Mississippi River Delta Region Research Articles

Return of the Phrag-i: evaluating sexual reproduction mechanisms amenable to dieback recovery and potential invasiveness across Phragmites australis haplotypes

Phragmites australis is one of the most invasive wetland plants on the planet with both native and invasive haplotypes occurring in the United States. Three Phragmites haplotypes (Delta-, EU- and Gulf-types) co-occur in marshes of the Mississippi River Delta (MRD), where a recent dieback of Phragmites has prompted investigations about the potential for recolonization by seed. In other areas of the US, the invasive EU-type has been shown to spread by seed, yet little is known about reproduction modes of the Delta- and Gulf-types. We conducted a survey at 35 sites along the Mississippi River Delta region in southeast Louisiana to examine the potential for sexual reproduction across haplotypes as well as the potential for hybridization. Seed and pollen samples were collected from Phragmites populations to examine flowering phenology and determine pollen viability of the three lineages. We also conducted a seedbank assay in stands of three haplotypes to test the potential for recruitment by seed. Despite the observed potential for sexual reproduction in Delta- and EU- types, no Phragmites seedlings germinated from the seedbank. EU was the only haplotype to exhibit germination from seeds collected from seed heads. Both spatial separation and temporal isolation in flowering times indicate that hybridization between Phragmites haplotypes in the lower MRD is unlikely. High pollen production, increased pollen production following dieback, and viable seeds in the EU-type suggest that this invasive haplotype has a greater potential to invade new areas and adapt to stressors through sexual reproduction compared to than Delta-or Gulf haplotypes.

Whole Stand Variable Density Yield Equations for Oak-Gum-Cypress Bottomland Hardwood Forests

Abstract Variable density yield equations were constructed using fuzzy linear regression for bottomland oak-gum-cypress forests along the US Gulf Coast and lower Mississippi River Delta region. The USDA Forest Service (Forest Service)’s Forest Inventory and Analysis program provided plot data (n = 526). Predictors included stand age, growing stock basal area per acre, sweetgum site index (base age 50 years), and US Environmental Protection Agency ecoregion dummy variables located in Alabama, Arkansas, Louisiana, Mississippi, Tennessee, and Texas. Dependent variables were per acre growing stock cubic foot yield (GSV) and Doyle board foot sawlog yield (SLV). Plots averaged 58 years, 90 ft2/ac basal area, 79 ft site index, 2,556 ft3/ac GSV, and 11,183 Doyle bf/ac SLV. Adjusted R2 were 0.98 (GSV) and 0.77 (SLV). Basal area possessed fuzziness in the GSV model, whereas the SLV model’s intercept was fuzzy. Six ecoregions possessed fuzziness in each model, but these were not identical across models.

FEASIBILITY OF SHORT STORY CLUBS IN A HEMATOLOGY/ONCOLOGY PROGRAM

Background The death rate from colorectal cancer is high and affects poor and medically underserved populations disproportionately. In the United States, health disparities are particularly acute in the Lower Mississippi River Delta region. Because many in the region have limited access to basic health care resources, they are not screened for cancer, even though screening is one of the most effective strategies to prevent colorectal cancer. Community-based participatory research is a promising approach to prevent colorectal cancer in this population. Community Context The Empowering Communities for Life program was implemented in 2 underserved counties in the Arkansas Lower Mississippi River Delta. The program arose from a 9-year partnership between the University of Arkansas for Medical Sciences and 9 cancer councils across Arkansas. Methods Empowering Communities for Life is a community-based participatory intervention designed to increase colorectal cancer screening in rural, un...

