bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Normal Annual and Diurnal Temperature Oscillations in Non‐Mountainous Mainland United States
Authors: Fernández C.J. 
Published: July 2010

AbstractSimulation of air temperature data may add flexibility to many computer programs for modeling crop growth. An empirical model was developed to simulate both average annual air temperatures and average diurnal oscillations of air temperature, at any location within the USA east of the Rocky Mountains and with elevation below 1500 m above sea level. The target region was divided into four zones according to average annual rainfall and proximity to the Atlantic Ocean. Annual oscillations of the daily mean, maximum, and minimum temperatures for a given location were simulated with single sine‐wave equations. The average and amplitude parameters of these equations are calculated from estimates of the monthly maximum and minimum temperature normals of January and July. These four temperature normals were estimated using regression equations on latitude. Different sets of equations were used for each location zone. Diurnal oscillations of temperature on a given day at the given location were simulated by joining two sine waves to give a single smooth asymmetrical wave. The average and amplitude parameters of these diurnal oscillations were obtained from the annual curves previously simulated. The accuracy of the model in simulating annual oscillations of daily maximum and minimum temperatures was tested. Simulated and observed average monthly temperatures recorded at 27 weather stations correlated with r = 0.993 (significant at Ρ = 0.01). Plots of residuals against months showed that the model underestimated the monthly temperatures around the vernal equinox (average residuals ranged from −1.76 to −2.66°C). The accuracy of the model in simulating diurnal oscillation was also tested. Simulated and observed temperatures at 3‐h intervals for 18 cloudless days and 18 overcast days correlated with r = 0.992 (significant at P = 0.01). Plots of residuals against time showed that the model underestimated the temperature during the warming phase in clear‐sky days (average residuals were about −3°C.
Microcomputer‐Based Experiment Management System: II. Data Analysis
Authors: Loussaert Dale 
Published: July 2010

AbstractMicrocomputer‐based statistical analysis can provide a convenient, inexpensive means of data analysis. Computer software has been developed to complement a general experiment management system. The software will perform analysis of variance, with or without covariant analysis, of data arranged in various experimental designs. Regression analysis, best fit regression and multiple regression analysis can also be conducted with this software. Data can be input as a continuation of complementary experiment management software or entered through a text file. The treatment means can be grouped in any combination of treatments or treatment interactions desired and comparisons may be made using Least Significant Difference comparisons, a Student's t‐probability matrix, or specific treatment means may be pooled to make specific comparisons. This system provides a convenient means of doing lower level statistical comparisons using an IBM/compatible computer.
Early Maturing Soybean Nodulation and Performance with Selected Bradyrhizobium japonicum Strains
Authors: Wiersma J. V. , Orf J. H. 
Published: July 2010

AbstractSeed inoculation with Bradyrhizobium japonicum (Kirchner) Jordan is a common production practice for most soybean [Glycine max (L.) Merr.] growers in northwest Minnesota; however, plants seldom are well‐nodulated. Our objectives were to (i) identify strains of B. japonicum that enhance nodulation and agronomic performance of Maturity Group 00 soybean cultivars grown on soils having a range of NO3−−N concentrations; and (ii) assess cultivar‐by‐strain specificity. Six cultivars and five B. japonicum strains were evaluated in six field trials during 1988 to 1990. Nonfertilized (1988–1990) and N fertilized (1990), uninoculated controls were included. Soil NO3−−N concentrations (0–60 cm) at planting ranged from 52 to 175 kg N ha−1. Residual soil NO3−−N values were low and substantially less than initial values in only three environments. Nonetheless, significant increases in response to inoculation were observed for grain yield, seed weight, and grain N concentration in 17 of 18 comparisons. In 1990 trials, fertilizer N (168 kg ha−1) increased seed weight and grain N concentration significantly more than inoculation. Nodule number (r = −0.89; significant at P = 0.05) and dry weight (r = −0.97; significant at P = 0.01) were inversely correlated with soil NO3−−N (0–60 cm) at planting. Estimated (difference method) N2 fixation (r = ‐0.93; significant at P = 0.05) and relative increases in grain yield (r = −0.93; significant at P = 0.05), seed weight (r = ‐0.97; significant at P = 0.01) and grain N concentration (r = −0.95; significant at P = 0.05) were inversely correlated with soil NO3−−N (0–60 cm) at harvest. Although similar responses were observed among all cultivars, B. japonicum strains 61A152 and 61A212 generally outperformed other strains. Cultivar‐by‐strain specificity could not be detected. Soybean producers in northwest Minnesota should realize significant increases (10% or greater) in grain yield in response to inoculation of rhizobia‐free soils, provided initial soil NO3−−N concentrations (0–60 cm) are less than 110 kg N ha−1 and N mineralization during the growing season is minimal.
Nitrogen, Phosphorus, and Potassium Fertilization for Histosol‐Grown St. Augustinegrass Sod
Authors: Cisar J. L. , Snyder G. H. , Swanson G. S. 
Published: July 2010

