bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation Control for No‐Tillage Corn Planted into Warm‐Season Perennial Species
Authors: Broome Malcolm L. , Triplett Glover B. , Watson Clarence E.
Published: July 2010

The success of no‐tillage corn (Zea mays L.) planted into sod in the Southeast depends on control of warm‐season perennials. Preemergence (PRE) and postemergence (POST) herbicides were evaluated for control of warm‐season perennial and annual species in no‐tillage corn production. Vegetation spectrum differences at the various locations influenced both herbicide rate and timing of application required for 90% control by imazapyr {(±)‐2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐3‐pyridinecarboxylic acid}, imazethapyr {2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1 H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid}, glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl) butanoic acid], or imazapyr + imazethapyr. Imazapyr controlled established bermudagrass (Cynodon dactylon L.), broomsedge (Andropogon virginicus L.), johnsongrass [Sorghum halepense (L.) Pers.], tall fescue (Festuca arundinacea Schreb.), and dallisgrass (Paspalum dilatatum Poir.) in all instances. Several herbicides were used in selected combinations for PRE and/or POST applications in discrete rate trials. These were imazapyr, imazethapyr, glufosinate, imazapyr + imazethapyr, paraquat (1, 1′‐dimethyl‐4,4′‐bipyridinium ion), atrazine [6‐chloro‐N‐ethyl‐N1‐(1‐methyethyl)‐1,3,5‐triazine‐2,4‐diamine], and glyphosate [N‐(phosphonomethyl)glycine]. The glufosinate‐resistant corn hybrid in 1997 at Holly Springs, MS, with glyphosate PRE at 0.84 kg a.i. ha−1 followed by glufosinate POST (28 DAP) at 0.45 kg ha−1 produced a maximum yield of 10.2 Mg ha−1. Results from this study indicate that vegetation can be controlled for corn production in untilled sod comprised of warm‐season perennials when transgenic hybrids are grown.
Soybean Yield Response to Reproductive Stage Soil‐Applied Nitrogen and Foliar‐Applied Boron
Authors: Freeborn John R. , Holshouser David L. , Alley Marcus M. , Powell Norris L. , Orcutt David M.
Published: July 2010

Research on the effects of N and B applications on soybean [Glycine max (L.) Merr.] yield is limited. Experiments were conducted to determine the effect of (i) application rate and reproductive stage timing of N or B on soybean seed yield and (ii) cultivar, row spacing, or planting date on the response of soybean to R3‐stage N and B applications. Nitrogen was applied to the soil at 0, 14, 28, 56, 84, 112, or 168 kg ha−1, or B was applied to the foliage at 0, 0.14, 0.28, or 0.56 kg ha−1 to either R3‐ or R5‐stage soybean in the rate and timing experiments. Treatments for the cultivar, row‐spacing, and planting‐date experiments included 0 + 0, 56 + 0, 0 + 0.28, and 56 + 0.28 kg ha−1 N + B, respectively. In yield environments ranging from 2400 to 5300 kg ha−1, application of N or B did not increase seed yield at any rate or application stage, nor did cultivar, row spacing, or planting date alter this lack of response. Analysis of leaf tissue taken at the R2 soybean development stage and before nutrient application indicated that N and B concentrations were above the minimum level required by soybean for maximum yields not limited by N or B. Lack of response to supplemental N or B suggested that N supplied via fixation and soil organic matter mineralization and native levels of B in soils are adequate for high yields in the Mid‐Atlantic Coastal Plain soybean production region.
Separating the Impacts of Crop Diversification and Rotations on Risk
Authors: Helmers Glenn A. , Yamoah Charles F. , Varvel Gary E.
Published: July 2010

It has been commonly accepted that crop rotations reduce risk compared with monoculture systems. Quantifying this phenomenon requires that effects of yield stability on risk (positive or negative) arising from rotating crops be separated from other risk elements. Using an ARS–University of Nebraska series of yields for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] grown over a 14‐yr period, both in rotation and in monoculture, the impact of crop rotation on risk was isolated and estimated. Risk was defined as the failure to meet an annual per‐hectare net return target. A corn–soybean rotation had significantly less risk than monoculture practices. Diversification was found to contribute to part of this reduction while higher yields and reduced cost contributed to the remainder. This reduction in risk occurred even though the corn–soybean rotation had a higher yield variance.
Predicting Forage Quality in Switchgrass and Big Bluestem
Authors: Mitchell Rob , Fritz John , Moore Ken , Moser Lowell , Vogel Ken , Redfearn Daren , Wester David
Published: July 2010

Predicting forage quality would help producers schedule hay harvesting to obtain desired hay quality. Our objective was to determine if growing degree day (GDD), day of the year (DOY), mean stage count (MSC), and mean stage weight (MSW) could be used to predict in vitro digestible dry matter (IVDDM), crude protein (CP), and neutral‐detergent fiber (NDF) of ‘Trailblazer’ switchgrass (Panicum virgatum) and ‘Pawnee’ big bluestem (Andropogon gerardii Vitman) grown in Nebraska and Kansas. This field study was conducted from 1990 to 1993 at Mead, NE on Typic Argiudoll soils and from 1992 to 1993 at Manhattan, KS on Aquic Argiudoll soils. Plants were sampled at 1‐wk intervals in 1990 and 1991 and at 2‐wk intervals in 1992 and 1993. They were morphologically classified as MSC and MSW and analyzed for IVDDM, CP, and NDF. Switchgrass IVDDM and CP were best predicted by GDD models, which accounted for 86 and 91% of the variation, respectively, whereas NDF was best predicted by MSC and MSW. Big bluestem IVDDM was best predicted by MSW and CP was best predicted by GDD, which both accounted for 90% of the variation. Mean stage weight accounted for 74% of the variability in big bluestem NDF. The DOY model adequately predicted forage quality due primarily to the determinate growth habit of these species. Morphological development accurately predicted forage quality in many instances. Although no universal parameter adequately predicted concentrations of IVDDM, CP, and NDF, it was possible to accurately predict quality with readily available environmental data and measures of plant maturity.
Glyphosate‐Resistant Soybean Cultivar Response to Glyphosate
Authors: Elmore Roger W. , Roeth Fred W. , Klein Robert N. , Knezevic Stevan Z. , Martin Alex , Nelson Lenis A. , Shapiro Charles A.
Published: July 2010

