bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yield and Nitrogen Use Efficiency of Irrigated Corn in the Northern Great Plains
Authors: Wienhold Brian J. , Trooien Todd P. , Reichman George A. 
Published: July 2010

AbstractNitrogen and water are the two most common limitations to crop production in the semiarid northern Great Plains. Little is known about N use efficiency by irrigated corn (Zea mays L.) in this region. A study was conducted to determine how irrigation and N fertility levels affect growth and N use efficiency by corn. Corn was grown under three irrigation levels: precipitation plus irrigation equal to one, two, and three times the calculated evapotranspiration (ET) rate. Fertilizer use efficiency was determined using 15N‐enriched fertilizer applied at rates equivalent to 100 and 200 kg N ha−1. Grain and dry matter yields, N content, and utilization of fertilizer N all exhibited yearly variations, probably the result of annual weather patterns, especially temperature. For years when temperatures during the growing season were below the 30‐yr average and affected corn growth, there were no differences in yields and N content between the two fertility levels. For years when temperatures during the growing season were warm enough for favorable growth, corn responded to increasing N fertility with 60% greater yields, 75% greater N content, and 60% greater percentage N derived from fertilizer with the higher N fertility treatment. Averaged across rates, grain utilized 35% and stover an additional 15% of the applied fertilizer, while 30% remained in the upper 0.6 m of the soil profile at the end of the growing season. Twenty percent of the applied fertilizer could not be accounted for, lost to leaching or denitrification. Supplemental irrigation and N fertilization are viable management practices available to producers in the semiarid northern Great Plains.
A Classification System for Factors Affecting Crop Response to Nitrogen Fertilization
Authors: Lory John A. , Russelle Michael P. , Randall Gyles W. 
Published: July 2010

AbstractCrop response to N fertilizer (Nf) is influenced by factors such as Nf management, soil type, crop sequence, and supply of residual and mineralized N, but there is no framework to define the best strategy to account for a given factor in an Nf recommendation. This paper describes a three‐component classification system for evaluating the effect of any factor on yield response to Nf. This system provides (i) a vocabulary to describe clearly the effect of a factor on Nf recommendations, and (ii) insight on how to adjust Nf recommendations for the effect. Factors that affect yield response to Nf but not to N supply (Ns) were classified as shift effects (i.e., movement of a response curve in the x and/or y direction, with no change in coefficients of curvature). Factors that interact with Nf and Ns response were classified as interaction effects. Nitrogen supply was defined as the sum of aboveground plant N content of the control (0 N applied) plot, postharvest fall NO‐3 in the surface 1.5 m of the control plot, and Nf applied. Two 2‐yr experiments were conducted at Rosemount and Waseca, MN, to compare Nf response of continuous corn (Zea mays L.) with that of first‐ and then second‐year corn following alfalfa (Medicago sativa L.). We used the classification system to evaluate effects of crop sequence, year, and location on corn yield response to Nf. Year and crop sequence effects at Rosemount were primarily shift effects, implying that quantifying the effect on Ns would be sufficient to account for these effects on Nf recommendations. In contrast, the interaction model predominated at Waseca. Consequently, at this location simple adjustments of Ns were not sufficient to account for the complexity of crop sequence effects on Nf recommendations. This classification system facilitates the organization, evaluation, and communication of the many factors that influence crop yield.
Morphological Development of Switchgrass in Diverse Environments
Authors: Sanderson Matt A. , Wolf Dale D. 
Published: July 2010

