Lower Mississippi Delta Region Research Articles

Evaluation of single and mixed cover crops species in a sandy loam soil under corn production

AbstractInformed selection of cover crop species is critical for optimizing their benefits by considering the costs of adoption and potential initial negative impact on yields against the proven benefits for sustainable production. The Lower Mississippi Delta region is lagging in cover crop adoption, partly due to a paucity of this information from the area, despite being one of the major row crop‐producing regions in the United States. Common cover crop species in the region, cereal rye (CR) (Secale cereale), hairy vetch (HV) (Vicia villosa), and crimson clover (CC) (Trifolium incarnatum), and their possible two‐ and three‐combination mixes were evaluated for their impact on biomass production, enzyme activities, nutrient cycling, and corn (Zea mays) yields. HV + CC + CR and HV + CR produced the highest biomass and lowest yields compared to all treatments. HV and CC produced the least biomass but comparable yields to no cover crop. HV + CC + CR, HV + CR, CR, CC, and HV treatments had comparable total nitrogen, phosphorus, and soil organic carbon levels in the surface 0‐ to 5‐cm depth. Generally, CC alone and the HV + CR mix consistently displayed significantly higher phosphatase, N‐acetylglucosaminidase, β‐glucosidase, and cellobiohydrolase activities compared to all other treatments, while CR had the lowest. The single species of CC or HV may be the best option in the short term for initial cover crop implementation, rotating with CR a few years down the line for optimum long‐term benefits under corn production in this region.

Effect of irrigation regimes and planting patterns on maize production in humid climates

AbstractTwin‐row planting in maize (Zea mays L.) has potential for reducing plant‐crowding stress for optimizing grain yield and resource use. A study was conducted in 2020 and 2021 on a Dundee silt loam in the Lower Mississippi Delta (LMD) region of the United States to evaluate maize grain yield and irrigation water use efficiency (IWUE) in single‐row (SR) and twin‐row (TR) planting patterns with same seed rate under four irrigation regimes: rainfed (RF), all‐furrow irrigation (FI), alternate‐furrow irrigation (AFI), and every third‐furrow irrigation (TFI). The TR enhanced grain yield by 9.2% in 2020 and 10.9% in 2021 over the SR system. The average final plant density at the reproductive phase was highest under AFI (73,900 ha−1) and lowest under RF (70,480 ha−1). Across all irrigation regimes, the leaf area index was significantly higher in the TR system. Average grain yields under SR were 10.01, 10.44, 9.48 and 9.10 Mg ha−1, respectively, in FI, AFI, TFI and RF; average grain yields under TR were 11.58, 11.32, 10.13 and 9.91 Mg ha−1. The AFI and FI recorded similar grain yields. The IWUE was highest in TR planting (0.028 kg m−3), followed by SR planting (0.024 kg m−3) under AFI. The IWUE of TFI in TR planting was 0.020 kg m−3 and in SR was 0.011 kg m−3. Economic analysis revealed that the TR‐FI and TR‐AFI had average profits of 446 and 432 US$ ha−1, respectively. The study suggests that maize producers in the LMD can save a significant amount of irrigation water without compromising grain yields by adapting the AFI‐TR system.

