Response Of Irrigated Corn To Nitrogen Fertility Level Within Two Tillage Systems

Irrigated farmers generally utilize intensive tillage to manage crop residues and prepare a seedbed for com. Nitrogen fertilizer management practices have been developed for conventional-till (CT) irrigated com production. Little information is available for no-till (NT) and reduced-till (RT) irrigated com production systems. This paper compares the response of irrigated continuous com to N fertility level under CT and NT or RT production systems on a Fort Collins clay loam soil from 1999 through 2001. Grain yields increased similarly with increasing available N level [soil NO3-N (0-3 ft) plus fertilizer N added] in 1999,2000, and 2001 for both tillage systems. The CT com yields were greater than the RT or NT com yields in 1999 and 2001, respectively. Based on the results from this study, similar N levels were required. for optimum com yields in all tillage systems. Additional years of data are needed to determine if NT will require a higher level of N fertilizer input than CT to optimize com grain yields. Current N fertilizer recommendations for CT irrigated com production would appear to be adequate for irrigated NT com production

Occurrence of birefringent retinal inclusions in cynomolgus monkeys after high doses of canthaxanthin

urpose. To reproduce and investigate in a primate animal model the phenomenon of the red carotenoid canthaxanthin (/?,/5-carotene-4'4'-dione) to induce crystal-like retinal deposits as they have been observed in the ocular fundus of humans after high canthaxanthin intake (i.e., more than 30 mg/day). Methods. Groups of four cynomolgus monkeys (Macaco, fascicularis) per gender and dose were administered 5.4, 16.2, or 48.6 mg candiaxanthin/kg body weight daily by oral gavage for 2.5 years. Eight control animals received placebo. In vivo ophthalmoscopy was performed at intervals of 3 months along with electroretinography after 12 and 24 months and retinal biomicroscopy just before the monkeys were killed. Retinal wholemounts or frozen sections were investigated postmortem by polarization, bright field, and differential interference contrast microscopy. Retinal and preterminal plasma canthaxanthin concentrations were determined by high-performance liquid chromatography (HPLC). Results. By ophthalmoscopy and retinal biomicroscopy in vivo, no crystals or other lightreflecting particles were observed in the central paramacular retina. However, postmortem polarization microscopy of all 24 canthaxanthin-treated animals showed a circular zone in the peripheral retina containing birefringent, polymorphous red, orange, or white inclusions. The density of these inclusions was diminished within 1 to 8 mm posterior to the ora serrata. These inclusions were located mainly in the inner retinal layers, that is, the nerve fiber layer and ganglion cell layer, inner plexiform layer, and inner nuclear layer. Twelve of the 24 canthaxanthin-treated animals showed yellow, golden birefringent inclusions in die macula. Retinas of placebo-treated monkeys were free of birefringent, crystal-like inclusions. The HPLC confirmed the presence of all-trans canthaxanthin, and 4-OH-echinenone and isozeaxanthin as well, in the retinas of all can thaxan dim-treated animals. Neither electroretinography nor histopathology indicated any adverse effects of the canthaxanthin-induced retinal inclusions seen in this study. Conclusions. A high intake of canthaxanthin for 2.5 years led to the deposition of crystal-like birefringent inclusions in the inner layers of the peripheral retina and, to some extent, the central retina of cynomolgus monkeys. The presence of these deposits did not interfere with morphology nor with retinal function. Invest Ophthalmol Vis Sci. 1997;38:741-752. A he carotenoid canthaxanthin (/?,/3-carotene-4'4'-dione) is synthesized in nature by the mushroom Cantharellus cinnabarinus. It also occurs in a variety of other plants and animals (e.g., in algae, Crustacea, birds, o

230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

230Th normalization is a valuable paleoceanographic tool for reconstructing high-resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th-normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size-dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (\u3e1,000 m water depth)

230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Costa, K. M., Hayes, C. T., Anderson, R. F., Pavia, F. J., Bausch, A., Deng, F., Dutay, J., Geibert, W., Heinze, C., Henderson, G., Hillaire-Marcel, C., Hoffmann, S., Jaccard, S. L., Jacobel, A. W., Kienast, S. S., Kipp, L., Lerner, P., Lippold, J., Lund, D., Marcantonio, F., McGee, D., McManus, J. F., Mekik, F., Middleton, J. L., Missiaen, L., Not, C., Pichat, S., Robinson, L. F., Rowland, G. H., Roy-Barman, M., Alessandro, Torfstein, A., Winckler, G., & Zhou, Y. 230 Th normalization: new insights on an essential tool for quantifying sedimentary fluxes in the modern and quaternary ocean. Paleoceanography and Paleoclimatology, 35(2), (2020): e2019PA003820, doi:10.1029/2019PA003820.230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).We thank Zanna Chase and one anonymous reviewer for valuable feedback. K. M. C. was supported by a Postdoctoral Scholarship at WHOI. L. M. acknowledges funding from the Australian Research Council grant DP180100048. The contribution of C. T. H., J. F. M., and R. F. A. were supported in part by the U.S. National Science Foundation (US‐NSF). G. H. R. was supported by the Natural Environment Research Council (grant NE/L002434/1). S. L. J. acknowledges support from the Swiss National Science Foundation (grants PP002P2_144811 and PP00P2_172915). This study was supported by the Past Global Changes (PAGES) project, which in turn received support from the Swiss Academy of Sciences and the US‐NSF. This work grew out of a 2018 workshop in Aix‐Marseille, France, funded by PAGES, GEOTRACES, SCOR, US‐NSF, Aix‐Marseille Université, and John Cantle Scientific. All data are publicly available as supporting information to this document and on the National Center for Environmental Information (NCEI) at https://www.ncdc.noaa.gov/paleo/study/28791

