ISRN Soil Science The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. The Effect of Minjingu Phosphate Rock and Triple Superphosphate on Soil Phosphorus Fractions and Maize Yield in Western Kenya Tue, 04 Mar 2014 07:49:07 +0000 We tested the effects of triple superphosphate (TSP) and Minjingu phosphate rock (MPR), when applied at phosphorus (P) rates of 50 or 250 kg P ha−1 in a factorial combination with urea or Tithonia diversifolia green manure as nitrogen sources, on P availability and maize yields for two seasons at Nyabeda and Khwisero in Kenya. Phosphorus availability was determined by the Olsen method or sequential fractionation. There was no significant difference in Olsen P as influenced by TSP and MPR at 50 kg P ha−1 irrespective of the N source at both sites in both seasons. However, at 250 kg P ha−1, TSP gave significantly higher Olsen P than MPR. The labile P fractions generally followed the same trend as the Olsen P. Maize yields increased with increasing amount of P applied. Generally, there was no significant difference between TSP and MPR on maize yields irrespective of the N source. The Olsen-P, Resin-P, and sodium bicarbonate inorganic P correlated well with maize yields when TSP was used but the correlations between these P tests and maize yields for MPR were not consistent and therefore their use on soils treated with MPR should be exercised with caution. Robert Orangi Nyambati and Peter Asbon Opala Copyright © 2014 Robert Orangi Nyambati and Peter Asbon Opala. All rights reserved. Maya and WRB Soil Classification in Yucatan, Mexico: Differences and Similarities Sat, 28 Dec 2013 10:51:34 +0000 Soils of the municipality of Hocabá, Yucatán, México, were identified according to both Mayan farmers’ knowledge and the World Reference Base for Soil Resources (WRB). To identify Maya soil classes, field descriptions made by farmers and semistructured interviews were utilized. WRB soils were identified by describing soil profiles and analyzing samples in the laboratory. Mayan farmers identified soils based on topographic position and surface properties such as colour and amount of rock fragments and outcrops. Farmers distinguished two main groups of soils: K'ankab or soils of plains and Boxlu’um or soils of mounds. K'ankab is a group of red soils with two variants (K'ankab and Haylu’um), whereas Boxlu’um is a group of dark soils with five variants (Tsek'el, Ch'ich'lu’um, Chaltun, Puslu’um, and Ch'och'ol). Soils on the plains were identified as Leptosoils, Cambisols, and Luvisols. Soils identified in mounds were Leptosols and Calcisols. Many soils identified by farmers could be more than one WRB unit of soil and vice versa; in these cases no direct relationship between both classification systems was possible. Mayan and WRB soil types are complementary; they should be used together to improve regional soil classifications, help transference of agricultural technologies, and make soil management decisions. Héctor Estrada-Medina, Francisco Bautista, Juan José María Jiménez-Osornio, José Antonio González-Iturbe, and Wilian de Jesús Aguilar Cordero Copyright © 2013 Héctor Estrada-Medina et al. All rights reserved. The Variations in the Soil Enzyme Activity, Protein Expression, Microbial Biomass, and Community Structure of Soil Contaminated by Heavy Metals Thu, 26 Dec 2013 16:20:35 +0000 Heavy metals have adverse effects on soil ecology. Given the toxicity of heavy metals, there is an urgent need to select an appropriate indicator that will aid in monitoring their biological effects on soil ecosystems. By combining different monitoring techniques for various aspects of microbiology, the effects of heavy metals on soil microorganisms near a smelter were studied. Our goal was to determine whether proteins could be a proper indicator for soil pollution. This study demonstrated that the activities of acid phosphatase and dehydrogenase, as well as the levels of microbial biomass carbon and proteins, were negatively affected by heavy metals. In addition, significantly negative correlations were observed between these microbial indicators and heavy metals. Denaturing gradient gel electrophoresis analysis was used in this study to demonstrate that heavy metals also have a significantly negative effect on soil microbial diversity and community structure. The soil protein expression was similar across different soils, but a large quantity of presumably low molecular weight protein was observed only in contaminated soil. Based on this research, we determined that the soil protein concentration was more sensitive to heavy metals than acid phosphatase, dehydrogenase, or microbial biomass carbon because it was more dramatically decreased in the contaminated soils. Therefore, we concluded that the soil protein level has great potential to be a sensitive indicator of soil contamination. Further research is essential, particularly to identify the low molecular weight protein that only appears in contaminated soil, so that further insight can be gained into the responses of microbes to heavy metals. Xi Zhang, Feng Li, Tingting Liu, Chen Xu, Dechao Duan, Cheng Peng, Shenhai Zhu, and Jiyan Shi Copyright © 2013 Xi Zhang et al. All rights reserved. Significance of Some Soil Amendments and Phosphate Dissolving Bacteria to Enhance the Availability of Phosphate in Calcareous Soil Wed, 25 Dec 2013 11:15:57 +0000 A field experiment was carried-out on a private farm at the Salah El-Din village, El-Bostan district, Nobaria, El-Behera Governorate, Egypt. The aim of this study was to evaluate the best combination of rock phosphate (RP), sulphur (S), organic manure, and phosphate dissolving bacteria (PDB) inoculation to enhance the availability of phosphorous from rock phosphate