Central Iowa Research Articles

Assessment of drought tolerance of 49 switchgrass (Panicum virgatum) genotypes using physiological and morphological parameters.

BackgroundSwitchgrass (Panicum virgatum L.) is a warm-season C4 grass that is a target lignocellulosic biofuel species. In many regions, drought stress is one of the major limiting factors for switchgrass growth. The objective of this study was to evaluate the drought tolerance of 49 switchgrass genotypes. The relative drought stress tolerance was determined based on a set of parameters including plant height, leaf length, leaf width, leaf sheath length, leaf relative water content (RWC), electrolyte leakage (EL), photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), intercellular CO2 concentration (Ci), and water use efficiency (WUE).ResultsSRAP marker analysis determined that the selected 49 switchgrass genotypes represent a diverse genetic pool of switchgrass germplasm. Principal component analysis (PCA) and drought stress indexes (DSI) of each physiological parameter showed significant differences in the drought stress tolerance among the 49 genotypes. Heatmap and PCA data revealed that physiological parameters are more sensitive than morphological parameters in distinguishing the control and drought treatments. Metabolite profiling data found that under drought stress, the five best drought-tolerant genotypes tended to have higher levels of abscisic acid (ABA), spermine, trehalose, and fructose in comparison to the five most drought-sensitive genotypes.ConclusionBased on PCA ranking value, the genotypes TEM-SEC, TEM-LoDorm, BN-13645-64, Alamo, BN-10860-61, BN-12323-69, TEM-SLC, T-2086, T-2100, T-2101, Caddo, and Blackwell-1 had relatively higher ranking values, indicating that they are more tolerant to drought. In contrast, the genotypes Grif Nebraska 28, Grenville-2, Central Iowa Germplasm, Cave-in-Rock, Dacotah, and Nebraska 28 were found to be relatively sensitive to drought stress. By analyzing physiological response parameters and different metabolic profiles, the methods utilized in this study identified drought-tolerant and drought-sensitive switchgrass genotypes. These results provide a foundation for future research directed at understanding the molecular mechanisms underlying switchgrass tolerance to drought.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-015-0342-8) contains supplementary material, which is available to authorized users.

Watershed features and stream water quality: Gaining insight through path analysis in a Midwest urban landscape, U.S.A.

Urban stream condition is often degraded by human activities in the surrounding watershed. Given the complexity of urban areas, relationships among variables that cause stream degradation can be difficult to isolate. We examined factors affecting stream condition by evaluating social, terrestrial, stream hydrology and water quality variables from 20 urban stream watersheds in central Iowa, U.S.A. We used path analysis to examine and quantify social and ecological factors related to variation in stream conditions. Path models supported hypotheses that stream water quality was influenced by variables in each category. Specifically, one path model indicated that increased stream water conductivity was linked to high road density, which itself was associated with high human population density. A second path model revealed nitrogen concentration in stream water was positively related to watershed area covered by cropland, and that cropland increased as human population density declined. A third path model indicated phosphorus concentration in stream water declined as percent of watershed residents with college education increased, although the mechanism underlying this relationship was unclear and could have been an artifact of lower soil-derived nutrient input from watersheds dominated by paved surfaces. To improve environmental conditions in urban streams, land use planning strategies should include limiting or reducing road density near streams, installing treatment trains for surface water runoff associated with roads, and establishing vegetated buffer zones to reduce inputs of road salt and other pollutants. Additionally, education/outreach should be conducted with residents to increase understanding of how their own behaviors influence stream water quality.

Evaluation of Palmer Drought Severity Index in Central Iran

The Palmer Drought Severity Index (PDSI), which uses hydrometeorological variables to solve a simple water balance equation in the soil and considers the drought or wet conditions as dynamic phenomena, is used for the assessment of drought conditions in many parts of the world. The main goal of this study was to assess the PDSI based on its original assumptions, its regionalized status, using the outputs of already calibrated and validated SWAT model in central regions of Iran. The PDSI was assessed through five methods: 1) original Palmer Index without calibration in which the climate coefficients and the severity equation were derived for Kansas and central Iowa; 2) original Palmer Index in which the coefficients of severity equations were adjusted; 3) the Palmer Index with the calibration of equations in central areas of Iran; 4) the Palmer Index using the soil moisture and potential evapotranspiration from SWAT model; and 5) the Palmer Index using the soil moisture, potential evapotranspiration and runoff from SWAT model. The evaluation was conducted for 17 major basins covering the entire country with a monthly time step for the period 19902002. Then, using all five methods, the severity of the drought for 160 sub basins located in central Iran was calculated and evaluated. The results of this study indicated that method 4 provides more acceptable results. Also, the results of this research showed these methods clearly demonstrated (1992) as the wettest year and (2001) as the driest year. The approach used in this study is applicable to regional calibration of Palmer Index and the outputs of other hydrological models.

