Papers by Cristine Morgan
Soil Science Society of America Journal, 2003
... Lowering fertilization rates in these areas that are over fertilized could reduce leaching an... more ... Lowering fertilization rates in these areas that are over fertilized could reduce leaching and still achieve similar yields (Vanotti and Bundy, 1994). ... Site Description. A 30.4-ha privately owned field located in Dane County near Waunakee, WI, was used in this study. ...
Minutes of The Proceedings, 1924
Visible and near-infrared (VNIR, 4002500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, ... more Visible and near-infrared (VNIR, 4002500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, proximal-sensing method that has proven useful in quantifying constituents of dried and ground soil samples. Very little is known, however, about how DRS performs in a field ...
Remote Sensing, 2014
The United States Forest Service Forest Inventory and Analysis (FIA) Program provides a diverse s... more The United States Forest Service Forest Inventory and Analysis (FIA) Program provides a diverse selection of data used to assess the status of the nation's forests using sample locations dispersed throughout the country. Airborne laser scanning (ALS) systems are capable of producing accurate measurements of individual tree dimensions and also possess the ability to characterize forest structure in three dimensions. This study investigates the potential of discrete return ALS data for modeling forest aboveground biomass (AGBM) and gross volume (gV) at FIA plot locations in the Malheur National Forest, eastern Oregon utilizing three analysis levels: (1) individual subplot (r = 7.32 m);
Soil Science Society of America Journal, 2012
Fluctuation and Noise Letters, 2007
Soil bulk density affects water storage, water and nutrient movement, and plant root activity in ... more Soil bulk density affects water storage, water and nutrient movement, and plant root activity in the soil profile. Its measurement is difficult in field conditions. Vibration-induced conductivity fluctuation was investigated to quantify soil bulk density with possible field applications in the future. The AC electrical conductivity of soil was measured using a pair of blade-like electrodes while exposing the soil
Direct determination of soil hydraulic properties is often costly and laborious hence the use of ... more Direct determination of soil hydraulic properties is often costly and laborious hence the use of indirect methods such as pedotransfer functions (PTFs). Despite progress made in PTF development in general, little evaluation of PTFs has been done for the sandy soils of Niger. We tested the ability of three PTFs, (Campbell, van Genuchten, and Vauclin) to determine soil water retention
Geoderma, 2011
In the literature of visible and near infrared diffuse reflectance spectroscopy (VNIR-DRS) for so... more In the literature of visible and near infrared diffuse reflectance spectroscopy (VNIR-DRS) for soil characterization, the effects of instruments and scanning environments on reflectance spectra and calibration models have not been well documented. To fill this knowledge gap, the goal of this study is to compare soil reflectance spectra and calibration models obtained with different spectrometers operated under different lab environments. Two sets of soil samples were used in this study. The first set (containing 180 samples collected from Quemado, Texas) was scanned by three spectrometers and no effort was provided to control the scanning protocol. The second set (containing 264 samples from Central Texas) was scanned by two spectrometers, and efforts were provided intentionally to control the scanning protocol. Partial least squares regression was applied to develop calibration models for soil organic carbon (OC) content using the first derivative spectra. Three calibration transfer methods (namely, slope and bias correction, direct standardization, and piecewise direct standardization) were used to transfer calibration models from one instrument to another. In the experiment where no scanning control was provided, significant differences were seen in mean soil spectra by different spectrometers. But cross-validation indicated that all three models can predict OC accurately. However, the OC models are quite dissimilar to each other in terms of the regression coefficients at each wavelength, and their application to the spectra measured by other instruments generally yielded poor results. All three calibration transfer methods provided a satisfactory application of the OC model calibrated on the primary instrument to secondary instruments. In the experiment where some controls were provided, mean soil spectra by different spectrometers matched each other well. The two OC models were quite similar, and model application to the spectra measured by the other instrument yielded satisfactory predictions. When scanning control was provided; however, model transfer methods improved the calibration model only marginally. All results indicate that VNIR-DRS calibration models are highly instrument/scanning environment dependent, and their extent of applicability could be highly limited. Provision of controls over the scanning protocol has the potential to remove a great deal of spectral variations that are related to extraneous effects due to multiple instruments/scanning environment. The results of this study have important implications on the future use of VNIR-DRS as a routine method for soil characterization, such as comparisons among VNIR prediction models derived from different soil labs and a global soil spectral library, where multiple instruments have to be involved.
Soil Science Society of America Journal, 2009
Soil Science Society of America Journal, 2003
... Lowering fertilization rates in these areas that are over fertilized could reduce leaching an... more ... Lowering fertilization rates in these areas that are over fertilized could reduce leaching and still achieve similar yields (Vanotti and Bundy, 1994). ... Site Description. A 30.4-ha privately owned field located in Dane County near Waunakee, WI, was used in this study. ...
Soil Science Society of America Journal, 2009
Abstract Multi-field/multi-season approaches used to calibrate apparent soil electrical conductiv... more Abstract Multi-field/multi-season approaches used to calibrate apparent soil electrical conductivity (EC a) models for predicting soil spatial variability across large landscapes are time-consuming. In this study an alternative calibration approach was evaluated. The study was conducted on an agricultural watershed in Texas with the objectives of (i) assessing the contribution of different soil properties to EC a variability; and (ii) evaluating the feasibility of using a single calibration approach to predict soil variability across different fields. Of the ...
