Missouri Valley Times News, IA
10-26-07
Fight the urge to fall till say crop experts from the NRCS
DESMOINES-Staff from the Natural Resources Conservation Service (NRCS) in
Iowa are discouraging farmers from fall tillage operations. "With such an early
harvest and yields so good, you might be tempted to get back on that equipment
and disk things up a bit," says NRCS State Conservation Agronomist Barb
Stewart. "Unless you just like wasting fuel or destroying good soil structure, I'd
ask you to do something else this fall and leave that residue alone which will
protect the soil quality characteristics you've built over the last year."
Whether landowners planted corn or beans this year, leaving crop residue on the
soil surface over the winter is a valuable contribution to the quality of the soil and
the erosion protection available on the farm. For landowners committed to a notill operation, a reduced-tillage operation, or any conservation tillage system,
resisting this urge to till saves money and offers a variety of other environmental
benefits."
It means fewer trips across the field, less wear and tear on equipment, better
erosion control, improved soil quality, wildlife habitat establishment, and water
quality enhancements, just to name a few," Stewart explains.
Stewart also notes that harvest progress is on pace to be completed earlier than
normal in some regions of the state. The early harvest provides more time for
farmers to complete normal fall activities such as applying fertilizer. Farmers are
urged to delay nitrogen application until the soils are cooler. Applying nitrogen to
warm soils creates a high potential for losses to occur and making nitrogen
unavailable next year to the following corn crop. Part of the nitrogen lost can
leach into the ground water or be drained from the field through tile lines.
"Nitrogen loss represents an economic loss to producers and is detrimental to
water quality at the same time," notes Stewart. According to the Iowa State
University Extension Service, applications of anhydrous ammonia should not
start until mid-day soil temperatures, at a 4-inch depth, are below 50 degrees
Fahrenheit and trending lower.
Historically, soil temperatures at a 4-inch depth cool below 50 degrees in the
northern third of the state during the first week of November. In central and
southern Iowa, soil temperatures cool below 50 degrees during the second and
third weeks of November, according to Iowa State University Extension.
"Cooler soil temperatures slow biological activity," says Stewart, "allowing
nitrogen to stay in the ammonium (NH4) form longer. Then it has a better chance
of being retained in the soil."
"Take advantage of this early harvest and the extra time it gives you but don't let
it tempt you to do things that make take their toll on the environment or your
bottom line," adds Roberts.