Origin of a washboard moraine of the Des Moines Lobe inferred from sediment properties

Geometric characteristics of the washboard moraines of the Des Moines Lobe (DML) of the Laurentide ice sheet agree with their proposed origin as crevasse-squeeze ridges, but study of their sediments is required to help further test this hypothesis. A 70-m-long, 3–5m high section through a moraine ridge in central Iowa revealed till with irregular, isolated lenses of silt, sand, and gravel that dip to varying extents upglacier. The texture and density of the till are like those of the basal till of the DML studied elsewhere in Iowa, and preconsolidation pressures determined from tests on till and silt of the ridge indicate that it developed subglacially rather than at the glacier margin. Preconsolidation pressures additionally demonstrate that pore-water pressures in the bed supported most of the glacier's weight, which would have contributed to till mobility. Fabrics based on the anisotropy of magnetic susceptibility of 3125 intact till specimens collected at 125 locations in the section indicate two end-member states of strain that varied with location in the ridge and caused sediment mounding: simple shear that was directed downglacier along shear planes inclined upglacier, together with pure shear where an overlying crevasse allowed the sediment bed to extend upward and laterally. Meltwater that likely flowed along the crevasse deposited sorted sediments that were incorporated in till, deformed, and rotated. This positive test of the crevasse-squeeze hypothesis indicates that the DML was in longitudinal extension near its margin, reinforcing previous arguments that the lobe surged. The predominance of fabrics caused by simple shear demonstrates that crevasse filling was underway before the surge had fully halted. This study should prompt caution in using similar transverse ridges, such as those geophysically imaged in some submarine glacier forefields, as indicators of retreat rates.

Origin of washboard moraines of the Des Moines Lobe: Spatial analyses with LiDAR data

The Des Moines Lobe (DML)—the largest lobe along the southern margin of the Laurentide ice sheet—deposited low-relief (1–5m) transverse moraine ridges, herein called washboard moraines, that are most prominent in central Iowa. Their origin as either subglacial or ice-marginal features bears on the dynamics of the lobe, geomorphic reconstructions of it, and interpretations of similar ridges elsewhere. Data from airborne laser swath mapping provide the first digital elevation models with sufficient spatial resolution to study in detail the geometric attributes of these topographically subtle features. Spectral analysis of profiles perpendicular to ridge crests indicates that most of them are spaced with statistically significant periodicities, with dominant wavelengths of 70–150m. Normalizing and stacking these profiles indicate that, on average, they display no systematic asymmetry. Locally, washboard moraines are intersected by discontinuous longitudinal ridge segments. Trends of the crests of moraines are scalloped, with cusps that point upglacier and are coincident with outwash trains, which were overridden by the lobe. Our interpretation of these data is that the moraines formed subglacially as crevasse-squeeze ridges. Overridden outwash trains likely supported low basal water pressures and resulted in anomalously slow basal slip, causing upglacier deflection of crevasses that extended to the bed. This crevasse-squeeze interpretation reinforces evidence that the DML surged to its maximum position. Bering Glacier, as a temperate, surge-type glacier that deposited crevasse-squeeze ridges similar to the washboard moraines of the DML, may be a good analog for the lobe.

An enhanced two-source evapotranspiration model for land (ETEML): Algorithm and evaluation

Satellite remote sensing provides a promising way to estimate regional evapotranspiration (ET) in a spatially distributed manner. In this study, an enhanced two-source evapotranspiration model for land (ETEML) is proposed based on a trapezoid framework of the vegetation fractional cover and land surface temperature (VFC/LST) space. In ETEML, a VFC/LST trapezoid space is theoretically defined for each pixel, and a pixel-wise mixed surface temperature decomposition method is proposed. ETEML is based on a two-source scheme, and the crop water stress index (CWSI) concept is applied to parameterize the soil evaporation and the vegetation transpiration separately. The proposed model was applied to the Soil Moisture–Atmosphere Coupling Experiment (SMACEX) site in central Iowa, USA. Evaluation with a remotely sensed dataset from Landsat was carried out to assess the performance of ETEML. Compared with the tower observations, the mean absolute deviation (MAD) and the root mean square deviation (RMSD) for the ETEML estimated latent heat flux (LE) are, respectively, 49W/m2 and 59W/m2, comparable to retrieval accuracies published in other studies. Comparison between ETEML and variations on a simpler trapezoid interpolation model (TIM1 and TIM2) indicates that ETEML reduces the subjectivity and uncertainties involved in TIM1 and TIM2. Overall, the results suggest that ETEML is promising and can expand the application of the trapezoid framework-based ET modeling approaches to heterogeneous surfaces.

