Development of a Method for Evaluating the Yield Goal Approach

Yield goals have been used to determine N recommendations in South Dakota, North Dakota, and western Minnesota. However, some states, such as Wisconsin and Iowa have eliminated yield goals from N recommendations because of poor correlation between yield and economically optimum N rates. The objective of this study was to determine the feasibility of switching from a yield goal approach to a non-yield goal approach in South Dakota. Field experiments were conducted in Aurora, South Dakota between 2002 and 2003. Treatments were natural rainfall and natural rainfall + irrigation and four N rates (0, 60, 120, 180 kg N /ha). Plant samples were analyzed for 13C discrimination (Δ) and total N. Research results showed that; (i) adding N rates increased yield and Δ; (ii) applying supplemental irrigation increased yield and decreased Δ; (iii) yields were not influenced by an interaction between water and nitrogen; and (iv) δ15N values increased with irrigation and decreased with increasing N. These results suggest that nitrogen and water stress had independent impact on yield, and irrigation increased N mineralization. These findings partially support the hypothesis that fertilizer rates should be independent of yield goal. Research needs to be conducted to determine the long term impact of changing the recommendation approach on soil N levels

Nitrogen and Water Stress Impact on Hard Red Spring Wheat Crop Reflectance, Yield and Grain Quality

Water and nitrogen stress impact hard red spring wheat (Triticum aestivum) crop reflectance, yield and grain quality. To minimize yield losses from nitrogen (N) and water stress, it is essential to apply appropriate N in relation to water stress. The objective of this experiment was to determine the influence of N and water stress on hard red spring wheat crop reflectance, yield, and grain quality. Complete randomized block experiments were conducted in 2003, 2004 and 2004 in dryland and irrigated fields at three locations in central South Dakota. Treatments consisted of N rates and N application at different growth stages. Nitrogen fertilizer rates ranged from 0 to 200 kg ha-1. Nitrogen fertilizer application times were (1) planting; (2) planting and tillering (Feekes 2 -3) or (3) tillering (Feekes 2 -3). Reflectance data was collected using a Cropscan and a CropCircle radiometer. Reflectance data was collected at bare soil, tillering (Feekes 2-3) and flag leaf (Feekes 9-10). Carbon 13 isotopic discrimination (Ä) was used to determine yield loss to nitrogen or water stress. Reflectance data was compared to yield and Ä values or grain quality and Ä values. Correlation of crop reflectance (measured at the different growth stages and by the different radiometers) with yield loss to nitrogen or water and grain quality will be presented. Information presented will be used to make corrective nitrogen treatments and improve marketing decisions as related to grain quality

Fish Assemblage Relationships with Physical Characteristics and Presence of Dams in Three Eastern Iowa Rivers

Fish assemblages in rivers of the Midwestern United States are an important component of the region\u27s natural resources and biodiversity. We characterized the physical environment and presence of dams in a series of reaches in three eastern Iowa rivers tributary to the Mississippi River and related these characteristics to the fish assemblages present. Some physical characteristics were similar among the 12 study reaches, whereas others differed substantially. We found a total of 68 species across the 12 study reaches; 56 in the Turkey River, 51 in the Maquoketa River and 50 in the Wapsipinicon River. Seventeen species could be described as ‘downstream-distributed’; 15 being found only in the lowest reach of one or more rivers and the other two being found only in the lowest reaches or two or more contiguous reaches including the lowest reach. Two species could be described as ‘upstream-distributed’, being found only in an uppermost reach. Non-metric multidimensional scaling ordination illustrated similarities among reaches, and five physical variables were significantly correlated with assemblage similarities. Catchment area and number of dams between reaches and the Mississippi River were strongly correlated with assemblage similarities, but the directions of their effects were opposite. Catchment area and number of dams were confounded. The collective evidence to date suggests that the pervasiveness of dams on rivers significantly alters fish assemblages, making underlying patterns of species change and relationships with naturally varying and human-influenced physical characteristics along a river\u27s course difficult to discern