AbstractHistosol‐grown sod is a major agricultural commodity in Florida. Sod fertility requirements need to be identified in order to maximize sod productivity, avoid fertilizer waste, and minimize undesirable impacts on water quality. An experiment was conducted for two consecutive years to determine the effect of N, P, and K fertilization on St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] sod production on a well‐decomposed Histosol (muck). Treatment comparisons were based on turf growth, turf visual quality ratings, cut sod piece quality, tear resistance of cut sod pieces, and measures of cut sod transplantability on sand soil. Nitrogen fertilization improved visual quality and clipping yield of the sod, and of sod pieces re‐established on a sand soil, but did not affect sod tear resistance or quality of sod pieces as judged by experienced sod growers. When the initial water‐extractable P soil‐test was low (3.7 mg P L−1), all measured parameters (except tear resistance) were increased by P fertilization. Potassium fertilization did not affect any measured parameters of sod production, even when the initial acetic acid‐extractable K soil‐test index was 54 mg K L−1, which is low for most crops. Overall, results indicate that N, P, and K fertilizer rates used for sod production on Histosols can be reduced substantially from previous recommendations.
Potassium in Two Humid Tropical Ultisols under a Corn and Soybean Cropping System: II. Dynamics
Authors: Cox F. R. , Uribe E. 
Published: July 2010

AbstractUnderstanding the dynamics of soil K is important for the formulation of a sound fertilizer management strategy. Two experiments were conducted to determine the behavior of K in the soil after fertilization. Five rates of K (0 to 120 kg ha−1) were applied to two Typic Paleudults, a loam and a sandy loam, in the Peruvian Amazon Basin. A three‐crop rotation of corn (Zeu mays L.), corn, and soybean [Glycine max (L.) Merr.] was planted at each site. Three additional crops of corn were grown at the loam site. Potassium rates were applied only to the first crop of each three‐crop cycle. The corn stover was returned, while the soybean stover was removed. Soil samples were taken at germination, flowering, and harvest of each crop at 20‐cm depth intervals to 60 cm in the loam and 80 em in the sandy loam. Soil K was extracted with NaHCO3, NH4OAc, and concentrated H2SO4. Topsoil exchangeable K increased markedly with K addition, either as fertilizer or as stover, but rapidly decreased during cropping. Changes in the exchangeable pool were characterized with an exponential model. Increases in exchangeable K below 20 cm were of minor significance for the loam. For the sandy loam, however, subsoil exchangeable K was significantly increased to 60 cm. Evidences of K fixation and release were detected in the loam where the topsoil non‐exchangeable pool peaked after K additions and decreased during cropping. There was no evidence of fixation in the sandy loam. These differences suggest that higher K rates can be applied to the finer textured soils and there is less risk of loss of K from the rooting zone.
Yield Enhancement in Cotton by Frequent Irrigations during Fruiting
Authors: Radin J.W. , Reaves L.L. , Mauney J.R. , French O.F. 
Published: July 2010