Corn Stover Nutrient Removal Estimates for Central Iowa, USA

One of the most frequent producer-asked questions to those persons striving to secure sustainable corn (Zea mays L.) stover feedstock supplies for Iowa’s new bioenergy conversion or other bio-product facilities is “what quantity of nutrients will be removed if I harvest my stover?” Our objective is to summarize six years of field research from central Iowa, U.S.A. where more than 600, 1.5 m2 samples were collected by hand and divided into four plant fractions: vegetative material from the ear shank upward (top), vegetative material from approximately 10 cm above the soil surface to just below the ear (bottom), cobs, and grain. Another 400 stover samples, representing the vegetative material collected directly from a single-pass combine harvesting system or from stover bales were also collected and analyzed. All samples were dried, ground, and analyzed to determine C, N, P, K, Ca, Mg, S, Al, B, Cu, Fe, Mn, and Zn concentrations. Mean concentration and dry matter estimates for each sample were used to calculate nutrient removal and estimate fertilizer replacement costs which averaged $25.06, $20.04, $16.62, $19.40, and $27.41 Mg−1 for top, bottom, cob, stover, and grain fractions, respectively. We then used the plant fraction estimates to compare various stover harvest scenarios and provide an answer to the producer question posed above.

AgBufferBuilder: A geographic information system (GIS) tool for precision design and performance assessment of filter strips

Spatially nonuniform runoff reduces the water quality performance of constant-width filter strips. A geographic information system (GIS)-based tool was developed and tested that employs terrain analysis to account for spatially nonuniform runoff and produce more effective filter strip designs. The computer program, AgBufferBuilder, runs with ArcGIS versions 10.0 and 10.1 (Esri, Redlands, California) and uses digital elevation models to identify detailed spatial patterns of overland runoff to field margins. The tool then sizes filter dimensions according to those patterns using buffer area ratio relationships. The resulting design is larger along segments where more runoff flows and smaller along segments where runoff is less and delivers a constant level of trapping efficiency around the field margin for sediment and sediment-bound pollutants. The tool also can estimate trapping efficiency of existing filter strips or hypothetical configurations. In a validation test, estimates of sediment trapping efficiency using the tool9s assessment function compared closely to measurements taken on large field plots in central Iowa. Using AgBufferBuilder, designs developed for a sample of fields in the midwestern United States were estimated to trap nearly double the sediment, on average, during a design storm than constant-width configurations having equivalent total filter area. AgBufferBuilder can be used to bolster environmental performance of filter strips where runoff is spatially nonuniform. The AgBufferBuilder tool is publicly available on the websites http://www2.ca.uky.edu/BufferBuilder and http://nac.unl.edu/tools/AgBufferBuilder.

Direct and indirect effects of human population density and land use on physical features and invertebrates of Iowa (U.S.A.) streams

To improve understanding of human impacts on headwater stream condition, we quantified relationships between human, terrestrial landscape, and stream system variables in 29 central Iowa watersheds. Across study watersheds, between 0 and 100 % of total land area was characterized as “urban” (developed and barren land), whereas cultivated land constituted between 0 and 71 % of watershed area. Several variables were measured for each stream and associated watershed. Strengths of correlative relationships were used to select variables for path analysis, which we used to gain insight into factors affecting stream condition by evaluating direct and indirect effects of human system variables, terrestrial landscape variables, and physical stream variables on stream invertebrates. Results indicated that in predominantly urban watersheds, contaminant inputs to streams (measured by streamwater conductivity) negatively affected invertebrates, including EPT taxa (Ephemeroptera, Plecoptera, Trichoptera), and streamwater contaminant concentrations increased with impervious surface and human population density in the watershed. In rural watersheds, high streamwater nitrogen concentrations associated with cultivated land were related to declines in invertebrate taxon richness. Independent of land use, invertebrate abundance and taxonomic diversity were positively related to coarse substrate abundance on the streambed. Additionally, stream flow (discharge) increased with watershed area, which in turn increased invertebrate taxonomic diversity. Apparently, mechanisms responsible for human impacts on stream condition in central Iowa depend on dominant land use in the watershed. Additionally, stream ecosystems with high quality benthic habitat, and those located in large watersheds with greater flow, appear to be more resilient to land use effects.