and their effects on yield of broad bean plants (cv. Luz doe Otono L.). It was found that either sulphur application or PDB inoculation with RP had a significant effect on broad bean yield and its quality. Application of RP and different soil amendments individually or together increased N, P, and K contents in straw and seeds of broad bean plant. The highest contents of the studied nutrients were found when the plants were fertilized by a mixture of RP and different soil amendments. Results also showed the important role of organic matter, sulphur, and PDB for releasing phosphorus from rock phosphate. The combination of soil amendments with RP as a natural P-source, has the possibility of saving significant quantities of industrialized inorganic phosphate fertilizers. Ahmed A. Khalil Copyright © 2013 Ahmed A. Khalil. All rights reserved. Agricultural Land-Use Changes and Soil Quality: Evaluating Long-Term Trends in a Rural Mediterranean Region Wed, 25 Dec 2013 08:54:49 +0000 Land-Use Changes (LUCs) are the result of interacting environmental and socioeconomic factors. Although in southern Europe traditional agroforestry systems are an important component of the Mediterranean landscape, intensification and simplification of the rural space coupled with the increasing sensitivity to soil degradation are potentially harmful for the integrity of natural resources and biodiversity stock. The present study introduced a quantitative assessment of rural LUCs that occurred in a region devoted to agriculture and experiencing a progressively higher human impact from both urbanization and land abandonment. The assessment was carried out at the municipality scale along forty years (1970–2010) using data collected every ten years in the framework of the National Census of Agriculture. The Maximum potential Water Capacity (MWC) in the soil, taken as a proxy for agricultural soil quality, and an index of crop intensity have been introduced in the analysis as supplementary variables. A Multiway Factor Analysis (MFA) was developed to evaluate stability or dynamics in the investigated land-use classes. Results illustrate relevant changes in the rural landscape by identifying the classes “moving” towards better soils. An integrated evaluation of rural LUCs and soil resources based on long-time inventories available at an adequate spatial scale is a tool informing policies against soil degradation. Luca Salvati Copyright © 2013 Luca Salvati. All rights reserved. Variability of Soil Physical Properties in a Clay-Loam Soil and Its Implication on Soil Management Practices Mon, 23 Dec 2013 10:44:09 +0000 We assessed the spatial variability of soil physical properties in a clay-loam soil cropped to corn and soybean. The study was conducted at Lincoln University in Jefferson City, Missouri. Soil samples were taken at four depths: 0–10 cm, 10–20, 20–40, and 40–60 cm and were oven dried at 105°C for 72 hours. Bulk density (BDY), volumetric (VWC) and gravimetric (GWC) water contents, volumetric air content (VAC), total pore space (TPS), air-filled (AFPS) and water-filled (WFPS) pore space, the relative gas diffusion coefficient (DIFF), and the pore tortuosity factor (TORT) were calculated. Results showed that, in comparison to depth 1, means for AFPS, Diff, TPS, and VAC decreased in Depth 2. Opposingly, BDY, Tort, VWC, and WFPS increased in depth 2. Semivariogram analysis showed that GWC, VWC, BDY, and TPS in depth 2 fitted to an exponential variogram model. The range of spatial variability () for BDY, TPS, VAC, WFPS, AFPS, DIFF, and TORT was the same (25.77 m) in depths 1 and 4, suggesting that these soil properties can be sampled together at the same distance. The analysis also showed the presence of a strong (≤25%) to weak (>75%) spatial dependence for soil physical properties. Samuel I. Haruna and Nsalambi V. Nkongolo Copyright © 2013 Samuel I. Haruna and Nsalambi V. Nkongolo. All rights reserved. Temporal and Spatial Variability of Water Surplus in Ontario, Canada Thu, 05 Dec 2013 14:20:57 +0000 The temporal variability in estimated water surplus in 12 climatic regions of the province of Ontario, Canada, and its spatial distribution throughout most of the province are discussed in this paper. Surplus water is that which results from precipitation that runs off the land surface and that which drains through the soil profile to the water table and through subsurface drainage. A one-dimensional, deterministic model (DRAINMOD) that simulates soil water flow, including plant uptake, evapotranspiration, and freeze/thaw conditions, was used to estimate the water surplus. Simulations were performed using daily climatic data from January 1954 to December 2001 for each region. A reference corn crop and the predominant local soil conditions in each region, with the hydraulic properties for each layer in the soil profile, were used as model inputs. There was considerable year-to-year variability in annual water surplus in all regions caused by both precipitation and soil conditions. It was the least (~150 mm) in three regions and it exceeded 350 mm in another three regions, where winter snowfall is the greatest as a result of these regions being in the lea of one of the Great Lakes. The variability in water surplus generally increased as average water surplus increased. D. Murray Brown, Humaira Dadfar, David J. Fallow, Robert J. Gordon, John D. Lauzon, and Gary W. Parkin Copyright © 2013 D. Murray Brown et al. All rights reserved. The Influence of Polychlorinated Biphenyls Contamination on Soil Protein Expression Wed, 04 Dec 2013 17:49:11 +0000 Polychlorinated biphenyls (PCBs) are typical representative of chlorinated organic pollutants. Given the toxicity of PCBs, there is an urgent need to select