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Soil Science Society of America Journal : Just Published

 

Accepted, edited articles are published here after author proofing to provide rapid publication and better access to the newest research. Articles are compiled into issues at dl.sciencesocieties.org/publications/sssaj, which includes the complete archive.

Citation | Articles posted here are considered published and may be cited by the doi.

Nouwakpo, S. K. and C.-H. Huang. 2012. A Fluidized Bed Technique for Estimating Soil Critical Shear Stress Soil Sci. Soc. Am. J. doi:10.2136/sssaj2012.0056

Current issue: Soil Sci. Soc. Am. J. 80(5)



  • ERRATUM

    • Robson André Armindo and Ole Wendroth
      Physical Soil Structure Evaluation based on Hydraulic Energy Functions

      doi:10.2136/sssaj2016.03.0058er
      Published: November 28, 2016
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    • Amir Sadeghpour, Quirine M. Ketterings, Francoise Vermeylen, Gregory S. Godwin and Karl J. Czymmek
      Erratum: Soil Properties under Nitrogen- vs. Phosphorus-Based Manure and Compost Management of Corn

      doi:10.2136/sssaj2016.03.0086er
      Published: October 27, 2016
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  • NUTRIENT MANAGEMENT & SOIL & PLANT ANALYSIS

    • Jordon Wade, William R. Horwath and Martin B. Burger
      Integrating Soil Biological and Chemical Indices to Predict Net Nitrogen Mineralization across California Agricultural Systems

      Predicting the capacity of soil to supply crop N (i.e., inorganic N) has proved difficult due to the myriad of interacting soil biophysical factors. We examined soil chemical and biological indices commonly found in commercial soil testing laboratories—total soil C and N, water-extractable organic C and N, K2SO4–extractable C and N, mineralizable C on rewetting, and permanganate-oxidizable C—to estimate net N mineralization across a variety of soils from cover-cropped and non-cover-cropped fields in California (47 sites, n = 157). Results show that both biological and chemical indices are variable in their ability to predict N mineralization, with better relationships being shown for cover-cropped fields. Total C and N contents were the best chemical indicators for both management systems, describing up to 21.8% of the variance. (continued)

      Core Ideas:
      • Agricultural soils with and without a winter cover crop were surveyed.
      • Stronger relationships occurred between soil tests and N mineralization in cover-cropped fields.
      • Integrated models only improved the variance explained for cover-cropped fields.
      • Within management systems, preferred predictors varied by climate, independent of soil C.

      doi:10.2136/sssaj2016.07.0228
      Published: December 1, 2016



    • Charles Shapiro, Ahmed Attia, Santiago Ulloa and Michael Mainz
      Use of Five Nitrogen Source and Placement Systems for Improved Nitrogen Management of Irrigated Corn

      Improved N management for corn (Zea mays L.) production is necessary to maintain N in the root zone for greater yield and N uptake. Three field experiments were conducted in Nebraska on Thurman loamy sand at Concord in 2008, on Alcester silty clay loam at Haskell Agricultural Laboratory (HAL) in Concord in 2009, and on Hord silt loam at Pierce in 2009. Treatments included four N rates (56, 112, 168, and 224 kg N ha−1) and five N-source–placement systems. The five N systems were broadcast polymer-coated urea (PCU), broadcast urea–NH4NO3 (UAN), a broadcast 7:3 mixture of UAN and Nitamin–Nfusion (NF), band UAN, and band NF. (continued)

      Core Ideas:
      • Slow-release fertilizers improve the synchronization of N release and crop needs.
      • Applying N source in a band conserves N for greater corn yield and N uptake.
      • Chlorophyll readings and stalk NO3–N are useful tools for improving corn N management.

      doi:10.2136/sssaj2015.10.0363
      Published: November 3, 2016



    • Stefania C. Appelhans, Ricardo J. Melchiori, Pedro A. Barbagelata and Leonardo E. Novelli
      Assessing Organic Phosphorus Contributions for Predicting Soybean Response to Fertilization