Accounting for DEM Error in Sea Level Rise Assessment within Riverine Regions; Case Study from the Shatt Al-Arab River Region

Global elevation datasets such as the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) are the best available terrain data in many parts of the world. Consequently, SRTM is widely used for understanding the risk of coastal inundation due to climate change-induced sea level rise. However, SRTM elevations are prone to error, giving rise to uncertainty in the quality of the inundation projections. This study investigated the error propagation model for the Shatt al-Arab River region (SARR) to understand the impact of DEM error on an inundation model in this sensitive, low-lying coastal region. The analysis involved three stages. First, a multiple regression model, parameterized from the Mississippi River delta region, was used to generate an expected DEM error surface for the SARR. This surface was subtracted from the SRTM DEM for the SARR to adjust it. Second, residuals from this model were simulated for the SARR. Modelled residuals were subtracted from the adjusted SRTM to produce 50 DEM realizations capturing potential elevation variation. Third, the DEM realizations were each used in a geospatial “bathtub” inundation model to estimate flooding area in the region given 1 m of sea level rise. Across all realizations, the area predicted to flood covered about 50% of the entire region, while predicted flooding using the raw SRTM covered only about 28%, indicating substantial underprediction of the affected area when error was not accounted for. This study can be an applicable approach within such environments worldwide.

Flooded with Error: Handling Uncertainty in SRTM for the Assessment of Sea Level Rise in the Mississippi River Delta

Digital elevation data are essential to estimate coastal vulnerability to flooding due to sea-level rise. Shuttle Radar Topography Mission (SRTM) 1 arc-second global is considered the best free global digital elevation data set available. Inundation estimates from SRTM, however, are subject to uncertainty due to inaccuracies in the elevation data. Small systematic errors in low, flat areas can generate large errors in inundation models, and SRTM is subject to positive bias in the presence of vegetation canopy, such as along channels and within marshes. In this study, we conducted an error assessment and developed a statistical error model for SRTM to improve the quality of elevation data in the Mississippi River Delta (MRD) region. Vegetation cover, SRTM elevation, and slope were found to be closely associated with SRTM error for a random sample of 10,000 small sites across the MRD region, with an ordinary least squares regression model using these variables explaining over 80 percent of the variation in error. Residuals from this model were spatially autocorrelated, and a variogram model was readily fit to them. We conclude by speculating on the utility of application of this model, developed for the MRD region, to similar near-coastal riverine regions around the world.

Soil quality indices as affected by long‐term burning, irrigation, tillage, and fertility management

AbstractUnderstanding the impacts of long‐term agricultural practices on soil quality (SQ) is key for sustaining agroecosystem productivity. This study investigated conventional and no‐tillage (NT), residue burning and no burning, residue level (high and low), and irrigation (irrigated and dryland) effects on soil properties, SQ, and crop yields following 16 yr of a wheat (Triticum aestivum L.)–soybean [Glycine max (L.) Merr.] double‐crop system via the Soil Management Assessment Framework (SMAF). A field experiment was conducted in the Lower Mississippi River Delta region on a silt‐loam soil. Bulk density, soil organic C (SOC), total N (TN), pH, electrical conductivity (EC), and soil P and K from the 0‐ to 10‐cm soil depth were used as SQ indicators investigated individually and as an overall soil quality index (SQI). Following 16 yr, residue burning reduced SOC (1.1%) compared with no burning (1.24%). Irrigation resulted in greater soil TN than dryland management systems (p < 0.05). Reduced soil pH and extractable soil P and K occurred under NT, high residue, and irrigated treatments. Irrigation increased soybean yields, regardless of the tillage system. Burned, NT–high residue management increased wheat yields (3.45 Mg ha−1). Irrigation reduced SQ because of low EC and K scores. High residue reduced SQ compared with the low residue treatment within NT systems, owing to low pH scores. The SMAF indices identified the impacts of irrigation, NT, and optimal N fertilization on SQ. Monitoring of soil pH, P, and K may be needed to maintain SQ in long‐term wheat–soybean systems.