an appropriate indicator to monitor their biological effects on soil ecosystems. For this purpose, we investigated the impacts of PCBs on soil protein and the potential of using protein as a biological indicator to assess soil contamination due to PCBs. This study demonstrated that soil protein concentration and expression were negatively affected by PCBs. In addition, significantly () negative correlation was observed between protein concentration and PCBs. Subsequently, protein size distribution separated by SDS-PAGE revealed that with the increase in PCBs concentration there are less large molecular weight proteins and more low molecular weight proteins (40 kD). Consequently, soil protein level has the potential to be an indicator of soil contamination, and these low molecular weight proteins have significant meaning for getting insight into the ecological effects of PCBs on the soil environment. Xi Zhang, Feng Li, Tingting Liu, Cheng Peng, Dechao Duan, Chen Xu, Shenhai Zhu, and Jiyan Shi Copyright © 2013 Xi Zhang et al. All rights reserved. Effects of Unburned Lime on Soil pH and Base Cations in Acidic Soil Tue, 26 Nov 2013 14:48:55 +0000 Sustainable agriculture is threatened by the widespread soil acidity in many arable lands of Rwanda. The aim of this study was to determine the quality of unburned limes and their effects on soil acidity and base cations in acidic soils of high land of Buberuka. The lime materials used were agricultural burned lime and three unburned lime materials, Karongi, Musanze, and Rusizi. The test crop was Irish Potato. All lime materials were analyzed for Calcium Carbonate Equivalent (CCE) and Fineness. A field trial in Randomized Complete Block Design was established in 2011 at Rwerere research station. The treatments comprised of the four lime materials applied at four levels: 0, 1.4, 2.8, and 4.3 t ha−1 of CCE. Soil cations (Ca2+, Mg2+, K+, and Na+) were determined by extraction method using atomic absorption spectrophotometer for Ca and Mg and flame photometer for K and Na. The Al3+ was determined using potassium chloride extraction method. Experimental soil baseline showed that the soil was very strongly acidic (2.8 cmol kg−1 Al3+). The unburned limes were significantly () different in terms of CCE and fineness. A higher CCE was recorded in agricultural burned and Rusizi unburned limes (86.36% and 85.46%, resp.). In terms of fineness, agricultural burned and Musanze unburned lime were higher (70.57 and 63.03%, resp.). Soil acidity significantly affected from 4.8 to 5.6 pH and exchangeable Al reduced from 2.8 cmol kg−1 to 0.16 cmol kg−1 of Al3+. Similarly all cations affected by unburned limes application, significantly () Ca saturation increased from 27.44 to 71.81%, Mg saturation from 11.18 to 36.87% and significantly () Al saturation reduced from 58.45 to 3.89%. The increase of Mg saturation was observed only with Karongi unburned lime application. This study recommends therefore, the use of 2.8 t ha−1 of CaCO3 of Rusizi or Musanze unburned lime as alternative to the agricultural burned lime for improving soil acidity and base cations in acidic soils. Athanase Nduwumuremyi, Vicky Ruganzu, Jayne Njeri Mugwe, and Athanase Cyamweshi Rusanganwa Copyright © 2013 Athanase Nduwumuremyi et al. All rights reserved. Application of Digital Image Cross Correlation to Study Sinkhole Collapse Sun, 01 Sep 2013 13:33:56 +0000 This paper presents the results of a study using a transparent soil experimental technique and numerical modeling to detect 3D deformations resulting from submerged cavities that lead to a sinkhole. Excessive deformations from underground activity beneath highway pavements could lead to sinkhole collapse. The formation of a sinkhole is often sudden and can lead to extensive damage and loss of life, especially in urban areas. The use of transparent soils permitted the visualization of internal ground deformations which allowed for comprehensive evaluation of the extension of failure. A series of finite element analyses have also been carried out for the tests conditions. The observed sinkhole, at the surface, is found to be a small indicator of the final size and magnitude of the internal deformations as a subsequent funnel-shaped depression developed with a hole at the center. The modeling results emphasized the need to extend the repair zone following sinkhole collapse by a minimum distance that equals twice the cavity diameter away and ahead of the developed hole. Results of this study are believed to be of practical interest for predicting surface and internal ground deformations following sinkhole collapse which could be useful for the stability assessment of underground utilities and the development of a restoration plan after collapse occurred. The results also provided approximate bounds to areas affected by the sinkhole allowing for collapse risk to be assessed. Mahmoud Ahmed Copyright © 2013 Mahmoud Ahmed. All rights reserved. Prediction of Soil Organic Carbon for Ethiopian Highlands Using Soil Spectroscopy Thu, 20 Jun 2013 11:40:18 +0000 Soil spectroscopy was applied for predicting soil organic carbon (SOC) in the highlands of Ethiopia. Soil samples were acquired from Ethiopia’s National Soil Testing Centre and direct field sampling. The reflectance of samples was measured using a FieldSpec 3 diffuse reflectance spectrometer. Outliers and sample relation were evaluated using principal component analysis (PCA) and models were developed through partial least square regression (PLSR). For nine watersheds sampled, 20% of the samples were set aside to test prediction and 80% were used to develop calibration models. Depending on the number of samples per watershed, cross validation or independent validation were used. The stability of models was evaluated using coefficient of determination (), root mean square error (RMSE), and the ratio performance deviation (RPD). The (%), RMSE (%), and RPD, respectively, for validation were Anjeni (88, 0.44, 3.05), Bale (86, 0.52, 2.7), Basketo (89, 0.57, 3.0), Benishangul (91, 0.30, 3.4), Kersa (82, 0.44, 2.4), Kola tembien (75, 0.44, 1.9), Maybar (84. 