September 30, 2002
Avoid Fall Tillage to Reduce Wind Erosion, Save Crop Residue
LINCOLN, Neb. — Farmers should avoid tilling their fields or shredding their corn stalks this fall to conserve moisture and decrease soil erosion, said a University of Nebraska Cooperative Extension engineer.
Due to poor crop stands and grasshopper damage this summer, some Nebraska fields already have little crop residue left to help keep soil intact and keep it from turning into a blowing dust storm like Nebraskans witnessed last spring, said Paul Jasa, NU extension engineer.
The best way to avoid wind and water erosion is to have standing vegetation or crop residue, Jasa said.
"In Nebraska, I haven't found a crop land soil yet that we can't no-till," Jasa said.
Many Nebraska farmers take their disks and shredders to the field after harvest to start preparing the soil for next year's crop and save time next spring.
"Tilling or shredding stalks, traditionally done to help break down the residue, will only cut them loose so they will blow away," Jasa said.
Contrary to the idea that the soil needs to be opened so the water can soak in, water infiltrates better into soil without tillage because the residue absorbs the raindrop impact, Jasa said.
With tillage, precipitation can crust the soil, resulting in more runoff.
NU research has shown that the reduced crusting and improved soil structure with no-till can decrease runoff and erosion by more than 80 percent. Residue also serves as a mulch to reduce moisture evaporation and shade the soil. This means residue covered soils don't get as hot as bare soils, promoting better root development during drought conditions.
"Tilling dries out soil moisture and decreases the available moisture for next year's crop," Jasa said.
An average silt loam soil can hold about 2 inches of available soil moisture per foot of soil. Disking 6 inches deep or chiseling 12 inches deep and allowing the soil to dry to the depth of tillage could result in a soil moisture loss of 1 to 2 inches of water, Jasa said.
Shallower tillage, even with a rolling stalk chopper, still can result in moisture losses of about 1/2 inch per trip.
Next summer, irrigation costs also will be increased because more water must be applied to replace the lost moisture. In addition, tillage "plants" weed seeds, increasing competition for soil moisture.
Tilling also adds to fuel, labor and equipment costs.
No-till uses less than half the fuel, the Institute of Agriculture and Natural Resources engineer added. No-till fuel usage is 1.4 gallons to the acre, compared to 3.8 gallons per acre. No-till includes knifing in fertilizer, planting and two herbicide sprayings, but, as the name implies, no tilling. The typical tillage system includes three tillage trips and knifing in fertilizer, planting and one row-crop cultivation.
09/30/02-SA
Paul Jasa
Biological Systems Engineering
Extension Engineer
(402) 472-6715
Sandi Alswager Karstens IANR News and Photography (402) 472-3030
Department: Biological Systems Engineering
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