      The use of organic P fraction in soil test P for soybean [Glycine max (L.) Merr.] under no-till could improve the accuracy to predict crops response to P fertilization. The research objectives were to assess the contribution and accuracy of P indices that include organic-P fractions to predict soybean yield response to P fertilization in comparison with Bray soil test P (BP). The study included P fertilization experiments conducted in the Pampas Region of Argentina during three growing seasons. We selected sites considering Cate and Nelson quadrants (I, II, III), established by a critical BP concentration of 9 mg P kg−1 and a relative soybean yield (RY) of 85%. (continued)

      Core Ideas:
      • The contribution of P indices that include organic P to predict soybean P fertilization response was evaluated.
      • Bioavailable P and MA-P indices correlated with soybean relative yield.
      • MA-P index correlated with labile organic P fractions.
      • MA-P index improved the accuracy to predict soybean yield response to applied P.

      doi:10.2136/sssaj2016.04.0130
      Published: October 20, 2016



  • PEDOLOGY

    • Aoesta K. Mohammed, Daniel R. Hirmas, Daniel Giménez, Rolfe D. Mandel and James R. Miller
      A Digital Morphometric Approach for Quantifying Ped Shape

      Ped shape is an important property with considerable influence over soil processes, such as root penetration, water infiltration, and solute transport. Despite the host of methods employed to quantify other soil morphological properties, ped shape quantification remains elusive. Existing methods attempting to quantify soil structure utilize laboratory techniques that have limitations on sample size and resolution. Our goal was to overcome these limitations by developing an approach to quantify ped shape using morphometrics created from published digital photographs of soil profiles and structure specimens. (continued)

      Core Ideas:
      • Ped shapes were quantified from digital photographs.
      • Circularity was the most useful morphometric for distinguishing ped types.
      • Experience and training influenced ability to recognize prismatic peds.
      • Existing photographs can be analyzed with this approach without the need to resample.

      doi:10.2136/sssaj2016.06.0203
      Published: November 17, 2016



    • Jiaping Wang, Curtis Monger, Xiujun Wang, Matteo Serena and Bernhard Leinauer
      Carbon Sequestration in Response to Grassland–Shrubland–Turfgrass Conversions and a Test for Carbonate Biomineralization in Desert Soils, New Mexico, USA

      This study uses an experimental pedology approach to examine (i) how the conversion of native C4 grassland to C3 woody shrubs then to irrigated C4 turfgrass affects both soil organic C (SOC) and soil inorganic C (SIC) and (ii) whether SIC can be enhanced by microbial biomineralization. Three sites were studied in the Chihuahuan Desert of New Mexico. At each site, SOC, SIC, and their δ13C values were measured on control soil samples and compared to samples treated with liquid growth medium and Ca(OH)2 at 10 and 40 cm. The treated samples were left to react for 1 mo in February, May, and August of 2014. (continued)

      Core Ideas:
      • Soil carbonate is typically viewed as a soil mineral that requires centuries to accumulate; our study indicates that it can be generated in months to years.
      • If the source of Ca is directly from silicate minerals, soil carbonate could be managed to sequester atmospheric CO2.
      • Carbon-13 values can change in less than a decade for both soil organic and inorganic C.
      • This study uses an experimental pedology approach using controls, treatments, and replications.

      doi:10.2136/sssaj2016.03.0061
      Published: November 3, 2016



  • REVIEW & ANALYSIS—SOIL & WATER MANAGEMENT & CONSERVATION

    • H. Henry Janzen
      The Soil Remembers

      Terrestrial ecosystems worldwide face mounting stresses and upheavals, mostly from human demands and interferences. Our search for better ways of living on these lands, however, is constrained by a most vexing variable: time. The final outcomes of our management choices—well intended or not—will often fully emerge only after decades, when we are no longer there to see them. A way around this dilemma is to view a longer span of time by studying the land’s own memories, notably those in the soil. (continued)