Spatial and temporal patterns of land loss in the Lower Mississippi River Delta from 1983 to 2016

The Mississippi Delta in coastal Louisiana has some of the highest rates of land loss in the world. This land-loss crisis might become a global problem because most major deltas are expected to be vulnerable to land loss during the remainder of the 21st century and beyond. Despite this predicament, we do not understand how land loss in a deltaic environment proceeds in time and space. Here, we evaluate the spatial and temporal trends of land loss in the Lower Mississippi River Delta (LMRD) region using spatial statistics and landscape metrics. We used nearly 4800 Landsat images to construct a series of three-year cloud-free composites from 1983 to 2016. From these data, we created a stability index (SI), which is a dimensionless measure of the number of land-to-water transitions that a land pixel makes before being considered lost. Our results indicate that on the LMRD, 75% of land loss is a single transition from land to water, while about 25% of land pixels have two or more transitions before being considered lost. Using a local indicator of spatial association, we show that pixels with similar SI tend to cluster together. Single transition clusters (low SI) form elongated shapes, they are densely packed, and they are predominantly, but not always, found on marsh edges. On the other hand, multi-transition clusters (high SI) form square-like shapes, they are more fragmented, and they are usually found in marsh interiors. Our analysis further shows that the land-loss area within the spatial patches with both high and low stability is strongly related to the density of land patches and their shape (R2 of 0.717 and 0.545 respectively). Our analysis suggests that land-loss pixels on the marsh edges undergo different temporal patterns of land loss compared to those in the marsh interior. We hypothesize that this arises because wave edge-erosion drives land loss on marsh edges, whereas subsidence-related flooding drives land loss in marsh interiors. The stability index provides a useful way to characterize the processes causing land loss.

Abstract D097: Association between high mammographic density and environmental chromium and arsenic exposure in a pilot study of women living in rural communities

Abstract Background Environmental contamination with heavy metals, such as metalloid arsenic (As), cadmium (Cd), and chromium (Cr), in soil in the Mississippi River Delta region has been documented by the US Geological Survey. Rural residents are more likely to be exposed throughout their life than those who live in urban cities because much of the vegetation grown in this area has a potentially higher content of these heavy metals. At the same time, this region also experiences higher breast cancer (BC) disparity when compared to the other parts of the country. Mammographic density (MD) is one of the strongest risk factors for nonfamilial BC and it is also related to long-term prospective increases in tumor incidence, independent of its masking effects on detection. High MD thus is directly related to breast carcinogenesis. Methods Urine samples and lifestyle factors were obtained from a subcohort of women recruited through a mobile mammography unit into the Arkansas Rural Community Health Study cohort. Mammography at enrollment is available on everyone in this subcohort. Urinary samples were analyzed for heavy metal exposure, including As, Cd, and Cr concentration using Fisher-Thermo inductively coupled plasma mass spectrometry (ICP-MS). All samples were analyzed in duplicates and concentrations were presented as microgram/gram creatinine. Mammographic density was assessed by staff radiologist based on the American College of Radiology (ACR) Breast Imaging Reporting and Data System (BI-RADS) and verified with the LIBRA software, developed by the University of Pennsylvania. MD was categorized as dichotomous high (C and D) and low (A and B). Multivariable logistic regression was used to calculate odds ratios (OR) and 95% confidence interval (CI). Results Among 189 subjects who have completed follow-up interviews and contributed blood and urine samples, wee analyzed urine samples for heavy metal concentration, adjusted for urinary creatinine value and specific gravity. The mean (standard deviation) concentration of Cr, As and Cd were 0.27 (0.04), 0.28 (0.38) and 0.13 (0.11) ppb, respectively. We evaluated the association between MD and three major heavy metals of interest. When comparing the highest tertile urine Cr to the lowest tertile, Cr is positively associated with high MD (OR = 5.50, 95%CI = 1.08, 27.98) after adjusting for age, BMI, race, education, hormonal use, age at menarche, age at last menstrual cycle, and family history of breast cancer. Urine As is also positively associated with high MD (OR = 2.39, 95%CI = 0.98, 5.87, p = 0.06), adjusted for age and BMI. Cd was not significantly associated with MD with the current sample size. Conclusion Cr, As, and Cd are considered as Group 1 carcinogens according to the International Agency for Research on Cancer. This study suggests that there is a significantly increased odds of high MD even at very low levels of exposure to environmental Cr and As. Identifying sources of these contaminants would reduce the risk of breast cancer in rural communities. Citation Format: L. Joseph Su, Tung-Chin Chiang, Lora J Rogers, Gail A Runnells, Susan A Kadlubar, Zoey Crystal, Christopher Wardell, Sharp Malak. Association between high mammographic density and environmental chromium and arsenic exposure in a pilot study of women living in rural communities [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D097.