Interview with John R. Wunder

Interview with John R. Wunder Jon K. Lauck (bio) In May 2014 the historian John R. Wunder, who spent the largest part of his career at the University of Nebraska–Lincoln, took time out from his current projects to discuss his career in general, and more particularly, his interest in regional history, including the history of the Plains and the Midwest. Wunder, born in Iowa, earned his ba and law degrees at the University of Iowa before earning his PhD in history under the guidance of Vernon Carstensen at the University of Washington. John taught at several universities around the United States—in the Pacific Northwest, the Midwest, the southern Great Plains, and the Deep South. Eventually, Wunder became the director of the Center for Great Plains Studies and a professor of history at the University of Nebraska. He also served as associate dean of the University of Nebraska’s College of Arts and Sciences and president of the Western History Association and the Mari Sandoz Heritage Society. He is the author or editor of nineteen books and over fifty academic articles. Wunder retired from the University of Nebraska in August 2011. He still lives in Lincoln, where he continues his research and writing. Where were you born? I was born in a hospital in Vinton, Iowa, a small county seat town in east central Iowa on January 7, 1945, to Mary (Remley) Wunder and Arnold Wunder. My middle name was my mother’s maiden name. I spent the first eighteen years of my life in Dysart, Iowa, which is a town of eight hundred about fifteen miles west of Vinton. What did your parents do for a living? My mother graduated from the University of Iowa and was a high school social studies teacher. She taught in several Iowa communities before she married my father, but her career was interrupted by my birth and then shortly thereafter by her contracting the awful disease multiple sclerosis which eventually [End Page 289] paralyzed her. My father graduated from Dysart High School; he worked first as a mechanic in a local gas station and then he had his own business supplying fuel oil and petroleum products to farmers and local businesses and homes. Where did you go to college and what did you study? I went to Iowa as a major in mathematics. We had had a wonderful high school math teacher who was a spinster and tough as nails. She taught us algebra, and trigonometry, geometry, and advanced algebra, but at Iowa I soon learned in my geometry class I just didn’t have a theoretical mathematics brain. At the end of my first semester and the beginning of the second, I first changed my major to accounting. That lasted one week. Instead I became a history major because my Western Civilization classes both semesters convinced me that history was to be my life’s work. I majored in history and political science graduating with a ba in 1967. I was captivated by the history of the American West classes (two courses for an entire academic year) taught by Professor Malcolm Rohrbough. I then took a fellowship to study the American West with Professor Rohrbough’s major professor, who was then at the University of Washington, Professor Vernon Carstensen.1 Rohrbough joked he was sending a son to study with his grandfather. [In 1974, after earning my PhD, I] received a position as a visiting assistant professor at Case Western Reserve University. There I taught the American survey, American West, and American legal history. If I recall correctly, you also encountered Christopher Lasch during your time at Iowa.2 Is that correct? Yes, he often would entertain an informal group of students at the student union. I remember once (probably spring of 1968) when tension was very high on campus with Vietnam demonstrations, I sat on the ballroom floor along with a hundred students as Lasch, also sitting on the floor, talked at length about historic American wars and compared them to Vietnam. He was quite inspirational. At some point, his departure that year from Iowa was not a happy one for him or the history department. It has been noted...

Observing and Simulating the Summertime Low-Level Jet in Central Iowa

Abstract In the U.S. state of Iowa, the increase in wind power production has motivated interest into the impacts of low-level jets on turbine performance. In this study, two commercial lidar systems were used to sample wind profiles in August 2013. Jets were systematically detected and assigned an intensity rating from 0 (weak) to 3 (strong). Many similarities were found between observed jets and the well-studied Great Plains low-level jet in summer, including average jet heights between 300 and 500 m above ground level, a preference for southerly wind directions, and a nighttime bias for stronger jets. Strong vertical wind shear and veer were observed, as well as veering over time associated with the LLJs. Speed, shear, and veer increases extended into the turbine-rotor layer during intense jets. Ramp events, in which winds rapidly increase or decrease in the rotor layer, were also commonly observed during jet formation periods. The lidar data were also used to evaluate various configurations of the Weather Research and Forecasting Model. Jet occurrence exhibited a stronger dependence on the choice of initial and boundary condition data, while reproduction of the strongest jets was influenced more strongly by the choice of planetary boundary layer scheme. A decomposition of mean model winds suggested that the main forcing mechanism for observed jets was the inertial oscillation. These results have implications for wind energy forecasting and site assessment in the Midwest.

