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Full-Text Articles in Life Sciences
Winter Grazing Management, Stephen K. Barnhart, James R. Russell, Douglas L. Karlen, Michael J. Tidman
Winter Grazing Management, Stephen K. Barnhart, James R. Russell, Douglas L. Karlen, Michael J. Tidman
Douglas L Karlen
Why winter grazing? Beef cow herd and sheep flock records show that winter feeding costs are livestock producers' single largest production expense. Managing through winter weather while keeping feeding costs low is an essential part of maintaining a profitable operation. Iowa's climate generally allows forage growth only during a 7-to-8 month period. Extending the grazing of this forage--even an extra 3 or 4 weeks in late autumn and winter--is an economical way to maintain or increase livestock profitability. Some producers extend the grazing season by using stockpiled forage, whereas others use crop residue, and many combine the use of stockpiled …
Engineering, Nutrient Removal, And Feedstock Conversion Evaluations Of Four Corn Stover Harvest Scenarios, Reed L. Hoskinson, Douglas L. Karlen, Stuart J. Birrell, Corey W. Radtke, Wally Wilhelm
Engineering, Nutrient Removal, And Feedstock Conversion Evaluations Of Four Corn Stover Harvest Scenarios, Reed L. Hoskinson, Douglas L. Karlen, Stuart J. Birrell, Corey W. Radtke, Wally Wilhelm
Douglas L Karlen
Crop residue has been identified as a near-term source of biomass for renewable fuel, heat, power, chemicals and other bio-materials. A prototype one-pass harvest system was used to collect residue samples from a corn (Zea mays L.) field near Ames, IA. Four harvest scenarios (low cut, high-cut top, high-cut bottom, and normal cut) were evaluated and are expressed as collected stover harvest indices (CSHI). High-cut top and high-cut bottom samples were obtained from the same plot in separate operations. Chemical composition, dilute acid pretreatment response, ethanol conversion yield and efficiency, and thermochemical conversion for each scenario were determined. Mean …
Protocol For Indicator Scoring In The Soil Management Assessment Framework (Smaf), Brian J. Wienhold, D.L. Karlen, S.S. Andrews, D.E. Stott
Protocol For Indicator Scoring In The Soil Management Assessment Framework (Smaf), Brian J. Wienhold, D.L. Karlen, S.S. Andrews, D.E. Stott
Douglas L Karlen
Assessment tools are needed to evaluate agronomic management effects on critical soil functions such as carbon sequestration, nutrient cycling and water partitioning. These tools need to be flexible in terms of selection of soil functions to be assessed and indicators to be measured to ensure that assessments are appropriate for the management goals. The soil management assessment framework (SMAF) is being developed to meet this need. The SMAF uses soil physical, chemical and biological indicator data to assess management effects on soil function using a three-step process for (1) indicator selection, (2) indicator interpretation and (3) integration into an index. …
N-Management And Crop Rotation Effects On Yield And Residual Soil Nitrate Levels, A. Bakhsh, R. S. Kanwar, D. L. Karlen, C. A. Cambardella, T. B. Bailey, T. B. Moorman, T. S. Colvin
N-Management And Crop Rotation Effects On Yield And Residual Soil Nitrate Levels, A. Bakhsh, R. S. Kanwar, D. L. Karlen, C. A. Cambardella, T. B. Bailey, T. B. Moorman, T. S. Colvin
Douglas L Karlen
Swine production facilities are becoming more concentrated in Iowa, and public is concerned about the impact of using swine manure for crop production on soil and water quality. This field study was conducted from 1996 to 1998 to compare the effects of liquid swine manure and urea ammonium nitrate (UAN) application on crop yield and residual soil nitrate for continuous corn (Zea mays L.) and corn-soybean (Glycine max (L.) Merr.) rotation systems. Six N management treatments were replicated three times in a randomized complete block design at Iowa State University's northeastern research center in Nashua, Iowa. Injected UAN provided 135 …
Review And Interpretation: Nitrogen Management Strategies To Reduce Nitrate Leaching In Tile-Drained Midwestern Soils, Dana L. Dinnes, Douglas L. Karlen, Dan B. Jaynes, Thomas C. Kaspar, Jerry L. Hatfield, Thomas S. Colvin, Cynthia A. Cambardella
Review And Interpretation: Nitrogen Management Strategies To Reduce Nitrate Leaching In Tile-Drained Midwestern Soils, Dana L. Dinnes, Douglas L. Karlen, Dan B. Jaynes, Thomas C. Kaspar, Jerry L. Hatfield, Thomas S. Colvin, Cynthia A. Cambardella
Douglas L Karlen
Balancing the amount of N needed for optimum plant growth while minimizing the NO3 that is transported to ground and surface waters remains a major challenge for everyone attempting to understand and improve agricultural nutrient use efficiency. Our objectives for this review are to examine how changes in agricultural management practices during the past century have affected N in Midwestern soils and to identify the types of research and management practices needed to reduce the potential for nonpoint NO3 leakage into water resources. Inherent soil characteristics and management practices contributing to nonpoint NO3 loss from Midwestern soils, the impact of …
Fluid Fertilizer’S Role In Sustaining Soils Used For Bio-Fuels Production, John L. Kovar, Douglas Karlen
Fluid Fertilizer’S Role In Sustaining Soils Used For Bio-Fuels Production, John L. Kovar, Douglas Karlen
Douglas L Karlen
The short- and long-term effects on soil nutrient cycling, physical properties, and biological activity of striving for higher grain yields and removing crop residues for bio-fuels production must be understood to provide more quantitative crop and soil management guidelines. This study focuses on potassium (K) and sulfur (S) requirements of corn (Zea mays L.) grown for bioenergy feedstock production. Our objectives for 2008 were to: i) evaluate the performance of several S fertilizers, including liquid ammonium thiosulfate (12-0-0-26S), as S sources for corn grown in Iowa, and ii) establish a comprehensive tillage, nutrient management, crop residue removal, and cover crop …