Glyphosate (N‐(phosphonomethyl) glycine)‐resistant (GR) soybean [Glycine max (L.) Merr.] technology is gaining acceptance in U.S. cropping systems, yet potential yield suppression from either cultivar genetic differentials, the GR gene/gene insertion process, or glyphosate is a concern. Other work shows that the GR gene/gene insertion process may suppress soybean yield. No one has reported the effects of glyphosate on a diverse group of commercially available GR soybean cultivars. In this study we evaluated one of the potential sources of GR yield suppression—the effect of glyphosate on yield, growth, and development of GR cultivars. Field experiments were conducted at four Nebraska locations with12 GR cultivars in 1998 and 13 GR cultivars in 1999. Soybean response to glyphosate, ammonium sulfate (AMS), and water application at 21 and 42 d after soybean emergence was compared with control plots treated with AMS and water in 1998. An additional control, water alone, was added in 1999. Grain yield among cultivars differed as expected with a range of 3.44 to 3.96 Mg ha−1 in the 2‐yr averages. Glyphosate did not affect the majority of the soybean growth and development characteristics measured. Grain yield of GR soybean was not affected by glyphosate at any location or when averaged over locations. Two‐year average grain yield of cultivars treated with glyphosate, AMS, and water was 3.74 Mg ha−1; this was not different from 3.79 Mg ha−1 with AMS and water treatment.
Potassium Placement and Tillage System Effects on Corn Response following Long‐Term No Till
Authors: Vyn Tony J. , Janovicek Ken J.
Published: July 2010

Stratification of immobile nutrients in long term no‐till (NT) fields may reduce corn (Zea mays L.) yield potential. Five field studies were conducted from 1995 to 1998 to evaluate corn response to different K placements and rates when fields with a NT cropping history were either fall zone‐tilled (ZT), fall moldboard‐plowed [conventional tillage (CT)], or continued in the NT system. The silt loam to silty clay loam soils had medium or high soil‐test K (0–15 cm) ratings with varying degrees of K stratification to the 30‐cm depth. Fall‐applied K at rates of 0, 42 and 84 kg ha−1 was surface‐broadcast in the NT system, deep‐banded to 15‐cm depth in the ZT system, and surface‐broadcast and incorporated in the CT system. Potassium was also shallow‐banded with the planter at rates of either 0 to 8 kg ha−1 (low) or 42 to 50 kg ha−1 (high). Average concentrations of corn ear‐leaf K near silking increased from 10.9 g kg−1 with no K to 15.2 g kg−1 with highest fall plus spring K rates on the three sites with soil‐test K levels of <100 mg kg−1. For these same sites, ear‐leaf K concentrations averaged 1.2 g kg−1 higher in CT compared with NT or ZT. On four of the five field sites, corn yields in the NT and ZT systems were maximized by applying the high rate of starter K, even when no K fertilizer was applied the previous fall. On long‐term NT soils with medium soil‐test K, corn producers may derive most K fertility benefit from shallow banding at planting.
Modeling Interactions among Carbon Dioxide, Nitrogen, and Climate on Energy Exchange of Wheat in a Free Air Carbon Dioxide Experiment
Authors: Grant Robert F. , Kimball Bruce A. , Brooks Talbot J. , Wall Gary W. , Pinter Paul J. , Hunsaker Doug J. , Adamsen Floyd J. , Lamorte Robert L. , Leavitt Steven W. , Thompson Thomas L. , Matthias Allan D.
Published: July 2010

Changes in mass and energy exchange by crops under rising atmospheric CO2 concentration (Ca) may be affected by N and weather; Ca interacts with weather on mass and energy exchange through limitations on latent heat flux imposed by stomatal conductance, which is affected by Ca, and aerodynamic conductance, which is affected by weather. We examined the bases for these interactions with the ecosystem model ecosys Simulation results were tested with energy flux data from a Free Air CO2 Enrichment (FACE) experiment in which wheat (Triticum aestivum L.) was grown under 548 vs. 363 μmol mol−1 Ca and fertilized with 7 vs. 35 g N m−2. Both model and experimental results indicated that raising Ca from 363 to 548 μmol mol−1 reduced midday latent heat fluxes by ca. 50 W m−2 for wheat fertilized with 35 g N m−2, and by ca. 100 W m−2 for wheat fertilized with only 7 g N m−2 when N deficits developed later in the growing season. These reductions were smaller under low wind speeds (<5 km h−1) and stable boundary conditions when aerodynamic conductance became the dominant constraint to transpiration. At a seasonal time scale, raising Ca from 363 to 548 μmol mol−1 reduced simulated (measured) evapotranspiration of wheat by 9% (7%) when fertilized with 35 g N m−2, and by 16% (19%) with 7 g N m−2. Changes with Ca in mass and energy exchange used in climate change studies should therefore reflect the site‐specific availability of N, as well as climate attributes such as wind speed.
Maize Leaf Development Biases Caused by Air–Apex Temperature Differences
Authors: Vinocur Marta G. , Ritchie Joe T.
Published: July 2010