Climate Change Effects on Irrigated Corn Growth in the Lower Mississippi Delta

Abstract In this study, the possible climate change impacts on irrigated corn production in the lower Mississippi delta (LMD) region were analyzed. The observed daily maximum and minimum air temperature, wind speed, relative humidity (RH), and precipitation from 1960 to 2018 were used in the analysis. The length of the growing season, evapotranspiration (ET), and crop yield estimates from the precalibrated Root Zone Water Quality Model (RZWQM) were also used. Trend analyses were performed on growing-season averages for temperature, RH, and wind speed; growing-season totals for precipitation and ET; daily values of minimum and maximum temperature; and averages of RH and wind speed at critical corn growth stages. The last day of spring freezing (LDSF) and days with an average daily air temperature Ta of more than 35°C during corn silking were also included in the analysis. The trend analysis was performed using the modified Mann–Kendall test, Pettitt test, and Sen’s slope at a significance level of p ≤ 0.05. The results from our study pointed out increases in minimum Ta, increases in the number of days with Ta exceeding 35°C during the corn silking stage, increases in RH and decreases in ET, advancement of the LDSF by 2 weeks, and 8% reductions in corn yield that could be attributed to changes in climate. If the observed trends in climate (climate variability and change) and yield reductions continue in the region, it could be challenging to grow the corn crop in the LMD profitably. Significance Statement In recent years, growing corn and soybeans instead of cotton has been gaining popularity in the lower Mississippi delta (LMD) region. Our study is aimed to understand how climate change in the recent past (1960–2018) has affected irrigated corn production in LMD. This will help us to better understand the expected consequences of the future climate. We used observations of daily weather data from 1960 to 2018 and corn yield, water balance, and crop yield results from a computer model designed to simulate corn production. Tools were used to analyze trends and patterns in the data and results. Our analysis pointed out significant changes in weather, water balance, and yield decline for irrigated corn in the LMD.

Eddy covariance quantification of corn water use and yield responses to irrigations on farm‐scale fields

AbstractFurrow irrigations dominate row‐crop irrigation scenarios in many regions worldwide. In this study, corn (Zea mays L.) yield and evapotranspiration (ET) in an all‐furrow irrigation (FI) were compared against irrigations applied through alternate furrows irrigation (SFI, skip‐furrow irrigation) and rainfed (RF) systems on farm‐scale fields in 2017 and 2019 {corn phases of a soybean [Glycine max (L.) Merr.]–corn rotation} in clay soil in the Lower Mississippi Delta region, United States. Evapotranspiration was monitored using the eddy covariance (EC) method. The average corn yield in the SFI was significantly (12.1 Mg ha−1) higher (4.9%) than in the FI (11.7 Mg ha−1). Corn yield in RF (10.2 Mg ha−1) was significantly lower (10.7%) than in the FI. However, the leaf area index (LAI) in SFI was lower than in FI. Seasonal average ET was 556, 573, and 540 mm in FI, SFI, and RF, respectively. The average water use efficiencies (WUEs) were 0.021, 0.021, and 0.019 Mg ha−1 mm−1, respectively (10.5 % lower in RF than FI and SFI). This investigation revealed that adapting the SFI irrigation regime in the corn cropping system could produce grain yields equal to or higher than corn grown under the conventional FI, saving ∼40% of irrigation water. The farm‐scale studies conducted in this investigation gave better confidence to recommend SFI to replace conventional FI systems in the region for water conservation in corn cropping systems. Further investigations may be needed to evaluate the viability of SFI in other contrasting soils and climates and recommend the system for adoption by the farming community.

Investigating soybean (Glycine max L.) responses to irrigation on a large-scale farm in the humid climate of the Mississippi Delta region

The shallow Lower Mississippi River Valley Alluvial Aquifer, which supports irrigated agriculture in the Lower Mississippi Delta (LMD) region, is fast depleting from unsustainable water extractions for irrigations. The survival of irrigated agriculture in the region today hinges on enhancing the irrigation use efficiencies of the water pumped out. Furrow irrigation practices (surface or flood irrigation) dominate the LMD region's irrigated agriculture scenario. We investigated soybean productivity in response to irrigations applied through every furrow (FI), applied through alternate furrow (AFI), and rainfed (RF, no irrigation). Approximately half the volume of water applied in FI was applied in the AFI. The experiments were conducted in 2016, 2018, and 2020, which constituted the soybean phases of a corn-soybean rotation trial conducted on a clay soil in farm-scale plots (15 ha). The plots were equipped with eddy covariance systems for quantifying crop water use (ET, evapotranspiration). There was no appreciable difference in soybean grain yield between FI and AFI, but RF yielded significantly lower than FI and AFI. Leaf area index was also significantly lower in RF compared to FI and AFI. Across the three years, the average reduction in soybean yield was only 2% in AFI, while it was 24% in RF compared to FI. Average grain yields were 4507, 4413, and 3422 kg ha−1; seasonal ET were 549, 562, and 527 mm; and water use efficiencies (WUE) were 8, 8, and 7 kg ha−1 mm−1 in FI, AFI, and RF, respectively. This large farm-scale study demonstrated that grain yields from irrigating soybean through alternate furrows were comparable to irrigating through every furrow, thus saving about half the water pumped out of the aquifer. This unique study was conducted in farm-scale fields; as such, the results obtained directly apply to a farm environment, so they are ready for recommendation to soybean farmers for adoption without further field trials.

