Extension Ag Update
September/October 2006
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Manure Increases Losses of Veterinary Antibiotics From Grassland

Christian Leua, Heinz Singer, Stephan R. Müller, René P. Schwarzenbach, and Christian Stamm


Antibiotic resistance in the environment continues to be a concern.  Scientists investigated the role of animals  by putting sulfonamides into the environment by applying liquid pig manure. Manure containing a sulphonamide was used due to its regular administration to pigs. Surface runoff was induced by artificial irrigation and antibiotic losses were quantified. Surprisingly, manure largely influenced antibiotics’ fate and transport. It increased the antibiotics’ chemical availability for transport and runoff volume. This resulted in 10 to 40 times larger losses from manured plots compared to the aqueous controls with losses 0.2 -2 percent of applied mass.

Plant-To-Plant Grain Yield Varies

K. L. Martin, P. J. Hodgen, K. W. Freeman, Ricardo Melchiori, D. B. Arnall, R. K. Teal, R. W. Mullen, K. Desta, S. B. Phillips, J. B. Solie, M. L. Stone, Octavio Caviglia, Fernando Solari, Agustin Bianchini, D. D. Francis, J. S. Schepers, J. L. Hatfield, and W. R. Raun


Corn grain yields vary from plant to plant. A study evaluated changes in by-plant corn grain yields in various production environments and established relationships among mean grain yield, standard deviation, coefficient of variation, and yield range. Corn was harvested by plant in Argentina, Mexico, Iowa, Nebraska, Ohio, Virginia and Oklahoma. Overall sites, plant-to-plant variation in corn grain yield averaged around 44 bu /A. As average grain yields increased, plant-to-plant variability increased. Yield ranges increased with increasing yield level. When corn grain yields were averaged over distances > about 0.5 yard, it removed the extreme by-plant variability. Thus, variable rate technologies must operate at scales at < about 0.5 yard. 

Shade Location and Water Troughs To Reduce Stream Contamination By Cattle

H. L. Byers, M. L. Cabrera, M. K. Matthews, D. H. Franklin, J. G. Andrae, D. E. Radcliffe, M. A. McCann, H. A. Kuykendall, C. S. Hoveland, and V. H. Calvert, II


Cattle can contaminate unfenced streams flowing through pastures. Scientists monitored stream water quality. One pasture had less shade away from the stream than a second pasture. Both pastures had similar amount of shade near the stream. During part of the monitoring period, cattle had access to water troughs located away from the stream. During the remaining portion, cattle had no access to water troughs. This study showed stream contamination by cattle was greatest in the pasture with less shade away from the stream. Water trough availability decreased sediment and pathogenic contamination. Shade location and water trough availability away from the stream may decrease cattle contaminating unfenced streams located in pastures.