      Core Ideas:
      • Sustainability can only be measured over long time periods.
      • To evaluate sustainability, therefore, we need a way of keeping track—a memory.
      • Soil offers such a memory because the soil stays.
      • An underlying aim of soil science is to extract and describe soils’ memories.

      doi:10.2136/sssaj2016.05.0143
      Published: October 20, 2016



  • SOIL & WATER MANAGEMENT & CONSERVATION

    • Sandra F. Yanni, H. Henry Janzen, Edward G. Gregorich, Ben H. Ellert, Francis J. Larney, Barry M. Olson and Francis Zvomuya
      Organic Carbon Convergence in Diverse Soils toward Steady State: A 21-Year Field Bioassay

      The response of soil organic matter (SOM) to an abrupt change in environment and management was studied in a long-term field bioassay. Thirty-six soils, with a wide range of SOM reflecting large differences in management, climate, and ecological histories, were selected and transported to a common site at Lethbridge, Alberta, Canada. The experiment included control and N-fertilized treatment plots. The plots were seeded annually to spring wheat and managed under no-till rain-fed conditions, with annual removal of aboveground residues. (continued)

      Core Ideas:
      • We report long-term SOM change in different soils transplanted to one plot.
      • Mainly, initial SOM concentrations highly influence change over time.
      • Sand and land management history influence SOM change.
      • High C soils lose C and low C soils gain C; thus, soils converge to new equilibrium.
      • Light-fraction OM converges at a faster rate than C and N.

      doi:10.2136/sssaj2016.07.0214
      Published: December 8, 2016



    • Yingcan Zhu, Alla Marchuk and John McLean Bennett
      Rapid Method for Assessment of Soil Structural Stability by Turbidimeter

      A rapid and inexpensive method to evaluate soil structural stability via assessment of soil clay dispersion is needed. Such a method would provide critical information for decision-making for soil and agricultural management not currently undertaken due to the expense of testing. The aim of this work was to validate the use of a turbidimeter for quantifying clay released from soil and to relate this back to dispersive parameters. Ten Australian soils with different physicochemical properties were studied. (continued)

      Core Ideas:
      • A quantitative dispersion assessment chart is developed for rapid diagnosis of soil structural stability.
      • Turbidity and the amount of dispersed clay have a strong linear relationship.
      • The color and mean particle size of colloidal solution has a negligible effect on the linearity of turbidity.

      doi:10.2136/sssaj2016.07.0222
      Published: November 17, 2016



    • Lijun Su, Quanjiu Wang, Yuyang Shan and Beibei Zhou
      Estimating Soil Saturated Hydraulic Conductivity using the Kostiakov and Philip Infiltration Equations

      Direct measurement of saturated hydraulic conductivity (Ks) is time and labor consuming, so Ks is often estimated by mathematical models describing soil–water infiltration. The Kostiakov infiltration equation is widely used to estimate soil–water infiltration rate (i) with only two empirical parameters m and n, which are highly dependent on Ks. The objective of this study was to develop a new method to estimate Ks using the parameters of the Kostiakov equation for short infiltration times. The new method is based on the relationship between the Kostiakov equation and Philip’s two-term equation. (continued)

      Core Ideas:
      • We analyzed the relationships between the parameters of the Kostiakov and Philip infiltration equations.
      • A new method was proposed to estimate the Ks by parameters in Kostiakov equation.
      • Effect of soil hydraulic parameters on a new method was discussed.

      doi:10.2136/sssaj2016.04.0125
      Published: November 10, 2016



    • Kipling S. Balkcom, Leah M. Duzy, Charles C. Mitchell and Dennis P. Delaney
      A Simple Approach to Enhance Multiprobe Soil Cone Penetrometer Analyses