Accurate determination of leaf appearance rate is required in crop simulation models to estimate canopy development and ultimately crop yield. Most crop simulation models use air temperature for thermal time calculations to estimate leaf appearance rate, although the near soil temperature is more closely related to the growing apex temperature than air temperature before stem elongation. A field experiment was conducted in 1996 at East Lansing, MI, to determine the effect of soil, air, and apex temperatures on maize (Zea mays L.) leaf development. Maize leaf tip appearance dates and leaf numbers were observed on four sowing dates to provide variations in the thermal regime of developing plants. Solar irradiance and temperature of the air (1.5 m height), apex, and soil (1−, 3−, and 5‐cm depths) were recorded on 0.5‐h (half‐hourly) intervals. The daily average soil temperature at the 3− to 5‐cm depth was reasonably close (+0.6°C in average) to the daily average apex temperature for use as a surrogate for apex temperature to increase the accuracy of maize development simulation in the sowing to ninth leaf tip stage. Thereafter, the air temperature was sufficiently accurate to estimate plant development. Using apex temperatures from leaf 3 to 9, this study indicated that the phyllochron was near 55°C d (degree days) per leaf tip appearance. The consistent bias between air and apex temperature from sowing to V6 found in this study clearly indicates the necessity of using the right temperature in thermal time calculations for accurate maize development simulation.
Soil Nitrogen Mineralization in Mixtures of Eastern Gamagrass with Alfalfa and Red Clover
Authors: Gil Jose L. , Fick Walter H.
Published: July 2010

The amount and rate of soil N mineralization often influences the productivity and persistence of a grass–legume mixture. This research investigated soil N availability in monoculture and binary mixtures of alfalfa (Medicago sativa L.) or red clover (Trifolium pratense L.) with eastern gamagrass [Tripsacum dactyloides (L.) L.] on sandy and clay loam soils near Manhattan, KS. Soil inorganic N and in situ net N mineralization were monitored monthly during the growing seasons of 1996 and 1997. Soil inorganic N was two‐ to threefold higher with alfalfa, red clover, and gamagrass–alfalfa mixture than with gamagrass in monoculture at the end of 1996. At the midseason of 1997, soil inorganic N was three‐ to ninefold higher at the clay loam site, but at the sandy site, only alfalfa monoculture was three‐ to fivefold higher than the other treatments in both years. Soils under alfalfa at both sites in 1997 had the highest cumulative net N mineralized (35–100 kg N ha−1 yr−1), followed by the gamagrass–legume mixtures (15–62 kg N ha−1 yr−1) and then the gamagrass monoculture treatment (2–15 kg N ha−1 yr−1). A high correlation (r2 > 0.9, P < 0.05) was found between C/N ratio of the aboveground biomass and the total net N mineralized in the 2nd yr for both sites, suggesting that litter quality is an important driving variable on N mineralization. Our results emphasize the importance of forage legumes in maintaining soil quality and productivity and quality of forage mixtures.
Row Spacing, Plant Density, and Hybrid Effects on Corn Grain Yield and Moisture
Authors: Farnham Dale E.
Published: July 2010

Producing corn (Zea mays L.) in narrow row spacings has been attempted over the last several decades with varying degrees of success. The objectives of this study, are to determine: (i) if there is a different optimum plant density or (ii) if hybrids of varying relative maturity respond differently for corn grown in narrow row spacings (38 cm) compared with conventional row widths (76 cm). These studies were conducted at six locations across Iowa over 3 yr. Averaged across years, locations, and plant densities, corn grown in 76‐cm row spacings produced higher yields than that grown in 38‐cm rows (10.5 vs. 10.3 Mg ha−1, respectively). Harvest moisture content of corn grown in 38‐cm row spacings was significantly less than that of corn grown in 76‐cm row spacings (160 vs. 161 g kg−1, respectively). Averaged across years and locations, there was no statistically significant (P < 0.05) yield difference between the two row spacings for four of the six hybrids tested. Hybrid MAX23 yielded significantly more grain in 76‐cm row spacings (9.4 vs. 8.9 Mg ha−1) while ‘MAX454’ yielded more grain in 38‐cm row spacings (10.0 vs. 9.8 Mg ha−1). It is thus concluded that optimum plant densities for narrow‐row corn production are similar to those required to produce maximum yields for conventional wide‐row corn production. In addition, a strong hybrid × row spacing interaction among the six hybrids tested here suggests that certain hybrids may perform better at prescribed row spacings.
Legume Cover Crops with Winter Cereals in Southern Manitoba
Authors: Martens Joanne R. Thiessen , Hoeppner Jeff W. , Entz Martin H.
Published: July 2010