\u3csup\u3e230\u3c/sup\u3eTh Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (\u3e1,000 m water depth)

INNOVATIVE REMOTE SENSING TECHNIQUES TO INCREASE NITROGEN USE EFFICIENCY OF CORN

Nitrogen (N) fertilizer recommendations made without adequate knowledge of the N supply capability of a soil can lead to inefficient use of N. Proper crediting of N from manure and legumes as well as mineralization of N from organic matter is difficult. Remote sensing techniques that use the crop to indicate its N status show considerable promise for improving N management. Objectives of this paper were twofold: 1) to compare the N Reflectance Index (NRI) calculated from ground-based radiometer measurements acquired over irrigated corn (Zea mays L.) at a nadir view (0 °) and an oblique view (75 °) with measured plant N and 2) to evaluate the NRI obtained from both view angles for correcting in-season N deficiencies in a commercial corn field. The NRI calculated from canopy reflectance was not representative of plant N at the sixth leaf growth stage (V6) for either view angle because of the soil background influence on canopy reflectance. However, the oblique view NRI was a good predictor of plant N at V9 and V12 as was the nadir view NRI at V12. The nadir view NRI was not as sensitive as the oblique view NRI at the V9 growth stage because soil was still visible through the canopy. Consequently, the nadir view NRI provides a conservative estimate of plant N prior to complete canopy cover. Use of the nadir view NRI to detect in-season corn N deficiencies for the 1999 growing season reduced N application during the growing season by 39.2 kg N ha-1 without reducing grain yield. If the oblique view NRI would have been used to assess the plant N status, the first fertigation would not have been recommended which would have saved additional N

Development of a soil moisture model for use with passive microwave remote sensors

Vita.Soil moisture profiles were simulated for a hypothetical loamlike soil with a water and heat balance model. Expected X-band and L-band radiometer response to these conditions were simulated by a radiative transfer model. From these simulations, a model was developed to estimate soil water content in two layers of a 1.5 m soil profile. Soil water content in the top 21 cm of the hypothetical soil was related to L-band emissivity over a wide range of soil moisture conditions. Inverted soil moisture profiles which result from small rains were classified by use of the rate of change in L-band emissivity one day after the rain. The amount of water added to the soil profile below the 21 cm depth due to percolation was related to a ratio of the rate of change in X-band and L-band emissivities one day after the rain. These relationships were combined into a comprehensive model that predicts soil moisture in two zones of the soil profile. This model was tested with measurements of soil water content and soil temperature collected during the four seasons of the year in a sandy loam soil contained in an array of lysimeters. X-band and L-band emissivities required in the predictor equations were calculated by the radiative transfer model from measured soil moisture and soil temperature data. The technique developed from simulated results to classify inverted soil moisture profiles was found to be seasonally dependent. It was also found that the second layer algorithm showed seasonal dependence. Predictions of soil water content in the top 21 cm of the soil profile from L-band emissivity calculated by the radiative transfer model occasionally conformed with measured soil water content. Since the equation to estimate soil water content for inverted soil moisture profiles did not fit the measured data, soil water content on such occurrences was overpredicted. Applications of small amounts of water produced the most disagreement between predicted and measured soil water content. ..

Development of a soil moisture model for use with passive microwave remote sensors

Vita.Soil moisture profiles were simulated for a hypothetical loamlike soil with a water and heat balance model. Expected X-band and L-band radiometer response to these conditions were simulated by a radiative transfer model. From these simulations, a model was developed to estimate soil water content in two layers of a 1.5 m soil profile. Soil water content in the top 21 cm of the hypothetical soil was related to L-band emissivity over a wide range of soil moisture conditions. Inverted soil moisture profiles which result from small rains were classified by use of the rate of change in L-band emissivity one day after the rain. The amount of water added to the soil profile below the 21 cm depth due to percolation was related to a ratio of the rate of change in X-band and L-band emissivities one day after the rain. These relationships were combined into a comprehensive model that predicts soil moisture in two zones of the soil profile. This model was tested with measurements of soil water content and soil temperature collected during the four seasons of the year in a sandy loam soil contained in an array of lysimeters. X-band and L-band emissivities required in the predictor equations were calculated by the radiative transfer model from measured soil moisture and soil temperature data. The technique developed from simulated results to classify inverted soil moisture profiles was found to be seasonally dependent. It was also found that the second layer algorithm showed seasonal dependence. Predictions of soil water content in the top 21 cm of the soil profile from L-band emissivity calculated by the radiative transfer model occasionally conformed with measured soil water content. Since the equation to estimate soil water content for inverted soil moisture profiles did not fit the measured data, soil water content on such occurrences was overpredicted. Applications of small amounts of water produced the most disagreement between predicted and measured soil water content. ..

Crop response at various stages of growth to sprinkler and furrow irrigation

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