Three datasets for nutrition environment measures of food outlets located in the Lower Mississippi Delta region of the United States.

This data note provides details of a research database containing 266 food outlets located in five rural towns in the Lower Mississippi Delta region of Mississippi, whose nutrition environments were measured from 2016 to 2018. The food outlet types include grocery stores, convenience stores, full-service restaurants, and fast food restaurants. The purpose of this publication is to describe the three datasets for external researchers who may be interested in making use of them. The datasets are available from the USDA National Agricultural Library's Ag Data Commons under a CC0 1.0 Universal License: https://doi.org/10.15482/USDA.ADC/1503704.

Sea-level rise enhances carbon accumulation in United States tidal wetlands

Sea-level rise enhances carbon accumulation in United States tidal wetlands

Vulnerabilities of irrigated and rainfed corn to climate change in a humid climate in the Lower Mississippi Delta

The use of fossil fuels for energy needs increases atmospheric greenhouse gas (GHG) concentrations to levels that can significantly exacerbate the climate on earth. Assessing the vulnerability of regional crop production systems to such an altered climate in the future is essential for implementing appropriate adaptation and mitigation strategies for sustainable agriculture. We investigated the possible impacts of climate change (CC) projected by multiple global climate models (GCMs) on rainfed and irrigated corn (Zea mays L., a C4 plant) in the Lower Mississippi Delta region (LMD), USA. The CSM-CROPGRO-Maize v4.6 module in the RZWQM2 model (hereafter referred to as the “corn model”) was previously calibrated and validated for modeling corn at Stoneville, Mississippi, a representative location in the LMD was used. The CC scenarios considered in this study were ensembles of climate projections of multiple GCMs (97 ensemble members) that participated in the Climate Model Inter-comparison and Improvement Program 5. These CC scenarios were bias-corrected and spatially downscaled (BCSD) at the location for the years 2050 and 2080. Four representative GHG concentration pathways (RCP) 2.6, 4.5, 6.0, and 8.5 drove these CC scenarios. Under both irrigated and rainfed conditions, corn yield responses to enhanced CO2 were weak; thus, yield declined significantly in response to the enhanced air temperatures under all the RCP scenarios in both 2050 and 2080. The yield declines across RCPs ranged between 10 and 62% under irrigated conditions, and between 9 and 60% under rainfed conditions, mainly due to increased frequency of extreme temperatures and reduced crop durations. Water use efficiency declined between 22 and 150% under irrigated, and 8 and 54% under rainfed management. As an adaptation measure, planting corn up to 9 weeks earlier in the season, in general, failed to boost yields from increased crop duration and reduction in upper extreme air temperatures, as incidences of lower extreme temperatures also increased alarmingly. Development of cultivars that are more heat tolerant and produce higher yields under extreme temperatures would be required to combat corn yield decline in the region from climate change.

Three datasets for nutrition environment measures of food outlets located in the Lower Mississippi Delta region of the United States

This data note provides details of a research database containing 266 food outlets located in five rural towns in the Lower Mississippi Delta region of Mississippi, whose nutrition environments were measured from 2016 to 2018. The food outlet types include grocery stores, convenience stores, full-service restaurants, and fast food restaurants. The purpose of this publication is to describe the three datasets for external researchers who may be interested in making use of them. The datasets are available from the USDA National Agricultural Library’s Ag Data Commons under a CC0 1.0 Universal License: https://doi.org/10.15482/USDA.ADC/1503704.