“It’s Not Your Everyday Classroom”

A school-based enterprise (SBE) is an entrepreneurial operation managed and operated by students in a school setting. School-based enterprises reinforce classroom instruction through practice-based learning and can enhance creativity, innovation, problem-solving, critical thinking, and other skills. In addition to creating a more engaging, enriching learning environment, SBE bridges the gap between classroom instruction and the world of work and can benefit students, schools, and communities. This paper utilized the systems view of school climate framework to assess differences in perceptions of school climate between students participating in SBE and students not participating in SBE at a high school in the Mississippi River Delta Region. The qualitative analysis of five focus groups with 36 students examined differences in relationships, values, and beliefs and findings indicated that SBE can produce more meaningful, enriching learning experiences than students not participating in SBE. This research adds to the sparse empirical analyses of SBE and suggests directions for future inquiry.

Long-term residue and water management practice effects on particulate organic matter in a loessial soil in eastern Arkansas, USA

Long-term sustainability of soils with a prolonged history of crop production can be better understood by characterizing soil aggregation, particularly the distribution of carbon (C) and nitrogen (N) among particulate organic matter (POM) fractions within various soil aggregate-size fractions. The objective of this field study was to evaluate the effects of residue level, residue burning, tillage, and irrigation on macro-aggregate (>250 μm), micro-aggregate (53–250 μm), coarse (>250 μm) and fine POM (53–250 μm), and silt-clay fractions and their associated C and N in the top 10 cm of a highly erodible loessial soil (Glossaquic Fraglossudalf) after 13 years of consistent management in a wheat-soybean, double-crop (WSDC) system in the Lower Mississippi River Delta region of eastern Arkansas. The total aggregated soil fraction was 11.2% greater (P = 0.02) in the no-tillage (NT)-irrigated compared to the average of the other three tillage-irrigation combinations, which did not differ. Averaged over irrigation, burn, and residue-level treatments, the C concentration in the sand-free macro-aggregate fraction was 8.8% less (P < 0.05) under conventional tillage (15.6 g kg−1) than under NT (17.1 g kg−1). Fine POM C and N concentrations within sand-free-adjusted aggregates were 1.9 times greater (P ≤ 0.04) in the burn-low (2.59 and 0.21 g kg−1, respectively) compared to the burn-high treatment (1.35 and 0.11 g kg−1, respectively), while that in the no-burn under either residue level, which did not differ, were intermediate (2.43 and 0.23 g kg−1, respectively). Results showed that alternative management practices, such as NT and non-burning, can contribute to improved soil health and long-term sustainability and the mitigation of climate-change-related greenhouse gas concentrations in the atmosphere by reducing SOM oxidation, microbial respiration, and carbon dioxide emissions.