An Analysis of Current and Future Wind Energy Gain Potential for Central Iowa

Using a significant quantity of fossil fuels has adverse impacts on our lives and will affect future generations. Additionally, there are limited and decreasing numbers of nonrenewable resources around the world. In contrast, renewable resources are not depleted and provide energy with negligible pollution. Wind energy is one of the more common renewable energy resources. This project aims to evaluate Iowa's wind energy potential and to provide suggestions to improve the future well ‐being of this state. A preliminary analysis shows that Iowa has great potential for wind energy. Based on the preliminary analysis, Ames, Iowa, is selected as a case study of its potential in terms of wind energy. Some important characteristics of wind energy, such as mean wind speed, wind distribution, and wind direction are evaluated for Ames. It is observed that although Iowa has the greatest wind power capacity density in the U.S., there are some untapped places in Iowa that can be utilized to harvest wind power. Results indicate that the city of Ames is one of the places that have strong wind speeds. According to the results, if a wind farm is installed in the city of Ames, reliance on non-renewable energy resources will be considerably decreased.

Management of Sweet Sorghum for Biomass Production

Sweet sorghum [Sorghum bicolor (L.) Moench] has been suggested as a biofuel feedstock due to its high productivity, low N requirements, and drought tolerance but little data exist on its management in the Midwestern US Corn Belt. In 2005 and 2006 in central Iowa, USA, plots were seeded with ‘Top 76-6’ sweet sorghum on three dates; late May, early June, and late June, at rates of 4.5, 11.2, and 17.9 kg ha−1 with row widths of 20, 38, and 76 cm, and fertilized at either 84 or 168 kg N ha−1 to determine how sweet sorghum yield and plant composition respond to changes in management. Yields were highest when sweet sorghum was planted in 20 cm row widths in late May (26.3 Mg ha−1) or early June (29.0 Mg ha−1). Several plant carbohydrates were affected by seeding date in 2005, but not 2006. Theoretical ethanol yields averaged 10,616 and 11,408 L ha−1 in 2005 and 2006, respectively, and were highest when sweet sorghum was planted earlier in the season and in narrow rows. In contrast, N fertilization and seeding rate had few impacts on sweet sorghum growth, biomass yield or ethanol potential. Based on these results, sweet sorghum in Iowa should be planted in May or June in 20 cm rows at a low to moderate seeding rate and a low N fertilization rate.

Evaluation of Alternative Cropping and Nutrient Management Systems with Soil and Water Assessment Tool for the Raccoon River Watershed Master Plan

The Soil and Water Assessment Tool (SWAT) ecohydrological model was used to assess a suite of adaptive nutrient management, alternative cropping system and combination scenarios in support of a Master Plan that was developed to help guide policy makers, land owners and other stakeholders in improving water quality for the 9,400 km2 Raccoon River watershed in west central Iowa, located in the Corn Belt region of the United States. Calibration and validation of SWAT showed that the model was able to accurately replicate most streamflow and pollutant loss conditions, with r2 and Nash-Sutcliffe modeling Efficiency (NSE) statistics exceeding 0.5 for the majority of indicators. The largest reduction in predicted nitrate losses at the overall watershed scale for the adaptive nutrient management scenarios was slightly over 12%, in response to a scenario in which 100% of the anhydrous ammonia fertilizer application was applied in the watershed four weeks after planting of corn. Considerably larger impacts on nitrate loss and other sediment and nutrient indicators, with some reductions exceeding 50%, were predicted for scenarios representing widescale conversion of corn-soybean rotations to six-year rotation of Corn-Soybean-Corn-Alfalfa-Alfalfa-Alfalfa (CSCAAA) or combinations of adaptive nutrient management, conversion to CSCAAA rotations and the insertion of a rye cover crop on a portion of the area managed with corn and soybean within the CSCAAA rotations.