Breast cancer staging by subtype in the Lower Mississippi Delta region States

IntroductionTo evaluate disparities in breast cancer stage by subtype (categorizations of breast cancer based upon molecular characteristics) in the Delta Regional Authority (Delta), an impoverished region across eight Lower Mississippi Delta Region (LMDR) states with a high proportion of Black residents and high breast cancer mortality rates. MethodsWe used population-based cancer registry data from seven of the eight LMDR states to explore breast cancer staging (early and late) differences by subtype between the Delta and non-Delta in the LMDR and between White and Black women within the Delta. Age-adjusted incidence rates and rate ratios were calculated to examine regional and racial differences. Multilevel negative binomial regression models were constructed to evaluate how individual-level and area-level factors affect rates of early- and late-stage breast cancers by subtype. ResultsFor all subtypes combined, there were no Delta/non-Delta differences in early and late stage breast cancers. Delta women had lower rates of hormone-receptor (HR+)/human epidermal growth factor 2 (HER2-) and higher rates of HR-/HER2- (the most aggressive subtype) early and late stage cancers, respectively, but these elevated rates were attenuated in multilevel models. Within the Delta, Black women had higher rates of late-stage breast cancer than White women for most subtypes; elevated late-stage rates of all subtypes combined remained in Black women in multilevel analysis (RR = 1.10; 95% CI = 1.04–1.15). ConclusionsBlack women in the Delta had higher rates of late-stage cancers across subtypes. Culturally competent interventions targeting risk-appropriate screening modalities should be scaled up in the Delta to improve early detection.

Disparities in breast cancer subtypes among women in the lower Mississippi Delta Region states.

To describe and elucidate rates in breast cancer incidence by subtype in the federally designated Mississippi Delta Region, an impoverished region across eight Southern/Midwest states with a high proportion of Black residents and notable breast cancer mortality disparities. Cancer registry data from seven LMDR states (Missouri was not included because of permission issues) were used to explore breast cancer incidence differences by subtype between the LMDR's Delta and non-Delta Regions and between White and Blackwomen within the Delta Region (2012-2014). Overall and subtype-specific age-adjusted incidence rates and rate ratios were calculated. Multilevel negative binomial regression models were used to evaluate how individual-level and area-level factors, like race/ethnicity and poverty level, respectively, affect rates of breast cancers by subtype. Women in the Delta Region had higher rates of triple-negative breast cancer, the most aggressive subtype, than women in the non-Delta (17.0 vs. 14.4 per 100,000), but the elevated rate was attenuated to non-statistical significance in multivariable analysis. Urban Delta women also had higher rates of triple-negative breast cancer than non-Delta urban women, which remained in multivariable analysis. In the Delta Region, Black women had higher overall breast cancer rates than their White counterparts, which remained in multivariable analysis. Higher rates of triple-negative breast cancer in the Delta Region may help explain the Region's mortality disparity. Further, an important area of future research is to determine what unaccounted for individual-level or social area-level factors contribute to the elevated breast cancer incidence rate among Black women in the Delta Region.

Spatial Accessibility to Mammography Services in the Lower Mississippi Delta Region States.

To characterize spatial access to mammography services across 8 Lower Mississippi Delta Region (LMDR) states. These states include the Delta Region, a federally designated, largely rural, and impoverished region with a high proportion of black residents and low mammography utilization rates. Using the enhanced 2-step floating catchment area method, we calculated spatial accessibility scores for mammography services across LMDR census tracts. We compared accessibility scores between the Delta and non-Delta Regions of the LMDR. We also performed hotspot analysis and constructed spatial lag models to detect clusters of low spatial access and to identify sociodemographic factors associated with access, respectively. We obtained mammography facility locations data from the Food and Drug Administration and sociodemographic variables from the American Community Survey and the US Department of Agriculture. Overall, there were no differences in spatial accessibility scores between the Delta and non-Delta Regions, though there was some state-to-state variation. Clusters of low spatial access were found in parts of the Arkansas, Mississippi, and Tennessee Delta. Spatial lag models found that poverty was associated with greater spatial access to mammography. The lack of identified differences in spatial access to mammography in the Delta and non-Delta Regions suggests that psychosocial or financial barriers play a larger role in lower mammography utilization rates. Identifying clusters of low spatial access to mammography services can help inform resource allocation. Further, our study underscores the value of using coverage-based methods rather than travel time or container measures to evaluate spatial access to care.