Relationships between soil properties and the occurrence of the most agronomically important weed species in the field margins of eastern Arkansas – implications for weed management in field margins

SummaryThe work presented in this study adds to previous research on the occurrence, distribution and growth habitat of common weeds along roadsides in the Mississippi River Delta region of eastern Arkansas, USA. It addresses the relationships between soil properties (i.e. defined as a group of individual soil characteristics or attributes such as P, K, Ca, Mn and other nutrients) and the most agronomically important weeds of which the occurrence at field margins accounted for ≥ 10% of the total sampling sites. These were three broad‐leaved weeds (Amaranthus palmeri, Ipomoea spp. and Sida spinosa) and four grass weeds (Echinochloa crus‐galli, Urochloa platyphylla, Sorghum halepense and Digitaria sanguinalis). Soil properties were used as explanatory variables for weed occurrence (presence–absence) using partition analysis; the occurrences of the weeds under examination were partitioned by the application of a decision‐tree method. The most important soil properties explaining the occurrence of these weeds in field margins were extractable soil nutrients, specifically sodium, boron and copper content, as well as soil physical attributes, in order of importance, bulk density, silt content, field moisture capacity, hydraulic conductivity, wilting point, available water and clay content. Soil chemical properties proved least reliable in explaining weed occurrence at roadside field margins. Knowledge of the relationships between soil properties and weed occurrence can add to our understanding of weed biology and hence enhance the efficiency of weed management strategies. For example, the occurrence of A. palmeri, in soils with high bulk density (&gt;1.4 g cm−3) and low organic matter content (&lt;2.7%) and thus lower residual herbicide activity, will require integrated weed management of this species in field margins. This is of interest given the occurrence of herbicide resistance in roadside arable weeds, mainly A. palmeri, E. crus‐galli and S. halepense, in the Mississippi River Delta region of eastern Arkansas and other parts of the world.

Nitrogen Source Effects on Methane Emissions From Drill-Seeded, Delayed-Flood Rice Production

Rice (Oryza sativa L.) cultivation is unique compared with the production of most other upland row crops in that rice is typically produced under flooded-soil conditions, which can result in net emissions of methane (CH4). Nutrient applications for optimum production, specifically nitrogen (N), which can be organic or inorganic sources, are carefully managed in rice production. However, how nutrient-source effects on CH4 emissions from rice production may interact with other known factors affecting CH4 emissions, such as previous crop/crop rotation and soil texture, are poorly understood, particularly in the midsouthern United States where rice production is concentrated. The objective of this study was to evaluate CH4 fluxes and season-long emissions as affected by fertilizer-N source (i.e., ammonium sulfate [AS], pelletized poultry litter [PPL] + urea, and urea only) and previous crop in rotation (i.e., soybean [Glycine max L.] or rice) from rice production on a clayey Epiaquert and a silt-loam Albaqualf in the Lower Mississippi River Delta region of eastern Arkansas. Methane fluxes, measured using 30-cm-diameter, enclosed-headspace chambers, peaked near heading for all treatments, with PPL + urea resulting in greater (P 0.05) by previous crop on the silt-loam soil. Results clearly indicate that the choice of fertilizer-N source for certain soil textures, specifically AS application to a silt-loam soil, has the potential to mitigate CH4 emissions and reduce the large, negatively perceived, C footprint associated with rice production.

Diurnal Methane Fluxes as Affected by Cultivar from Direct-Seeded, Delayed-Flood Rice Production

Methane (CH4) emissions are known to differ between rice (Oryza sativa L.) cultivars, where CH4 emissions from pure-line cultivars are often greater than from hybrids. Numerous field studies have shown that CH4 emissions follow a diurnal pattern, typically reaching their maximum during afternoon hours. However, it is unknown whether cultivar affects CH4 fluxes/emissions at various measurement times of day or how those cultivar effects may differ spatially across soil textures and temporally throughout the rice growing season. The objective of this field study was to evaluate the effects of time of day (300, 800, 1200, 1800, and 2300 hours) and cultivar (one hybrid and one pure-line) on CH4 fluxes before and after heading from a silt-loam and clay soil in a direct-seeded, delayed-flood rice production system. Enclosed headspace chambers, 30 cm in diameter, were used for CH4 gas sampling on 22 July and 19 August at a silt-loam site and on 29 July and 26 August, 2014 at a clay-soil site in the Lower Mississippi River delta region of eastern Arkansas. Methane fluxes measured pre- and post-heading ranged from 0.7 to 2.2 mg CH4-C m-2· hr-1 from the clay soil and from 2 to 7 mg CH4-C m-2·hr-1 from the silt-loam soil. Hourly CH4 fluxes and estimated daily emissions differed among measurement times of day (P 4 flux or daily emissions for a given day differs by soil texture and rice growth stage, but conducting CH4 flux measurements around late morning to mid-day appear to be optimum to best capture the mean CH4 emissions for the day.

