Soil Science Masters Theses

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How Salinity Influences Soil Organisms: Earthworms, Archaea, Bacteria and Fungi
(North Dakota State University, 2023) Castleberry, Cecelia Bartley
Soil salinity is a naturally-occurring issue in the Great Plains. Current standards for saline soil designation are based on plant tolerance levels. This thesis expands salinity knowledge into salinity responses of other soil organisms. I used laboratory mesocosms to examine survival and fecundity or cocoon production of earthworms in the Apporectodea complex to increasing levels of salinity, with or without supplemental organic matter (OM). I then used a split-bin design to examine earthworm choice between combinations of saline and non-saline soils, with and without supplemental OM. I found that earthworms avoided saline soils, but survival and production was steady across salinity levels and in some cases decreased with added OM. I then quantified abundance and diversity of microbial groups in field-collected saline and non-saline soils in increments to 120 cm depth. The response of microbes to depth were stronger than their responses to salinity. Both important groups of soil organisms appear tolerant to salinity levels.
An Evaluation of Electrical Conductivity Meters for Making In-Field Soil Salinity Measurements
(North Dakota State University, 2010) Briese, Lee Galen
Soil electrical conductivity (EC) can be used as a parameter to assist agricultural producers in making economically important management decisions. Since particular crops and crop varieties respond dynamically to soluble salt levels in relation to crop growth stage and soil moisture content, many management decisions regarding crop type and variety must be made prior to planting. Some crop stress factors could be removed or mitigated if a handheld EC meter could be implemented during the growing season. The objectives of this research were to 1) determine the accuracy of four handheld EC meters for measuring soil EC across a range of environmental temperatures of 15, 20 and 25° C, soil clay concentrations of 10.2, 17.8, 19.3, 32.3 and 50.4 %, and salt solutions containing NaMg- SO4 or Na-Mg-Cl at concentrations of approximately 0, 1, 2, 4 and 8 dS m-1 under controlled laboratory conditions; 2) identify functional differences of the meters that might pose problems for in-field use; and 3) determine if meter price is related to accuracy. The EC values provided by three of the handheld EC meters were significantly different than the standard meter at all treatment levels. Measurements at different temperatures of the standard KCI calibration solution (known EC 1.413 dS m ·1 ) varied by ±0.15, -0.01 to +0.16, -0.14 to -0.03, and ±0.03 dS m-1, for the Hanna Black (Hl993310), Hanna Blue {Hl98331), Field Scout, and SenslON 5 meters, respectively. When salinity was 3 dS m-1 or greater the difference between the test meters and standard meter (EC Response} was larger. Test meter measurements for the salinity by clay interaction were different than the standard meter by ±0.5, ±1, and -2.5 to +1.5 dS m-1, for EC levels of less than 3, 3 to 4, and greater than 4 dS m-1, respectively. The SenslON 5 handheld was the only meter tested that was not significantly different than the standard meter {p::; 0.48}. Test meter accuracy was highly dependent on temperature. Therefore, the most important criteria for selecting a portable meter for in-field EC measurements is the accuracy of the specific meter's temperature measurement and temperature compensation model.
Shifting Perspectives: Desocialization and the Journey Toward Critical Consciousness
(North Dakota State University, 2010) Mathers, Angela Marie
The purpose of this study was to investigate how a service-learning course fosters students' development of a critical consciousness. Participants of this research study were students who participated in the 2009 International Service Seminar, a three-credit course that culminated with a service trip to Antigua, Guatemala. Interviews were conducted with participants that focused on students' experiences both during the class and in the year since the completion of the course. Utilizing critical pedagogy literature, I focused on the work of Jennifer Moon (1999) and Ira Shor (1992) to analyze the processes through which students gain critical consciousness. What became clear in my analysis is that desocialization was a significant component of the process of moving toward critical consciousness. In fact, the highly personal ways in which desocialization was woven into each students' experiences in the course, demonstrated that the journey toward critical consciousness occurs in a jagged manner. Understanding the nature of the desocialization process provides instructors of service learning courses the opportunity to foster critical consciousness in a more successful manner.
