Slaton N.A.,University of Arkansas |
Golden B.R.,Agricultural Center |
DeLong R.E.,University of Arkansas |
Mozaffari M.,University of Arkansas
Soil Science Society of America Journal | Year: 2010
The ability of soil tests to identify nutrient-deficient soils and recommend fertilizer rates that optimize agronomic yield is essential for profitable soybean [Glycine max (L) Merr.] production. Our objectives were to correlate relative soybean yield to Mehlich-3 and 1 mol L -1 HNO 3-extractable soil K and trifoliolate-leaf K concentration at the R1 to R2 development stage and calibrate the K rates for Mehlich-3-extractable soil K. Experiments were established on silt loams at 34 site-years planted with a Maturity Group IV or V cultivar and fertilized at five K rates (0-148 kg K ha ). Mehlich-3-extractable soil K ranged from 46 to 167 mg K kg -1 and produced relative soybean yields of 59 to 100% when no K was applied. Eleven sites had Mehlich-3-extractable K < 91 mg K kg -1 and all responded positively to K fertilization. Soybean grown in soil having 91 to 130 mg K kg -1 responded positively at nine of 15 sites. Mehlich-3 soil K explained 76 to 79% of the variability in relative yields and had critical concentrations of 108 to 114 mg K kg -1, depending on the model. The linear-plateau model predicted the critical HNO 3-extractable soil K to be 480 mg K kg -1. Trifoliolate-leaf K concentration increased significantly, positively, and linearly as Mehlich-3- and HNO 3-extractable soil K increased, but Mehlich-3 soil K explained only 49 to 53% of the variation in trifoliolate-leaf K. Mehlich-3-extractable K is an excellent predictor of soil K availability for soybean grown on silt loams in eastern Arkansas. © Soil Science Society of America, 5585 Guilford Rd.. Madison 53711 USA All rights reserved.
So C.-L.,Agricultural Center |
Eberhardt T.L.,U.S. Department of Agriculture
Journal of Near Infrared Spectroscopy | Year: 2010
Gross calorific value (GCV) has been predicted by building models based on near infrared (NIR) spectroscopy and multivariate analysis; however, to date, the impact of feedstock chemical composition on the models has not been directly assessed. In the present study, 20 longleaf pine trees were sampled at two positions (breast and mid-height) for calorimetric and spectroscopic analyses. The GCVs, which ranged from 20 MJ kg-1 to 24 MJ kg-1, showed a strong correlation with the wide-ranging values of acetone-soluble extractives content. After extraction of the samples with acetone, the range for the GCV was both lower and slightly narrower (19-21 MJ kg-1) and was poorly correlated to lignin content with its narrow range of values. Near infrared (NIR) spectroscopy coupled with multivariate analysis was applied to the samples and provided a strong coefficient of determination (R2) between the values predicted by NIR and those determined by calorimetry for the unextracted, but not the extracted, samples. Plotting the regression coefficients validated the results by showing very similar plots for GCV and extractives content, thereby indicating that the same molecular features are driving the models. NIR spectroscopy coupled with multivariate analysis can predict GCV for bioenergy feedstocks and also provide insight into chemical features with the greatest impact on fuel value. © IM Publications LLP 2010.
Parajuli R.,Louisiana State University |
Chang S.J.,Agricultural Center |
Hill R.C.,Louisiana State University
Forest Science | Year: 2015
The ongoing softwood lumber trade dispute between the United States (US) and Canada is one of the most contentious and longest bilateral trade battles in international trade history. The Softwood Lumber Agreement (SLA) 2006 is the latest temporary solution for this dispute, requiring Canada to impose mandatory export charges on lumber shipments to the United States. By estimating a system of supply and demand equations for the US softwood lumber market, this article assesses the possible effects of the export tax on the lumber trade between the US and Canada. Unlike previous studies, this study computes the actual monthly export tax collected by Canada during the period of SLA 2006 and incorporates it into the empirical modeling. The findings reveal that SLA 2006 has no statistically significant effect on the softwood lumber trade between the United States and Canada. The Canadian lumber exports from SLA-included provinces are found to be price elastic, whereas the US domestic supply schedule is price inelastic. Further, Canadian overseas lumber exports significantly influence the Canadian lumber exports to the United States. Given that SLA 2006 is scheduled to expire in October 2015, this article provides useful insights into the decades-long trade battle between the otherwise friendly neighboring nations. © 2015 Society of American Foresters.
