Agronomy and Horticulture, Department of


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Noble Foundation Scientific Report: 2005-2009


Copyright 2009 by The Samuel Roberts Noble Foundation, Inc.,


Guretzky specializes in research on forage and bioenergy crop management that will assist agricultural producers and landowners in meeting their goals. The first area of research involves Drs. Jon Biermacher and Billy Cook for the evaluation of management practices of switchgrass in forage and bioenergy systems. Objectives include: 1.) assessing potential on-farm biomass yields and production economics of switchgrass; 2.) documenting effects of location, harvest system and nitrogen fertilizer rates on biomass yields, forage quality, stand persistence and nutrient removal rates; 3.) evaluating establishment and biomass production responses to phosphorus and potassium fertilization; 4.) determining how stocker cattle gains on switchgrass vary with stocking density; 5.) determining switchgrass persistence and end of season biomass yields following early season grazing; and 6.) determining economics of stocker cattle ownership on switchgrass.

The second area of collaborative research involves Drs. Twain Butler, Ryan Reuter and Jon Biermacher and focuses on evaluation of legume species in pastures. Research objectives include: 1.) evaluating spring forage availability of winter annual legume species; and 2.) documenting net returns to land, labor and management from stocker cattle grazing N-fertilized and legume-interseeded pastures. Results have been promising. From 2006 to 2008, hairy vetch and Austrian winter pea produced dry matter yields ranging from 2,204 to 6,720 lb/acre across six environments. In 2008, a grazing experiment was established to compare bermudagrass fertilized with urea at 112 kg N/ ha; bermudagrass interseeded with a grazingtype alfalfa; and bermudagrass interseeded with a mixture of winter annual legumes (hairy vetch, crimson clover and arrowleaf clover). Net returns were $292, $109 and $227/ha for N-fertilized, alfalfa and annual legume systems, respectively. Net returns between the N-fertilized and the annual legume system were sensitive to price of N, gain/ha, value of gain and grazing days.

The third area of research evaluates the use of fire to improve rangeland for beef cattle and wildlife. In collaboration with Ken Gee and others, research at the Oswalt Road Ranch will examine how controlled burning affects stocker cattle production, herbaceous and woody species composition and biomass, and land management economics. Three experimental units will be controlled burned and grazed, and three will receive grazing only. Annual changes in herbage mass and plant communities will be documented beginning in 2009 and prescribed burning and grazing will continue until 2020.