0.57, 2.5), Megech (85, 0.15, 2.6), and Wondo Genet (86, 0.52, 2.7) indicating that the models were stable. Models performed better for areas with high SOC values than areas with lower SOC values. Overall, soil spectroscopy performance ranged from very good to good. Tadele Amare, Christian Hergarten, Hans Hurni, Bettina Wolfgramm, Birru Yitaferu, and Yihenew G. Selassie Copyright © 2013 Tadele Amare et al. All rights reserved. Rapid Screening of Berseem Clover (Trifolium alexandrinum) Endophytic Bacteria for Rice Plant Seedlings Growth-Promoting Agents Wed, 19 Jun 2013 18:39:30 +0000 A simple screening method to detect berseem clover (Trifolium alexandrinum) endophytic bacteria for rice plant growth-promoting agents on the basis of a root colonization bioassay and a plant growth promoting trait is characterized. Firstly, 200 isolates (80 endophytes and 120 rhizospheric isolates) isolated from berseem clover were inoculated as 10 mixtures of 20 strains each on two rice varieties under gnotobiotic conditions. Then, the reisolated endophytic strains from two rice varieties were characterized for plant growth promoting (PGP) traits. Secondly, the colonization and growth promoting effects of endophytic strains were compared in inoculated rice plantlets as single-strain inoculants. A significant relationship among indole-3-acetic acid (IAA) producing isolates, the size of root colonization, and plant growth was observed. Our results suggest that the ability of IAA production by the endophytic bacteria which may have a stimulatory effect on plant development may be the first plant growth promoting trait for screening bacteria isolated from clover plant for rice plant growth promoting agents. In addition, this study indicates that the selected bacterial isolates based on their IAA producing trait have the potential for PGP and more colonization of rice plant. H. Etesami, H. Mirsyedhosseini, and H. A. Alikhani Copyright © 2013 H. Etesami et al. All rights reserved. Passive and Active Restoration Strategies to Activate Soil Biogeochemical Nutrient Cycles in a Degraded Tropical Dry Land Wed, 19 Jun 2013 11:44:31 +0000 The potential use of two restoration strategies to activate biogeochemical nutrient cycles in degraded soils in Colombia was studied. The active model was represented by forest plantations of neem (Azadirachta indica) (FPN), while the passive model by successional patches of native plant species was dominated by mosquero (Croton leptostachyus) (SPM). In the field plots fine-litter traps and litter-bags were established; samples of standing litter and surface soil samples (0–10 cm) were collected for chemical analyses during a year. The results indicated that the annual contributions of fine litterfall in FPN and SPM were 557.5 and 902.2 kg ha−1, respectively. The annual constant of decomposition of fine litter (k) was 1.58 for neem and 3.40 for mosquero. Consequently, the annual real returns of organic material and carbon into the soil from the leaf litterfall decomposition were 146 and 36 kg ha−1 yr−1 for FPN and 462 and 111 kg ha−1 yr−1 for SPM, respectively. Although both strategies showed potential to activate soil biogeochemical cycles with respect to control sites (without vegetation), the superiority of the passive strategy to supply fine litter and improve soil properties was reflected in higher values of soil organic matter content and cation exchange capacity. Manuel F. Restrepo, Claudia P. Florez, Nelson W. Osorio, and Juan D. León Copyright © 2013 Manuel F. Restrepo et al. All rights reserved. Predicting Saturated Hydraulic Conductivity by Artificial Intelligence and Regression Models Tue, 11 Jun 2013 15:20:05 +0000 Saturated hydraulic conductivity (), among other soil hydraulic properties, is important and necessary in water and mass transport models and irrigation and drainage studies. Although this property can be measured directly, its measurement is difficult and very variable in space and time. Thus pedotransfer functions (PTFs) provide an alternative way to predict the from easily available soil data. This study was done to predict the in Khuzestan province, southwest Iran. Three Intelligence models including (radial basis function neural networks (RBFNN), multi layer perceptron neural networks (MLPNN)), adaptive neuro-fuzzy inference system (ANFIS) and multiple-linear regression (MLR) to predict the were used. Input variable included sand, silt, and clay percents and bulk density. The total of 175 soil samples was divided into two groups as 130 for the training and 45 for the testing of PTFs. The results indicated that ANFIS and RBFNN are effective methods for prediction and have better accuracy compared with the MLPNN and MLR models. The correlation between predicted and measured values using ANFIS was better than artificial neural network (ANN). Mean square error values for ANFIS, ANN, and MLR were 0.005, 0.02, and 0.17, respectively, which shows that ANFIS model is a powerful tool and has better performance than ANN and MLR in prediction of . R. Rezaei Arshad, Gh. Sayyad, M. Mosaddeghi, and B. Gharabaghi Copyright © 2013 R. Rezaei Arshad et al. All rights reserved. Assessing Sediment-Nutrient Export Rate and Soil Degradation in Mai-Negus Catchment, Northern Ethiopia Tue, 04 Jun 2013 09:55:57 +0000 Even though soil degradation challenges sustainable