AbstractSwitchgrass (Panicum virgatum L.) has been proposed as a model species for biomass fuel production. To better manage switchgrass as a biofuel crop, knowledge of its morphological development in several environments would be useful. This study was conducted to determine how morphological development of switchgrass varies in different field environments and to relate development to soil moisture status and other meteorological indicators. An established stand of ‘Alamo’ switchgrass at Stephenville, TX (32°13' N, 98°12' W; 399 m elevation), was sampled weekly or biweekly from April to September in 1991 and 1992. Field plots of Alamo and ‘Cave‐in‐Rock’ were established at Stephenville in 1992 and sampled 17 times during 1993. Established field plots of Alamo and Cave‐in‐Rock at Blacksburg, VA (37°11' N, 80°25' W; 610 m elevation) were sampled at 11 dates in 1992 and 9 dates in 1993 from May to September. Maturity stage at each harvest was determined according to a maturity scale developed at Stephenville. Morphological development and apical meristem elevation of both cultivars were closely related to cumulative degree days (DD, base 10°C) at each location. The developmental patterns were similar among years and were not affected by differences in soil moisture or rainfall distribution at Stephenville. Cave‐in‐Rock and Alamo matured about 4 wk earlier at Stephenville than at Blacksburg. The duration of the vegetative period was about 300 DD shorter at Blacksburg than at Stephenville for both Alamo and Cave‐in‐Rock. The close association of morphological development with DD in different environments could simplify morphological development models; however, the models would need to be location specific, because the timing and duration of phenological events differed as switchgrass cultivars were moved southward or northward.
Natural Herbicide Potential of Alfalfa Residue on Selected Weed Species
Authors: Chung Ill‐Ming , Miller Darrell A. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) contains water‐soluble substances that are toxic to itself (autotoxicity) and to other species (allelopathy). Experiments were conducted to determine the potential of using alfalfa residue as a natural herbicide for inhibition of weed seed germination, seedling growth, and development. Various weed species were germinated in aqueous extracts from dried alfalfa using cold (5°C), warm (24°C), and hot (80°C) treatments. Results indicated that inhibition of weed seed germination was dependent on the aqueous extraction method, residue application rate (w/v or w/w), and weed species. The greatest inhibition of germination was 44%, when 60% (w/v) warm aqueous extract was applied to lambsquarters (Chenopodium album L.). Seedling growth was also inhibited by residue application at various rates. Root length was more inhibited than increase in shoot length. In terms of total seedling length, giant foxtail (Setaria faberii Herrm.) was the most resistant species and lambsquarters was the most susceptible among the weed species studied to alfalfa aqueous extracts. Weed seed germination percentage decreased as incubation time increased from 8, 16, 24, and 48 h. An alfalfa aqueous extract incubated for 48 h caused the greatest inhibition of velvetleaf (Abutilon theophrasti Medic.) seed germination (25%). When alfalfa residue was incorporated with silica sand, the growth and development of lambsquarters, pigweed (Amaranthus retroflexus L.), velvetleaf, and crabgrass [Digitaria sanguinalis (L.) Scop.], as measured by plant height, leaf area, and total, shoot, leaf, and root dry weight, were significantly inhibited as the rate increased from 0.0 to 2.0 g kg−1. Dried alfalfa residue significantly stimulated plant height, leaf area, and total dry weight including shoot, leaf, and root of giant foxtail and cheatgrass (Bromus secalinus L.). Results suggest that alfalfa residue has a contrasting effect on weed growth and development due to water‐soluble allelochemicals present in the residue.
Estimation of Soybean Yields at County and State Levels Using GLYCIM: A Case Study for Iowa
Authors: Haskett Jonathan D. , Pachepsky Yakov A. , Acock Basil 
Published: July 2010

AbstractGlobal climate change could have a significant impact on important food crops such as soybean [Glycine max (L.) Merr.]. To assess the impact of these environmental changes, estimates of crop yields are needed, with special reference to regional responses in key production areas. The objective of this study was to examine the performance of the GLYCIM soybean crop model in modeling regional soybean yields in Iowa at the state and county level, over a 20‐yr period. The GLYCIM model has been extended to run for multiple years and combined with aggregations of soil and weather data to provide simulation over large areas. Soils data were aggregated to the soil association level in 18 sample counties so as to provide two‐county data sets in each Crop Reporting District (CRD). Weather files for each CRD spanning the period 1972 to 1991 were used to provide current climate information. Simulation runs were made for each year and county. Statewide yields were estimated as an average of county yields. Statistical measures of simulation success indicated that, using aggregated characteristics, the model was best able to simulate the 20‐yr mean yield at the state and county level, as well as long‐term yield variability. Poorer results of modeling yields in particular years were obtained. This validation establishes the model's ability to simulate long‐term yield averages under current conditions, and lays the groundwork for future simulations using altered climate scenarios.
A Weather‐Soil Variable for Estimating Soil Moisture Stress and Corn Yield Probabilities
Authors: Dale Robert F. , Daniels James A. 
Published: July 2010