      Soil penetrometers measure penetration resistance to characterize soil strength for different management practices, primarily tillage. Our objective was to demonstrate a simple approach to quantify soil strength differences among treatments collected with a multiprobe cone penetrometer using cone index measurements to complement contour graphs and statistical analyses. The approach involves obtaining average cone index values by row position and calculating the area under the curve for cone index (AUCC.I.), with units of megapascal-centimeters (MPa-cm). Data were collected from a tillage and cover crop experiment in Prattville, AL (November 2009), and at the Old Rotation experiment in Auburn, AL (December 2014). (continued)

      Core Ideas:
      • We describe a method to quantify soil strength with a multiprobe cone penetrometer.
      • An area-under-the-curve calculation compares soil strength across treatments.
      • This value simplifies comparisons for depths and row positions of the soil profile.

      doi:10.2136/sssaj2016.05.0157
      Published: November 3, 2016



  • SOIL BIOLOGY & BIOCHEMISTRY

    • Timothy B. Parkin, Thomas C. Kaspar, Dan B. Jaynes and Thomas B. Moorman
      Rye Cover Crop Effects on Direct and Indirect Nitrous Oxide Emissions

      Winter cover crops can have a pronounced effect on N cycling in agricultural ecosystems. By reducing available soil mineral N during active growth and by providing a substrate for denitrifying bacteria after they are killed, cover crops can potentially influence soil N2O emissions. However, there have been conflicting reports regarding cover crop effects on increasing or decreasing N2O emissions. In this study, direct soil emissions of N2O were measured for a 10-yr period in a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation, with and without a winter rye (Secale cereale L.) cover crop. (continued)

      Core Ideas:
      • A rye cover crop in a Midwest corn–soybean rotation did not reduce direct N2O emissions.
      • NO3 leaching and indirect N2O emissions were reduced with a winter rye cover crop.
      • Large year-to-year variations in precipitation were a major determinant of N2O losses.

      doi:10.2136/sssaj2016.04.0120
      Published: December 1, 2016



  • SOIL CHEMISTRY NOTE

    • Anthony P. Miller and Yuji Arai
      Comparative Evaluation of Phosphate Spectrophotometric Methods in Soil Test Phosphorus Extracting Solutions

      Phosphate spectrophotometric methods are valuable in agro-environmental research because of the orthophosphate-specific detection. While optimum wavelength and detection limits for these methods are suggested in ultrapure water, they have rarely been evaluated in soil test P (STP) extracting solutions such as Bray P-1 and Mehlich III. When four different phosphate spectrophotometric methods (Murphy and Riley, He et al., Dick and Tabatabai, and Asher) were evaluated in these STP extracting solutions, we found (i) that the methods of Murphy and Riley and He et al. are still sensitive at P concentrations <2 mg L−1 in STP solutions, (ii) a new optimum wavelength (886–888 nm) in STP solutions for the Dick and Tabatabai method, and (iii) a new optimum wavelength and limit of detection for Asher’s methods in ultrapure water and STP solutions. (continued)

      Core Ideas:
      • Original ascorbic acid methods are sensitive in STP solutions at phosphate <2 mg L−1.
      • New optimum wavelengths for the Dick and Tabatabai method in STP extraction solutions.
      • A new optimum wavelength of 888 nm for Asher’s methods is recommended.

      doi:10.2136/sssaj2016.08.0256n
      Published: November 23, 2016



  • SOIL FERTILITY & PLANT NUTRITION

    • Xiying Hao, Ben W. Thomas, Virginia Nelson and Xiaomei Li
      Agronomic Values of Anaerobically Digested Cattle Manure and the Separated Solids for Barley Forage Production

      As biogas production expands, digestates from that industry are increasingly available as potential nutrient sources for crop production, but their agronomic value is poorly understood. Thus, a 5-yr field experiment was conducted to determine the agronomic values of anaerobically digested solid beef cattle feedlot manure (ADM) and the separated solids (SS) from ADM under a semiarid reduced-tillage dryland barley (Hordeum vulgare L.) forage cropping system. Three organic amendments, ADM, SS, and undigested solid beef cattle feedlot manure (CM), were applied annually at 200 or 400 kg total N ha−1 for 4 yr, while the residual effect was examined in the fifth year. The higher N and P availability in ADM translated into greater barley forage yields, total N uptake, amendment-derived N uptake, and apparent N recovery (ANR) from ADM-amended soil than SS- and CM-amended soils, while there were no significant differences between soils receiving SS or CM. (continued)

