PMID(sorted ascending)
results of a nationwide survey to determine feedstuffs fed to lactating dairy cows.a nationwide survey to determine feedstuffs used in the diets of dairy cows was conducted. this survey was mailed to dairy nutritionists at universities in each state to describe the use of 144 feedstuffs. twenty-eight states responded and were grouped by region as follows: northeast (maine, maryland, new hampshire, new york, ohio, vermont, and west virginia), northwest (idaho, oregon, and washington), midwest (iowa, illinois, michigan, minnesota, missouri, nebraska, north dakota, south dakota, ...199910068966
puzzling industry response to prodigene fiasco. 200312511893
increasing nitrogen use efficiency of corn in midwestern cropping systems.nitrogen (n) loss from agricultural systems raises concerns about the potential impact of farming practices on environmental quality. n is a critical input to agricultural production. however, there is little understanding of the interactions among crop water use, n application rates, and soil types. this study was designed to quantify these interactions in corn ( zea mays l.) grown in production-size fields in central iowa on the clarion-nicollet-webster soil association. seasonal water use var ...200112805822
estimated historical and current nitrogen balances for illinois.the midwest has large riverine exports of nitrogen (n), with the largest flux per unit area to the mississippi river system coming from iowa and illinois. we used historic and current data to estimate n inputs, outputs, and transformations for illinois where human activity (principally agriculture and associated landscape drainage) have had a dominant impact. presently, approximately 800,000 mg of n is added each year as fertilizer and another 420,000 mg is biologically fixed, primarily by soybe ...200112805881
long-term effects of nitrogen fertilizer use on ground water nitrate in two small watersheds.changes in agricultural management can minimize no3-n leaching, but then the time needed to improve ground water quality is uncertain. a study was conducted in two first-order watersheds (30 and 34 ha) in iowa's loess hills. both were managed in continuous corn (zea mays l.) from 1964 through 1995 with similar n fertilizer applications (average 178 kg ha(-1) yr(-1)), except one received applications averaging 446 kg n ha(-1) yr(-1) between 1969 and 1974. this study determined if no3-n from these ...201314674538
simulating nitrate drainage losses from a walnut creek watershed field.this study was designed to evaluate the improved version of the root zone water quality model (rzwqm) using 6 yr (1992-1997) of field-measured data from a field within walnut creek watershed located in central iowa. measured data included subsurface drainage flows, no3-n concentrations and loads in subsurface drainage water, and corn (zea mays l.) and soybean [glycine mar (l.) merr.] yields. the dominant soil within this field was webster (fine-loamy, mixed, superactive, mesic typic endoaquolls) ...200414964365
trap height and orientation of yellow sticky traps affect capture of chaetocnema pulicaria (coleoptera: chrysomelidae).field studies were conducted in iowa during 2001 and 2002 to determine the optimal sampling height and orientation for using yellow sticky cards to monitor populations of chaetocnema pulicaria melsheimer, the vector of the bacterial pathogen pantoea stewartii subsp, stewartii, the causal organism of stewart's disease of corn, zea mays l.. sticky cards were placed at five different heights (0.15, 0.30, 0.45, 0.60, and 0.90 m) and three orientations (horizontal, vertical, and 30 degree angle) at t ...200414998138
effect of environment on resistance to the european corn borer (lepidoptera: crambidae) in maize.the european corn borer, ostrinia nubilalis (hübner) (lepidoptera: crambidae), is a major pest of maize, zea mays l., in many temperate parts of the world. genotype-by-environment interaction effects can make relative performance unpredictable and may hamper selection for resistance to european corn borer. the objective of this study was to determine the effect of environment on genotypic reaction to european corn borer resistance in maize. a set of 12 maize inbred lines was chosen to represent ...200415568368
agricultural practices influence flow regimes of headwater streams in western iowa.agricultural tillage influences runoff and infiltration, but consequent effects on watershed hydrology are poorly documented. this study evaluated 25 yr (1971-1995) hydrologic records from four first-order watersheds in iowa's loess hills. two watersheds were under conventional tillage and two were under conservation (ridge) tillage, one of which was terraced. all four watersheds grew corn (zea mays l.) every year. flow-frequency statistics and autoregressive modeling were used to determine how ...200916091607
nontarget arthropod abundance in areawide-managed corn habitats treated with semiochemical-based bait insecticide for corn rootworm (coleoptera: chrysomelidae) control.impacts of semiochemical-based insecticidal bait applications on beneficial arthropod groups common to field corn, zea mays l., habitats were assessed in areawide-managed field sites in south dakota and iowa during 1997 and 1998. slam, a commercial bait formulation comprised of 87% cucurbitacin and 13% carbaryl insecticide, was used for management of adult rootworm, diabrotica spp., and controls consisted of cornfield habitats without bait applications. effects on beneficial organisms were varia ...200516539120