AbstractAgricultural technology has increased crop yield potentials, but on rain‐fed crops yields are still severely reduced with the normal climatic frequency of drought. Objectives were (1) to determine an interaction regression of county average corn (Zea mays L.) yield on a soil moisture stress variable and technology trend and (2) to estimate the probability of soil moisture stress and resulting average corn yield in Tippecanoe County, Indiana. The soil moisture stress variable (Sc) was the sum of modeled daily ratios of actual to potential evapotranspiration [Σ(ET/PET)] over critical corn growth and development periods. The interaction regression model of corn yield on Sc andyield on Sc andyield on Sc andyield on Sc and technology trend (T = year) for Tippecanoe County was associated with 70% of the variance in the 1961 to 1992 average county corn yields when Sc was a 90‐d period (S90) from 39 d before corn silking to 50 d after. With no moisture stress (S90 = 90), the technology trend over the last 32 yr was 0.17 t ha−1 yr−1 (2.7 bu acre−1 yr−1). With 1992 technology, each deficit unit of S90 reduced the yield 0.19 t ha−1 (3.1 bu acre−1). The distributions of S90 and predicted corn yield were highly negatively skewed. The probability of having an S90 less than 85 (at least some moisture stress), and a county corn yield less than 9.5 t ha−1 (152 bu acre−1) is 69%, but the probability of severe stress (S90 < 75) and corn yield less than 7.5 ± 0.8 t ha−1 (139 ± 13 bu acre−1) is 22%. For the same weather regime, the probability of moisture stress and resulting corn yields differs greatly for individual soils. For a poorly drained soil (Typic Argiaquoll) the probability of having an S90 less than 85 is 41%, but for a well‐drained soil (Typic Argiudoll) the probability is 90%.
Radiation‐Use Efficiency in Summer Rape
Authors: Morrison Malcolm J. , Stewart Doug W. 
Published: July 2010

AbstractThe radiation‐use efficiency (RUE) is a parameter that represents a crop canopy's ability to convert intercepted solar energy to dry matter. The RUE is used in simulation models and can vary with crop type and environment. The objective was to examine the effects of varying row width and seeding rate on the amount of intercepted photosynthetically active radiation (IPAR) and the RUE in summer rape (Brassica napus L.). ‘Westar’ summer rape was seeded at rates of 1.5, 3.0, 6.0, and 12.0 kg ha−1 in rows spaced 15 or 30 cm apart. Plant sampling was done at key growth stages, and the leaf and pod areas and total plant dry weights were determined. After flowering, plants intercepted more PAR when grown in 15‐cm‐wide rows than 30‐cm‐wide rows. For both row widths, as seeding rate increased from 1.5 to 12.0 kg ha−1, IPAR increased. The RUE was greater for plants grown in 15‐cm‐wide rows than for those grown in 30‐cm rows; however, RUE decreased with increasing seeding rate. The mean RUE value was 2.83 g MJ−1 PAR. When the pod area was added to the leaf area, the IPAR increased and the RUE decreased.
Managing Alfalfa and Berseem Clover for Forage and Plowdown Nitrogen in Barley Rotations
Authors: Westcott M. P. , Welty L. E. , Knox M. L. , Prestbye L. S. 
Published: July 2010

AbstractAnnual legume plowdown systems, which utilize fall regrowth for N contributions to rotational crops, have not been adapted to irrigated, intermountain areas of the Northern Rockies. Our objective was to evaluate plowdown systems using ‘Nitro’ alfalfa (Medicago sativa L.) and ‘Bigbee’ berseem clover (Trifolium alexandrinum L.). These two legumes were grown under five harvest management systems (zero to three forage harvests prior to fall plowdown of regrowth, or a standard three harvest system with no herbage plowdown) at two sites in western MT differing in soil characteristics. They were assayed for forage and plowdown production and for N benefits to ‘Clark’ barley (Hordeum vulgare L.; syn. H. distichon L.) for two subsequent years. Maximum herbage plowdown N was 125 to over 200 kg N ha−1 for berseem clover and 87 kg N ha−1 for alfalfa. A two‐harvest system resulted in 3.6 to 6.6 Mg ha−1 forage and 45 to 78 kg N ha−1 in herbage plowdown. Effects of plowdown were measured directly in increased soil N availability and correlated increases in N uptake in subsequent barley; benefits were expressed in increased grain yields and/or grain N concentrations and were apparent for two successive years at the site of lower native fertility. Alfalfa N benefits were superior to berseem clover, though disproportionate to herbage plowdown N quantities, possibly due to greater root and crown N in alfalfa. Where the management goal is primarily forage production with moderate benefit of plowdown N, berseem clover works well in a two‐harvest system; Nitro alfalfa is preferred where greater benefits of plowdown N are desired.
Cotton Rooting Patterns in Relation to Soil Temperatures and the Thermal Kinetic Window
Authors: Burke John J. , Upchurch Dan R. 
Published: July 2010