      Core Ideas:
      • Agronomic values of anaerobically digested solid cattle manure are poorly defined.
      • Separated solids of anaerobically digested cattle manure supplied N similar to cattle manure.
      • Anaerobically digested cattle manure had high NH4–N/total N ratio.
      • Anaerobically digested cattle manure had less P buildup than cattle manure.
      • Digestate separated solids can be managed similar to cattle manure.

      doi:10.2136/sssaj2016.05.0132
      Published: December 1, 2016



    • Zejiang Cai, Suduan Gao, Aileen Hendratna, Yinghua Duan, Minggang Xu and Bradley D. Hanson
      Key Factors, Soil Nitrogen Processes, and Nitrite Accumulation Affecting Nitrous Oxide Emissions

      A better understanding of the factors and processes affecting N2O emissions is essential for developing mitigation strategies. This research aimed to examine the factors and processes affecting N2O emissions and N dynamics. Laboratory incubation experiments examined the effects of N (urea) application rate (0–150 mg N kg-1); soil water content (5–30%, w/w); temperature (10–40°C); and incorporation of biochar (1%, w/w), a urease inhibitor (Agrotain Ultra), and a nitrification inhibitor (N-Serve 24) on N2O emissions and N transformation dynamics in a Hanford sandy loam soil. Nitrous oxide emissions, soil pH, and mineral N species were monitored for 35 d. (continued)

      Core Ideas:
      • Nitrite concentration was highly correlated with N2O emissions within two distinct water content ranges.
      • Soil moisture was the most important environmental factor affecting N2O emissions.
      • Nitrous oxide emissions increased exponentially as the N application rate increased.
      • Biochar and N transformation inhibitors showed great potential to reduce N2O emissions.

      doi:10.2136/sssaj2016.03.0089
      Published: November 17, 2016



  • SOIL FERTILITY & PLANT NUTRITION NOTE

    • Maria Julia Cabello, Flavio H. Gutiérrez Boem, Cesar E. Quintero and Gerardo Rubio
      Soil Characteristics Involved in Phosphorus Sorption in Mollisols

      The role of different soil properties on defining the P sorption capacity was investigated in a group of Mollisols of the Pampean Region (Argentina). Two-single point and three-multiple point P sorption indices were evaluated. Both simple and multiple regression models indicated that ammonium oxalate extractable Al (Alox) and ammonium oxalate extractable Fe (Feox) were the main properties defining P sorption. Ammonium oxalate extractable Al prevailed as the best predictor of short-term P sorption indices and Feox as the best predictor for those indices that involves longer interaction periods. (continued)


      doi:10.2136/sssaj2016.07.0235n
      Published: December 8, 2016



  • SOIL PHYSICS & HYDROLOGY

    • Mehdi Rahmati and Mohammad Reza Neyshaboury
      Soil Air Permeability Modeling and Its Use for Predicting Unsaturated Soil Hydraulic Conductivity

      Since the direct measurement of soil hydraulic conductivity [Kw(θ)] is time consuming and difficult, several methods have been suggested for its prediction. However, their application still requires some kind of direct or experimental measurement, even after calibration. Considering much easier measurement of the air permeability [Ka(θ)] and the water and air flows in the soil medium, several attempts have been made to link Kw(θ) and Ka(θ), most of which have used Ka(θ) to predict the saturated hydraulic conductivity (Ks). The current research was aimed to model the air permeability and evaluate its application for Kw(θ) prediction. (continued)

      Core Ideas:
      • Ka(θ) was modeled by considering a similar phenomenon between water and air flows in soil medium.
      • Kw(θ) and Ka(θ) were theoretically linked by considering a similar intrinsic permeabilities for both water and air.
      • The proposed models were tested with laboratory-measured data showing reasonable accuracy.