The opportunity to include late‐season cover crops in northern cropping systems has been enhanced with the adoption of winter cereal production; however, cover crop feasibility has not been evaluated in these regions. Field experiments were conducted at two sites in Manitoba in 1998 and 1999 to (i) assess establishment and dry matter (DM) production of legume cover crops that were relay‐cropped [alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.)] or double‐cropped [chickling vetch (Lathyrus sativus L.) and black lentil (Lens culinaris Medik. subsp. culinaris)] with winter cereals [winter wheat (Triticum aestivum L.) and fall rye (Secale cereale L.)], (ii) assess the effect of relay cover crops on cereal grain yield, and (iii) characterize the effects of a red clover cover crop on the microclimate after winter wheat harvest. Establishment and midseason DM of the relay crops were not affected consistently by cereal crop type. Legume DM at freeze‐up was similar in winter wheat and fall rye systems and ranged from 190 to 1800 kg ha−1, with moisture availability being the critical factor. Across all site‐years, final DM for red clover, alfalfa, chickling vetch, and lentil averaged 1157, 690, 746, and 634 kg ha−1. Relay crops did not affect main‐crop grain yield but did significantly reduce main‐crop DM production in some cases. The red clover cover crop created a moderating effect on late summer and fall surface (5‐cm height) air temperatures and decreased soil moisture availability. Including relay and double crops in winter cereal‐based cropping systems appears feasible in southern Manitoba.
Sequential Grazing of Cool‐ and Warm‐Season Pastures
Authors: Moore K. J. , White T. A. , Hintz R. L. , Patrick P. K. , Brummer E. C.
Published: July 2010

Pasture productivity in Iowa is often limited by low productivity of cool‐season grasses during summer. Our overall objectives were to (i) evaluate the impact of legumes on the productivity and nutritive value of cool‐season pastures, (ii) evaluate warm‐season grasses for summer grazing, and (iii) determine the effects of pasture sequence on the productivity of season‐long grazing systems. Cool‐season pastures consisted of smooth bromegrass (Bromus inermis Leyss.) alone or in mixture with birdsfoot trefoil (Lotus corniculatus L.), alfalfa (Medicago sativa L.), or kura clover (Trifolium ambiguum M. Bieb.). Warm‐season pastures were monocultures of big bluestem (Andropogon gerardii Vitman) or switchgrass (Panicum virgatum L.). Kura clover was the only legume that persisted well over time, and because of this, pastures interseeded with kura clover maintained a higher nutritive value than either those interseeded with alfalfa or birdsfoot trefoil. This resulted in higher total liveweight gains for cattle grazing sequences that included pastures interseeded with kura clover. In general, rotating cattle to warm‐season grass pastures during summer was less advantageous than having them remain on cool‐season pastures at a lower stocking rate because warm‐season pasture nutritive value was lower and declined more rapidly. However, despite lower nutritive value and consequently animal performance, sequences with warm‐season grass pastures did perform well under some conditions and may be a desirable alternative under some circumstances. Having a warm‐season grass pasture in the grazing sequence provides an opportunity to relieve cool‐season pastures when growth conditions become limiting and introduces flexibility into the management system.
Economics of Purchasing a Yield Monitor for Split‐Planter Corn Hybrid Testing
Authors: Cox William J. , Knoblauch Wayne A. , van Es Harold M. , Katsvairo Tawainga W. , Glos Michael A.
Published: July 2010

Economic studies have not been conducted on yield monitors because it is difficult to separate out costs and benefits of yield mapping. We conducted split‐planter studies in 1999 on two farms to test a new (‘37M81’) and proven (‘3752’) corn (Zea mays L.) hybrid ($10 bag−1 seed cost difference) to determine if farmers could offset yield monitor costs by identifying the better hybrid to plant in subsequent years. At one farm, 37M81 yielded 0.48 Mg ha−1 greater than 3752 in 1999. In 2000 and 2001, 37M81 yielded 1.03 Mg ha−1 greater for an $85 ha−1 return above seed costs. If 37M81 were planted on 20 ha in 2000 and 2001, additional revenue from higher yields offset annual fixed costs ($1655) of a yield monitor. If 37M81 were planted to 320 ha, relative profit ($79 ha−1) did not equal the $85 ha−1 return for planting 37M81 without on‐farm testing. At the other farm, 3752 yielded 0.39 Mg ha−1 greater in 1999 but the same (7.7 Mg ha−1) in 2000 and 2001. Savings in seed costs ($9 ha−1) did not offset annual yield monitor costs in 2000 and 2001. If 3752 were planted to more than 200 ha, relative profit from the yield monitor purchase exceeded relative profit for planting 37M81 without on‐farm testing. We recommend that farmers who plant 200 or more corn hectares conduct split‐planter studies to compare new hybrid releases vs. proven hybrids because seed costs have increased significantly.
Pest Management Implications of Reduced Fallow Periods in Dryland Cropping Systems in the Great Plains
Authors: Peairs F. B. , Bean B. , Gossen B. D.
Published: July 2010

The intensification of traditional wheat (Triticum aestivum L.)–fallow production systems may have important consequences for management of insects, pathogens, and weeds in Great Plains dryland production systems. Assessment of these consequences is difficult due to the diversity of production systems, environmental conditions, and pests found in the region. Certain pest groups, such as weeds, traditionally controlled during the fallow period, may be favored by intensified cropping while others, such as those specializing on wheat, should be disadvantaged. Changes in pest and disease complexes will likely be evolutionary rather than revolutionary, as has been the case with other significant changes in production practices. Preventive practices in dryland production systems currently emphasize the control of grassy weeds while intensified systems may have less emphasis on the control of volunteer wheat. Crop rotation will remain a key avoidance strategy for pathogens and will help broaden herbicide options. Pest monitoring provides essential information on pest activity and environmental conditions and will become more complex as production systems are intensified. Important suppressive practices for dryland production systems include conservation biological control, tillage, and chemical controls. Chemical control, in particular, is expected to become more complicated due to drift concerns, rotational restrictions, the possible need for herbicide‐tolerant crops, and the development of weed populations resistant to glyphosate. Pest management requirements should be considered during cropping system design and establishment.
Large‐Area Maize Yield Forecasting Using Leaf Area Index Based Yield Model
Authors: Baez‐Gonzalez Alma Delia , Kiniry James R. , Maas Stephan J. , Tiscareno Mario L. , Macias C. Jaime , Mendoza Jose L. , Richardson Clarence W. , Salinas G. Jaime , Manjarrez Juan R.
Published: July 2010