AbstractDaily drip irrigation often increases yield and water‐use efficiency of cotton (Gossypium hirsutum L.) compared to conventional irrigations applied at long intervals. A 2 yr experiment was designed to test whether these benefits could be achieved without using an expensive drip system. Cotton was irrigated every 10 d in the first year and every 14 d in the second year (control treatment). A supplemental irrigation was applied during either one or two long irrigation cycles coinciding with peak fruiting. The total amount of water applied was minimally changed from the control because other irrigations were reduced to compensate for the supplementation. Another treatment was drip‐irrigated daily throughout most of the season. One supplement increased seedcotton yield 15% over the control, and two supplements increased it 25%, compared to a 40% yield increase with drip irrigation. These three treatments increased crop water‐use efficiency (yield per unit applied water plus rainfall) by 12, 22 and 50%, respectively. Yield increases were associated with a lengthened period of profuse flowering and a delay in the onset of cutout. Both drip irrigation and mid‐cycle supplements increased midday leaf water potential and apparent hydraulic conductance of the plants for an extended period during fruiting, indicating enhanced water uptake and transport capacity compared to plants on long cycles. The results show that a drip system is not necessary for substantial improvements of yield and water‐use efficiency. Doubling the number of irrigations for a short period during peak fruiting achieved much of the benefits of drip irrigation.
Grain Sorghum and Pearl Millet Response to Date and Rate of Planting
Authors: M'Khaitir Y. O. , Vanderlip R. L. 
Published: July 2010

AbstractPearl millet [Pennisetum glaucum (L.) R. Br.] often is grown in the same areas as sorghum [Sorghum bicolor (L.) Moench]. The crops are similar in use and adaptation, but differ in ways that might affect management requirements. For example, the high tillering capability of millet might result in different responses to plant population and planting date. A study to compare pearl millet and sorghum yield response to rate and date of planting was conducted for 2 yr at St. John, on a Naron fine sandy loam (fine‐loamy, mixed, thermic Udic Argiustoll), and Manhattan, KS, on a Reading silt loam (fine, mixed, mesic Typic Arguidoll). In 1988, a millet hybrid (81‐1056 ✕ 86‐9001), a millet variety (Senegal bulk), and a sorghum hybrid (DeKalb 39Y) were planted at 15 000, 45 000, and 135 000 plants/ha on three dates. In 1989, another millet hybrid (81‐1086 ✕ 87‐8025) was added. The experiment was a modified split‐plot design with dates of planting as main plots stripped across replicates and combinations of population and variety as subplots. Planting date had no consistent effect on either crop. Plant population had no effect on millet yield. Some yield components, particularly heads per plant, increased and compensated for low populations. Sorghum yield increased with increasing population, but plant population had no consistent effect on sorghum yield components. Sorghum yielded significantly more than millet at high populations, but not at low and medium populations. These results indicate that precise plant population is much less critical for pearl millet than for sorghum in determining final yield.
Quality and Growth Response of Centipedegrass to Extended Drought
Authors: Hook J. E. , Hanna W. W. , Maw B. W. 
Published: July 2010

AbstractMany of today's landscapes require turfgrasses that can survive extended drought periods without supplemental water. Centipedegrass [Eremochloa ophiuroides (Munro.) Hack.] has long been used as a low‐maintenance lawn grass for the Southeast. A controlled drought study was used to determine the quality, growth, and recovery of centipedegrass held in stress for periods of 7 to 30 d. Common centipedegrass, established under an automated rainfall shelter, was subjected to three drought (drydown) regimes ‐ NOSTRESS, watered twice per week; MODERATE, 2 to 3 wk between watering; and SEVERE, 4 to 6 wk between watering. Soil water was monitored daily to 0.7 m depth with resistance type sensors. Clipping biomass, relative leaf water content, and visual rating were monitored weekly. Available water dropped below 30% in the 0.7 m profile in 7 to 14 d after complete rewetting, and drought stress, indicated by wilting, became evident. The period of drought stress extended for 10 to 30d during which weekly clipping biomass decreased by 50 to 70% below that of NOSTRESS turf. Visual ratings declined along with biomass decrease, falling below acceptable quality rating when drought stress lasted longer than 7 to 10 d. Relative leaf water content declined from about 80% for NOSTRESS to as low as 40% at the end of the SEVERE drought periods. Recovery of leaf water content following watering was not complete, due either to an adaptive response to drydown or to incomplete recovery of the grass. When as much as 3 wk elapsed between watering, irrigation of centipedegrass resulted in recovery of clipping biomass and visual ratings nearly to that of the NOSTRESS treatment. When drought extended for 6 wk, turf quality was low, but centipedegrass survived and recovered to levels suitable for lawns.
Nitrogen Assimilation Traits and Dinitrogen Fixation in Soybean and Common Bean
Authors: George T. , Singleton P.W. 
Published: July 2010

