS were mixed with amendments by mixing rates 10 and 25%. These amendments include coal fly ash (CFA), bentonite (B), sugar beet factory lime (SBFL), calcium carbonate, rice straw (RS), water hyacinth (WH), and cotton stalks (CS). Treated and untreated SS had been applied to fluvial and calcareous soil with application rate 2.5% and incubated for one and two month. After incubation, soil samples were analyzed for Olsen-P and DTPA-extractable Cu and Zn. Application of SS increased significantly Olsen-P and DTPA extractable Cu and Zn compared to control. Application of stabilized SS increased significantly Olsen-P, with high increasing rate with SBFL and WH-stabilized SS. Stabilized-SS decreased significantly Cu and Zn availability compared to mono SS treatment. Bentonite-, SBFL and CFA-stabilized SS were the highest among inorganic treatments for reducing available Cu and Zn either in fluvial or calcareous soil, while WH and RS-stabilized SS treatment were the most suitable organic ones for reducing DTPA-extractable Cu and Zn. S. M. Shaheen, M. S. Shams, F. A. Elbehiry, and S. M. Ibrahim Copyright © 2012 S. M. Shaheen et al. All rights reserved. Wed, 01 Aug 2012 10:01:27 +0000 http://www.hindawi.com/journals/aess/2012/201462/ Land application of biosolids has proven a cost-effective method of waste disposal by beneficially recycling organic matter and nutrients and improving soil quality; however, it may also pose potential threat to the environment and human health. The purpose of this paper is to provide information on recent research progresses and regulation efforts regarding land application of biosolids, including forms and types and nutrient values of biosolids, environmental and health concerns, and related best management practices (BMPs) of biosolids application, with emphasis on its land application in agriculture. More research and regulations are expected to minimize potential risks of biosolids land application, especially its long-term impacts. Qin Lu, Zhenli L. He, and Peter J. Stoffella Copyright © 2012 Qin Lu et al. All rights reserved. Mon, 30 Jul 2012 08:38:40 +0000 http://www.hindawi.com/journals/aess/2012/518206/ A large volume of generated sewage sludge makes its disposal a problem. The usage of sludge in agriculture is highlighted by a number of advantages. However, heavy metals and other toxic compounds may exercise harmful effects to soil organisms. This study evaluated the possible toxic effects of a biosolid sample, under laboratory conditions, for 30 days, using diplopods Rhinocricus padbergi and plants Allium cepa (onion) as test organisms. The data obtained demonstrated that the biosolid raw sample had genotoxic potential for Allium cepa root tip cells. In the diplopods exposed to biosolid sample, epithelium disorganization in the midgut and a reduction of the volume of the hepatic cells were observed after 7 days of exposure. After 30 days, the animals still showed a reduction of the volume of the hepatic cells, but in minor intensity. Allium cepa analysis showed genotoxicity, but this effect was reduced after 30 days of bioprocessing by diplopods. This study was important to know the effects as well as to determine how this waste could be applied concerning the soil living organisms and plants. Cintya Ap. Christofoletti, Annelise Francisco, and Carmem S. Fontanetti Copyright © 2012 Cintya Ap. Christofoletti et al. All rights reserved. Thu, 19 Jul 2012 09:35:42 +0000 http://www.hindawi.com/journals/aess/2012/632172/ Bromus tectorum L. (cheatgrass) is an Eurasian annual grass that has invaded ecosystems throughout the Intermountain west of the United States. Our purpose was to examine mechanisms by which established perennial grasses suppress the growth of B. tectorum. Using rhizotrons, the experiment was conducted over 5 growth cycles: (1) B. tectorum planted between perennial grasses; (2) perennials clipped and B. tectorum planted; (3) perennials clipped and B. tectorum planted into soil mixed with activated carbon; (4) perennials clipped, B. tectorum planted, and top-dressed with fertilizer, and; (5) perennial grasses killed and B. tectorum planted. Water was not limiting in this study. Response variables measured at the end of each growth cycle included above-ground mass and tissue nutrient concentrations. Relative to controls (B. tectorum without competition), established perennial grasses significantly hindered the growth of B. tectorum. Overall, biomass of B. tectorum, grown between established perennials, increased considerably after fertilizer addition and dramatically upon death of the perennials. Potential mechanisms involved in the suppression of B. tectorum include reduced nitrogen (possibly phosphorus) availability and coopting of biological soil space by perennial roots. Our data cannot confirm or reject allelopathic suppression. Understanding the mechanisms involved with suppression may lead to novel control strategies against B. tectorum. Robert R. Blank and Tye Morgan Copyright © 2012 Robert R. Blank and Tye Morgan. All rights reserved. Sun, 15 Jul 2012 08:35:43 +0000 http://www.hindawi.com/journals/aess/2012/838254/ The NST 3.0 mechanistic nutrient uptake model was used to explore P uptake to a depth of 120 cm over a 126 d growing season in simulated buffer communities