Large‐area yield prediction early in the growing season is important in agricultural decision‐making. This study derived maize (Zea mays L.) leaf area index (LAI) estimates from spectral data and used these estimates with a simple LAI‐based yield model to forecast yield under irrigated conditions in large areas in Sinaloa, Mexico. Leaf area index was derived from satellite data with the use of an equation developed with LAI measurements from farmers' fields during the 2001–2002 autumn–winter growing season. These measurements were correlated with the normalized difference vegetation index values from 2002 Landsat ETM+ (enhanced thematic mapper) data. The equation was then tested with 2003 Landsat imagery data. A yield model was validated with maximum LAI and yield data measured in farmers' fields in northern and central Sinaloa during three consecutive autumn–winter growing seasons (1999–2000, 2000–2001, and 2001–2002). The yield model was further validated with 2002–2003 autumn–winter ground LAI (gLAI) and satellite‐derived LAI (sLAI) data from 71 farmers' fields in northern and central Sinaloa. Grain yield was predicted with a mean error of −9.2% with maximum gLAI and −11.2% with sLAI. Results indicate that the yield model using LAI can forecast yield in large areas in Sinaloa in the middle of the growing season with a mean absolute error of −1.2 Mg ha−1. The use of sLAI in place of ground measurements increased the mean absolute error by 0.3 Mg ha−1. Nevertheless, the use of sLAI would eliminate laborious LAI measurements for large‐area yield prediction in Sinaloa.
Field‐Scale Variability in Optimal Nitrogen Fertilizer Rate for Corn
Authors: Scharf Peter C. , Kitchen Newell R. , Sudduth Kenneth A. , Davis J. Glenn , Hubbard Victoria C. , Lory John A.
Published: July 2010

Applying only as much N fertilizer as is needed by a crop has economic and environmental benefits. Understanding variability in need for N fertilizer within individual fields is necessary to guide approaches to meeting crop needs while minimizing N inputs and losses. Our objective was to characterize the spatial variability of corn (Zea mays L.) N need in production corn fields. Eight experiments were conducted in three major soil areas (Mississippi Delta alluvial, deep loess, claypan) over 3 yr. Treatments were field‐length strips of discrete N rates from 0 to 280 kg N ha−1. Yield data were partitioned into 20‐m increments, and a quadratic‐plateau function was used to describe yield response to N rate for each 20‐m section. Economically optimal N fertilizer rate (EONR) was very different between fields and was also highly variable within fields. Median EONR for individual fields ranged from 63 to 208 kg N ha−1, indicating a need to manage N fertilizer differently for different fields. In seven of the eight fields, a uniform N application at the median EONR would cause more than half of the field to be over‐ or underfertilized by at least 34 kg N ha−1. Coarse patterns of spatial variability in EONR were observed in some fields, but fine and complex patterns were also observed in most fields. This suggests that the use of a few appropriate management zones per field might produce some benefits but that N management systems using spatially dense information have potential for greater benefits. Our results suggest that further attempts to develop systems for predicting and addressing spatially variable N needs are justified in these production environments.
The Dissolution of Synthetic Goethites: The Early Stage
Authors: Cornell R. M. , Posner A. M. , Quirk J. P.
Published: July 2010

The kinetic curve for the early stage of dissolution of synthetic goethite is linear except for a small curved region close to the origin. This curved region has been shown to be due to the very rapid dissolution of a small amount of amorphous ferric hydroxide which is associated with the goethite.

The amount of amorphous ferric hydroxide is usually no more than 0.2% of the total mass of goethite. Its presence cannot be detected even by electron diffraction methods.
Distribution and Characterization of Noncrystalline Inorganic Components in Spodosols and Spodosol‐Like Soils
Authors: Kodama H. , Wang C.
Published: July 2010

Three pedons of Spodosols or Spodosol‐like soils from Quebec and Ontario containing a considerable amount of acid‐oxalate extractable Al, Fe, and Si were examined in detail by additional selective chemical dissolution, x‐ray diffraction, infrared absorption, and Mössbauer methods to characterize noncrystalline and/or short‐range ordered soil mineral components. The ratio of Fe extracted by acid oxalate to Fe extracted by dithionite‐citrate was nearly unity for most of the clay samples from B and C horizons, indicating that almost all free Fe existed in noncrystalline forms. Amounts of Fe and Al extracted by acid‐oxalate were comparable to those by alkaline Tiron. However, Tiron (1,2‐dihydroxybenzene,3,5‐disulfonic acid disodium salt, C6H4Na2O8S2) generally extracted more Si than acid‐oxalate and Si was mostly concentrated in surface horizons. The difference in the amounts of Si extracted was related to the difference in solubilities of opaline silica in the acid‐oxalate and alkaline Tiron solutions. The presence of opaline silica was further supported by differential x‐ray diffraction and infrared absorption data. Noncrystalline Fe and Al were concentrated in lower horizons and in one case more Al than Fe appeared to be accumulated in slightly lower B subhorizons. Differential XRD patterns of samples from B horizons showed broad maxima at 0.33, 0.25, 0.22, 0.17, and 0.15 nm, indicating the presence of allophane and ferrihydrite. The presence of ferrihydrite was also supported by Mössbauer data.
Evaluation of Measurement Scale Using Imbibition Experiments in Volcanic Tuffs
Authors: Flint Alan L. , Flint Lorraine E. , Richards Kenneth A.
Published: July 2010