Soybean Water Stress Development and Mitigation in West-Central North Dakota
(North Dakota State University, 2020) Wirtz, Jeremy
In recent years, soybean [Glycine max. (L.) Merr.] production has moved into west-central North Dakota, an area known for common deficits between potential plant water use and annual rainfall. Soybean seed yield reductions due to water stress are the greatest during reproductive stages of growth. In a year of limited rainfall, foliar-applications of five different water use modulating chemicals applied at early reproductive growth stages commonly reduced seed yields, while improvements were few and inconsistent. Seed-applied plant growth regulators (PGRs) were recognized as possible seed treatments to conserve soil water by reducing vegetative plant growth, thus improving water dynamics later in the growing season. In the following field study, late-terminated, fall-seeded cover crops were shown to significantly reduce spring soil water levels. However, favorable rainfall throughout the growing season buffered any cover crop or seed-applied PGR treatment effects on growing season soil water, plant water status, and soybean seed yield.
Effects of Major Flooding on Water and Sediment Characteristics in an Urban Enviromnent
(North Dakota State University, 2011) Guy, Adam Christopher
Spring flooding of the Red River of the North is a common phenomenon, but no infonnation exits on how these flooding events impact both water and sediment quality within an urban area. The objectives of this study were to assess if urban enviromnents affect floodwater quality and to determine the quality of sediment deposited in an urban environment after floodwaters recede. Water samples were taken on 12 dates from two locations before and after the city limits of Pargo, North Dakota and Moorhead, Minnesota (F-M), and were measured for 12 variables including total sediment, P04, 17/3-estradiol, and diesel range organics. Sediment and underlying soil samples were collected from three locations within F-M where, at each location, there were three equidistant transects parallel to the river channel, and analyzed for 40 variables including dry sediment mass, carbon, nitrogen, diesel and gasoline range organics, and trace elements. Considering river discharge and total sediment and P04 concentrations at each sampling date, about 4500 Mg of sediment and 30 Mg of P04 were estimated to have been deposited within F-M. l 7Bestradiol was detected in 9 of 24 water samples with an average concentration of0.61 ng L1 and diesel range organics were detected in 8 of 24 samples with an average concentration of 80.0 µg L-1. Average mass of sediment across locations and transects ranged from about 2 to 1 O kg m·2 where transects closest to the river channel had the higher mass deposits of sediment. Total carbon and nitrogen within the sediment was determined to be mostly organic and ranged from about 40 to 59 g kg' 1 and about 1,760 to 4,930 mg kg·1, respectively, with the highest concentrations occurring at the transect furthest from the river channel. No gasoline range organics were detected, but diesel range organics were detected in 26 of the 27 sediment samples analyzed with a maximum concentration of 49.2 µg g-1• Total Hg concentrations in the sediment and soil averaged about 55 and 61 ng g-1, respectively, and all trace elements detected in the sediments were within ranges for noncontaminated sites. Although sediments remaining after floodwaters recede can be unsightly and cleanup efforts can be labor intensive, these sediments can also provide essential plant nutrients for urban riverine ecosystems, which may include turf grass, fruits and vegetables, and horticultural plants.
Evaluation of 1:5 Soil to Water Extract Electrical Conductivity Methods and Comparison to Electrical Conductivity of Saturated Paste Extract
(North Dakota State University, 2011) He, Yangbo
Conducting a 1 :5 soil:water extract to measure electrical conductivity (EC) is an approach to assess salinity and is the preferred method used in Australia. However, the influence of salinity on plant growth is predominantly based on saturated paste extract electrical conductivity (ECe) and ECe is recommended as a general method for estimating soil salinity internationally, so it is necessary to convert EC1:s to ECe, The objectives of this research were to 1) compare methods of agitation (shaking plus centrifuging (shaking/centrifuging), shaking, and stirring) for determining EC1: 5; 2) determine optimal times for equilibration for each method across a range of salinity levels determined from saturated paste extracts (ECe) (objectives 1 and 2 are for paper 1); and 3) develop predictive models to convert ECu data to ECe based on four different 1 :5 extraction methods listed above and a USDA-NRCS equilibration technique ( objective 3 is for paper 2). The soils evaluated for the two studies were from north central North Dakota, USA, where 20 soil samples having ECe values ranging from 0.96 to 21 dS m-1were used for the first study (objectives 1 and 2), and 100 samples having ECe values ranging from 0.30 to 17.9 dS m-1were used in the second study (objective 3). In the first study, for each method, nine equilibrium times were used up to 48 hrs. In the second study, a uniform agitation time (8 hrs) was applied to the first three agitation methods, and 1 hr was also used for the USDA-NRCS method. For the first study, significant relationships (p < 0.05) existed between values