Eating Good and Moving Like We Should: A Consideration for Registered Dietitians in Schools

Background: While teachers and school nurses may not be able to provide nutrition education to students because of their other duties, registered dietitians have the necessary training in counseling, nutrition education, nutrition therapy, and food service management to be effective at childhood obesity prevention. Objectives: The purpose of eating good and moving like we should (EGMLWS), a school-based intervention, was to create a successful program to prevent and reduce childhood obesity in the Mississippi Delta by providing nutrition education by a registered dietitian. Methods: The subjects were 1,891 third (school year 2012 - 2013) and fourth graders (2013 - 2014) in 7 Mississippi schools in the north Mississippi River Delta region. The school-based nutrition and physical activity education program was designed to address overweight and obesity in the Mississippi Delta and north Mississippi regions by helping children make healthier nutrition and physical activity choices. The registered dietitian provided nutrition education and consulted to make school menus healthier and more appealing. Pre-and post-school year heights and weights were measured. Results: Paired t-tests showed significantly lowered mean BMI in 5 schools (P < 0.05); no change in 2 schools and no change over all schools, although all schools had individuals with decreased BMI. Conclusions: School-based nutrition interventions that feature a registered dietitian can make an impact. The EGMLWS program improved the nutrition knowledge and nutrition-related attitudes of north Mississippi Delta third and fourth graders and significantly improved BMI in 5 of 7 schools.

Assessment of Factors Contributing to Health Outcomes in the Eight States of the Mississippi Delta Region.

IntroductionThe objective of this observational study was to examine the key contributors to health outcomes and to better understand the health disparities between Delta and non-Delta counties in 8 states in the Mississippi River Delta Region. We hypothesized that a unique set of contributors to health outcomes in the Delta counties could explain the disparities between Delta and non-Delta counties.MethodsData were from the 2014 County Health Rankings for counties in 8 states (Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee). We used the Delta Regional Authority definition to identify the 252 Delta counties and 468 non-Delta counties or county equivalents. Information on health factors (eg, health behaviors, clinical care) and outcomes (eg, mortality) were derived from 38 measures from the 2014 County Health Rankings. The contributions of health factors to health outcomes in Delta and non-Delta counties were examined using path analysis.ResultsWe found similarities between Delta counties and non-Delta counties in the health factors (eg, tobacco use, diet and exercise) that significantly predicted the health outcomes of self-rated health and low birthweight. The most variation was seen in predictors of mortality; however, Delta counties shared 2 of the 3 significant predictors (ie, community safety and income) of mortality with non-Delta counties. On average across all measures, values in the Delta were 16% worse than in the non-Delta and 22% worse than in the rest of the United States.ConclusionThe health status of Delta counties is poorer than that of non-Delta counties because the health factors that contribute to health outcomes in the entire region are worse in the Delta counties, not because of a unique set of health predictors.

Engaging Underrepresented Minorities in Research: Our Vision for a "Research-Friendly Community".