Sullivan B.T.,U.S. Department of Agriculture |
Allison J.D.,Natural Resources Canada |
Coyer R.A.,Agricultural Center |
Shepherd W.P.,U.S. Department of Agriculture
Journal of Economic Entomology | Year: 2015
The baldcypress leafroller, Archips goyerana Kruse (Lepidoptera: Tortricidae), is a specialist on Taxodium distichum (L.) Richard and has caused serious defoliation in swamps of southeastern Louisiana, accelerating decline of baldcypress forests concurrently suffering from nutrient depletion, prolonged flooding, and saltwater intrusion. We investigated the composition of the sex pheromone of this species. Coupled gas chromatography-electroantennographic detection (GC-EAD) analyses indicated that male antennae were sensitive to four compounds [(Z)-11-tetradecenyl acetate (Z11-14:OAc), (E)-11-tetradecenyl acetate (E11-14:OAc), (Z)-9-tetradecenyl acetate (Z9-14:OAc), and (Z)-11-tetradecen-1-ol (Z11-14:OH)] present in female abdominal tip extracts in an approximately 100:1.5:0.6:10 ratio. In trapping trials performed in a cypress-tupelo swamp in southeastern Louisiana, moths were attracted to blends of these four components presented in approximately the female-produced ratios. Elimination of Z11-14:OH had no impact on moth response, whereas elimination of any of the three acetates strongly reduced or eliminated attraction. A blend in which the E11:Z11 ratio of 14:OAc was 5:100 was much less attractive than the same blend with the female produced ratio of 1.5:100. A. goyerana is closely related to the sympatric species Archips argyrospilus (Walker) with which it was previously synonymous. Our data revealed differences between the pheromone composition of A. goyerana and that reported for A. argyrospilus, which could account for the apparent absence of cross-attraction between these species. We conclude that a lure containing a 100:1.5:0.6 ratio of Z11-14:OAc, E11-14:OAc, and Z9-14:OAc has the potential to be used in traps to detect and measure A. goyerana populations and thereby monitor an important biotic factor contributing to the loss of coastal baldcypress forests. © Published by Oxford University Press on behalf of Entomological Society of America 2015.
Boldor D.,Louisiana State University |
Kanitkar A.,Louisiana State University |
Terigar B.G.,Louisiana State University |
Leonardi C.,Pennington Biomedical Research Center |
And 2 more authors.
Environmental Science and Technology | Year: 2010
Chinese tallow tree (TT) seeds are a rich source of lipids and have the potential to be a biodiesel feedstock, but currently, its invasive nature does not favor large scale cultivation. Being a nonfood material, they have many advantages over conventional crops that are used for biodiesel production. The purpose of this study was to determine optimal oil extraction parameters in a batch-type and laboratory scale continuous-flow microwave system to obtain maximum oil recovery from whole TT seeds using ethanol as the extracting solvent. For the batch system, extractions were carried out for different time-temperature combinations ranging from 60 to 120 °C for up to 20 min. The batch system was modified for continuous extractions, which were carried out at 50, 60, and 73 °C and maintained for various residence times of up to 20 min. Control runs were performed under similar extraction conditions and the results compared well, especially when accounting for extremely short extraction times (minutes vs hours). Maximum yields of 35.32% and 32.51% (by weight of dry mass) were obtained for the continuous and batch process, respectively. The major advantage of microwave assisted solvent extraction is the reduced time of extraction required to obtain total recoverable lipids, with corresponding reduction in energy consumption costs per unit of lipid extracted. This study indicates that microwave extraction using ethanol as a solvent can be used as a viable alternative to conventional lipid extraction techniques for TT seeds. © 2010 American Chemical Society.