development, the use of degradation indicators such as nutrient export (NE) and nutrient replacement cost is not well documented at landform level. This study is aimed to investigate the extent of soil degradation, NE rates, and their replacement cost across landforms in the Mai-Negus catchment, northern Ethiopia. Different erosion-status sites (aggrading, stable, and eroded) in the landforms were identified, and soil samples were randomly collected and analysed. Nutrient export, replacement cost, and soil degradation were calculated following standard procedures. This study showed that soil degradation in the eroded sites ranged from 30 to 80% compared to the corresponding stable site soils, but the highest was recorded in the mountainous and central ridge landforms. Average NE of 95, 68, 9.1, 3.2, 2.5, and 0.07 kg ha−1 y−1 for soil calcium, carbon, nitrogen, potassium, magnesium, and phosphorus, respectively, was found from the landforms. Significantly strong relationships between NE and sediment yield in the landforms were observed. Annual nutrient replacement costs varied among the landforms though the highest was in the reservoir (€9204 in May 2010). This study thus suggests that while introducing antierosion measures, priority should be given to erosion sources to the reservoir such as mountainous and central ridge landforms. Gebreyesus Brhane Tesfahunegn and Paul L. G. Vlek Copyright © 2013 Gebreyesus Brhane Tesfahunegn and Paul L. G. Vlek. All rights reserved. Organochlorine Pesticide Residues in Sediments and Waters from Cocoa Producing Areas of Ondo State, Southwestern Nigeria Wed, 20 Mar 2013 08:38:27 +0000 This study investigated levels of organochlorine pesticide (OCP) residues in water and sediment samples from eleven rivers serving as drinking water sources and receiving runoff from nearby cocoa plantations in Ondo State, Nigeria. Twenty-two composite samples of surface water and sediments (0–3 cm) were collected randomly using grab technique and replicated thrice per season. The efficiency of the two techniques [supercritical fluid extraction (SFE) and liquid/liquid extraction (LLE)] was evaluated with percentage analyte recoveries to for SFE and to 1 for LLE. Determination of OCPs by gas chromatography with electron capture detection gave higher concentrations for sediments compared to the equivalent water samples. The commonly occurring pesticide residues in the sediments were (range, μg g−1) cis-chlordane 0.03–6.99; α-endosulfan 0.03–6.99; p,p′-DDE 0.08–19.04; and dieldrin 0.01–7.62; in the sediments and dieldrin (not detected-1.51 μg L−1) in water samples, during the dry season. OCP levels were significantly higher in dry season than wet season among the rivers. The study concluded that most of the rivers in cocoa growing areas were contaminated with OCPs associated with agricultural activities. Aderonke Adetutu Okoya, Aderemi Okunola Ogunfowokan, Olabode Idowu Asubiojo, and Nelson Torto Copyright © 2013 Aderonke Adetutu Okoya et al. All rights reserved. Spatiotemporal Changes of Rainfall Erosivity in Loess Plateau, China Wed, 13 Mar 2013 09:51:31 +0000 The reason for the severity of soil erosion in Loess Plateau can be attributed to three nonanthropogenic factors: rainfall erosivity, slope gradient, and loess soil. The rainfall erosivity is controlled by the rainfall characteristics. Generally, rainfall characteristics change drastically in space and time. The rainfall erosivity has been investigated using the modified Fournier index (MFI), annual rainfall, and precipitation concentration index (PCI). The study showed a decrease in average MFI by 10%. However, the difference between the MFI in 1960s and 1990s was found to decrease in a large area in Loess Plateau, whereas there was an increase in MFI at the high latitude. The maximum decrease in the rainfall erosivity was higher in the southeast than that in the north and west. The was found to have a trend similar to the MFI, which further indicates that the MFI follows, to a high extent, the annual rainfall trend. The PCI was found to have trend opposite to MFI and . The PCI increased in the north and west and decreased toward the southeast. The average temporal difference in the PCI between the 1960s, and 1990s was two percent. Mohamed A. M. Abd Elbasit, Jinbai Huang, CSP Ojha, Hiroshi Yasuda, and Eltayeb O. Adam Copyright © 2013 Mohamed A. M. Abd Elbasit et al. All rights reserved. Remote Sensing of Soil Moisture Thu, 07 Mar 2013 17:18:58 +0000 Soil moisture is an important variable in land surface hydrology as it controls the amount of water that infiltrates into the soil and replenishes the water table versus the amount that contributes to surface runoff and to channel flow. However observations of soil moisture at a point scale are very sparse and observing networks are expensive to maintain. Satellite sensors can observe large areas but the spatial resolution of these is dependent on microwave frequency, antenna dimensions, and height above the earth’s surface. The higher the sensor, the lower the spatial resolution and at low elevations the spacecraft would use more fuel. Higher spatial resolution requires larger diameter antennas that in turn require more fuel to maintain in space. Given these competing issues most passive radiometers have spatial resolutions in 10s of kilometers that are too coarse for catchment hydrology applications. Most local applications require higher-spatial-resolution soil moisture data. Downscaling of the data requires ancillary data and model products, all of which are used here to develop high-spatial-resolution soil moisture for catchment applications in hydrology. In this paper the author will outline and explain the methodology for downscaling passive