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By Jim Byford
University of Tennessee - Martin
There's a lot of debate these days about genetically modified organisms (GMOs). Most of the folks against GMOs don't understand them - how they're developed and how they work.
Some are concerned about the ethics of tinkering with genetic systems, some are worried about health risks, and some are worried about environmental effects.
Corn, soybeans and cotton with built-in resistance to insects, diseases, and herbicides are big technological steps for some folks to take - and with the promise of built in medicinal qualities, there's much more to come.
From an ethical standpoint, I can't see any difference - except by scale - from the way we've been improving varieties for years. Through plant breeding, we have selected for those genotypes that served our needs. We have sped up the process of evolution - but instead of survival of the fittest, it has been a man-made selection process. We have done this to help 1.6 percent of us feed and clothe all of us. Genetic engineering is just a faster way to speed up evolution.
Health Risks
As far as health risks from eating GMO food, it appears to me they are no different from food we have been eating for centuries. Hybrid corn is just as healthy as Indian corn. And with the promise of built in medicinals, GMOs look, to be more healthy.
So let's talk about environmental effects. To explore this consideration, let's look at how a modern GMO plant propagation system works - cotton for example.
The system begins immediately after the previous crop is harvested, by leaving the crop residue undisturbed. A herbicide may or may not be used to control fall weeds.
Using a no-till drill, a winter cover crop is seeded without ever exposing the soil itself.
In the spring, phosphorous and potassium fertilizer is added to the surface or injected through the crop residue. Herbicide is added two to three weeks before planting to kill competing vegetation, then once more at planting time.
Cotton seed which is genetically modified to resist herbicides, and specific insect pests are drilled through last year's crop residue directly into the soil.
During the growing season, one or two herbicide applications are made to control competing weeds. Due to genetic tolerance, the herbicides don't kill the cotton plants.
The field is scouted regularly for insects and insecticides are applied only if insects reach certain levels - otherwise they are not applied at all.
Similar GMO crop production systems are used for corn and soybeans.
Now, what does all this mean in terms of environmental stewardship?
First of all, farmers will more likely use such systems, because studies show they can make significantly higher profits with genetically modified cropping systems. Even though the seed costs more - compared to conventional tillage systems - farmers don't have to spray as many pesticides, make as many trips over the field, or use as large a tractor.
Environmentally speaking, there are numerous advantages. Fewer trips over the field reduces soil compaction. This keeps the soil more porous, which facilitates soil aeration and encourages earthworms - both of which help decompose crop residue, breaking it down more easily into organic matter, an important soil component. This helps the soil filter rainfall and hold water longer - good for crops and aquifers (water stored beneath the surface).
The soil residue also protects the field from erosion and streams from siltation.
According to one official of the Environmental Protection Agency (EPA), cotton insecticides have been reduced because of GMOs by 75 percent since 1996. The North American Breeding Bird Survey has shown corresponding increases in populations of songbird which frequent cotton-associated habitats - 20 percent in Arizona, 37 percent in Mississippi, 34 percent in Alabama, and 10 percent in Texas. Most of Texas' increase was in one species, the northern rough-winged swallow, but increases in the other states were well scattered among other species.
The USDA Agricultural Research Service examined pesticide runoff reduction from 1996 to 1999 as a result of GMO cotton production systems on a 7,000 acre cotton production area in Mississippi. While runoff from non-GMO sites had very slight amounts of pyrethroid insecticides, runoff from GMO sites had almost none at all.
In another study, EPA found a 90 percent decrease in methyl parathion use from 1995 to 2000. This insecticide can be harmful to mammals and fish, and EPA classifies it as "very highly toxic" to birds, aquatic invertebrates, and honey bees. Acephate has been reduced from 0.35 treatments per acre in 1995 to 0.18 treatments per acre in 2000.
Positive Trends
Farm managers throughout cotton growing states (South Carolina, Georgia, Arizona, North Carolina, and Mississippi) have noticed increases in quail, rabbit, and turkey populations. They cite examples of quail nesting right in the cotton fields themselves, something unheard of until recently.
Before GMO crop production systems, farmers regularly burned wheat stubble and plowed under other crop stubble residues to help control pests. Now these practices aren't necessary. This keeps waste seed on top of the ground to feed wildlife during the winter.
Combine that fact with an increase in cover crops, and in vegetative filter strips (encouraged by the farm bill which gives farmers financial incentives to establish conservation practices), and you have significantly better quail, turkey and rabbit habitat - along with less erosion and cleaner streams.
Fewer pesticides also mean higher populations of helpful insects which help control harmful insects as well as provide "bugging" areas for quail and turkey poults - an absolutely necessary ingredient in game bird habitat.
So - there you have it, another perspective. Are GMO crop production systems a good idea? You decide. You can easily see my bias - I think they are. After all, wildlife have long been recognized as barometers of our environmental health. If GMOs are good for wildlife, they are probably alright for us too.
Reprinted with permission from the December 18, 2002 issue of Southeast Farm Press
Copyright 2002, PRIMEDIA Business Magazines & Media Inc. All Rights Reserved. SEP 03 DF
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