nitrous oxide emissions from corn-soybean systems in the midwest.soil n2o emissions from three corn (zea mays l.)-soybean [glycine max (l.) merr.] systems in central iowa were measured from the spring of 2003 through february 2005. the three managements systems evaluated were full-width tillage (fall chisel plow, spring disk), no-till, and no-till with a rye (secale cereale l. 'rymin') winter cover crop. four replicate plots of each treatment were established within each crop of the rotation and both crops were present in each of the two growing seasons. nitr ...201316825470
population dynamics of a western corn rootworm (coleoptera: chrysomelidae) variant in east central illinois commercial maize and soybean fields.three on-farm sites in iroquois county, il, each containing an adjacent 16.2-ha commercial production maize, zea mays l., and soybean, glycine max (l.) merr., field, were monitored for western corn rootworm, diabrotica virgifera virgifera leconte (coleoptera: chrysomelidae), adults from june through september 1999-2001. mean captures of d. v. virgifera adults as measured with pherocon am yellow sticky traps were significantly greater in maize than in soybean. overall mean numbers of d. v. virgif ...200717849858
comparison of fate and transport of isoxaflutole to atrazine and metolachlor in 10 iowa rivers.isoxaflutole (ixf), a newer low application rate herbicide, was introduced for weed control in corn (zea mays) to use as an alternative to widely applied herbicides such as atrazine. the transport of ixf in streamwater has not been well-studied. the fate and transport of ixf and two of its degradation products was studied in 10 iowa rivers during 2004. ixf rapidly degrades to the herbicidally active diketonitrile (dkn), which degrades to a biologically inactive benzoic acid (ba) analogue. ixf wa ...200717993131
effect of liquid swine manure rate, incorporation, and timing of rainfall on phosphorus loss with surface runoff.excessive manure phosphorus (p) application increases risk of p loss from fields. this study assessed total runoff p (tpr), bioavailable p (bap), and dissolved reactive p (drp) concentrations and loads in surface runoff after liquid swine (sus scrofa domesticus) manure application with or without incorporation into soil and different timing of rainfall. four replicated manure p treatments were applied in 2002 and in 2003 to two iowa soils testing low in p managed with corn (zea mays l.)-soybean ...200818178885
effect of nitrogen fertilizer application on growing season soil carbon dioxide emission in a corn-soybean rotation.nitrogen application can have a significant effect on soil carbon (c) pools, plant biomass production, and microbial biomass c processing. the focus of this study was to investigate the short-term effect of n fertilization on soil co(2) emission and microbial biomass c. the study was conducted from 2001 to 2003 at four field sites in iowa representing major soil associations and with a corn (zea mays l.)-soybean (glycine max l. merr.) rotation. the experimental design was a randomized complete b ...201318268294
epic modeling of soil organic carbon sequestration in croplands of iowa.depending on management, soil organic carbon (soc) is a potential source or sink for atmospheric co(2). we used the epic model to study impacts of soil and crop management on soc in corn (zea mays l.) and soybean (glycine max l. merr.) croplands of iowa. the national agricultural statistics service crops classification maps were used to identify corn-soybean areas. soil properties were obtained from a combination of ssurgo and statsgo databases. daily weather variables were obtained from first o ...200818574164
use of spectral vegetation indices derived from airborne hyperspectral imagery for detection of european corn borer infestation in iowa corn plots.eleven spectral vegetation indices that emphasize foliar plant pigments were calculated using airborne hyperspectral imagery and evaluated in 2004 and 2005 for their ability to detect experimental plots of corn manually inoculated with ostrinia nubilalis (hübner) neonate larvae. manual inoculations were timed to simulate infestation of corn, zea mays l., by first and second flights of adult o. nubilalis. the ability of spectral vegetation indices to detect o. nubilalis-inoculated plots improved ...200818950044
increasing corn for biofuel production reduces biocontrol services in agricultural landscapes.increased demand for corn grain as an ethanol feedstock is altering u.s. agricultural landscapes and the ecosystem services they provide. from 2006 to 2007, corn acreage increased 19% nationally, resulting in reduced crop diversity in many areas. biological control of insects is an ecosystem service that is strongly influenced by local landscape structure. here, we estimate the value of natural biological control of the soybean aphid, a major pest in agricultural landscapes, and the economic imp ...200819075234
nitrogen fertilizer effects on soil carbon balances in midwestern u.s. agricultural systems.a single ecosystem dominates the midwestern united states, occupying 26 million hectares in five states alone: the corn-soybean agroecosystem [zea mays l.-glycine max (l.) merr.]. nitrogen (n) fertilization could influence the soil carbon (c) balance in this system because the corn phase is fertilized in 97-100% of farms, at an average rate of 135 kg n x ha(-1) x yr(-1). we evaluated the impacts on two major processes that determine the soil c balance, the rates of organic-carbon (oc) inputs and ...200919688919
