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11.
David C. RobertsB. Wade Brorsen John B. SolieWilliam R. Raun 《Agricultural Systems》2011,104(4):307-314
This paper estimates the relative profitability of using optical reflectance-based measures to predict crop needs for topdress nitrogen application to hard red winter wheat (Triticum aestivum). The data are from nitrogen yield response experiments where midseason optical reflectance data were recorded. Both nitrogen-rich strips and ramped strips are considered. Unlike past research, optimal nitrogen recommendations are calculated with and without accounting for parameter uncertainty. The expected profit-maximizing strategy is to follow the historical extension advice of applying 90 kg ha−1 preplant nitrogen using anhydrous ammonia. This strategy is more profitable than the best optical reflectance-based prediction system by $18.74 ha−1. When anhydrous ammonia is unavailable and preplant nitrogen must be applied as dry urea, the extension recommendation and the optical reflectance-based predictors are not significantly different. Ramped strips are no better than nitrogen-rich strips. Accounting for estimation uncertainty in the parameters increases expected profit by about $10 ha−1. 相似文献
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The effect of acepromazine maleate, xylazine and thiopentone on the packed cell volume, plasma protein content, factor VIII activity and von Willebrand factor antigen concentration of blood was studied in normal dogs. The same variables were measured in dogs with haemophilia A given acepromazine maleate and thiopentone. Both the packed cell volume and plasma protein content decreased after the administration of either acepromazine maleate or xylazine. Values were not changed further after administration of thiopentone. Changes in the haemostatic variables measured were generally small. Consequently, blood samples collected from dogs under the influence of premedicant doses of acepromazine maleate or xylazine, and when subsequently anaesthetised with thiopentone, are adequate for the assay of factor VIII activity and von Willebrand factor antigen concentration for establishing an animal's haemophilia A and von Willebrand's disease status. 相似文献
13.
Christopher N. Boyer B. Wade Brorsen William R. Raun D. Brian Arnall John B. Solie 《Journal of plant nutrition》2013,36(12):1776-1790
Past research about the efficiency of nitrogen application in winter wheat (Triticum aestivum L.) based on source and timing has produced inconsistent results. The majority of the literature used data from few locations over short time periods. This study used a unique data set of yields and nitrogen quantities from 2002–2009 at ten different locations in Oklahoma, USA. The objective of this research was to determine wheat yield response for granular pre-plant, uniform foliar topdress, and variable rate foliar topdress. Topdress liquid nitrogen had a 19% higher NUE than pre-plant urea, and was the most profitable source of nitrogen. 相似文献
14.
Is data needed from every field to determine in-season precision nitrogen recommendations in winter wheat? 总被引：1，自引：0，他引：1
The research reported here seeks to determine whether it is necessary to obtain optical reflectance measurements with a GreenSeeker® handheld sensor from each field to make accurate in-season nitrogen application recommendations for winter wheat, and how much precision—and profit—would be lost by moving from site-specific (or field-specific) optical reflectance sampling to region-level sampling. The approach used was to estimate a separate linear response-plateau regression every year using yield and optical reflectance data from randomized complete block experiments. Profits from region-level sampling and field-level sampling were statistically indistinguishable, but this result was mostly due to both being imprecise. Furthermore, the region- and field-based sampling systems were no better than break-even with the historical extension advice to apply preplant anhydrous ammonia at 90 kg ha?1. The approach of estimating a new regression every year is too imprecise, whether at the field or region level. This research goes beyond past research by accounting for the uncertainty in the estimated relationships. The poor performance of the systems is directly related to the imprecise relationship between yield and optical reflectance responses to nitrogen. 相似文献
15.