Barriers Preventing Latina Immigrants from Seeking Advocacy Services for Domestic Violence Victims: A Qualitative Analysis

Domestic violence is a national public health problem resulting in numerous deaths, physical injuries, and mental and emotional disorders (Malley-Morrison and Hines 2007). While domestic violence influences communities of all races, socioeconomic statuses, educational levels, and geographical settings (Hass, Dutton, and Orloff 2000), some groups, such as Latina immigrants, are especially vulnerable as they face additional challenges. The purpose of this study is to document, analyze, and report the voices of Latina immigrants in Central Iowa as they share their experiences with outreach services. Through semi-structured individual interviews and a focus group with undocumented Latinas, we examine the multiple challenges faced by this vulnerable population. Our findings reveal that intersecting structural and institutional conditions make it more complicated for Latina victims to respond to partner abuse. Some of the most salient barriers include: unstable residency status, experiences of institutional discrimination, and economic inequality. Policy recommendations and implications are also discussed.

Organized variability of surface runoff responses across neighboring hillslopes in Iowa

Summary Characterizing the spatial and temporal variability of small scale runoff responses is essential to distributed hydrologic modeling. To explore the variability of runoff responses, we analyzed surface runoff hydrographs from 12 neighboring hillslopes in central Iowa, USA that were observed for 72 runoff events over a four-year period. These agricultural experimental hillslopes receive various prairie filter strip treatments and drain areas ranging from 0.48 to 3.19 ha. The distances between them vary from tens of meters to about 3 km. We compared the hydrographs from the remaining 11 hillslopes to the hydrograph at the benchmark hillslope (i.e., hillslope B6 with no treatment). The results showed that: (1) for any individual event in which noticeable surface runoff occurred, the hydrographs from these hillslopes had similar shapes but different magnitudes; (2) for any paired hillslopes, the shape similarity persisted, but the scaling factor (the regression slope between two flow series) changed across events; and (3) for any runoff event, no simple relationship exists between the spatial variation of the scaling factor and the slope, slope length, area, and prairie strip width at the footslope of the hillslopes. Interestingly, we found that for 9 out of the 11 paired hillslopes, 40–70% of the temporal variation in the scaling factors can be explained by the antecedent wetness condition and the maximum hourly rain accumulation. These results suggest that the small-scale surface runoff responses are spatially variable but organized linearly, i.e., shape similarity (or linearity) in space is another feature of the small-scale runoff process. This phenomenon seems to result from the spatial vicinity and small-scale spatial variability of rainfall intensity and antecedent soil moisture.

Assessing Linkages between E. coli Levels in Streambed Sediment and Overlying Water in an Agricultural Watershed in Iowa during the First Heavy Rain Event of the Season

Abstract. This study involved field observations in Squaw Creek watershed, located in central Iowa, to investigate the impact of a heavy rain event (rainfall of 71 mm in 24 h) on E. coli levels in the streambed sediment and overlying water. We assessed relationships between streamflow and E. coli and nutrient levels in the water column and streambed sediment. The results showed that during a heavy rain event, E. coli levels in the water column varied considerably, ranging from 360 to 37,553 CFU per 100 mL with a mean of 7,598 CFU per 100 mL. Elevated streamflow resulted in greater levels of E. coli in the water column. Streambed sediment E. coli levels ranged from 896 to 6,577 CFU per 100 g with a mean of 3,355 CFU per 100 g. Regression analysis found exponential relationships between streamflow and E. coli levels in the water column (R 2 = 0.56) and between streamflow and E. coli levels in the streambed sediment (R 2 = 0.45). R 2 values of the exponential relationship between streamflow and water column E. coli levels increased considerably when regressions for the rising and falling limbs of the hydrograph were performed separately (R 2 = 0.64 and 0.94, respectively). The exponential relationship between total suspended solids (TSS) and water column E. coli levels yielded an R 2 of 0.38, while TSS and streamflow yielded an exponential relationship with an R 2 of 0.64. The results presented here provide information on in-stream bacteria dynamics of an agricultural watershed during the first heavy rain of the season. We anticipate that the results will improve the understanding of in-stream E. coli transport during rain events and provide insight for policy makers to allocate E. coli loads in impaired water bodies.