sources of nitrate yields in the mississippi river basin.riverine nitrate n in the mississippi river leads to hypoxia in the gulf of mexico. several recent modeling studies estimated major n inputs and suggested source areas that could be targeted for conservation programs. we conducted a similar analysis with more recent and extensive data that demonstrates the importance of hydrology in controlling the percentage of net n inputs (nni) exported by rivers. the average fraction of annual riverine nitrate n export/nni ranged from 0.05 for the lower miss ...201021043271
perennial filter strips reduce nitrate levels in soil and shallow groundwater after grassland-to-cropland conversion.many croplands planted to perennial grasses under the conservation reserve program are being returned to crop production, and with potential consequences for water quality. the objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (no3-n) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (pfs) to mitigate increases in no3-n levels. the study, conducted at the neal smith national wildlife ref ...201321284298
abundance and distribution of western and northern corn rootworm (diabrotica spp.) and prevalence of rotation resistance in eastern iowa.the western corn rootworm diabrotica virgifera virgifera leconte (coleoptera: chrysomelidae) and the northern corn rootworm diabrotica barberi smith & lawrence (coleoptera: chrysomelidae) are major pests of corn (zea mays l.). historically, crop rotation has been an effective management strategy, but both species have adapted to crop rotation in the midwest. for both species in eastern iowa, we measured abundance and prevalence of rotation resistance using sticky traps and emergence cages in fie ...201323448029
the impact of prairie strips on aphidophagous predator abundance and soybean aphid predation in agricultural catchments.reconstructing prairie vegetation in row crop-dominated agricultural landscapes may contribute to several ecosystem services, including the biological control of insect pests, such as the soybean aphid aphis glycines matsumura. the influence of the amount and configuration of reconstructed prairie vegetation on the delivery of ecosystem services was investigated in several small catchments at neal smith national wildlife refuge in iowa. treatments include catchments entirely in row crops under a ...201425199149
insect pollinators in iowa cornfields: community identification and trapping method analysis.availability of mass flowering plants in landscapes dominated by agriculture can have a strong positive impact on the density of generalist, native pollinators. row-crop production in iowa accounts for 75% of the arable acres, with corn, zea mays, representing the majority of hectares planted. to date, there has been no description of the insect pollinator community found within iowa cornfields. we report a field study to determine the optimal sampling methodology to characterize the community o ...201627459648
defining the insect pollinator community found in iowa corn and soybean fields: implications for pollinator conservation.although corn (zea mays l.) and soybeans (glycine max l.) do not require pollination, they offer floral resources used by insect pollinators. we asked if a similar community of insect pollinators visits these crops in central iowa, a landscape dominated by corn and soybean production. we used modified pan traps (i.e., bee bowls) in both corn and soybean fields during anthesis and used nonmetric multidimensional scaling (nms) to compare the communities found in the two crops. summed across both c ...201627516433
root parameters show how management alters resource distribution and soil quality in conventional and low-input cropping systems in central iowa.plant-soil relations may explain why low-external input (lei) diversified cropping systems are more efficient than their conventional counterparts. this work sought to identify links between management practices, soil quality changes, and root responses in a long-term cropping systems experiment in iowa where grain yields of 3-year and 4-year lei rotations have matched or exceeded yield achieved by a 2-year maize (zea mays l.) and soybean (glycine max l.) rotation. the 2-year system was conventi ...201627792744
residual soil nitrate content and profitability of five cropping systems in northwest iowa.many communities in the midwestern united states obtain their drinking water from shallow alluvial wells that are vulnerable to contamination by no3-n from the surrounding agricultural landscape. the objective of this research was to assess cropping systems with the potential to produce a reasonable return for farmers while simultaneously reducing the risk of no3-n movement into these shallow aquifers. from 2009 to 2013 we conducted a field experiment in northwest iowa in which we evaluated five ...201728248976
maximum soil organic carbon storage in midwest u.s. cropping systems when crops are optimally nitrogen-fertilized.nitrogen fertilization is critical to optimize short-term crop yield, but its long-term effect on soil organic c (soc) is uncertain. here, we clarify the impact of n fertilization on soc in typical maize-based (zea mays l.) midwest u.s. cropping systems by accounting for site-to-site variability in maize yield response to n fertilization. within continuous maize and maize-soybean [glycine max (l.) merr.] systems at four iowa locations, we evaluated changes in surface soc over 14 to 16 years acro ...201728249014
Displaying items 1 - 28 of 28