WEEDS: ERADICATING NOTHING BUT DOING SOMETHING
October 5, 2003
R.M. Dixon
During a century of row cropping in the cornbelt region, half of the 18 inches of rich topsoil has eroded into the Mississippi River and is now deposited in the river's delta with colloidal clays going out to sea. Agricultural sustainability is essential if this region is to maintain its historic productivity to help provide food for the world's current 6.1 billion people. Historically, the deep soils of this region were formed by tall-grass prairie over many millennia since the last ice age. Tall grasses are uniquely capable of growing topsoil, rich in organic matter, and holding it in place against the erosive forces of wind, rainfall, and rainwater. Now that one-half of the topsoil is gone with a corresponding loss in water holding capacity, short-term droughts cause much greater crop stress than occurred before the soil was eroded away. Supplemental irrigation is often required.
Now for a strategy for stopping this trend of continuing erosion from row crops including corn, soybeans and grain sorghum. The solution to this problem is to replace the row crop annuals with solid stands of perennial grasses and legumes on all but the relatively level land of river valleys, The science and technology for making this transformation in cropping practices is already available and the cost is quite low especially where government cost-sharing programs apply.
Grasses and legumes can be established without exposing the land to erosion with the new land imprinting method that forms V-shaped indentations ( 1-square-foot in size ) that, in turn, funnel resources to the bottom of the depression where they work in concert to germinate seeds and establish seedlings. Imprinting is a once-over, no-till treatment that can be fall applied to fields covered with the row crop residues of the preceding crop. No tillage before imprinting is recommended. Fall imprinter seeding of grasses and legumes allows the seedlings to get a head start on weeds as the soil warms in the spring. Including a cover crop such as the cereal grains and cool season legumes in the seed mix help control spring weedy annuals. Once established, the perennial vegetation can be grazed by livestock or cut as silage or hay for winter feed. Sustainable rotational grazing schemes have been developed by Andre Voisson & widely promoted by Allen Savory. Native grasses can be used in the seed mix where ecological restoration of the tall grass prairie is the land management goal. Buffalo ( bison ) rather than cattle can even be the grazing ungulate to mimic the historic ecosystem of the cornbelt. Their hoofprints, the natural form of imprinting, are helpful in reseeding the native grasses.
But what about the lost acreage in corn, soybean and sorghum production? Actually, it will not be missed because most of this production was used to feed livestock which would be fattened on forages after the crop conversion. Forage-fattened livestock yield leaner meat cuts that are much more healthful--especially considering the major obesity problem of U.S. citizens. Our own food needs for corn and soybeans would be easily met by the yield of the level floodplain acreages.
But what about the need for corn to produce fuel alcohol? Corn alcohol production should be discontinued as it takes more than twice as much crude oil to produce a gallon of alcohol as it takes to produce a gallon of gasoline or diesel fuel. Furthermore, alcohol tends to be unstable when mixed with gasoline, gumming up the fuel system of internal combustion engines including our cars, trucks and buses. Also, contrary to popular belief, burning of alcohol contributes substantially to air pollution and greenhouse gases, especially if one considers that it takes more than 2 gallons of fossil fuel to produce one gallon of alcohol.
Finally, what benefits can farmers and society derive from the foregoing conversion of annual row crops to perennial grasses and legumes? The benefits are numerous, a few of which are listed below in the order at which they roll off my mind.
1. Elimination of our polluting hog and cattle feedlots.
2. Production of healthier, leaner grass-fed meat
3. Reduced human obesity and the associated diseases.
4. Lower air, water, and soil pollution from row-crop chemicals.
5. Reduced wind and water erosion
6. Topsoil building instead of topsoil loss.
7. Fewer endangered and exterminated plant and animal species.
8. More natural ecosystem services including:
- clean air, water, and soil
- soil erosion prevention
- accelerated rainwater and snowmelt infiltration to feed soils and underlying aquifers
- greater biodiversity and biogeographical stability
- better pollination of the legumes, prairie communities, and flat-land row crops
9. Reduced farmland production costs including the expense of:
- pesticides
- fertilizers
- row-crop machinery
- crop insurance
- grain bins & conveyers
- grain dryers
- grain transport trucks
- bank loan interest
- irrigation equipment
- land degradation
- surface water pollution
10. Last, but not least, the satisfaction of knowing that our farmland is improving and that our children will enjoy a better life because we converted our unsustainable annual row crops in the cornbelt into sustainable perennials.
Now for several after thoughts:
(1) The row crops grown on the relatively flat bottomlands can be slowly converted to the new no-till culture to maximize soil conservation and sustainability. Again land imprinting is unexcelled for holding soil and water resources in place for crop production. Corn, soybeans and grain sorghum should be bred for solid planting to achieve weed control through competition for light, moisture and nutrient resources, and to eliminate erosion prone row cropping.
(2) Much of the foregoing approach for making the Cornbelt sustainable can be applied to the Great Plains . Historically this was a vast prairie with tall grasses along the eastern side next to the Cornbelt grading into short grasses on the western side next to the foothills of the Rocky Mountains . Again dryland and irrigated row cropland can be restored to native prairie ecosystems, whereas the wheatlands can be farmed with low-cost no-till practices to achieve equal or greater productivity and sustainability. No-till would eliminate the need for fallowing wheatland every other year because of more efficient soil moisture recharge and conservation. Imprinting is ideally suited to no-till of wheatland, with the imprinter seeding done directly into the stubble of the previous wheat crop. The land would never be without a cover to provide continuous wind and water erosion protection.
(3) The arid public rangeland of western United States can be liberated from livestock grazing by transferring these foraging animals to the newly seeded pasturelands in the Cornbelt, and Great Plains . Western rangelands can then be ecologically restored to native vegetation to, in turn, realize the many inherent services of natural ecosystems.
(4) Who will oppose the above suggestions and proposals? Mostly those who will suffer economic loss, namely the cattle & hog feedlots, fat/fast food industry, fat exercise clinics, prescription and over-the-counter drug companies, farm chemical companies, farm machinery manufacturers, pollution control consultants and supply industries, and those individuals and organizations who are unconcerned about the legacy we leave our children and their children. Future generations will suffer greatly unless our agriculture soon becomes sustainable.
Land imprinting for sustainability in agriculture. Photos: Interseeding legumes into bluegrass pasture, Lancaster Experimental Farm, WI. ( Photos by Art Peterson)
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