This article introduces our "Research-Friendly Community" vision, placing research in the arena of social justice by giving citizens a voice and opportunity to actively determine research agendas in their community. The mission of Tri-County Rural Health Network, a minority-owned, community-based nonprofit serving 16 counties in Arkansas' Mississippi River Delta region, is to increase access to health-related services and opportunities to both participate in and shape research. Tri-County has built trust with the community through the use of Deliberative Democracy Forums, a model devised by the Kettering Foundation and through a community health worker program called Community Connectors. Over time, a partnership was formed with investigators at the University of Arkansas for Medical Sciences (UAMS). Tri-County serves as a boundary spanner to link community members, other community organizations, local politicians, policy maker, and researchers. We describe our experience for other nonprofits or universities who might want to develop a similar program.

Daily soil surface CO2 flux during non-flooded periods in flood-irrigated rice rotations

Carbon dioxide (CO2) emitted from the soil, as a result of root and microorganism respiration, is a major process in the global carbon cycle. Since CO2 production is dependent on oxygen availability, prolonged saturated soil conditions in rice (Oryza sativa) can decrease the quantity of soil carbon released in the form of CO2 over time. At present, a deficiency exists in the scientific literature on soil surface CO2 flux in well-established, flood-irrigated rice systems, which are flooded for approximately 3 months a year during the rice growth period. Plenty of studies have examined soil surface CO2 flux in dryland cropping systems and methane emissions in paddy-grown rice, but flood-irrigated rice does not easily fall into either of these categories due to the cyclic nature of seasonal flooding. Therefore, this is the first study to examine daily soil surface CO2 flux during non-flooded periods in well-established, flood-irrigated rice rotations. For a comprehensive analysis, soil surface CO2 flux was measured for 2 years on 10 different rice-based rotations, which had been managed using conventional tillage or no-tillage for 10 and 11 years. Rotations included continuous rice and various combinations of rice rotated with soybean (Glycine max), corn (Zea mays), and/or winter wheat (Triticum aestivum) and were located on a silt-loam soil in the Mississippi River Delta region of Arkansas in the USA. Results showed that 7 of the 16 measurement dates differed in daily soil surface CO2 flux among tillage and/or crop rotations. However, these differences were determined to be from crop maturity, in relation to early- or late-season planting, instead of patterns of long-term flood irrigation. Years that rice was grown reduced the cumulative CO2 emissions, but substantial differences over time were minimized in rotations with soybean or corn. Findings from this experiment are valuable in the scientific understanding of carbon gas cycling in rice-based cropping systems because the aerobic periods between flooding were evaluated, which is the time period often ignored when examining carbon gas emissions in rice. Overall, this study provides evidence that the commonly used rice-based cropping systems reach a somewhat equilibrium state in daily CO2 fluxes over time, regardless of the frequency in periodic soil saturation.

Residue and Water Management Effects on Aggregate Stability and Aggregate-Associated Carbon and Nitrogen in a Wheat-Soybean, Double-Crop System

Agricultural sustainability rests on the principle that the needs of the present population can be met while protecting the ability of future generations to meet their needs. Consequently, soil sustainability is paramount to assuring continued agricultural production. Soil structure and C storage can be influenced by producers' choices regarding residue and water management techniques. The objective of this study was to evaluate the long-term effects of alternative residue (i.e., tillage, residue burning, and fertility–residue level) and water management (irrigated and dryland) practices and soil depth after 10 yr of consistent management on total water-stable aggregate (TWSA; >0.25 mm) concentrations, size-separated aggregate concentrations, and corresponding C and N concentrations in a wheat (Triticum aestivum L.)–soybean [Glycine max (L.) Merr.] double-crop production system in the lower Mississippi River Delta region of eastern Arkansas. The TWSA concentration was unaffected by residue burning and not always negatively impacted by conventional tillage (CT). The TWSA concentrations were 19% greater (P < 0.05) under CT than no-tillage (NT) within the dryland low-fertility–residue treatment combination. High-fertility–residue resulted in 18% less (P < 0.05) TWSA than under low-fertility–residue within the irrigated-NT treatment combination. Under high-fertility–residue, TWSA concentrations were 13% less (P < 0.05) in the 5- to 10-cm depth under irrigation and were 10% less (P < 0.05) in the top 5 cm under dryland management compared to the low-fertility–residue treatment. The smallest two size classes (0.25–0.5 and 0.5–1.0 mm) comprised over 80% of the TWSA. Water-stable aggregate concentrations in the largest two size classes (1–2 and >2 mm) were unaffected by all treatments imposed. Results of this study indicate that interactions between long-term residue and water management practices can significantly impact soil aggregate stability, and thus are useful for aiding the determination of long-term agricultural management practices that improve soil quality in the Lower Mississippi River Delta region.