Resolving the contributing factors to Mississippi Delta subsidence: Past and Present

AbstractTo date, quantification of individual components that contribute to shallow and deep‐seated subsidence in passive margin deltas worldwide has proven problematic. A new, regional gridded chronostratigraphic dataset for the Lower Mississippi Delta region, derived from 80,928 well reports across the northern Gulf of Mexico (GOM), has bridged the disparity between geodetic mean rates measuring total land surface subsidence across annual‐to‐decadal timescales and the deep‐seated stratigraphic subsidence rates that record isostatic response over timescales of >104 years. Through a quantitative assessment of gridded chronostratigraphic surfaces, sections, and subsidence rates extending from the Middle Pleistocene (0.58 Ma) to the Late Pliocene (3.85 Ma), we identify both temporal and spatial variability in deep‐seated subsidence across the northern GOM. Targeted deep‐seated subsidence data extracted across prior GOM Holocene sea‐level sample locations have revealed more than an order of magnitude greater rates of isostatic compensation in the Mississippi depocentre versus similar GOM sea‐level control sites in Florida and Alabama, casting doubt on efforts towards a representative Holocene sea‐level curve. Spatial variability in subsidence was also assessed locally in both the strike and dip directions to assess the contributions of growth faults. Fault throw displacement magnitude was discovered to decrease with depth, accounting for less than half of the total deep‐seated subsidence record of the Middle Pleistocene. Temporal subsidence complexities were also revealed including a direct, inverse logarithmic relationship between subsidence rate and time indicating variable subsidence component controls across different timescales. Despite the spatial and temporal complexities, this dataset serves as the first regional baseline for deep‐seated subsidence rates across the northern GOM.

Abstract C87: Spatial accessibility to mammography services in the Lower Mississippi Delta states

Abstract Introduction: The Delta Regional Authority (DRA) is a federally designated region that includes 252 counties across 8 Lower Mississippi Delta Region states (Alabama, Arkansas, Illinois, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee) and contains nearly 10 million residents. The DRA has a high proportion of African American residents, high levels of poverty, and is largely rural. As such, the region has limited access to health care services, which likely leads to underutilization of mammography services and the higher breast cancer mortality of the region compared to the non-DRA counties within these eight states. Limited spatial access to mammography has been shown, in some studies, to be associated with more advanced stage at diagnosis, which may contribute to greater mortality risk. Objective: To assess spatial accessibility to mammography facilities in the DRA and non-DRA counties within the Lower Mississippi Delta Region states. Methods: We obtained the locations of all mammography facilities within the Lower Mississippi Delta Region states from the Food and Drug Administration. We used data from the US Census Bureau's American Community Survey to estimate the number women of recommended screening age (i.e., 45-74, the available data most congruent with recommendations) in each census tract in these states. We implemented the enhanced two-step floating catchment area method to calculate census-tract level spatial accessibility scores (SAS). This method considers both supply of and demand for mammography services within a specified catchment area, such as 60-minute travel time, with weights applied to account for distance decay (i.e., people are less likely to access services that are further away). We calculated Global Moran's I and Local Moran's I to determine if these SAS were spatially clustered and where they were clustered, respectively, within the DRA. We also calculated univariate statistics to compare SAS in the DRA and non-DRA designations of the Lower Mississippi Delta Region states and by rural-urban status using the United States Department of Agriculture's Rural-Urban Commuting Area codes. Because SAS were skewed (i.e., not normally distributed), the nonparametric, Wilcoxon Sum Rank Test was used to compared scores. Results: Global Moran's I indicated limited, but statistically significant, spatial autocorrelation within the DRA (Moran's I=0.17, Z-score=47.67, p<0.001). Local Moran's I showed clusters of high SAS in the DRA designation of Illinois and the westernmost part of the Kentucky DRA designation. Low spatial access was clustered in much of the Arkansas DRA designation and parts of Tennessee and Mississippi (i.e., a cluster of low spatial access around Memphis). Smaller clusters of low spatial access were seen in southern Louisiana as well. There was no statistically significant difference in SAS by DRA designation, with median scores of 0.000175 and 0.000161 in the DRA and non-DRA designations, respectively (p=0.69). There were no differences in SAS scores stratified by state except for Illinois where median SAS were higher in the DRA compared to the non-DRA part of the state (0.000243 and 0.000156, respectively, p<0.001). There were no differences in SAS between the rural and urban DRA and between the urban DRA and non-DRA. However, median spatial access was slightly higher in the rural DRA vs. the non-DRA (0.000171 vs. 0.000170, p=0.03). Discussion: Despite disparities in mammography utilization and breast cancer mortality in the DRA, we found no differences in spatial access to mammography compared to the non-DRA designation of the 8 Lower Mississippi Delta states. However, we identified clusters of low spatial access to mammography in specific parts of the DRA. These areas may be appropriate areas to target with mobile mammography initiatives or construction of free-standing mammography facilities. Citation Format: Whitney E. Zahnd, Sara McLafferty, Recinda Sherman, Susan Farner, Hillary Klonoff-Cohen, Karin Rosenblatt. Spatial accessibility to mammography services in the Lower Mississippi Delta states [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr C87.