TenTen: A New Array of Multi-TeV Imaging Cherenkov Telescopes

The exciting results from H.E.S.S. point to a new population of gamma-ray sources at energies E > 10 TeV, paving the way for future studies and new discoveries in the multi-TeV energy range. Connected with these energies is the search for sources of PeV cosmic-rays (CRs) and the study of multi-TeV gamma-ray production in a growing number of astrophysical environments. TenTen is a proposed stereoscopic array (with a suggested site in Australia) of modest-sized (10 to 30m^2) Cherenkov imaging telescopes with a wide field of view (8 to 10deg diameter) optimised for the E~10 to 100 TeV range. TenTen will achieve an effective area of ~10 km^2 at energies above 10 TeV. We outline here the motivation for TenTen and summarise key performance parameters.Comment: 4 pages, 2 figures, proceedings of the 30th ICRC, Merida, Mexico, 200

Spring‐applied Corn Herbicides Impact Fall‐planted Cover Crops in South Dakotaa

Early spring herbicide applications can have residuals that impede fall‐planted cover crop growth. A greenhouse study examined radish (Raphanus sativus L.) or rye (Secale cereale L.) growth in silty clay loam (southeastern South Dakota) and silt loam (north‐central South Dakota) where corn herbicides had been applied about 120 d prior to collection. S‐metolachlor, acetochlor, flumetsulam, metribuzin, bicyclopyrone + mesotrione + S‐metolachlor + atrazine, and primisulfuron‐methyl + prosulfuron (northern site only) were applied at the suggested timing and highest recommended rate and planted to corn (Zea mays L.). Two 11‐cm diam. soil cores to a 10‐cm depth were collected per plot after silage harvest, with nontreated soils also collected. Soil was mixed within each core and two subsamples were placed into conetainers and planted with four seeds of the crop species. Plant height, and fresh shoot and root weights were quantified after 6 wk and compared to growth in nontreated soil. Radish was unaffected by any herbicide in either soil. Rye growth was influenced by soil and herbicide. In the silt loam, rye shoot biomass was reduced 15–25% by flumetsulam, acetochlor, and primisulfuron + prosulfuron; and acetochlor reduced root biomass by 44%. In the silty clay loam, acetochor reduced shoot biomass by 59%; and all treatments reduced root biomass by 35% or more. These data suggest that spring herbicide applications and cover crop species should be carefully matched to help in cover crop success

Simulation Study of TenTen: A new Multi-TeV IACT array

TenTen is a proposed array of Imaging Atmospheric Cherenkov Telescopes (IACT) optimized for the gamma ray energy regime of 10 TeV to 100 TeV, but with a threshold of ~1 to a few TeV. It will offer a collecting area of 10 km2 above energies of 10 TeV. In the initial phase, a cell of 3 to 5 modest-sized telescopes, each with 10-30 m2 mirror area, is suggested for an Australian site. A possible expansion of the array could comprise many such cells. Here we present work on configuration and technical issues from our simulation studies of the array. Working topics include array layout, telescope size and optics, camera field of view, telescope trigger system, electronics, and site surveys.Comment: 4 pages, 7 figures, submitted to Proceedings of the ICRC 2007, pdf forma

Do Synergistic Relationships between Nitrogen and Water Influence the Ability of Corn to Use Nitrogen Derived from Fertilizer and Soil?

To improve site-specific N recommendations a more complete understanding of the mechanisms responsible for synergistic relationships between N and water is needed. Th e objective of this research was to determine the influence of soil water regime on the ability of corn (Zea mays L.) to use N derived from fertilizer and soil. A randomized split-block experiment was conducted in 2002, 2003, and 2004. Soil at the site was a Brandt silty clay loam (fine-silty, mixed, superactive frigid Calcic Hapludoll). Blocks were split into moderate (natural rainfall) and high (natural + supplemental irrigation) water regimes. Nitrogen rates were 0, 56, 112, and 168 kg urea-N ha–1 that was surface applied. Water, soil N, and N fertilizer use efficiencies were determined. Plant utilization of soil N was determined by mass balance in the unfertilized control plots and by using the δ15N approach in fertilized plots. Findings showed that: (i) plants responded to N and water simultaneously; (ii) N fertilizer increased water use efficiency (170 kg vs. 223 kg grain cm–1 in 0 and 112 kg N ha–1 treatments, respectively); and (iii) water increased the ability of corn to use N derived from soil (67.7 and 61.6% efficient in high and moderate water regimes, respectively, P = 0.002) and fertilizer (48 and 44% efficient in high and moderate water regimes, respectively, P = 0.10). Higher N use efficiency in the high water regime was attributed to two interrelated factors. First, total growth and evapotranspiration (ET) were higher in the high than the moderate water regime. Second, N transport to the root increased with water transpired. For precision farming, results indicate that: (i) the amount of N fertilizer needed to produce a kg of grain is related to the yield loss due to water stress; and (ii) the rate constant used in yield goal equations can be replaced with a variable