Soil Science Society of America Journal, 2007
Visible and near-infrared (VNIR, 4002500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, ... more Visible and near-infrared (VNIR, 4002500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, proximal-sensing method that has proven useful in quantifying constituents of dried and ground soil samples. Very little is known, however, about how DRS performs in a field ...
Journal of the American Water Resources Association, 2005
A precision scale landscape model designed for agricultural applications is described in this pap... more A precision scale landscape model designed for agricultural applications is described in this paper. The Precision Agricultural Landscape Modeling System (PALMS) is a combination of two process-based models: a diffusive wave runoff model with ponding (described in detail) and a biosphere model with a crops module (briefly reviewed). Several innovations, including numerical formulations for the hydrologic properties of the soil surface with crusting, slope/tillage angle interactions, and change of roughness and detention storage with cumulative precipitation have been included. The model is compared to observations on one 1.8 ha field planted with maize and soybeans during four growing seasons, and one 24 ha field planted with maize during one growing season. Daily average soil moisture is simulated well (within 5 percent volumetric), except in extended runoff/ponding episodes. Physical processes not simulated in the model suggest possible explanations for model errors. Planned improvements for PALMS are also presented. (KEY TERMS: plant growth modeling; precision agriculture; PALMS; runoff; soil moisture; ground water recharge.)
Journal of Soil and Water Conservation, 2009
... Erath County contained 117-dairy confined animal feeding opera-tions in October 2005, with ..... more ... Erath County contained 117-dairy confined animal feeding opera-tions in October 2005, with ... spatial variability of P across dairy landscapes vital for developing effective best managementpractices. ... The next question follows: Do the current sampling intensity and soil test P (STP ...
Journal of Hydrology, 2013
s u m m a r y An accurate estimate of the degree of soil cracking is important in partitioning ra... more s u m m a r y An accurate estimate of the degree of soil cracking is important in partitioning rainfall into soil infiltration and runoff in watersheds with clay soils that shrink and swell. Usually in the application of surface hydrology models, cracking is considered to be predicted by assuming equidimensional shrinkage and a 1:3 ratio of change in soil profile thickness to depth of water loss. Our objective was to use in situ measurements of soil profile subsidence with loss of water in an apparently uniform Vertisol to determine: (1) whether or not the soil profile subsidence followed the 1:3 ratio of change in thickness to depth of water loss and (2) how the ratio of subsidence to water loss varies with the Coefficient of Linear Extensibility (COLE). The research was conducted on a catena of Houston Black and Heiden clays. Vertical soil shrinkage and swelling along with soil water content were measured at the summit, shoulder, backslope, and footslope positions of the catena. Change in soil water content along with spatial variability in COLE were the primary drivers of temporal and spatial variability of shrinkage and swelling on the catena. The rate that soil shrank or swelled with change in the amount of water stored in the soil was related to COLE, which was negatively correlated with carbonate content of the soil. Shrinkage of the soil profile with water lost was less than the commonly used 1:3 ratio. Our data supported using COLE to predict the degree to which the ratio is less than 1:3. Incorporating COLE values into a hydrology model to simulate soil shrinkage with water loss is a useful approach because COLE values have been measured for soils with shrink-swell potential and that data is available in USDA NRCS Soil Survey databases.
Journal of Environment Quality, 2010
In the United States, petroleum extraction, refi nement, and transportation present countless opp... more In the United States, petroleum extraction, refi nement, and transportation present countless opportunities for spillage mishaps. A method for rapid fi eld appraisal and mapping of petroleum hydrocarbon-contaminated soils for environmental cleanup purposes would be useful. Visible near-infrared (VisNIR, 350-2500 nm) diff use refl ectance spectroscopy (DRS) is a rapid, nondestructive, proximal-sensing technique that has proven adept at quantifying soil properties in situ. Th e objective of this study was to determine the prediction accuracy of VisNIR DRS in quantifying petroleum hydrocarbons in contaminated soils. Forty-six soil samples (including both contaminated and reference samples) were collected from six diff erent parishes in Louisiana. Each soil sample was scanned using VisNIR DRS at three combinations of moisture content and pretreatment: (i) fi eld-moist intact aggregates, (ii) air-dried intact aggregates, (iii) and air-dried ground soil (sieved through a 2-mm sieve). Th e VisNIR spectra of soil samples were used to predict total petroleum hydrocarbon (TPH) content in the soil using partial least squares (PLS) regression and boosted regression tree (BRT) models. Each model was validated with 30% of the samples that were randomly selected and not used in the calibration model. Th e fi eld-moist intact scan proved best for predicting TPH content with a validation r 2 of 0.64 and relative percent diff erence (RPD) of 1.70. Because VisNIR DRS was promising for rapidly predicting soil petroleum hydrocarbon content, future research is warranted to evaluate the methodology for identifying petroleum contaminated soils.
Geoderma, 2009
... In some cases where the soil was high in clay, the piano wire did smear the soil face, but sm... more ... In some cases where the soil was high in clay, the piano wire did smear the soil face, but smearing was minimal compared to the purposefully smeared samples. Both halves of each core, smeared and unsmeared, were scanned at field-moist water content. ...
Geoderma, 2009
... a Department of Natural Resources and Environmental Management, Ball State University,Muncie,... more ... a Department of Natural Resources and Environmental Management, Ball State University,Muncie, IN 47306, USA. b Soil & Crop Sciences Department, Texas A&M University, 370 Olsen Boulevard, College Station, TX 77843-2474, USA. ...
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Papers by Cristine Morgan