AbstractThroughout the USA, cotton (Gossypium hirsutum L.) is irrigated to avoid the deleterious effects of drought stress on growth and development. Irrigation, while optimizing water status, results in a concomitant cooling of soil temperatures. Previous field studies have focused on soil water status effects on root growth independent of the soil temperature changes following irrigation. This study was designed to evaluate the soil temperature characteristics of irrigated and nonirrigated field plots of cotton to determine the time that temperatures are spatially and temporally within the range for optimal cotton root metabolism. Soil temperatures in the nonirrigated treatment were within cotton's thermal kinetic window (23.5 to 32°C) for 72% more time than in the irrigated treatment. Predicted rooting fronts fell between the 24 and 26°C isotherms in the irrigated treatment and the 26 and 28°C isotherms in the nonirrigated treatment. Greater root length density of cotton in the nonirrigated treatment, determined from soil cores, was associated with increased time at optimal temperatures. Near the soil surface, root length density decreased in the nonirrigated treatment because of reduced soil water status, not because of reduced time within the optimal temperature range. Soil temperatures cooled below the optimal range upon canopy closure in the irrigated treatment. The cooling trend was observed to a lesser extent in the nonirrigated treatments, which never realized full canopy closure. This study showed that greater cotton root development occurred across time and with depth in soils exhibiting temperatures within cotton's thermal kinetic window.
Early Planting of Early‐Maturing Soybean: Effects on Seed Germination and Phomopsis Infection
Authors: TeKrony Dennis M. , Grabau Larry J. , DeLacy M. , Kane M. 
Published: July 2010

AbstractThe use of early‐maturing soybean [Glycine max (L.) Merr.] cultivars has been suggested as a means of avoiding drought stress and extending harvest maturity in the southeastern USA. This experiment determined the effect of cultivar maturity on seed germination and Phomopsis longicolla T.W. Hobbs seed infection following early planting. Six cultivars ranging from Maturity Group (MG) 00 to IV were planted in late April, mid‐May, and early and late June in 1992 and 1993 at Lexington, KY. The May planting was sprayed at weekly intervals between growth stages R5 and R7 with the foliar fungicide benomyl [methyl 1‐(butylcarbamoyl)‐2‐benzimidazolecarbamate] to control seed infection. A single, recommended application of benomyl was also made at growth stage R6 for all planting dates in 1993. Seed was harvested at harvest maturity (HM, defined as the time when seed first dried to <140 g kg−1 moisture) and 3 wk after that date. Higher levels (>30%) of P. longicolla seed infection frequently occurred for the April and May plantings, which often resulted in lower (<85%) seed germination for earlier maturing cultivars. As harvest maturity was delayed due to later planting dates of early‐maturing cultivars (MG 00‐II or the use of full‐season cultivars (MG III, IV), seed quality improved. Weekly benomyl applications to the mid‐May planting reduced seed infection to low levels and increased seed germination to >90% at HM in both years for all cultivars. Thus, high‐quality soybean seed can be produced on early maturing cultivars grown outside the range of adaptation, if seed infection by P. longicolla is controlled. Cultural methods are discussed for reducing seed infection and improving seed quality of early‐maturing cultivars.
Nitrogen Fertilization and Burning Effects on Rumen Protein Degradation and Nutritive Value of Native Grasses
Authors: Cuomo Greg J. , Anderson Bruce E. 
Published: July 2010