      doi:10.2136/sssaj2015.12.0430
      Published: December 8, 2016



    • Samia Rafraf, Lamia Guellouz, Houda Guiras and Rachida Bouhlila
      A New Model Using Dynamic Contact Angle to Predict Hysteretic Soil Water Retention Curve

      We present a water retention model able to predict the hysteretic response of soils during wetting–drying cycles. This model is an extension of the original Arya–Paris (AP) model. We improved the model—first by linking the empirical parameter in the AP model, a soil water retention model, to physical properties of the soil, like tortuosity, porosity, and the air-entry point, and second by including the influence of hydraulic hysteresis through calculating the liquid–solid advancing and receding contact angles and taking into account the influence of volume change directly by considering the evolution of the soil water retention curves with void ratio variation. We assumed that the cyclic drying–wetting paths would depend on both void ratio and contact angle determination. (continued)

      Core Ideas:
      • We predicted the initial drying, main wetting, main drying, water retention, and scanning curves.
      • The model uses a process-dependent contact angle determination.
      • An experimental water retention curve was determined on clayey soils in slurry form.

      doi:10.2136/sssaj2016.01.0006
      Published: November 23, 2016



    • Mario L. Flores-Mangual, Birl Lowery and James G. Bockheim
      Episodic Rainwater Movement in a Hydrophobic Sparta Sand under Three Ecosystems in Lower Wisconsin River Valley

      Vegetation can directly affect soil water dynamics through rainfall interception and evapotranspiration. Vegetation type probably is one factor that causes soil hydrophobicity, and hydrophobicity can influence water infiltration and groundwater recharge. Surfactants can be used to alleviate non-wetting conditions. The objectives of this study were to determine the effects of vegetation type on soil water content and groundwater recharge and to explore if a soil-applied surfactant can increase both conditions. (continued)

      Core Ideas:
      • Prairie to pine conversion reduced soil water and drainage because of hydrophobicity and interception.
      • Soil-applied surfactant did not increase soil water content or water drainage.
      • Early afforested prairie had similar soil water content and drainage to natural prairie.
      • Early afforested prairie had greater soil water content and drainage than pine plantation.

      doi:10.2136/sssaj2016.04.0115
      Published: November 17, 2016



    • Cecilie Hermansen, Maria Knadel, Per Moldrup, Mogens H. Greve, René Gislum and Lis W. de Jonge
      Visible–Near-Infrared Spectroscopy Can Predict the Clay/Organic Carbon and Mineral Fines/Organic Carbon Ratios

      The ratios of mineral fines (<0.02 mm, clay + fine silt) to organic carbon (OC), consisting of the n-ratio (i.e., the clay/OC ratio) and m-ratio (i.e., the fines/OC ratio) have recently been used to analyze and predict soil functional properties such as tilth conditions, clay dispersibility, degree of preferential flow, water repellency, and chemical adsorption. Conventional texture and OC measurements are time consuming and expensive, and visible–near-infrared (vis-NIR) spectroscopy may provide a fast and inexpensive alternative for obtaining the n- and m-ratios. In this study, a total of 480 soil samples from seven Danish and one Greenlandic fields, with a large textural range (clay: 0.027–0.355 kg kg−1; OC: 0.011–0.084 kg kg−1; n-ratio: 0.49–16.80; m-ratio: 1.46–32.14), were analyzed for texture and OC and subsequently scanned with a vis-NIR spectrometer from 400 to 2500 nm. The spectral data were correlated to reference values of the n-ratio, m-ratio, clay, fine silt, fines, and OC with partial least squares regression. (continued)

      Core Ideas:
      • Visible–near-infrared spectroscopy is a fast and indirect method for soil analysis.
      • The ratios of clay and (clay + fine silt) to organic C relate to soil functions.
      • We predicted the clay and (clay + fine silt) to organic C ratios successfully.

