REMOVAL OF THE EFFECTS OF UNEVEN GRAZING IN PASTURE EXPERIMENTS     

Andrew L.  Gardner Gilberto A.  Centeno 《Grass and Forage Science》1966,21(4):264-269

An experiment is described in which uneven grazing by sheep introduced a bias in a white clover variety trial. The data were adjusted by covariance, using as the independent variable the position of the plots within the paddocks.
Attention is drawn to the errors that may result from uneven grazing and a comparison is made with errors due to transference of fertility. Means of avoiding similar occurrences are suggested.  相似文献   

Solutions to Locoweed Poisoning in New Mexico and the Western United States: Collaborative research between New Mexico State University and the USDA–Agricultural Research Service Poisonous Plant Lab     

David Graham  Rebecca Creamer  Daniel Cook  Bryan Stegelmeier  Kevin Welch  Jim Pfister  Kip Panter  Andres Cibils  Michael Ralphs  Manny Encinias  Kirk McDaniel  David Thompson  Kevin Gardner 《Herpetological Monographs》2009,31(6):3-8

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Simple phosphorus saturation index to estimate risk of dissolved P in runoff from arable soils   总被引：1，自引：0，他引：1  

S. Hughes  B. Reynolds  S.A. Bell  C. Gardner 《Soil Use and Management》2000,16(3):206-210

Abstract. There is increasing evidence that phosphorus has been accumulating in the surface horizons of agricultural soils to the extent that some soils represent a potential diffuse source of pollution to surface waters. The relationships between equilibrium phosphorus concentration at zero sorption (EPC ₀) of soil and a number of soil physicochemical variables were investigated in the surface layers of arable and grassland agricultural soils sampled from the Thame catchment, England. Soil EPC₀ could be predicted from an equation including soil test (Olsen) P, soil phosphate sorption index (PSI) and organic matter content (OM) (R²=0.88; P <0.001) across a range of soil types and land use. The simple index Olsen P/PSI was found to be a good predictor of EPC₀ (R²=0.77; P <0.001) and readily desorbable (0.02 m KCl extractable) P (R²=0.73; P <0.001) across a range of soil types under arable having soil organic matter contents of <10%.  相似文献   

Experimental demonstration of guiding and bending of electromagnetic waves in a photonic crystal   总被引：3，自引：0，他引：3  

SY Lin  E Chow  V Hietala  PR Villeneuve  JD Joannopoulos 《Science (New York, N.Y.)》1998,282(5387):274-276

The routing and interconnection of optical signals through narrow channels and around sharp corners are important for large-scale all-optical circuit applications. A recent computational result suggests that photonic crystals may offer a novel way of achieving this goal by providing a mechanism for guiding light that is fundamentally different from traditional index guiding. Waveguiding in a photonic crystal and near 100 percent transmission of electromagnetic waves around sharp 90 degree corners were observed experimentally. Bending radii were made smaller than one wavelength.  相似文献