Timing analysis techniques at large core distances for multi-TeV gamma ray astronomy

We present an analysis technique that uses the timing information of Cherenkov images from extensive air showers (EAS). Our emphasis is on distant, or large core distance gamma-ray induced showers at multi-TeV energies. Specifically, combining pixel timing information with an improved direction reconstruction algorithm, leads to improvements in angular and core resolution as large as ~40% and ~30%, respectively, when compared with the same algorithm without the use of timing. Above 10 TeV, this results in an angular resolution approaching 0.05 degrees, together with a core resolution better than ~15 m. The off-axis post-cut gamma-ray acceptance is energy dependent and its full width at half maximum ranges from 4 degrees to 8 degrees. For shower directions that are up to ~6 degrees off-axis, the angular resolution achieved by using timing information is comparable, around 100 TeV, to the on-axis angular resolution. The telescope specifications and layout we describe here are geared towards energies above 10 TeV. However, the methods can in principle be applied to other energies, given suitable telescope parameters. The 5-telescope cell investigated in this study could initially pave the way for a larger array of sparsely spaced telescopes in an effort to push the collection area to >10 km2. These results highlight the potential of a `sparse array' approach in effectively opening up the energy range above 10 TeV.Comment: Published in Astroparticle Physic

Alveolar macrophages lack CCR2 expression and do not migrate to CCL2

Background: The recruitment of mononuclear cells has important implications for tissue inflammation. Previous studies demonstrated enhanced CCR1 and CCR5 expression and decreased CCR2 expression during in vitro monocyte to macrophage differentiation. To date, no study examined the in vivo differences in chemokine receptor expression between human peripheral blood monocytes and alveolar macrophages. Methods: We examined the expression of these receptors in human peripheral blood monocytes and alveolar macrophages using microarray analysis, reverse-transcriptase PCR, flow cytometry and migration analyses. Results: In contrast to peripheral blood monocytes, alveolar macrophages did not express the CCL2 receptor, CCR2, and did not migrate toward CCL2. In contrast, monocytes and freshly isolated resident alveolar macrophages both migrated towards CCL3. However, up to 6-fold more monocytes migrated toward equivalent concentrations of CCL3 than did alveolar macrophages from the same donor. While peripheral blood monocytes expressed the CCL3 receptor, CCR1, alveolar macrophages expressed the alternate CCL3 receptor, CCR5. The addition of anti-CCR5 blocking antibodies completely abrogated CCL3-induced migration in alveolar macrophages, but did not affect the migration of peripheral blood monocytes. Conclusion: These data support the specificity of CCL2 to selectively drive monocyte, but not alveolar macrophage recruitment to the lung and CCR5 as the primary macrophage receptor for CCL3

Winter Wheat Quality Responses to Water, Environment, and Nitrogen Fertilization

Decreasing carbon (C) footprints by reducing nitrogen (N) and water inputs has been speculated to have negative impacts on wheat grain yield and flour processing quality. The objective of this study was to determine the impact of N and water stress on winter wheat grain yield, protein composition, and dough quality. Wheat fertilized at two N rates (unfertilized and recommended) was grown under water-stressed and well-watered environments. Nitrogen and water stress were measured using the 13C isotopic approach. Research showed that (1) N fertilizer and the water-management environment produced similar impacts on wheat quality and yield loss due to N stress and yield loss due to water stress (YLWS); (2) N fertilizer increased flour protein, dough stability, and relative concentration of glutenin (%Glu), unextractable polymeric protein (UPP), and relative amount of high-molecular-weight glutenin subunits (HMW-GS/LMW-GS); (3) the well-watered environment reduced protein contents when N mineralization was low, whereas it did not influence protein content when mineralization was high; and (4) the %Glu was negatively correlated with yield loss due to N stress (YLNS) and positively correlated with stability. This study showed that a clear understanding of the complex relationship between soil variability and climatic conditions should make it possible to develop adaptive management practices, increase profitability, and improve quality