A major issue in the site characterization at Yucca Mountain, Nevada, a potential site for a high‐level nuclear waste repository, is the relevance of laboratory‐scale measurements on cores to field‐scale processes, particularly water flow. Calculation of Philip's sorptivity parameter using imbibition of water into rock was selected as a simple test to describe hydrologic parameters at both laboratory and field scales and to study effects of sample size and spatial variability. Laboratory‐ scale imbition experiments were conducted on two sizes of core from two boreholes drilled in layered nonwelded tuff and fractured welded tuff. Laboratory experiments were compared with field experiments in the boreholes using neutron logs and a field‐scale Mariotte system. Measured sorptivity for both sizes of core were virtually identical and both could predict field‐scale sorptivity if enough samples were used to account for spatial heterogeneity. Core data was less useful in predicting the neutron log data due to the nature of the neutron probe measurement and difficulties in accounting for effects of the unique system geometry. Mean neutron log values could not predict the field results from the welded borehole due to fractures transmitting but not retaining water, and could not predict laboratory results because of scale and sampling volume differences. The mean neutron log data could, however, approximate the large‐scale field results in the nonwelded borehole.
Co‐Ion Exclusion by Clay Surfaces: I. Equations for 1:1, 2:1, and 3:1 Electrolyte Solutions
Authors: Pashley R. M. , Quirk J. P.
Published: July 2010

The distribution of co‐ions in the vicinity of charged clay surfaces has been treated theoretically within the context of an electric double layer structure consisting of a Stern layer and Gouy diffuse layer. Equations have been developed, using Gouy‐Chapman theory, that describe the depth of exclusion of co‐ions in terms of the electrolyte concentration and the Gouy plane potential for 1:1, 2:1, and 3:1 electrolyte solutions. The volume from which co‐ions are excluded is obtained by multiplying the depth of exclusion by the appropriate surface area of the clay. Since, in general, the surface potentials of clays are less negative than −100 mV, these equations, especially for 1:1 electrolytes, can be used to obtain surface potentials from exclusion volumes. These volumes can be used to obtain the surface potential across a wide range of electrolyte concentrations, if the area of the interface is known from crystallographic data or from N2 adsorption isotherms. The measured volume of exclusion for each concentration is, in this study, corrected for the volume of the Stern layer, with an assumed thickness of 5.5 Å.
Coliform status of water bodies from two districts in Ghana, west Africa: implications for rural water resources management
Authors: Anim F. , Nyame F. K. , Armah T. K.
Published: July 2010

Investigations were conducted on the total and faecal coliform status of streams, hand-dug wells and boreholes highly patronised by communities in the West Akim and Kwaebibirem Districts, Eastern Ghana. Total coliform values obtained range from 60–2,672 cfu, 0–680 cfu and 0–128 cfu for streams, hand-dug wells and boreholes, respectively. Faecal coliform values similarly range from 31–1,988 cfu, 0–136 cfu and 0–36 cfu for streams, hand-dugs and boreholes, respectively. The data indicates that samples from streams and hand-dug wells returned high coliform counts beyond the Maximum Permissible Levels (MPL) recommended by the World Health Organization (WHO). Some borehole water contained coliform counts above MPL. Because many rural people in the areas studied, and indeed in most areas in Ghana, depend heavily on these principal sources of water for drinking and other domestic purposes, a policy response that incorporates periodic assessment of water quality in rural communities may be appropriate. In addition, it would seem that current government and development partner programmes in the water resources sector that emphasise provision of borehole water must be integrated with land use considerations, water quality monitoring and education on environmental awareness in local communities.
Coleochaete Breb. and Bulbochaete Agardh from North-Eastern Uttar Pradesh, India
Authors: Srivastava A. K. , Mishra P. K.
Published: July 2010

Present communication deals with morpho-taxonomic descriptions of four taxa that includes two genera and four species of class Chlorophyceae. These species are Coleochaete scutata Brebisson Coleochaete soluta (Brebisson) Pringsheim, Bulbochaete nordestedtii (Wittrock) Him and Bulbochaete pseudoaerolata Bock and Bock. One of the species B. pseudoaerolata Bock and Bock is a new record for India. Key words: Fresh water, Chlorophyceae DOI: 10.3126/eco.v16i0.3474ECOPRINT 16: 59-63, 2009
Robert E. Grant's later views on organic development: the Swiney lectures on “Palaeozoology”, 1853–1857
Authors: DESMOND ADRIAN
Published: July 2010

SUMMARY

R. E. Grant's advocacy of transmutation is considered in relation to the scientific climate of the 1850s. To understand the palaeontological framework of his development theory, the unpublished “Palaeozoology” lectures, delivered in 1853–7, are analysed and his sources tabulated. The lectures are shown to contain the following additional themes: (1) a refutation of Lyell's steady-state geology, (2) support for serial development, (3) use of metamorphic effacement to explain the lack of pre-Silurian fossils, and (4) nebular hypothesis. The difficulty of supporting serial development using fossil evidence at this late date is discussed, and this difficulty is deemed to have contributed to the failure of Grant's theory of species “generation”.
Dr John Brickell's Catalogue of American Trees and Shrubs (1739): A bibliographic misadventure
Authors: SIMPSON MARCUS B.
Published: July 2010