AbstractNitrogen fertilization and burning can affect crude protein (CP) concentration of warm‐season grasses. While total CP concentration in these forages may limit animal performance, the amount of protein degraded in the rumen may be equally important. A 2‐yr study was undertaken to determine the effect of N fertilization and burning on protein degradation and quality components of three warm‐season grasses. Monocultures of switchgrass (Panicum virgatum L.), big bluestem (Andropogon gerardii Vitman), and indiangrass [Sorghastrum nutans (L.) Nash] were either burned in mid‐April or left unburned. One half of each burn treatment was either fertilized with 66 kg ha−1 of N or not fertilized. Plots were harvested in mid‐June and again in mid‐July of 1990 and 1991. Crude protein, rumen degradable protein (RDP), in situ organic matter disappearance, neutral‐detergent fiber (NDF), acid‐detergent fiber (ADF), and acid‐detergent lignin (ADL) were determined. Nitrogen fertilization increased (P < 0.01) CP concentration 18%. Sixty‐five percent of the additional CP associated with N fertilization was RDP. The percentage of CP that was RDP was greater in switchgrass and indiangrass than big bluestem in both years. Even though burning increased early‐season CP concentration 7%, it did not affect the RDP percentage. Increased CP levels, particularly RDP, indicate that rumen undegradable protein (RUP) would be a more appropriate supplement with N fertilized switchgrass and indiangrass, while supplementation with RDP would be more appropriate with big bluestem and forages from burned sites.
Rhizoma Peanut and Alfalfa Productivity and Nutrient Composition in Central Georgia
Authors: Terrill Thomas H. , Gelaye Seyoum , Mahotiere Sauveur , Amoah Eugene A. , Miller Schauston , Gates Roger N. , Windham William R. 
Published: July 2010

AbstractLimits of environmental adaptation of ‘Florigraze’ rhizoma peanut (Arachis glabrata Benth.), a high‐quality perennial warm‐season legume, have not been well defined. A field experiment compared yield and nutritive value of rhizoma peanut and alfalfa (Medicago sativa L.) in central Georgia on a Norfolk soil (fine‐loamy, siliceous, thermic Typic Kandiudults). Crude protein (CP), neutral‐detergent fiber (NDF), aciddetergent fiber (ADF), lignin, Ca, Mg, and P of total herbage, and dry matter (DM) yield and in vitro organic matter disappearance (IVOMD) of total herbage, leaf, and stem tissues were determined for three growing seasons. Annual DM yield of peanut and alfalfa averaged 7.6 and 11.8 Mg ha−1, respectively. In the first 2 yr, alfalfa outyielded rhizoma peanut, but there was no difference in yield in the third year. Leaf DM yield was higher for peanut than for alfalfa in the third year. Rhizoma peanut DM production occurred predominately during late summer and early autumn vs. spring for alfalfa. Rhizoma peanut total herbage DM was lower in CP and higher in Ca and Mg than that of alfalfa, but IVOMD was similar. Leaf IVOMD was higher for alfalfa than for rhizoma peanut, but IVOMD of peanut stems was equal to or higher than alfalfa stems. Rhizoma peanut has potential for central Georgia and other areas of the southern USA with a similar climate.
Soil‐Water and Root Dynamics under Hedgerow Intercropping in Semiarid Kenya
Authors: Govindarajan Muthiah , Rao Meka R. , Mathuva Moses N. , Nair P. K. Ramachandran 
Published: July 2010

AbstractCompetition for growth resources between woody and crop species is said to be the main reason for failure of hedgerow intercropping (alleycropping) in semiarid tropics, but the mechanisms of competition are not clearly understood. In this study, conducted in the semiarid highlands of Kenya, soil‐water changes and root dynamics were monitored during two rainy seasons from a long‐term, replicated, alleycropping experiment. The treatments were (i) maize (Zea mays L.) grown alone, without fertilizer; (ii) maize, without fertilizer, intercropped between hedgerows of leucaena [Leucaena leucocephala (Lam.) de Wit], with hedgerow prunings returned to the alleys; and (iii) maize grown alone, with fertilizer at 40 kg N and 18 kg P ha−1. Available water in 1.25 m of soil depth under alleycropping was lower than with maize alone. Depletion of soil water by hedgerows continued after maize harvest and carried water deficits in alleycropping from one season to the next. Leucaena provided 1.45 Mg ha−1 leaf biomass, which contained 41.6 kg N and 2.5 kg P ha−1; moreover, it added 0.51 Mg ha−1 season−1 of root biomass to the soil, equivalent to 7 kg N and 0.2 kg P ha−1. Therefore, N contributed through the alleycropping system was equivalent to the recommended fertilizer level; the system, however, did not meet the P requirements of the crop. Maize did not respond to fertilizer in both seasons, and the alleycropped maize yielded lower than the unfertilized maize. Our study indicates that under water‐limiting conditions, alleycropping is detrimental to crop yields because competition of trees with crops for water outweighs the likely soil‐fertility benefits.