ofEC1:s and agitation time across the three methods. Agitation methods were significantly different (p S 0.05) from each other for 65% of the soils and shaking/centrifuging was significantly different (p < 0.05) from stirring for all soils. In addition, for 75% of the soils, shaking/centrifuging was significantly different (p :S 0.05) from shaking. Based on these results, methods were analyzed separately for optimal equilibration times. The agitation times required for the three methods to reach 95 and 98% of equilibration were a function of the level of soil salinity. For soils with ECe values less than 4 dS m·1, over 24 hrs was needed to obtain both 95 and 98% of equilibration for the three methods. However, less than 3 and 8 hrs were needed to reach 95 and 98% equilibration, respectively, across methods for soils having ECe values greater than 4 dS m·1. These results indicate that establishing a standard method is necessary to help reduce variation across EC1:s measurements. In the second study, the value ofECe was highly correlated with EC1:s (p < 0.0001) across four agitation methods in non-transformed, log10- transformed, and dilution ratio models through regression analysis. The values of coefficient of determination (r2 ) were greatly improved and average about 0.87 using log10- transformation compared to other two models (r2 values of about 0.68 for the nontransformed models and 0.69 for the dilution ratio models). Since agitation methods were determined to be highly correlated with each other, any regression model determined under the four agitation methods were applicable for the estimation of ECe from another method. The results from this research indicate that comparing data across studies should be done with caution because both agitation method and time can influence results. Also, estimation ofECe from EC1:5 can be done with confidence, but models may not be transferrable across different soil orders or across various salt types.
An Examination of Land Preparation Methods to Alleviate Common Issues Associated With Pipeline Reclamation
(North Dakota State University, 2022) Lardy, Jarrett
Post-seeding land preparation methods can improve reclamation success; however, limited research is available for the Williston Basin. A field study evaluated four treatments: land imprinting, hydromulch, straw crimping, and the combination of hydromulch and land imprinting for their abilities to reduce simulated rainfall runoff and sediment losses and for their ability to promote plant growth. Straw crimping reduced total runoff and may likely be the best option for providing surface cover. However, vegetation establishment was found to be not significant among the treatments. Additionally, a laboratory study examined seven soils for their penetration resistances (PR) across variable water contents (Θg) and bulk densities (Bd). Overall, as Bd increased so did PR, with increases in Θg diminishing PR increases, yet still building strongly correlated relationships (r2 > 0.90). These results will enable reclamation specialists to better define soil conditions and methods for improving soil water retention and overall soil function.
Calcium Acetate: An Alternative to Gypsum for Brine Impacted Soils
(North Dakota State University, 2022) Peterson, Annalie
With North Dakota being ranked as a leading producer of oil and natural gas in the United States, the possibility of accidental produced water (aka “brine” or “salt water”) spills is a continuous concern. Brine water poses numerous threats to soil properties as it has the potential of causing soil dispersion by increased concentrations of sodium. The goal of this research was to compare the effectiveness of several calcium amendments: calcium acetate, flue gas desulphurization gypsum and pelletized gypsum, on improving the saturated hydraulic conductivity (Ks) and removing sodium of three brine impacted soils. Ultimately, increasing rates of calcium acetate had the greatest effect on increasing the Ks but, in general, increasing rates of any amendment increased the Ks and removed sodium. A secondary goal was to produce a resource about the origin of brine water in the Williston basin for those affected by or interested in this topic.
Soil Biological Functioning and Recovery in Soils Disturbed From Bakken Oil and Gas Activities
(North Dakota State University, 2022) Bartsch, Zachary John
Oil and gas activity-related soil disturbances can alter soil properties and reduce microbial function, which is crucial for nutrient cycling and proper soil function. The goal of this research was to investigate effects of remediation techniques on soil biological property recovery following various types of oil and gas disturbances. A series of studies evaluating microbial abundance, crop growth, and biological properties were conducted on crude oil-contaminated subsoils remediated either with thermal desorption or land farming. Thermally desorbed subsoil achieved similar yields to non-contaminated topsoil after four years. Additionally, biological properties in blended soil (1:1 topsoil to subsoil) were studied using two biostimulant inoculant products. Overall, biostimulant amendment improved microbial responses and plant growth over the control. While blended subsoil and/or remediated subsoil could replace topsoil during instances of topsoil scarcity and can facilitate soil biological property recovery similar to topsoil, biostimulants improved biological metrics regardless of soil blend.
