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Full-Text Articles in Physical Sciences and Mathematics

Fire-Induced Albedo Change And Its Radative Forcing At The Surface In Northern Austrailia, Y. Jin, David P. Roy Jul 2005

Fire-Induced Albedo Change And Its Radative Forcing At The Surface In Northern Austrailia, Y. Jin, David P. Roy

GSCE Faculty Publications

This paper investigates the impact of fire on surface albedo and the associated radiative forcing over 56% of continental Australia encompassing the fire-prone northern tropical savanna. Fire-affected areas and albedos are derived for the 2003 fire season using daily Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. Near-infrared and total shortwave albedos are observed to generally decrease after fire occurrence. Regionally, the total shortwave albedo drops by an average of 0.024, with increasing reductions as the dry season progresses and larger reductions in grasslands than woody savannas. These fire-induced albedo changes exert a positive forcing at the surface that increases …


Factors Influencing Spatial Variability Of Soil Apparent Electrical Conductivity, D. E. Clay, J. Chang, D. D. Malo, C. G. Carlson, C. Reese, S. A. Clay, M. Ellsbury, B. Berg Jan 2001

Factors Influencing Spatial Variability Of Soil Apparent Electrical Conductivity, D. E. Clay, J. Chang, D. D. Malo, C. G. Carlson, C. Reese, S. A. Clay, M. Ellsbury, B. Berg

Agronomy, Horticulture and Plant Science Faculty Publications

Soil apparent electrical conductivity (ECa) can be used as a precision farming diagnostic tool more efficiently if the factors influencing ECa spatial variability are understood. The objective of this study was to ascertain the causes of ECa spatial variability in soils developed in an environment with between 50 and 65 cm of annual rainfall. Soils at the research sites were formed on calcareous glacial till parent materials deposited approximately 10,000 years ago. Soil samples (0–15 cm) collected from at least a 60 by 60 m grid in four fields were analyzed for Olsen phosphorus (P) and …


Herbicide Movement And Dissipation At Four Midwestern Sites, S. A. Clay, R. H. Dowdy, J. A. Lamb, J. L. Anderson, B. Lowery, R. E. Knight, D. E. Clay May 2000

Herbicide Movement And Dissipation At Four Midwestern Sites, S. A. Clay, R. H. Dowdy, J. A. Lamb, J. L. Anderson, B. Lowery, R. E. Knight, D. E. Clay

Agronomy, Horticulture and Plant Science Faculty Publications

This study was conducted to evaluate atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl‐1, 3, 5‐triazine) and alachlor (2‐chIoro‐N‐(methoxymethyl)acetamide) dissipation and movement to shallow aquifers across the Northern Sand Plains region of the United States. Sites were located at Minnesota on a Zimmerman fine sand, North Dakota on Hecla sandy loam, South Dakota on a Brandt silty clay loam, and Wisconsin on a Sparta sand. Herbicide concentrations were determined in soil samples taken to 90 cm four times during the growing season and water samples taken from the top one m of aquifer at least once every three months. Herbicides were detected to a …


Precision Farming Protocols. Part 2. Comparison Of Sampling Approaches For Precision Phosphorus Management, David E. Clay, Jiyul Chang, C. Gregg Carlson, Doug Malo, Sharon A. Clay, Mike Ellsbury Jan 2000

Precision Farming Protocols. Part 2. Comparison Of Sampling Approaches For Precision Phosphorus Management, David E. Clay, Jiyul Chang, C. Gregg Carlson, Doug Malo, Sharon A. Clay, Mike Ellsbury

Agronomy, Horticulture and Plant Science Faculty Publications

Research is needed to compare the different techniques for developing site‐specific phosphorus (P) recommendations on a field‐wide basis. The objective of this study was to determine the impact different techniques for developing site‐specific P recommendation maps on yield and profitability. Enterprise analysis combined with a crop simulation model and detailed field characterization was used to estimate the value of spatial P information in a system where N was not limiting. The systems evaluated were continuous corn (Zea mays) and corn and soybean (Gfycine max) rotations where sampling and fertilizer applications were applied annually and semi‐annually, respectively. The sampling techniques tested …


Field Scale Variability Of Nitrogen And Δ15n In Soil And Plants, D. E. Clay, J. Chang, S. A. Clay, M. Ellsbury, C. G. Carlson, D. D. Malo, D. Woodson, T. Desttur Nov 1998

Field Scale Variability Of Nitrogen And Δ15n In Soil And Plants, D. E. Clay, J. Chang, S. A. Clay, M. Ellsbury, C. G. Carlson, D. D. Malo, D. Woodson, T. Desttur

Agronomy, Horticulture and Plant Science Faculty Publications

Understanding the factors that influence soil and plant nitrogen (N) spatial variability may improve our ability to develop management systems that maximize productivity and minimize environmental hazards. The objective of this study was to determine the field (65 ha) scale spatial variability of N and δ15N in soil and corn (Zea mays). Soil, grain, and stover samples were collected from grids that ranged in size from 30 by 30 m to 60 by 60 m. Plant samples, collected following physiological maturity in 1995, were analyzed for total N and δ15N. Soil samples, collected prior …


Factors Affecting Atrazine Fate In North Central U.S. Soils, W. C. Koskinen, Sharon Clay Jan 1997

Factors Affecting Atrazine Fate In North Central U.S. Soils, W. C. Koskinen, Sharon Clay

Agronomy, Horticulture and Plant Science Faculty Publications

Atrazine (6-chloro-N-ethyl-N′-(l-methylethyl)-l,3,5-triazine-2,4-diamine) is a herbicide of the triazine family used for controlling broadleaf and some grassy weeds in corn and sorghum. Since its introduction in the late 1950s, atrazine has been a popular herbicide because it is relatively inexpensive and, in most cases, gives good season-long weed control. It can be applied pre-or postemergence and is often tank mixed with grass herbicides, such as alachlor (2-chloro-N-(2,6-diethylphenyl-N-(methoxymethyl)acetamide), metolachlor(2-chloro-N-(2-2ethyl-6-methylphenyl)-N-(2-methoxy-l-methylethyl) acetamide), butylate (S-ethyl bis(2-methylpropyl)carbamothioate), or EPTC (S-ethyl dipropylcarbamothioate), or with other broadleaf herbicides, such as dicamba (3,6-dichloro-2-methoxybenzoic …


Historical Crop / Climate Relationships In South Dakota, D.G. Kenefick, J.C. Harlan, K.K. Weischedel, P.D. Evenson Jan 1984

Historical Crop / Climate Relationships In South Dakota, D.G. Kenefick, J.C. Harlan, K.K. Weischedel, P.D. Evenson

Agronomy, Horticulture, and Plant Science Publications

Crop performance and climatic records were collated for high production counties in South Dakota to evaluate the effects of temperature and precipitation on yields. The crops involved were corn, soybeans, sorghum, oats, spring wheat, and winter wheat. Records were compared for the period from 1965 to 1982. The computer data file for each county includes seven climatic parameters, dates of plant development, adjusted yield-and yield rank by year. The crop/climate record for the 17-year period was evaluated in sixteen counties per crop each year. Thus, 272 county x year observations were made for each crop, except for soybeans which involved …