microwave estimation of soil moisture. Venkat Lakshmi Copyright © 2013 Venkat Lakshmi. All rights reserved. Response of Cold-Tolerant Aspergillus spp. to Solubilization of Fe and Al Phosphate in Presence of Different Nutritional Sources Mon, 04 Mar 2013 09:49:15 +0000 Three species of Aspergillus, namely, A. niger, A. glaucus and A. sydowii, isolated from soil samples collected from the Indian Himalayan Region (IHR), have been investigated for solubilization of aluminium phosphate and iron phosphate in the presence of different carbon and nitrogen sources. Preference of each fungal species varied for nitrogen and carbon sources, in terms of phosphate-solubilization. Among three species, Aspergillus niger gave the best results; it solubilized 32% and 8% of the supplemented aluminium phosphate and iron phosphate, respectively. The results indicated that the effect of carbon and nitrogen sources can influence the phosphate solubilizing efficiency of all the three Aspergillus spp. tested. All the three species were found to be plant-growth promoters in bioassays conducted under greenhouse conditions. The Al and Fe phosphate solubilization efficiency, investigated in the present study, is at the lower end of their previously reported tricalcium phosphate solubilization efficiency. The cultures are likely to have better field applications in agrobiotechnology, due to their potential towards solubilization of Al and Fe phosphates, which are known to have lower solubility through microbial activity. K. Rinu, Mukesh Kumar Malviya, Priyanka Sati, S. C. Tiwari, and Anita Pandey Copyright © 2013 K. Rinu et al. All rights reserved. Carbon and Water in Upper Montane Soils and Their Influences on Vegetation in Southern Brazil Sun, 24 Feb 2013 08:18:32 +0000 Considering the many environmental functions of the upper montane soils, the aims of this study were (1) to verify if the soils of upper montane forests and grasslands of Caratuva Peak (1850 m a.s.l.) have similar characteristics to those found in other highlands in southern and southeastern Brazil; (2) to reinforce the geomorphological and pedological factors that impose the establishment of each type of vegetation in these highlands; and (3) to estimate potential soil carbon stocks and potential soil water retention. Folic and haplic histosols were found in the grasslands, and dystrophic regosols were found in the forests. The soils were dystrophic, extremely acidic, and saturated with Al and total organic carbon. In contrast to the grasslands, the upper montane forests were prevalent in valleys and subjected to morphogenetic processes resulting in soils that contained thicker mineral horizons. The grasslands occupied ridges and divergent convex ramps, and the pedogenetic processes in these regions promoted thicker histic horizons. The potential water retention capacities were high and strongly related to the high porosities of histic horizons associated with the gleyic horizons. In particularly, the carbon stocks were two- to three-fold higher than those found in soil ecosystems from the same latitude but lower altitude. M. B. Scheer, G. R. Curcio, and C. V. Roderjan Copyright © 2013 M. B. Scheer et al. All rights reserved. Diversity of Rhizobium leguminosarum from Pea Fields in Washington State Tue, 19 Feb 2013 15:05:57 +0000 Rhizobia-mediated biological nitrogen (N) fixation in legumes contributes to yield potential in these crops and also provides residual fertilizer to subsequent cereals. Our objectives were to collect isolates of Rhizobium leguminosarum from several pea fields in Washington, examine genetic diversity among these isolates and several commercial isolates of R. leguminosarum, and compare genetically distinct isolates for their ability to fix N in a range of pea hosts. Seventy-nine isolates were collected from pea root from four noninoculated pea fields. Sequence-related amplified polymorphism (SRAP) markers generated by PCR were used to discriminate among isolates. Isolates fell into 17 clusters with robust bootstrap support values. Nearly half of the isolates fell into a single large cluster, but smaller clusters were also detected for isolates from all four field locations. The majority of commercial isolates fell into a distinct cluster. Four genetically distinct isolates were compared for their efficiency in fixing N in a greenhouse experiment. Host plant variety effects were significant for plant biomass due to N fixation and also for the quantity of N fixed per variety. Significant effects of R. leguminosarum isolates were observed for the quantity of N fixed per isolate, plant biomass, and the quantity of N per plant. Rita Abi-Ghanem, Jeffrey L. Smith, and George J. Vandemark Copyright © 2013 Rita Abi-Ghanem et al. All rights reserved. Soil Erosion on Abandoned Land in Andalusia: A Comparison of Interrill- and Rill Erosion Rates Wed, 14 Nov 2012 09:58:33 +0000 The present paper is based on several field investigations (monitoring soil and rill erosion by aerial photography, rainfall simulations with portable rainfall simulators, and manmade rill flooding) in southern Spain. Experiments lead now to a closer understanding of the dynamics and power of different soil erosion processes in a gully catchment area. The test site Freila (Andalusia, Spain) covers an area of 10.01 ha with a rill density of 169 m ha−1, corresponding to a total rill length of 1694 m. Assuming an average rill width of 0.15 m, the total rill surface can be calculated at 250 m2 (0.025 ha). Given that, the surface covered by rills makes up only 0.25% of the total test site. Since the rill network drains 1.98 ha, 20% of the total runoff comes from rills. The rills’ sediment erosion was measured and the total soil loss was then