Application of an energy balance method for estimating evapotranspiration in cropping systems

Accurate quantification of evapotranspiration (ET, consumptive water use) from planting through harvest is critical for managing limited water resources for crop irrigation. Our objective was to develop and apply a land-crop surface residual energy balance (EB) method for quantifying ET and to estimate ET of corn (Zea mays L.) for the first time in the climate of the lower Mississippi Delta region. Actual ET (ETe) was estimated as the residual term of the energy balance equation from measurements of net solar irradiance (Rn) and computed sensible heat (H) and ground heat (Go) fluxes. The H flux was computed from measurements of the air and crop canopy temperature differential and modeling the aerodynamic resistance (ra) to heat and water transport in the turbulent atmospheric boundary layer above the canopy. The Go flux was estimated by measuring heat flux at 8 cm depth and accounting for heat storage in the soil layer above it. The developed EB procedure was tested using simultaneous measurements of EB data and lysimetric ET in a cotton (Gossypium hirsutum L.) field at Bushland, Texas, USA in 2008. The lysimeter measured ET compared well with the computed ETe under cotton (RMSE of daily ET = 1.2 mm, and seasonal ET within 1% error). Further, we quantified irrigated corn ET using EB in a silt loam soil at Stoneville, Mississippi, USA in 2016. The computed seasonal values of ETe were greater than shortgrass reference ET (ETo) by 27 mm and less than alfalfa reference crop ET (ETr) by 80 mm. The instrumentation used in the EB method can be moved, and the estimated ET was comparable with lysimeter measured ET. As such, this method provides a cost-effective, viable alternative for quantifying ET, which should be broadly tested in other locations and cropping systems.

Maternal weight in the postpartum: results from the Delta healthy sprouts trial

BackgroundExcessive postnatal weight retention may pose a threat to a woman’s health and future pregnancies. Women in the Lower Mississippi Delta (LMD) region of Mississippi suffer from among the highest rates of obesity in the U.S. and are more likely to gain an excessive amount of weight during pregnancy. The aim of this study was to determine if LMD women who received a lifestyle enhanced maternal, infant, and early childhood home visiting (MIECHV) curriculum had more favorable weight outcomes through 12-months postpartum compared to women who received a standard MIECHV curriculum.MethodsDelta Healthy Sprouts was a two-arm, randomized, controlled, comparative impact trial. Pregnant women at least 18 years of age, less than 19 weeks pregnant with a singleton pregnancy, and residing in the LMD region were recruited. On a monthly basis in the participant’s home, the control arm (PAT) received the Parents as Teachers curriculum while the experimental arm (PATE) received a lifestyle enhanced Parents as Teachers curriculum. Pre-pregnancy body weight via self-report and maternal body weight at baseline (gestational month 4) and at every subsequent monthly visit through 12 months postpartum was measured. Linear mixed models were used to test for significant treatment, time, and treatment by time effects on postnatal weight outcomes.ResultsMean postnatal weight losses were 0.8 and 1.1 kg at postnatal month (PM) 6 and PM 12, respectively, for PAT participants. Mean postnatal weight losses for PATE participants were 1.5 and 1.2 kg at PM 6 and PM 12, respectively. Mean weight retention, based on pre-pregnancy weight, were 5.2, 4.0, and 3.6 kg at PM 1, PM 6, and PM 12, respectively, for PAT participants. Mean weight retention for PATE participants were 6.3, 4.5, and 4.0 kg at PM 1, PM 6, and PM 12, respectively. Significant effects were not found for treatment, time, or treatment by time.ConclusionsAn enhanced MIECHV curriculum was not associated with more favorable postpartum weight outcomes when compared to a standard MIECHV curriculum in a cohort of LMD women during the 12 months following the birth of their infant. Trial registration: clinicaltrials.gov, NCT01746394. Registered 5 December 2012.