Seeding Time and Interseeded Cover Crop Species Influence Sugarbeet Yield and Quality
(North Dakota State University, 2020) Sigdel, Sailesh
Field experiments were conducted to evaluate cover crop interseeding time and species effect on sugarbeet production during 2018 and 2019 growing seasons. Cover crops were first interseeded in June and second interseeding was done in late June or early July. Four cover crops species, Austrian pea (Pisum sativum L.), winter rye (Secale cereale L.), winter camelina [Camelina sativa (L.) Crantz], and brown mustard (Brassica juncea L.), were examined. First interseeding resulted in significantly higher cover crop biomass than second interseeding. In 2018, the highest recoverable sugar yield was observed with pea (13.9 Mg ha-1) and camelina (6.6 Mg ha-1) first-interseeded, at Ada and Downer, MN, respectively. In 2019, camelina (11.2 Mg ha-1) at Ada, MN, and pea (12.4 Mg ha-1) at Prosper, ND both second-interseeded, had the highest recoverable sugar yield. Cover crops had no negative impacts on sugarbeet, but the selection of species and planting time are critical.
Can Soil Microbial Activity Be Improved With the Use of Amendments?
(North Dakota State University, 2020) Kruger, Matthew Wayne
Low microbial activity and associated nutrient cycling are concerns in agricultural problem soils. The objectives of this study were to investigate microbial response on problem soils to amendments, drying-wetting cycles, and the interaction of amendments and drying-wetting cycles. In this laboratory study, soil carbon dioxide (CO2) flux was measured from thermal desorption treated soils and saline soils in response to Proganics, spent lime, and composted beef manure applications. Microbial activity was measured through CO2 flux and its rate of change, permanganate oxidizable C, and residual inorganic nitrogen. Proganics had the greatest ability to elevate and sustain microbial activity on problem soils, but spent lime and compost had the greatest potential to improve microbial mediated nitrogen mineralization. In conclusion, spent lime and compost can be effective amendments for improving soil quality of saline and thermal desorption treated problem soils to increase microbial activity and associated nitrogen cycling.
The Effect of Salinity on Soil Microbial Community Structure
(North Dakota State University, 2020) Ries, Mackenzie Lynn
Soil salinity is a widespread problem that affects crop productivity. We expect that saline soils also have altered microbial community structure, soil food webs and related soil properties. To test this, we sampled field soils across four farms in eastern North Dakota that host salinity gradients. We evaluated microbial biomass carbon, phospholipid fatty acid analysis and nematode counts in moderately saline and low saline soils. Additionally, we measured soil properties that represent potential food sources and habitat characteristics that influence microbial communities. We found higher microbial group abundance in moderately saline soils than in the lower saline soils. In contrast, we found lower nematode abundances in the moderately saline soils. We also observed increased labile carbon, nitrogen, phosphorus, and water content in the moderately saline soils. Based on our results, saline soils appear to have unique soil biological characteristics, which have implications for overall soil function along salinity gradients.
Superabsorbent Polymer Effects on Soil Physical Properties and Use as a Compaction Alleviation Amendment in Surface Coal Mine Reclamation
(North Dakota State University, 2019) Ostrand, Megan Sue
Surface coal mine reclamation is challenged by alterations in soil characteristics, compaction being the most plant-yield reducing. Superabsorbent polymers (SAPs) ability to retain large volumes of water gives them the potential to alter soil properties. Laboratory objectives were to determine how SAPs alter water retention, liquid limit (LL), evaporation, saturated hydraulic conductivity (Ksat), and compression across five soil series. Increasing SAP application rates to 0.2% significantly increased plant available water (PAW), stage one evaporation duration, LL, stage two evaporative water loss, and significantly decreased stage one evaporative water loss, Ksat, and compression for various soil series. Field study investigated how SAP, deep ripping (R) and mulch (M) impacted penetration resistance and spring wheat yield (Triticum aestivum). Application of 0.04% SAP improved yields similar to R. Penetration resistance decreased with R, and SAP application showed reduction similar to R. While SAPs show potential as a reclamation tool, application longevity needs evaluation.