calculated for detachment rates between 1685 g m−2 and 3018 g m−2. The interrill areas (99.75% of the test site) show values between 29 and 143 g m−2. This suggests an important role of rill erosion concerning runoff and soil detachment. S. Wirtz, T. Iserloh, G. Rock, R. Hansen, M. Marzen, M. Seeger, S. Betz, A. Remke, R. Wengel, V. Butzen, and J. B. Ries Copyright © 2012 S. Wirtz et al. All rights reserved. Degradation of Trichloroethylene Contaminated Soil by Zero-Valent Iron Nanoparticles Sun, 14 Oct 2012 15:03:52 +0000 Trichloroethylene (TCE) contaminated soil has received extensive attention in the environmental issues. Nanoscale zero-valent iron (NZVI) is considered as an excellent reduction catalyst due to fast degradation of chlorinated solvents. Therefore, this paper aims to evaluate TCE removal from soil by surfactant modified nanoscale zero-valent iron (SNZVI). In this respect, fixed 500 g soil having a diameter range 0.5–1 mm was polluted with 10 mL TCE and put inside glass column of 2.5 cm diameter × 300 cm length. The NZVI solution was prepared from reduction of FeCL3 by NaBH4 and coating with 2.5 g nonionic surfactant (Tween 85) to produce iron nanoparticle concentration of 0.1 g/L. The prepared iron nanoparticle was poured into contaminated soil and left to stir at a constant rate for 24 days. The reductive dechlorination of TCE was measured as a function of increasing chloride ion. It was found that the TCE dechlorination in the presence of iron surfaces displayed pseudo first-order kinetics. The TCE degradation rate constant () is . Also, about 30% of TCE was removed within initial 6 days. The obtained specific rate constant () was and is lower than other studies carried into aqueous phase by about 23 orders of magnitude. Finally, the SNZVI was found to be effective and fully removed to TCE within 456 hours. Amira Kamal Ibrahem, Thanaa Abdel Moghny, Yasser Mohamed Mustafa, Nermine Elsyed Maysour, Farida Mohamed Saad El Din El Dars, and Reham Farouk Hassan Copyright © 2012 Amira Kamal Ibrahem et al. All rights reserved. Modeling of Permanent Wilting from Particle Size Fractions of Coastal Plain Sands Soils in Southeastern Nigeria Tue, 31 Jul 2012 13:28:46 +0000 Permanent wilting points in soils have been found to correlate significantly with particle size fractions. This study was conducted to establish functional relationship between soil particle size fractions and permanent wilting point of soils of coastal plain sands in southeastern Nigeria. A total of 102 surface samples were collected from three different dominantly Ultisols toposequences (i.e., 34 samples from each). Permanent wilting point experiment was carried out in pots with the 102 samples in the greenhouse while the particle size analysis was carried out in the laboratory. There was significant correlation among the textural separates, permanent wilting point correlated significantly with clay (𝑟=0.21, 𝑃≤0.05). The general linear model showed significant differences between permanent wilting point of soils found in the upper and lower slope positions. Regression equation established that 54% of the total variation in permanent wilting point could be accounted for by the clay and coarse sand content of the soils. Prediction of permanent wilting point of Ultisols formed on coastal plain sands soils of humid tropical southeastern Nigeria will effectively depend on reliability of determination of clay and coarse sand contents of the soils. Chinedu Innocent Obi, Jude C. Obi, and Emmanuel U. Onweremadu Copyright © 2012 Chinedu Innocent Obi et al. All rights reserved. Leaf Litter Decomposition and Nutrient Dynamics in Woodland and Wetland Conditions along a Forest to Wetland Hillslope Thu, 19 Jul 2012 14:07:51 +0000 Leaf litters of jarrah (Eucalyptus marginata Donn ex Sm.) and banksia (Banksia menziesii R. Br.) were decomposed at woodland and wetland conditions for two years to test site influence on the rates of decomposition. Weight loss was rapid in early rains but slowed substantially in the following months, resulting in 2/3 to 1/2 weights remaining after two years of field exposure. Litter weight loss was well described by a two-substrate quality decay model (𝑅2=0.97−0.99), and the half-lives were 2.6–3.2 weeks (labile fraction) and 6.4–6.9 years (recalcitrant fraction) for jarrah, and 1.0–1.7 weeks (labile) and 6.6–9.9 years (recalcitrant) for banksia. The nutrient mobility was K≈Mg≈S>Ca>P, and the losses of K, Mg and S were correlated with the weight loss of litter (𝑅2=0.77−0.94, 𝑃<0.03). P mass increased by 129% in jarrah litter and 174% in banksia litter in the woodland site, suggesting woodland with tree cover provided a better habitat for microbial biomass than non-inundated wetland, hence a notable P conservation in the decomposing litter. Song Qiu, Arthur J. McComb, and Richard W. Bell Copyright © 2012 Song Qiu et al. All rights reserved. Active Thrust on an Inclined Retaining Wall with Inclined Cohesionless Backfill due to Surcharge Effect Wed, 27 Jun 2012 11:09:29 +0000 A method based on the application of Kötter’s equation is proposed for the complete analysis of active thrust on an inclined wall with inclined cohesionless backfill under surcharge effect. Coulomb’s failure mechanism is considered in the analysis. The point of application of active thrust is determined from the condition of moment equilibrium. The coefficient of active pressure and the point of application of the active thrust are computed and presented in nondimensional form. One distinguishing feature of the proposed method is its ability to determine the point of application of active thrust on the retaining wall. A fairly good comparison is obtained with the existing solutions. D. M. Dewaikar, S. R. Pandey, and