composed of mixtures of cottonwood (Populus deltoids Bartr.), switchgrass (Panicum virgatum L.), and smooth brome (Bromus inermis Leyss). Model estimates of P uptake from pure stands of smooth brome and cottonwood were 18.9 and 24.5 kg ha−1, respectively. Uptake estimates for mixed stands of trees and grasses were intermediate to pure stands. A single factor sensitivity analysis of parameters used to calculate P uptake for each cover type indicated that 𝐼max, k, 𝑟𝑜, and 𝐿𝑜 were consistently the most responsive to changes ranging from −50% to +100%. Model exploration of P uptake as a function of soil depth interval indicated that uptake was highest in the 0–30 cm intervals, with values ranging from 85% of total for cottonwood to 56% for switchgrass. J. M. Kelly and J. L. Kovar Copyright © 2012 J. M. Kelly and J. L. Kovar. All rights reserved. Tue, 10 Jul 2012 14:37:02 +0000 http://www.hindawi.com/journals/aess/2012/632602/ We evaluated the effect of acidic deposition and nitrogen on Austrian forests soils. Until thirty years ago air pollution had led to soil acidification, and concerns on the future productivity of forests were raised. Elevated rates of nitrogen deposition were believed to cause nitrate leaching and imbalanced forest nutrition. We used data from a soil monitoring network to evaluate the trends and current status of the pH and the C : N ratio of Austrian forest soils. Deposition measurements and nitrogen contents of Norway spruce needles and mosses were used to assess the nitrogen supply. The pH values of soils have increased because of decreasing proton depositions caused by reduction of emissions. The C : N ratio of Austrian forest soils is widening. Despite high nitrogen deposition rates the increase in forest stand density and productivity has increased the nitrogen demand. The Austrian Bioindicator Grid shows that forest ecosystems are still deficient in nitrogen. Soils retain nitrogen efficiently, and nitrate leaching into the groundwater is presently not a large-scale problem. The decline of soil acidity and the deposition of nitrogen together with climate change effects will further increase the productivity of the forests until a limiting factor such as water scarcity becomes effective. Robert Jandl, Stefan Smidt, Franz Mutsch, Alfred Fürst, Harald Zechmeister, Heidi Bauer, and Thomas Dirnböck Copyright © 2012 Robert Jandl et al. All rights reserved. Thu, 05 Jul 2012 13:19:40 +0000 http://www.hindawi.com/journals/aess/2012/896090/ Application of sewage sludge with high lead (Pb) contents may pollute soils and contaminate crops. The objective of this work was to evaluate peanut responses to application of sewage sludge with varying Pb contents in order to supply phosphorus (P) to the plant. A greenhouse experiment was carried out with peanut grown on soil sample from a medium-textured Haplustox. Treatments were arranged in 3 × 2 + 2 factorial scheme, replicated three times, distributed in randomized block design, and consisted of: three Pb rates applied to soil with sewage sludge (3, 21, and 42 mg kg−1) × two times of sewage sludge application (30 days before peanut sowing and at the day of the sowing) + mineral fertilization + control (without sewage sludge and mineral fertilization). Sewage sludge was efficient to supply P to peanut. Sewage sludge containing high rates of Pb, when applied, did not harm biomass and yield of the plant, but increased HCl-extractable Pb in soil and Pb content in shoot, roots, and pod husks. Increase of Pb content in pod husks may represent contamination risk of kernels and their products with fragments from husks detached during manipulation or industrial processing of peanuts. Fábio Camilotti, Alysson Roberto Baizi e Silva, and Marcos Omir Marques Copyright © 2012 Fábio Camilotti et al. All rights reserved. Mon, 02 Jul 2012 08:42:56 +0000 http://www.hindawi.com/journals/aess/2012/307415/ Some soil microorganisms are involved in the complex interactions with plants and earthworms, through the production of indole acetic acid (IAA) which modifies plant growth and development. In a factorial experiment testing the impact of the presence/absence of plants and earthworms on IAA production by cultivable bacteria, we observed that plants were decreasing IAA production of 43%, whereas earthworms were increasing it of 46%. In the presence of both plant and earthworms, IAA production was as low as in the presence of plant control, showing that plants influence on IAA production by microorganisms prevails on earthworm influence. We discuss functional reasons which could explain this result. Ruben Puga-Freitas, Samir Abbad, Agnès Gigon, Evelyne Garnier-Zarli, and Manuel Blouin Copyright © 2012 Ruben Puga-Freitas et al. All rights reserved. Thu, 21 Jun 2012 15:03:15 +0000 http://www.hindawi.com/journals/aess/2012/584970/ Soil samples contaminated with Aroclor 1260 were analyzed for microbial PCB dechlorination potential, which is the rate-limiting step for complete PCB degradation. The average chlorines per biphenyl varied throughout the site suggesting that different rates of in situ dechlorination had occurred over time. Analysis of PCB transforming (aerobic and anaerobic) microbial communities and dechlorinating potential revealed spatial heterogeneity of both