Soil Biological Temporal Variability as Functions of Physiochemical States and Soil Disturbance
(North Dakota State University, 2019) Leitner, Zachary Robert
Within our ecosystems, soil biota control an array of functions, such as nutrient cycling and decomposition, and have been pursued as a soil quality indicator. Though microbial communities are known to be a reflection of their environment, small scales dynamics within an agricultural system have been overlooked for many years leading to gaps when inferring on relative microbial values. To further asses our current microbial knowledge, two experiments analyzing microbial phospholipid fatty acid (PLFA) structures and enzyme activities sought out to determine temporal fluctuations, cycles, and driving force behind simulated daily microbial parameter outputs. Across both studies, temporal effects, cyclical structures, and common driving forces were recorded, but further validation and characterization is needed to solidify the temporal dynamics of the microbial community. Overall, this information serves as a valuable step towards determining the most viable tillage systems based on environmental conditions, and physical proof of small scale microbial fluctuations.
Impacts of Kentucky Bluegrass and Patch-Burn Grazing Management on Soil Properties in the Northern Great Plains
(North Dakota State University, 2019) Gerhard, Leslie Marie
Kentucky bluegrass (Poa pratensis L.; hereafter referred to as bluegrass) has rapidly invaded the northern Great Plains over the past three decades, leading to declines in native plant diversity. A knowledge gap exists regarding the below-ground impacts that bluegrass has on soil properties. To address this knowledge gap, we measured soil physical, chemical, and biological conditions associated with bluegrass dominance resulting from idle management. We compared these results to patch-burn grazed areas with greater native plant species expression. Our results indicate that bluegrass influences soil microclimate, promoting cooler and wetter soil conditions. However, this shift does not appear to alter soil microbial abundance or carbon and nitrogen pools. Additionally, patch-burn grazing has limited impact on measured soil properties. We concluded that patch-burn grazing may be a practical land management technique for controlling bluegrass invasions without negative impacts on soil, and for promoting biological heterogeneity.
Relationship of Vegetation Indices from Drone-Based Passive Optical Sensors with Corn Grain Yield and Sugar Beet Root Yield and Quality
(North Dakota State University, 2019) Olson, Daniel O.
The main goal of this study was to calibrate small unmanned aircraft system (SUAS) based vegetation indices with fertilizer-N application rate and yield for corn and sugar beet. It was hypothesized that canopy reflectance would change with increasing fertilizer-N application rates. The objectives of this study were (i) to determine the crop yield and quality in response to fertilizer application rates at two field sites, (ii) map vegetation indices of the experimental plots using drone-based optical sensors, and (iii) calibration of vegetation indices with crop yield. During 2017 and 2018 growing seasons, field trials were conducted to determine corn and sugar beet response to fertilizer-N application rates. In general, the use of optical sensors for quantitative and qualitative relationships were greater after the V6 growth stage in both corn and sugar beet. Early season moisture deficiency, disease, and crop size could impact the quality of the optical sensing data collection.
The Relative Nitrogen Fixation Rate and Colonization of Arbuscular Mycorrhizal Fungi of Iron Deficient Soybeans
(North Dakota State University, 2011) Podrebarac, Frances Ann
Soybeans (Glycine max L. Merr.) are a symbiont of two beneficial associations: biological nitrogen fixation (BNF) with Bradyrhizobium japonicum, and arbuscular mycorrhizal fungi (AMF). Within the Northern Great Plains of the USA, iron deficiency chlorosis (IDC) of soybean is a yield-limiting factor. The effects of IDC on BNF and AMF are not well defined. This study was conducted to determine the effects of IDC on BNF and AMF. A laboratory study was performed to compare three methods of measuring ureide-N, a product of BNF in soybeans. Field studies in soybean were performed at three locations at eastern N011h Dakota. The experimental design was a factorial combination of three cultivars and three treatments. The three cultivars, in order of decreasing chlorosis susceptibility, were NuTech NT-0886, Roughrider Genetics RG 607, and Syngenta S01-C9 RR. The three treatments were control, Sorghum bicolor L. companion crop planted with the soybean seed, and FeEDDHA applied with the soybean seed. Chlorosis severity was the greatest and least for the NuTech and Syngenta cultivars, respectively. The FeEDDHA treatment decreased chlorosis severity. Ureide levels were abnormally high in plants severely stunted by JDC. The excess accumulation of ureides in IDC-stunted plants suggests that plant growth was reduced more than the rate of nitrogen fixation. The AMF population \vas at an adequate level at all locations and not affected by cultivar or treatment, in general. In the laboratory study, the Patterson et al. method had greater ureide concentrations due to the non-specific measuring of ammonium compounds compared to the Vogels and Van der Drift and Goos methods.