Jagabandhu Dixit Copyright © 2012 D. M. Dewaikar et al. All rights reserved. Within-Storm Rainfall Distribution Effect on Soil Erosion Rate Thu, 21 Jun 2012 09:30:23 +0000 This study investigates the effect of rainfall temporal distribution pattern within a storm event on soil erosion rate and the possibility of using rain power type model for rainfall erosivity. Various rainfall distribution patterns, simulated by rainfall simulator, were used on 1.0 m2 plot of silica sand and loam soil with a minimum of three replications. The results show that the soil erosion rates spiked following every sharp increase in rainfall intensity followed by a gradual decline to a steady erosion rate. Transient effects resulted in the soil erosion rates for an oscillatory rainfall distribution to be more than two fold higher than those obtained for a steady-state rainfall intensity event with same duration and same average rainfall intensity. The 3-parameter and 4-parameter rain power models were developed for a process-based measure of rainfall erosivity. The 4 parameter model yielded better match with the observed data and predicted soil erosion rates more accurately for silica sand under all rainfall distributions, and good results for loam soil under low intensity rainfall. More research is necessary to improve the accuracy of soil erosion prediction models for a wider range of rainfall distributions. S. I. Ahmed, R. P. Rudra, B. Gharabaghi, K. Mackenzie, and W. T. Dickinson Copyright © 2012 S. I. Ahmed et al. All rights reserved. Influence of Weathering on the Engineering Properties of Dacites in Northeastern Turkey Tue, 29 May 2012 15:44:39 +0000 The purpose of this study is to investigate dacites of different weathering grades from the Cakmakkaya and Damar open-pit copper mines in northeastern Turkey based on their mineralogical, petrographical, and geomechanical characteristics. The dacites for which surveys are carried out are mainly subjected to chemical weathering as well as physical disintegration and hydrothermal alteration. Discontinuities in this rock appear to be a major influence on the spatial distribution of weathering profiles, with the intensity of weathering increasing in the plagioclase phenocrystals and microlites as the weathering grade increases. The present results show that the type and amount of clay minerals increase as the weathering grade increases. As the weathering increases, the amount of mobile oxides, such as Na2O, MgO, and CaO, decreases while Fe2O3 and the loss on ignition (LOI) content increase for most of the dacite samples. The microfracture frequency (𝑞mf) may be a good indicator of fabric changes, and methylene blue adsorption (MBA) test and LOI may be good indicators of chemical weathering for the dacites. Geomechanical laboratory tests indicate that the strength of the samples is controlled by weathering. Field observations and mineralogical analyses show that the effects of weathering are critical for slope stability. Fehmi Arikan and Nihal Aydin Copyright © 2012 Fehmi Arikan and Nihal Aydin. All rights reserved. Rare Earth Elements: Their Importance in Understanding Soil Genesis Wed, 09 May 2012 09:22:02 +0000 The rare earth elements (REEs) are commonly defined as lanthanum (La) and the 14 elements comprising the Lanthanide series. The REE’s typically exhibit trivalent oxidation states; however, Europium may also occur as Eu2+ and Cerium may occur as Ce4+. The REE’s ionic radii decrease on progression from La to Lu, which results in a slight but predictable change in their chemical affinity. Typically, the light REE (La to Sm) reside in trace minerals such as apatite, epidote and allanite, whereas the heavy REE (Gd to Lu) are associated with minerals such as zircon. Investigations typically show that the REE are depleted in near-surface horizons and accumulate in deeper horizons or the regolith as clay-oxyhydroxide adsorbates or REE-phosphate precipitates. Numerous studies show the heavy REE accumulating in the deeper soil regions to a greater extent than the light REE, whereas other studies show the light REE’s preferentially accumulating at greater soil depths. The degree of interhorizon transport has great potential to become an index of weather intensity. The various REE soil migration pathways have been isolated, including lessivage, soil organic matter complexation, leaching in percolating water, adsorption by inorganic colloids, and precipitated by phosphate-bearing minerals. Michael T. Aide and Christine Aide Copyright © 2012 Michael T. Aide and Christine Aide. All rights reserved. An Ensemble of Neural Classifiers and Constructivist Algorithms in the Identification of Agricultural Suitability Complexes of Soils on the Basis of Physiographic Information Tue, 08 May 2012 10:56:34 +0000 The ensemble of classifiers for identification of agricultural suitability of soils on the basis of physiographic information was created in accordance with the stacking algorithm. It is comprised of five neural networks of various structures. The deciding element was a neural classifier optimised on the basis of input vectors composed of the indications of five classifiers making up the lower level. Among the architectures studied, the best result was achieved using the Radial Basis Function network as the decisive classifier, composed with the use of the constructivist Feature Space Mapping algorithm. In this configuration, the group correctly identified more than 99% of the elements of the validation set. The models may be used as tools for predicting expected soil condition, which is helpful in assessment of the range of substantial transformations. Stanislaw Gruszczynski Copyright © 2012 Stanislaw Gruszczynski. All rights reserved.