Dr John Brickell, the obscure author/compiler of the Natural History of North-Carolina (1737), has long been credited with a second work, commonly cited as A Catalogue of American Trees and Shrubs which will endure the Climate of England (1739). Careful review of the available data suggests that this attribution may have resulted from an error in Robert Watt's Bibliotheca Britannica, in which a broadside catalogue sheet bearing the title, issued by plant nurseryman Christopher Gray, was mistakenly credited to Brickell.
Maria Sibylla Merian, naturalist and artist (1647–1717): a commemoration on the occasion of the 350th anniversary of her birth
Authors: PIETERS FLORENCE F.J.M. , WINTHAGEN DINY
Published: July 2010

Maria Sibylla Merian was born on 2 April 1647 in Frankfurt (Germany) and grew up among artists. She was one of the first who studied the metamorphoses of insects, preceded by the Dutch naturalists Johannes Goedaert (1620–1668) and Jan Swammerdam (1637–1680). From 1674 she began to investigate these metamorphoses systematically, resulting in her first scientific book Der Raupen wunderbare Verwandelung und sonderbare Blumen-nahrung [The wondrous transformation of caterpillars and their remarkable diet of flowers]. The first part of this book was published in Nuremberg in 1679, containing 50 plates in quarto, all engraved by herself, and the second part in Frankfurt in 1683. Now she had discovered her definitive style, depicting the life cycle of a butterfly on the caterpillar's host plant in natural size on one plate, in a beautiful lay-out.

In 1685 she entered a Labadist cloister in Friesland, joined by her mother and her two daughters. However, as early as 1691 she left this cloister and settled in Amsterdam. From here she undertook an expedition to Surinam in 1699 to study its superb natural history, accompanied by her younger daughter. She stayed there for only 21 months because she became seriously ill, but she recovered and the publication of her folio volume on the metamorphoses of Surinam insects in 1705 made her worldfamous among natural scientists and art historians alike. However, she was also criticized and the reasons for this are discussed.

An additional letter by Merian (17 letters were hitherto known) was discovered in a Parisian collection.
The fate of Marmaduke Tunstall's collections
Authors: JESSOP L.
Published: July 2010

Dispersal of the Museum of Marmaduke Tunstall (1743–1790) began shortly after his death. His important systematic collection of birds was acquired first by George Allan of Darlington and subsequently by the Newcastle Museum. By the end of the nineteenth century the bird collection had all but disappeared. The possible reasons for the loss of this material are discussed within the context of the history of the Newcastle Museum and its successor the Hancock Museum. Surviving material from Tunstall's collection is listed.
Patrick Browne M.D. (c. 1720–1790), an Irish doctor in the Caribbean: his residence on Saint Croix (1757–1765) and his unpublished accounts of volcanic activity on Montserrat
Authors: NELSON E. CHARLES
Published: July 2010

Patrick Browne resided on the Caribbean islands of Saint Croix (a Danish possession) and Montserrat (an English possession) during the 1750s and 1760s. He collected and recorded the flora of Saint Croix; some of his notes about the plants of the island have survived and are transcribed. On Montserrat he made observations on the active volcano; the surviving manuscript accounts of the sulphur-rich springs are transcribed.
The correspondence between Louis Agassiz and the French naturalists Georges Cuvier, Lucien Bonaparte and Alexandre Brongniart in the manuscript collections of the Muséum National d'Histoire Naturelle and Institut de France
Authors: DASZKIEWICZ PIOTR , KEITH PHILIPPE
Published: July 2010

Louis Agassiz's stay in Paris (1832) and his correspondence with the French naturalists played a major role in his career. Some of this correspondence remains unpublished. This presentation and analysis of Agassiz's correspondence with Cuvier, Brongniart and Bonaparte introduces new biographical information about Agassiz. These letters give us an insight into the origins of Agassiz's ideas on taxonomic categories (species, genus) which left their mark on all his work. The letters show the hitherto unsuspected importance of Agassiz's role in the preparation of Bonaparte's Iconografia della Fauna Italia. A careful study of these letters has enabled us to offer a new interpretation of the correspondence between Agassiz and Cuvier on the subject of the Swiss and German fish collections, now in Muséum National d'Histoire Naturelle, Paris. Lastly, these letters allow us to understand the origin of the descriptions of certain species.
Light‐Switchable Janus [2]Rotaxanes Based on α‐Cyclodextrin Derivatives Bearing Two Recognition Sites Linked with Oligo(ethylene glycol)
Authors: Li Shujing , Taura Daisuke , Hashidzume Akihito , Harada Akira
Published: July 2010

Two Janus [2]rotaxanes, 5a and 5b, with α‐cyclodextrin (α‐CD) derivatives substituted on the 6‐position with two recognition sites (azobenzene and heptamethylene (C7)) that were linked with linkers of different lengths (oligo(ethylene glycol) with a degree of polymerization equal to 2 or approximately 21) were synthesized and characterized. 2D ROESY NMR spectroscopy and circular dichroism (cd) spectra demonstrated that the recognition site of the α‐CD moiety was switched by photoisomerization of the azobenzene moiety in 5a and 5b. The different size changes of 5a and 5b in hydrodynamic radius (RH) owing to the different length of linker between two recognition sites were observed by pulse‐field‐gradient spin‐echo NMR spectroscopy. The kinetic results indicated that the different length of linker had no or a weak effect for the photoisomerization process of 5a and 5b.
Peering into Biological Nanopore: A Practical Technology to Single‐Molecule Analysis
Authors: Wang Hai‐Yan , Ying Yi‐Lun , Li Yang , Long Yi‐Tao
Published: July 2010