Placemaking in rural new gateway communities

Placemaking, or the process of becoming intimate with ones′ surroundings, can serve as an indicator of immigrant integration. This article contributes to the scholarship of geographically sensitive immigrant integration with empirical research that documents the quality of localized placemaking. The dichotomy of ‘lived’ and ‘facilitated placemaking’ is introduced to differentiate between how newcomers begin embracing a new place and what governments do to engage people in governance. In a community undergoing rapid demographic change, i.e. a new gateway, the two kinds of placemaking impact newcomer empowerment. After examining the relationship between place and empowerment in the context of immigrant integration, we present an approach for testing placemaking and its findings from research conducted in central Iowa. Data collected from a series of community-based mapping workshops reveals that Latino participants engage in more, and different, placemaking than their non-Latino counterparts.

Ammonia and greenhouse gas emissions from a modern U.S. swine breeding-gestation-farrowing system

Aerial emissions from livestock production continue to be an area of attention and concern for both the potential health and environmental impacts. However, information of gaseous, especially greenhouse gas (GHG), emissions for swine breeding/gestation and farrowing production systems is limited. The purpose of this study was to quantify ammonia (NH3), carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) concentrations and emissions from a modern breeding-gestation-farrowing system located in central Iowa, USA. A 4300-sow farm was selected for the extensive field monitoring which employed a Mobile Air Emission Monitoring Unit equipped with state-of-the-art gas analyzers and a data acquisition system. The monitored portion of the farm facility consisted of a deep-pit breeding/early gestation (B/EG) barn (1800 head), a deep-pit late gestation (LG) barn (1800 head), and two shallow-pit (pull-plug) farrowing rooms (40 head per room). A dynamic flux chamber was used to monitor gaseous emissions from the external manure storage for the farrowing rooms. Data were collected for 29 consecutive months (January 2011 through June 2013). Daily indoor NH3, CO2, N2O, and CH4 concentrations (ppm, mean ± SD) were 12.0 (±7.6), 1594 (±797), 0.31 (±0.11), and 28.5 (±9.8), respectively, in the breeding/gestation barns; and 9.7 (±4.1), 1536 (±701), 0.30 (±0.10), and 78.3 (±37), respectively, in the farrowing rooms. Daily emissions per animal unit (AU, 500 kg live weight) were 35.1 g NH3, 7.46 kg CO2, 0.17 g N2O, and 263.4 g CH4 for sows in the B/EG barn; and 28.2 g NH3, 6.50 kg CO2, 0.12 g N2O, and 201.3 g CH4 for sows in the LG barn. The average daily emissions per AU (sow and piglets) of the farrowing rooms during the lactation period (birth to weaning) were: 59.7 g NH3, 16.4 kg CO2, 0.73 g N2O, and 107 g CH4. For the monitored period, the external manure storage had the following average daily emission per m2 surface area: 1.26 g NH3, 137 g CO2, and 94.8 g CH4, which was equivalent to daily emissions per AU in the farrowing rooms of 12.2 g NH3, 1.055 kg CO2, and 867 g CH4. Average daily emissions per AU for the total operation (including house-level and manure storage emissions) were 38.5 g NH3, 8.73 kg CO2 (including 7.3 kg from animal respiration), 0.25 g N2O, and 301 g CH4.

Radiation Use Efficiency: Evaluation of Cropping and Management Systems

Capture of solar radiation by plant canopies and conversion of this energy into biomass or grain has been described as radiation use efficiency. Radiation use efficiency (RUE) has been developed as a function of biomass accumulation and intercepted photosynthetically active radiation (IPAR) by the canopy and evaluated under conditions not limiting to plant growth. This study was designed to evaluate RUE across a number of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] experiments in central Iowa with various tillage and management inputs to determine how RUE changed as a function of agronomic management. In these studies, IPAR was derived through the use of a normalized difference vegetation index, which is a surrogate for the photosynthetically active radiation canopy interception term, and total canopy biomass was measured at five times during the growing season from the early vegetative stage through maturity. Grain yields were obtained from each plot with both hand‐ harvested and combine samples. Values for RUE showed a linear relationship between biomass and IPAR for the entire growing season, with the better fit when the relationship was confined to the vegetative development period. There were differences among years, with management and tillage systems affecting RUE values through the differences in biomass or grain yield. Grain yield relationships to IPAR showed more variation than total biomass, with yearly differences evident in the amount of IPAR during the grain‐filling period suggesting that the length of the grain‐filling period is a dominant factor in grain yield. Application of RUE to field‐scale observations will provide a method of assessing where crop productivity is limited.