Vulnerabilities and Adapting Irrigated and Rainfed Cotton to Climate Change in the Lower Mississippi Delta Region

Anthropogenic activities continue to emit potential greenhouse gases (GHG) into the atmosphere leading to a warmer climate over the earth. Predicting the impacts of climate change (CC) on food and fiber production systems in the future is essential for devising adaptations to sustain production and environmental quality. We used the CSM-CROPGRO-cotton v4.6 module within the RZWQM2 model for predicting the possible impacts of CC on cotton (Gossypium hirsutum) production systems in the lower Mississippi Delta (MS Delta) region of the USA. The CC scenarios were based on an ensemble of climate projections of multiple GCMs (Global Climate Models/General Circulation Models) for climate change under the CMIP5 (Climate Model Inter-comparison and Improvement Program 5) program, that were bias-corrected and spatially downscaled (BCSD) at Stoneville location in the MS Delta for the years 2050 and 2080. Four Representative Concentration Pathways (RCP) drove these CC projections: 2.6, 4.5, 6.0, and 8.5 (these numbers refer to radiative forcing levels in the atmosphere of 2.6, 4.5, 6.0, and 8.5 W·m−2), representing the increasing levels of the greenhouse gas (GHG) emission scenarios for the future, as used in the Intergovernmental Panel on Climate Change-Fifth Assessment Report (IPCC-AR5). The cotton model within RZWQM2, calibrated and validated for simulating cotton production at Stoneville, was used for simulating production under these CC scenarios. Under irrigated conditions, cotton yields increased significantly under the CC scenarios driven by the low to moderate emission levels of RCP 2.6, 4.5, and 6.0 in years 2050 and 2080, but under the highest emission scenario of RCP 8.5, the cotton yield increased in 2050 but declined significantly in year 2080. Under rainfed conditions, the yield declined in both 2050 and 2080 under all four RCP scenarios; however, the yield still increased when enough rainfall was received to meet the water requirements of the crop (in about 25% of the cases). As an adaptation measure, planting cotton six weeks earlier than the normal (historical average) planting date, in general, was found to boost irrigated cotton yields and compensate for the lost yields in all the CC scenarios. This early planting strategy only partially compensated for the rainfed cotton yield losses under all the CC scenarios, however, supplemental irrigations up to 10 cm compensated for all the yield losses.

Climate-Optimized Planting Windows for Cotton in the Lower Mississippi Delta Region