As a unique technique at the singe‐molecule level to explore the distribution and temporal order of events, nanopore technology has attracted increasing attention. In comparison to the previous applications in DNA sequencing, this Focus Review highlights the technical details of biological nanopores, especially α‐hemolysin, in the analysis of peptides and proteins. The instrument configurations, experimental interferences, and data analysis including the conformation of peptides and proteins and their interactions for single‐molecule detection are discussed.
L‐Prolinamides Derived from Chiral and Achiral 1,2‐Diamines as Useful Bifunctional Organocatalysts for Direct Diastereo‐ and Enantioselective Aldol Reaction
Authors: Pedrosa Rafael , Andrés José M. , Manzano Rubén , Rodríguez Paula
Published: July 2010

Diastereomeric catalysts 5 and epi‐5, which differ in the configuration of the stereocenter at the amino component, have been prepared from L‐proline and (S)‐N2,N2‐dibenzyl‐3‐methylbutane‐1,2‐diamine or (R)‐N1,N1‐dibenzyl‐3‐methylbutane‐1,2‐diamine, respectively. Diastereomeric prolinamides 10 and epi‐10, which are regioisomers of 5 and epi‐5, respectively, were obtained from the same starting compounds. All of the catalysts promoted high diastereo‐ and enantioselectivity in the cross‐aldol reaction between aromatic aldehydes and cyclohexanone using acetic acid as co‐catalyst. A small match/mismatch effect over the stereoselection was observed, depending on the configuration of thestereocenters at the proline and diamine components. In general, the best results were obtained with catalyst 5, which has the same configuration at both stereocenters. Under the same reaction conditions, prolinamide 20, which was synthesized from L‐proline and ethylene diamine, withoutstereocenters at the diamine component, behaved as an excellent enantioselective organocatalyst, giving the aldol products in very high diastereo‐ and enantioselectivity.
Love songs, bird brains and diffusion tensor imaging
Authors: De Groof Geert , Van der Linden Annemie
Published: July 2010

The song control system of songbirds displays a remarkable seasonal neuroplasticity in species in which song output also changes seasonally. Thus far, this song control system has been extensively analyzed by histological and electrophysiological methods. However, these approaches do not provide a global view of the brain and/or do not allow repeated measurements, which are necessary to establish causal correlations between alterations in neural substrate and behavior. Research has primarily been focused on the song nuclei themselves, largely neglecting their interconnections and other brain regions involved in seasonally changing behavior. In this review, we introduce and explore the song control system of songbirds as a natural model for brain plasticity. At the same time, we point out the added value of the songbird brain model for in vivo diffusion tensor techniques and its derivatives. A compilation of the diffusion tensor imaging (DTI) data obtained thus far in this system demonstrates the usefulness of this in vivo method for studying brain plasticity. In particular, it is shown to be a perfect tool for long‐term studies of morphological and cellular changes of specific brain circuits in different endocrine/photoperiod conditions. The method has been successfully applied to obtain quantitative measurements of seasonal changes of fiber tracts and nuclei from the song control system. In addition, outside the song control system, changes have been discerned in the optic chiasm and in an interhemispheric connection. DTI allows the detection of seasonal changes in a region analogous to the mammalian secondary auditory cortex and in regions of the ‘social behavior network’, an interconnected group of structures that controls multiple social behaviors, including aggression and courtship. DTI allows the demonstration, for the first time, that the songbird brain in its entirety exhibits an extreme seasonal plasticity which is not merely limited to the song control system as was generally believed. Copyright © 2010 John Wiley & Sons, Ltd.
Analysis of changes in tyrosine and serine phosphorylation of red cell membrane proteins induced by P. falciparum growth
Authors: Pantaleo Antonella , Ferru Emanuela , Carta Franco , Mannu Franca , Giribaldi Giuliana , Vono Rosa , Lepedda Antonio J. , Pippia Proto , Turrini Francesco
Published: July 2010

Phosphorylation of erythrocyte membrane proteins has been previously documented following infection and intracellular growth of the malarial parasite, Plasmodium falciparum in red cells. Much of this data dealt with phosphorylation of serine residues. In this study, we report detailed characterization of phosphorylation of serine and tyrosine residues of red cell membrane proteins following infection by P falciparum. Western blot analysis using anti‐phosphotyrosine and anti‐phosphoserine antibodies following 2‐DE in conjunction with double channel laser‐induced infrared fluorescence enabled accurate assessment of phosphorylation changes. Tyrosine phosphorylation of band 3 represented the earliest modification observed during parasite development. Band 3 tyrosine phosphorylation observed at the ring stage appears to be under the control of Syk kinase. Serine and tyrosine phosphorylation of additional cytoskeletal, trans‐membrane and membrane associated proteins was documented as intracellular development of parasite progressed. Importantly, during late schizont stage of parasite maturation, we observed widespread protein dephosphorylation. In vitro treatments that caused distinct activation of red cell tyrosine and serine kinases elicited phosphorylative patterns similar to what observed in parasitized red blood cell, suggesting primary involvement of erythrocyte kinases. Identification of tyrosine phosphorylations of band 3, band 4.2, catalase and actin which have not been previously described in P. falciparum infected red cells suggests new potential regulatory mechanisms that could modify the functions of the host cell membrane.