Phosphorus Dynamics and Crop Productivity in Bakken Crude-Oil Remediated Soils
(North Dakota State University, 2018) Croat, Samantha Jo
Thermal desorption (TD), a remediation method used to remove hydrocarbons from contaminated soils, may cause changes in soil properties that threaten soil function and plant productivity. The goal of this research is to better understand the effect that TD treatment has on soils intended for agricultural use. A series of soil phosphorus (P) sorption and desorption experiments were conducted on soils before and after TD treatment to determine P availability for plant uptake and risk for run-off. TD-treated soils retained more P, likely due to mineral transformations of Fe- and Al-oxides. In addition, a three-year field study using mixtures of topsoil (A), crude-contaminated soil (SP), and TD-treated soils (TDU) was conducted. Yields were significantly greater in plots that included A in the mixture compared to SP and TDU soils alone. TD-treated soils can be a replacement for topsoil, but the addition of topsoil will reduce the time to successful reclamation.
Redistribution and fate of applied ¹⁵N-enriched urea under irrigated continuous corn production
(North Dakota State University, 1996) Schindler, Frank Vincent
Understanding the redistribution and fate of N is essential for justification of Best Management Practices (BMP). This project was conducted on a Hecla fine sandy loam (sandy, mixed, Aquic Haploboroll) soil at the BMP field site near Oakes, North Dakota. One objective of this investigation was to evaluate the residence times of N03- -N in 20 undisturbed lysimeters and its infiltration time through the soil profile to tile drains. Corn (Zea mays L.) was fertilized with 135 kg N ha -1 as ¹⁵N-enriched urea plus 13.5 and 48.1 kg N ha -1 preplant for 1993 and 1994, respectively. Urea-N was band applied to 20 and 10 undisturbed lysimeters at 2.0 and 5.93 atom percent (at %) ¹⁵N in 1993 and 1994, respectively. Average resident times of N03- -N in the lysimeters was 11.7 months. Lysimeter and tile drainage indicate the presence of preferential pathways. Residence times of N03- -N depend on frequency and intensity of precipitation events. Another objective was to determine what portion of the total N in the crop was from applied urea-N and what portion was from the native soil-N. Nitrogen plots received ¹⁵N enrichments of 4.25 and 5.93 at % ¹⁵N in 1993 and 1994, respectively. At the end of the 1993 and 1994 growing season, 41.5% and 35.7% of the labeled fertilizer N remained in the soil profile, while the total recovery of applied ¹⁵N in the soil-plant system was 86.2% and 75.4%, respectively. Low recoveries of applied N may have been the result of soil or aboveground plant biomass volatilization, or denitrification or preferential flow processes. Further research needs to be conducted with strict accountability of gaseous loss and the mechanism(s) responsible.
Can We Increase Crop Yield Adopting Tile Drainage in Fargo Clay Soil?
(North Dakota State University, 2018) Acharya, Umesh
Subsurface drainage has recently become common for agriculturally productive soils and key to maintain and improve crop production in poorly drained, frigid clay soils. The first study was conducted for four years (2014-17) at Casselton, ND to determine best combination of drainage, tillage and crop rotation for higher corn yield. Our finding suggested corn yield was highest with no drainage, CS and CH combination in years with drought conditions. The second study was conducted for three years (2015-17) to evaluate subsurface drainage spacing (9, 12, and 15m) and depth (0.9 and 1.2m) combination on corn, soybean and sugarbeet yields and residual soil nitrate-nitrogen (NO3-N) contents. Results indicated that 9 m drain spacing produced highest corn and soybean yield when average across three years in contrast with drain depth that has no effect on corn and soybean yield except for sugarbeet where the 1.2m depth yielded higher than the 0.9m depth.

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