AbstractNitrogen derived from symbiotic and mineral sources by a legume is determined by the interactions between mineral N supply, plant N demand, and N assimilation traits. These interactions need to be understood to maximize legume N2, fixation and yield, and to identify plant traits supporting high N2‐fixation. These interactions were examined in inoculated soybean [Glycine max Merr. (L.)] and common bean (Phaseolus vulgaris L.) by varying N supply (9, 120, and 900 kg N ha−1) at two field sites. Nitrogen fixation was measured by 15N dilution method. Plants were sampled at full bloom (R2), 21 to 25 d from R2, and physiological maturity (R7). Total N of both legumes at R7 was 25% greater with 900 than 9 kg N ha−1. With 900 kg N ha−1, soybean N accumulation at R7 (271 kg N ha−1) was 42% more than common bean but was 22% less at R2 (78 kg N ha−1). Applied N had the largest impact on N accumulation rates before R2 and from the second sampling to R7, both periods of minimal N2 fixation. Rate of N accumulation by common bean (0.19 g N m−2 d−1) was more uniform over the growth cycle than by soybean (0.26 g N m−2 d−1) which peaked (0.58 g N m−2 d−1) between R2 and the second sampling. This peak also coincided with maximum N2 fixation rate. Our 15N uptake and extractable soil N data indicate that common bean derived more N from the mineral source than soybean because of more efficient uptake. Greenhouse data indicated greater root weight and uptake of mineral N per unit root weight for common bean than soybean. Maximizing both N2 fixation and yield might entail timing the mineral N supply during early vegetative and late reproductive phases. The limited N2 fixation capacity of common bean might be due to N assimilation traits favoring mineral N uptake.
Time Domain Reflectometry in Closed Container Studies
Authors: Richardson M. D. , Meisner C. A. , Hoveland C. S. , Karnok K. J. 
Published: July 2010

AbstractTime domain reflectometry (TDR) has been widely utilized to estimate soil water content in field plots, but applications to controlled environment experiments have not been adequately described. The TDR procedure was used in three closed‐container, greenhouse studies to monitor soil moisture levels and dictate watering schedules. In all experiments, TDR was an efficient method for monitoring soil water. Also, estimation of soil water content by TDR was highly correlated to gravimetric analysis of soil cores, with r2 values of 0.84, 0.96, and 0.98 for the three studies. Different soil types, with variable physical properties and bulk densities, had no apparent effect on estimations of soil water content. It was concluded that TDR could be useful in greenhouse studies to accurately determine soil water content.
Nonionic Surfactant and Supplemental Irrigation of Soybean on Crusting Soils
Authors: McCauley G. N. 
Published: July 2010

AbstractAgricultural land use in much of the Texas Coastal Prairie consists of 1 yr of rice (Oryza sativa L.) followed by 2 to 4 yr of native pasture. Replacing some of the native pasture with a cultivated rotational crop could benefit the area's agricultural base by reducing fixed costs and aiding pest management. Soybean [Glycine max (L.) Merr.] fits the crop rotation system well but yields are highly variable and marginally economical. Research was initiated in 1985 near Eagle Lake, TX, to evaluate the potential of a nonionic surfactant and supplemental irrigation to increase and stabilize soybean yields on the Nada soil (fine loamy, silicous, hyperthermic Typic Albaqualf). In addition the effect of the surfactant and irrigation on P and K fertilizer efficiency was evaluated. The nonionic surfactant (Amway ASPA 80; Amway Corp., Ada, MI) was injected through a lateral‐move irrigation system at 0.00, 0.36, 0.71, and 1.42 L ha−1 during a 7 mm irrigation. Adjuvant rate, repeated adjuvant applications within 1 yr and over 3 yr, and P and K at the recommended and half the recommended rates were evaluated. Supplemental irrigation was applied so irrigation plus rainfall equalled 19 mm wk−1. No measurable yield differences between P and K rates were detected. The adjuvant at 0.36 L ha−1 increased soybean yields 37% above the check. Adjuvant at the 0.71 and 1.42 L ha−1 rate decreased yield from the 0.36 L ha−1 rate. No phytotoxicity was observed. Multiple adjuvant applications during 1 yr, and repeated applications to the same area over years, had no additional beneficial yield effect.
Nitrogen Fertilizer and Cultivar Effects on Yield and Nitrogen‐Use Efficiency of Grain Amaranth
Authors: Elbehri A. , Putnam D.H. , Schmitt M. 
Published: July 2010