putative PCB transforming phylotypes and dechlorination activity. Some soil samples inhibited PCB dechlorination in active sediment from Baltimore Harbor indicating that metal or organic cocontaminants might cause the observed heterogeneity of in situ dechlorination. Bioaugmentation of soil samples contaminated with PCBs ranging from 4.6 to 265 ppm with a pure culture of the PCB dechlorinating bacterium Dehalobium chlorocoercia DF-1 also yielded heterologous results with significant dechlorination of weathered PCBs observed in one location. The detection of indigenous PCB dehalorespiring activity combined with the detection of putative dechlorinating bacteria and biphenyl dioxygenase genes in the soil aggregates suggests that the potential exists for complete mineralization of PCBs in soils. However, in contrast to sediments, the heterologous distribution of microorganisms, PCBs, and inhibitory cocontaminants is a significant challenge for the development of in situ microbial treatment of PCB impacted soils. Birthe V. Kjellerup, Piuly Paul, Upal Ghosh, Harold D. May, and Kevin R. Sowers Copyright © 2012 Birthe V. Kjellerup et al. All rights reserved. Thu, 14 Jun 2012 11:02:09 +0000 http://www.hindawi.com/journals/aess/2012/672914/ Two commonly applied single extractions procedures, namely extractions with ammonium-EDTA and acetic acid, were evaluated based on the analysis of 72 samples from alluvial sediments. For most trace elements (Cu, Zn, Cd, Ni, As, and Pb), a significant linear relationship could be established between their ammonium-EDTA or acetic acid extractable concentrations and their total concentrations, the organic carbon content, pH, and Fe , Al, and/or Ca content in the sediments. The scientific understanding of trace element partitioning in the complex soil-water system with these simple models is rather limited, but they offer the opportunity to use data from single extractions in a more comprehensive way. Despite the fact that these extractions cannot directly be related to the bioavailability of elements, they can provide input data for use in risk assessment models. Additionally, they also offer possibilities to perform a fast screening of the mobilizable pool of elements in soils and/or sediments. Valérie Cappuyns Copyright © 2012 Valérie Cappuyns. All rights reserved. Wed, 13 Jun 2012 10:44:04 +0000 http://www.hindawi.com/journals/aess/2012/239639/ A compost of vegetable waste and Posidonia oceanica mixture (70 : 30% vol : vol) was tested in vitro and in vivo for its efficacy against Fusarium oxysporum f.sp radicis-lycopersici (Forl), the causal agent of Fusarium wilt of Tomato (Lycopersicon esculentum cv. chourouk).The incorporation of non-sterilized VPC in the culture medium showed potent antifungal activity against Forl and complete inhibition of mycelium growth was observed for all the tested compost rates (0.5, 1, 2, 4, 6, 8, 10, 15 and 20%). However, only the highest rates (15 and 20%) of a sterilized suspension of VPC were effective in preventing mycelial growth. Nine indigenous bacterial strains isolated from VPC exhibited antagonism against Forl. Based on 16S rDNA sequence analysis, the isolates were assigned to Bacillus sphaericus (B12 and BS2), Pseudomonas putida PPS7 and Burkholderia gladioli BuC16. Under green house condition, seed inoculation by B12, BS2, PP7 and BuC16 strains protected significantly tomato against Fusarium oxysporum f.sp radicis-lycopersici (Forl) attacks. S. Kouki, N. Saidi, A. Ben Rajeb, M. Brahmi, A. Bellila, M. Fumio, A. Hefiène, N. Jedidi, J. Downer, and H. Ouzari Copyright © 2012 S. Kouki et al. All rights reserved. Thu, 07 Jun 2012 10:12:47 +0000 http://www.hindawi.com/journals/aess/2012/548620/ Soil management practices influence soil physical and chemical characteristics and bring about changes in the soil microbial community structure and function. In this study, the effects of long-term conventional and no-tillage practices on microbial community structure, enzyme activities, and selected physicochemical properties were determined in a continuous corn system on a Decatur silt loam soil. The long-term no-tillage treatment resulted in higher soil carbon and nitrogen contents, viable microbial biomass, and phosphatase activities at the 0–5 cm depth than the conventional tillage treatment. Soil microbial community structure assessed using phospholipid fatty acid (PLFA) analysis and automated ribosomal intergenic spacer analysis (ARISA) varied by tillage practice and soil depth. The abundance of PLFAs indicative of fungi, bacteria, arbuscular mycorrhizal fungi, and actinobacteria was consistently higher in the no-till surface soil. Results of principal components analysis based on soil physicochemical and enzyme variables were in agreement with those based on PLFA and ARISA profiles. Soil organic carbon was positively correlated with most of the PLFA biomarkers. These results indicate that tillage practice and soil depth were two important factors affecting soil microbial community structure and activity, and conservation tillage practices improve both physicochemical and microbiological properties of soil. Reji P. Mathew, Yucheng Feng, Leonard Githinji, Ramble Ankumah, and Kipling S. Balkcom Copyright © 2012 Reji P. Mathew et al. All rights reserved.