Extension Ag Update
September/October 2004
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Bt Corn Plants Do Not Contain More Lignin

H. G. Jung and C. C. Sheaffer, University of Minnesota

A Minnesota study compared 12 commercial hybrids (six Bt hybrids and their genetically identical non-Genetically Modified counterparts). They compared the lignin concentration of whole plants of Bt hybrids with their non-Bt counterpart. No differences between BT and no-Bt hybrids were found in the amount of lignin, fiber digestibility, concentrations of protein, starch and fiber or total corn silage yield. Presence of the Bt gene in GM corn hybrids did not affect the corn silage's feeding value.

Forage Yield and Quality of Temperate Perennial Grasses as Influenced by Stubble Height

Debbie J. R. Cherney, Department of Animal Science; Jerome H. Cherney, Department of Crop and Soil Sciences, Cornell University

Orchardgrass, reed canarygrass and tall fescue were treated in the spring with different nitrogen fertilizer rates of 0, 100 and 200 lb/acre. Cuttings were taken at different heights and the hay was analyzed for crude protein, neutral detergent fiber, in vitro true digestibility and digestible NDF. There was limited change in the nutritive value for every inch of stubble left. If a cutting is made late, past the optimum forage quality, higher cutting heights resulted in 12 percent less dry matter yield while only increasing the crude protein by 1 percent, regardless of nitrogen fertilization.

Plowing Decreases Phosphorus Levels in Surface Soil and Runoff

Andrew N. Sharpley, USDA-ARS, Pasture Systems and Watershed Management Research Unit, University Park, PA 16802-3702
One-time plowing studies were conducted in Oklahoma and Pennsylvania on fields that had received either dairy, poultry or swine manure for up to 20 years. The fields had three times the phosphorus levels needed by crops. Plowing once with a moldboard plow and then planting to orchardgrass decreased the phosphorus content of the surface layer and lowered the potential for phosphorus losses through runoff.

Tagged Nitrogen from Fertilizer Found in Soil 20 Years Later

D. S. Jenkinson, P. R. Poulton, A. E. Johnston and D. S. Powlson, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK

Nitrogen can last a long time in soil. Tagged nitrogen was applied to a Grass Continuous Hay experiment at Rothamsted Research Center in England. Over half of the tagged nitrogen was recovered in the hay the first year. Almost a third of the tagged nitrogen remained in the humus, soil microbes or in plant roots. Each year plants remove a little of the tagged nitrogen. After 20 years, scientists estimate that up to 15 percent of the tagged nitrogen is still in the soil.