AbstractKnowledge of fertility requirements or nitrogen‐use efficiency of amaranth (Amaranthus spp.) cultivars is limited. The objectives of this research were to determine the response of grain amaranth to applied N, P, and K, and to determine the effect of cultivar and fertilizer N on nitrogen‐use efficiency. Two field experiments were conducted. In the first, five rates of N, P, and K were applied in a central composite design with the cultivar Plainsman grown in five environments. In a second experiment, six amaranth cultivars, Amont, K266, K283, Plainsman, K432 and D136, were grown in three environments with five N rates (0, 45, 90, 135, and 180 kg N ha−1). There was no response to P and K applications when initial soil tests were above 68 kg P ha−1, and 172 kg K ha−1, respectively, but grain amaranth responded linearly to applied P at one location with initial soil P tests of 11 kg ha−1. Grain yield ranged from 794 to 1980 kg ha−1 and responded to N in most environments. Forage yield ranged from 6.1 to 16.6 Mg ha−1 and was increased at higher N rates. At all locations, lodging increased with application of N. Fertilizer N increased pre‐flowering N accumulation but not post‐flowering N accumulation. Nitrogen‐use efficiency (NUE) ratio of grain yield to total soil N supply ranged from 3.48 to 7.91 kg kg−1 across cultivars and environments. Nitrogen‐use efficiency decreased with increased soil N mainly because of decreasing N‐uptake efficiency (ratio of total plant N to total soil N). Grain amaranth is relatively inefficient in N‐use primarily because of its low harvest index (HI = 9–15%) and N harvest index (NHI = 12–26%). This suggests that selection for higher HI and NHI could be effective in improving grain yield and nitrogenuse efficiency of grain amaranth.
Evaluation of the Nitrogen Submodel of CERES‐Maize Following Legume Green Manure Incorporation
Authors: Bowen W. T. , Jones J. W. , Carsky R. J. , Quintana J. O. 
Published: July 2010

AbstractCrop simulation models that accurately predict the availability of N from decomposing plant residues would provide a powerful tool for evaluating legume green manures as potential N sources for nonlegume crops. Using measured data from a series of field experiments conducted on an Oxisol in central Brazil, we conducted this study to test the N submodel of CERES‐Maize for its ability to simulate N mineralization, nitrate leaching, and N uptake by maize (Zea Mays L.) following the incorporation of 10 different legume green manures. Legume or weed residue N at the time of incorporation varied from 25 to 300 kg ha−1 with C/N ratios varying from 13 to 37. Comparison of predicted and measured accumulation of inorganic N in uncropped soil showed that the model usually provided a realistic simulation of legume N release, although N release was overpredicted for some legumes. For all legumes, both simulated and measured data showed that about 60% of the organic N applied was recovered as inorganic N within 120 to 150 d after incorporation. To realistically simulate N availability when rainfall was excessive, we modified the model to account for delayed leaching due to nitrate retention in the subsoil. Nitrogen uptake by maize was generally overpredicted at high levels of available N. The N submodel was shown to realistically simulate legume N release, but further work is needed to determine the importance of subsoil nitrate retention in other soils and how best such retention might be described in the model.
Mid‐Infrared Microspectroscopy to Assess Lignin in Plant Tissues Related to Digestibility
Authors: Akin D. E. , Himmelsbach D. S. , Carl R. T. , Hanna W. W. , Barton F. E. 
Published: July 2010

AbstractTechniques are needed to rapidly assess the location of phenotics within cell types. The objective of this work was to investigate by midinfrared microspectroscopy a series of intact cell types, which have a range of digestibilities, from normal (N) and brown midrib (bmr) pearl millet [Pennisetum glaucum (L) R. Br.]. Rind and parenchyma tissues were evaluated using a Nicolet System 740 spectrometer equipped with a Nicolet 0.25 mm MCT‐A detector1 interfaced to a microscope. Spectra of rind were similar for normal and bmr mutants and closely resembled lignin spectra. Spectra of pith tissue were similar among plant types and to that for carbohydrates, but differed from rind spectra. Preliminary results indicated that spectra were different for tissues of different digestibilities and showed promise for the use of microspectroscopy in evaluating forage quality of cell types.