Extension Ag Update
November/December 2003
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Research

Biotech vs. Non-biotech for Grazing

Bruce Anderson, Extension Forage Specialist, Univ. of Nebraska, 402-472-6237, banderson1@unl.edu, source: Crop Watch - December 12, 2003

University of Nebraska scientists have reported that there are no differences in the performance of steers that grazed corn stalks from either Bt corn or Roundup Ready corn for 60 days compared to conventional corn. These results are similar to grazing results from other states. Although detailed health evaluations were not made, no illnesses or potential meat or milk residues have ever been reported due to corn stalks from genetically modified corn hybrids, so it appears that they can be grazed just like all other hybrids.

Some producers have reported that their cows appear to prefer grazing conventional corn stalk fields compared to Bt corn stalks. This might be expected when insect activity causes a little more corn grain to be available in conventional fields than from Bt cornfields. In carefully controlled university comparisons, though, cattle have shown no preference for either Bt or conventional corn stalks.

Still, if you have a choice between Bt corn stalks and other types of corn, it probably is smarter to choose the conventional stalks. Not because conventional stalks are better or safer, though, but because they are more likely to have extra grain on the ground.


Corn Growth Responses to Composted and Fresh Solid Swine Manures


Terrance D. Loecke, Matt Liebman, Cynthia A. Cambardella and Tom L. Richard
Dep. of Agronomy, 3405 Agronomy Hall, Iowa State Univ., Ames, IA, (mliebman@iastate.edu)

Swine production in deep-bedded hoop structures is a relatively new swine finishing system in which manure can be applied to fields fresh or after composting. Research was conducted in field-plot trials near Boone, IA, during two growing seasons (2000-2001) to determine the effects of fresh and composted swine hoop manures on corn growth and yield. Both fresh and composted manures were applied at the same rate in the spring before planting corn.

Phytotoxicity bioassays utilizing annual ryegrass (Lolium multiflorum Lam.) and cress (Lepidium sativum L.) seedlings as test species produced inconsistent responses to manures. During the two, corn in the composted manure treatment produced 10 percent more grain than did corn in the fresh manure treatment. Corn treated with composted manure produced 12 percent greater aboveground dry matter (DM) in 2000 and 15 percent greater DM in 2001 than did corn treated with fresh manure. Composting swine hoop manure before field application appears to be an effective alternative to fresh-manure application for corn production.