Pecan [Carya illinoinensis (Wang.) C. Koch.] trees were given four treatments: (i) control (no zinc application) (ii) DeltAg Zinc Plus® applied in fall, at budbreak, and after pollination (iii) DeltAg Zinc Plus applied in fall only and (iv) zinc sulfate 36.6% applied at budbreak, 3 weeks later, and after pollination. Leaf elemental concentration of zinc (Zn) increased with all zinc treatments in year one. In year two, the three applications of Zinc Plus produced the highest leaf elemental concentrations of Zn. The zinc sulfate treatment had a positive effect on nut and kernel weight in both years while the other two Zn treatments had effects that varied across years. Zinc sulfate had yields at least as good and nut quality at least as good as the other Zn treatments. Given that Zinc sulfate is the lowest-cost Zn treatment, the results reported here favor using zinc sulfate. 相似文献
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David?C.?RobertsEmail author B.?Wade?Brorsen Randal?K.?Taylor John?B.?Solie William?R.?Raun 《Precision Agriculture》2011,12(5):653-665
Ramped calibration strips have been suggested as a way for grain producers to determine nitrogen needs more accurately. The
strips use incrementally increasing levels of nitrogen and enable producers to conduct an experiment in each field to determine
nitrogen needs. This study determines whether predictions from the program Ramp Analyzer 1.2 are replicable in Oklahoma hard
red winter wheat (Triticum aestivum). Predictions are derived from 36 individual strips from on-farm experiments—two pairs of adjacent strips at each of nine
winter wheat fields in Canadian County, OK. The two pairs of strips within each field were between 120 and 155 m apart. Each
strip was analyzed three times during the 2006–2007 growing season. Nitrogen recommendations from Ramp Analyzer 1.2 are not
correlated even for strips that were placed side by side, and recommendations from strips in the same field show no more homogeneity
than randomly selected strips throughout the county. The results indicate that ramped calibration strips are unlikely to produce
accurate nitrogen requirement predictions at any spatial scale, whether at the county level or for subsections of a single
field. In contrast, a procedure that uses only measures from the plot with no nitrogen and the plot with the highest level
of nitrogen applied does show replicability. Thus, improvements in the ramped calibration strip technology are needed if it
is to become viable. 相似文献
18.
AIMS: To study the development and progression of lesions produced following experimental inoculations of possums with Bacille Calmette-Guérin (BCG) Pasteur Strain 1173P2 and to compare these with lesions that occurred following natural Mycobacterium bovis infection. METHODS: Possums were inoculated with 5 x 106 colony forming units (cfu) of BCG via the intra-dermal (I/D) route into the dorsum of the neck (n=38) or the left brachium (n=7), orally (n=10), via the endo-bronchial (E/B) route (n=12), or intravenously (I/V) (n=10, half of which received 5 x 106 cfu and half of which received 5 x 107 cfu of BCG). The possums were humanely killed between 1–4 weeks post inoculation (p.i.), and the nature and distribution of lesions examined grossly and histopathologically. RESULTS: The distribution of lesions following I/D inoculation via either route was similar to that of the natural disease, but there were few lesions in the lung. Endo-bronchial inoculation resulted in pulmonary disease but produced few lesions outside the respiratory tract. Lesions produced by I/V inoculation were similar in distribution to those seen in terminally ill tuberculous possums. No lesions were produced following oral inoculation. Regression of lesions commenced after 3 weeks p.i. CONCLUSIONS: Although the phenomenon of lesion resolution restricts the use of BCG to the study of early lesion development, it avoids the overwhelming disease induced using M. bovis and thus allows the early phases of the development and progression of tuberculosis in this species to be observed. Intra-dermal inoculation produced evidence that infection through the skin is associated with lesions in superficial lymph nodes, whereas pulmonary disease was associated with E/B inoculation. The results are consistent with the hypothesis that both percutaneous and respiratory routes are important in natural infection of possums with M. bovis. 相似文献
19.
T Fujisawa TH Oosterkamp van der Wiel WG BW Broer R Aguado S Tarucha LP Kouwenhoven 《Science (New York, N.Y.)》1998,282(5390):932-935
A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current was used to directly measure the rates for elastic and inelastic transitions between the two levels. For inelastic transitions, energy is exchanged with bosonic degrees of freedom in the environment. The inelastic transition rates are well described by the Einstein coefficients, relating absorption with stimulated and spontaneous emission. The most effectively coupled bosons in the specific environment of the semiconductor device used here were acoustic phonons. The experiments demonstrate the importance of vacuum fluctuations in the environment for quantum dot devices and potential design constraints for their use for preparing long-lived quantum states. 相似文献
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