Unique, variable summer climate of the lower Mississippi (MS) Delta region poses a critical challenge to cotton producers in deciding when to plant for optimized production. Traditional 2–4 year agronomic field trials conducted in this area fail to capture the effects of long-term climate variabilities in the location for developing reliable planting windows for producers. Our objective was to integrate a four-year planting-date field experiment conducted at Stoneville, MS during 2005–2008 with long-term climate data in an agricultural system model and develop optimum planting windows for cotton under both irrigated and rainfed conditions. Weather data collected at this location from 1960 to 2015 and the CSM-CROPGRO-Cotton v4.6 model within the Root Zone Water Quality Model (RZWQM2) were used. The cotton model was able to simulate both the variable planting date and variable water regimes reasonably well: relative errors of seed cotton yield, aboveground biomass, and leaf area index (LAI) were 14%, 12%, and 21% under rainfed conditions and 8%, 16%, and 15% under irrigated conditions, respectively. Planting windows under both rainfed and irrigated conditions extended from mid-March to mid-June: windows from mid-March to the last week of May under rainfed conditions, and from the last week of April to the end of May under irrigated conditions were better suited for optimum yield returns. Within these windows, rainfed cotton tends to lose yield from later plantings, but irrigated cotton benefits; however, irrigation requirements increase as the planting windows advance in time. Irrigated cotton produced about 1000 kg·ha−1 seed cotton more than rainfed cotton, with irrigation water requirements averaging 15 cm per season. Under rainfed conditions, there is a 5%, 14%, and 27% chance that the seed cotton production is below 1000, 1500, and 2000 kg·ha−1, respectively. Information developed in this paper can help MS farmers in decision support for cotton planting.

Maternal diet quality and nutrient intake in the gestational period: results from the delta healthy sprouts comparative impact trial.

BackgroundA woman’s diet while pregnant can play an important role in her reproductive health as well as the health of her unborn child. Diet quality and nutrient intake amongst pregnant women residing in the rural Lower Mississippi Delta (LMD) region of the United States is inadequate. The Delta Healthy Sprouts Project was designed to test the comparative impact of two home visiting programs on weight status, dietary intake, and health behaviors of women and their infants residing in the LMD region. This paper reports results pertaining to maternal diet quality and nutrient intake in the gestational period.MethodsThe experimental arm (PATE) received monthly home visits beginning in the second trimester using the Parents as Teachers curriculum enhanced with a nutrition and lifestyle behavior curriculum. The control arm (PAT) received monthly home visits using the Parents as Teachers curriculum only. Maternal diet was assessed via 24-h dietary recall at gestational months (GM) 4 (baseline), 6, and 8. Diet quality was computed using the Healthy Eating Index-2010 (HEI-2010).ResultsGestational period retention rates for PAT and PATE arms were 77 % (33/43) and 67 % (26/39), respectively. Significant effects were not found for time, treatment, or time by treatment for the HEI-2010 total or component scores, macro- or micronutrient intake or percentage of women meeting recommended nutrient intakes.ConclusionsPerhaps due to low participant enrollment and higher than expected rates of drop out and noncompliance, we were not able to demonstrate that the enhanced nutrition and lifestyle curriculum (PATE) intervention had a significant effect on diet quality or nutrient intake during pregnancy in this cohort of rural, Southern, primarily African American women.Trial registrationclinicaltrials.gov, NCT01746394. Registered 5 December 2012.

Psychosocial constructs were not mediators of intervention effects for dietary and physical activity outcomes in a church-based lifestyle intervention: Delta Body and Soul III.

Evaluating an intervention's theoretical basis can inform design modifications to produce more effective interventions. Hence the present study's purpose was to determine if effects from a multicomponent lifestyle intervention were mediated by changes in the psychosocial constructs decisional balance, self-efficacy and social support. Delta Body and Soul III, conducted from August 2011 to May 2012, was a 6-month, church-based, lifestyle intervention designed to improve diet quality and increase physical activity. Primary outcomes, diet quality and aerobic and strength/flexibility physical activity, as well as psychosocial constructs, were assessed via self-report, interviewer-administered surveys at baseline and post intervention. Mediation analyses were conducted using ordinary least squares (continuous outcomes) and maximum likelihood logistic (dichotomous outcomes) regression path analysis. Churches (five intervention and three control) were recruited from four counties in the Lower Mississippi Delta region of the USA. Rural, Southern, primarily African-American adults (n 321). Based upon results from the multiple mediation models, there was no evidence that treatment (intervention v. control) indirectly influenced changes in diet quality or physical activity through its effects on decisional balance, self-efficacy and social support. However, there was evidence for direct effects of social support for exercise on physical activity and of self-efficacy for sugar-sweetened beverages on diet quality. Results do not support the hypothesis that the psychosocial constructs decisional balance, self-efficacy and social support were the theoretical mechanisms by which the Delta Body and Soul III intervention influenced changes in diet quality and physical activity.