      doi:10.2136/sssaj2016.05.0159
      Published: November 10, 2016



    • Pingping Zhang, Yongxing Cui, Yanle Zhang, Junchao Jia, Xia Wang and Xingchang Zhang
      Changes in Soil Physical and Chemical Properties following Surface Mining and Reclamation

      In this study, soil physical and chemical properties, that is, texture, bulk density (BD), structural stability index (SI), water-stable aggregates (WSAs), mean weight diameter (MWD), steady-state infiltration rate (SIR) and organic carbon content (SOC) were measured in reclaimed mine sites (RMSs), including the revegetated sites (RVSs; arbors [A], bushes [B], arbor-bush mixtures [AB], and grasslands [G]) and natural recovery site (NRS), and in undisturbed native sites (UNSs). The objectives were to assess the changes in these properties of RMSs compared with UNSs and evaluate the effects of reclamation land uses on these properties. Sand content, SI, >0.25-mm WSAs, MWD, SOC were lower and BD was higher in RMSs than in UNSs, especially in the 15- to 30-cm depth. The surface BD, >0.25-mm WSAs, MWD in RVSs were lower by 13.6, 31.9, 48.5%, and SOC was higher by 120.4% than that in NRS. (continued)

      Core Ideas:
      • Mining and reclamation caused massive disturbance to soil properties.
      • Establishment of artificial vegetation had a better effectiveness than natural recovery in the restoration of mine lands.
      • Vegetation planting clearly improved the soil BD, SI, WSAs, SRI, and SOC of mine soils, but mainly in the surface (0-15 cm) layer.
      • The effect of soil property improvement was closely related to the vegetation types and planting grass should be encouraged.

      doi:10.2136/sssaj2016.06.0167
      Published: October 27, 2016



  • SOIL PHYSICS & HYDROLOGY NOTE

    • Dilia Kool, Joshua L. Heitman, Naftali Lazarovitch, Nurit Agam, Thomas J. Sauer and Alon Ben-Gal
      In Situ Thermistor Calibration for Improved Measurement of Soil Temperature Gradients

      Accurate measurement of soil temperature gradients is important for the estimation of soil heat flux and latent heat flux, both major components of the surface energy balance. Soil temperature gradients are commonly measured using heat-pulse sensors equipped with thermistors. In this study, individual thermistors showed absolute temperature differences on the order of 0.2°C when placed under uniform temperature conditions. These differences compromised measurement of soil temperature gradients over small depth increments and/or conditions with relatively minor variation in temperatures. (continued)

      Core Ideas:
      • Soil temperature gradients are important for soil (latent) heat flux estimation.
      • Heat-pulse sensor thermistors’ temperature differences were on the order of 0.2°C.
      • In situ calibration reduced uncertainty between thermistors to about 0.06°C.
      • In situ calibrated offsets between thermistors were similar to laboratory results.
      • Offsets were found to change very little over a 5-yr period.

      doi:10.2136/sssaj2016.05.0134
      Published: December 1, 2016



  • WETLAND SOILS

    • Nia Hurst, John R. White and Joseph Baustian
      Nitrate Reduction in a Hydrologically Restored Bottomland Hardwood Forest in the Mississippi River Watershed, Northern Louisiana

      Nitrogen loading from the Mississippi River leads to formation of water column hypoxia in the northern Gulf of Mexico every summer. Bottomland hardwood (BLH) forests located within the Mississippi River watershed could play a crucial role in reducing NO3 loading to the Gulf of Mexico. However, much river–floodplain connectivity has been muted due to building of levees and land conversion for agriculture. Restoring floodplain–river connectivity can potentially reduce river NO3. (continued)

      Core Ideas:
      • River–floodplain connectivity is low in the Mississippi River basin.
      • Floodplain restoration led to an increase in NO3 reduction from river water.
      • Recovery of NO3 reduction was faster than other soil microbial measures.

      doi:10.2136/sssaj2016.08.0250
      Published: November 17, 2016



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