Long-term Residue Management Effects on Soil Respiration in a Wheat-Soybean Double-Crop System

One of the most significant contributors to the greenhouse effect is carbon dioxide (CO2) gas in the atmosphere. Soil respiration, the combined production of CO2 from soil, as a result of root and microorganism respiration, is the largest flux of CO2 from the terrestrial ecosystem to the atmosphere. Considering land use can greatly impact soil C storage and cycling, agricultural management practices can also greatly affect soil respiration and CO2 emissions. Therefore, the effects of long-term residue management (i.e., residue burning and nonburning, and conventional [CT] and no-tillage [NT]) and residue level (i.e., high and low) on soil respiration during the soybean [Glycine max (L.) Merr.] growing season were examined over 2 consecutive years (i.e., 2011 and 2012) in a wheat (Triticum aestivum L.)–soybean, double-crop system in a silt-loam soil (Aquic Fraglossudalf) in the Mississippi River Delta region of eastern Arkansas after more than 9 years of consistent management. Soil respiration rates from individual plots ranged from 0.53 to 40.7 and from 0.17 to 13.1 μmol CO2·m−2·s−1 throughout the 2011 and 2012 soybean growing seasons, respectively, and differed (P < 0.05) among treatment combinations on two and five of nine and 11 measurement dates in 2011 and 2012, respectively. Regardless of residue level, soil respiration was generally greater (P < 0.05) from CT than NT. Estimated season-long CO2 emissions were 10.2% less (18.5 Mg CO2·ha−1) from residue burning than from nonburning (20.6 Mg CO2·ha−1; P = 0.032). Averaged over years and all other field treatments, estimated season-long CO2 emissions were 15.5% greater from CT (21.0 Mg CO2·ha−1) than from NT (18.1 Mg CO2·ha−1; P = 0.020). Understanding long-term management effects on soil C losses, such as soil respiration, from common and widespread agricultural systems, such as the wheat-soybean, double-crop system, in eastern Arkansas can help improve policies for soil and environmental sustainability throughout the lower Mississippi River Delta region.

Gaps in the primary care of rural and underserved populations: The impact of nurse practitioners in four Mississippi Delta states

The shortage and distribution of primary care providers (PCPs) has left a gap in the health care of society, particularly those residents within the Lower Mississippi River Delta region, where pockets of rural and underserved populations reside. Described in this study are the workforce distribution, characteristics, and likelihood of advanced practice nurses (APNs) to practice in these communities. Surveys were completed by 479 APNs in Arkansas, Louisiana, Mississippi, and Tennessee. Other sources included census data and the designation of Health Professional Shortage Areas as specified by Health Resources and Services Administration. Fifty-one percent of respondents indicated they practice in primary care; 24% practice in a designated Health Professional Shortage Areas; and 54% practice in a rural area. Family nurse practitioners (FNPs), in particular, were more likely to practice in rural and shortage areas. More APNs, especially nurse practitioners (NPs), are needed to address the PCP shortage. But more than just increased numbers of NPs is the need for redistribution of these providers. Efforts to expand the scope of practice and limit regulatory restrictions will enable NPs to practice more autonomously, which in turn will provide opportunities for better access and improved healthcare outcomes, especially in rural and underserved regions. Educational programs must include competencies and skill sets focused on meeting the needs of these populations.