Reduced tillage enhances soil and bottom line, but requires a different mindset
By Renee Stern
Vegetable growers can save time and money by working their fields as little as possibleor not tilling at all.
But zone or reduced tillage, and the more extreme no-till farming, may not suit all growers.
"Zone tillage is a compromise," says Fred Magdoff, professor of plant and soil sciences at University of Vermont inBurlington. "No (one) tillage system is perfect for every farm."
Some soils, whether heavy clay or heavily compacted, require extra preparation to succeed when tilling only the planting rows, says Omololu "John" Idowu, coordinator for a project on soil health and reduced tillage in vegetables at Cornell University in Ithaca, N.Y.
Large-seeded vegetables such as sweet corn and beans work well with this practice, but researchers have focused less on transplant and small-seeded crops, Idowu says.
The switch from conventional tilling also requires a mental adjustment to abandon neat furrows from field edge to field edge, says Donn Branton, owner of Branton Farms in LeRoy, N.Y.
Over the past 10 years Branton has moved all his grain and vegetable crops into either no-till or zone-till fields, including some crops that otherwise wouldn't thrive with conventional methods in his heavy clay soils.
"It can work on multiple crops," he says. "But you've got to have the desire and willingness."
That also includes going into zone till with some background in the practice.
"It does require some better management skills and some awareness of the pitfalls," says Harold van Es, professor of soil science at Cornell University.
Minimize soil exposure
Conventional tilling disrupts natural soil building systems where worms and other organisms pull fallen organic material below the surface, he says. Plowing organic material 6 to 8 inches under places that food source in the wrong location for worms to process.
Van Es describes plowed soil as full-frontal nudity. "Soil isn't supposed to be exposed this way," he says, and it exposes soil organisms to elements they haven't evolved to handle.
Conventional tilling also increases soil compaction, which creates a continual cycle of what van Es calls "an addiction to tillage." Dense, compacted soil demands annual tilling to fluff it up for good root growth.
Zone tillage promotes a more natural system that disrupts soil only where absolutely necessary. Idowu suggests building planting zones in the fall with a deep shank running ahead of wavy coulters to break the soil pan and then push the soil back into place.
Growers who opt for spring zone-building should wait three weeks before planting so soil has time to settle. "Otherwise the seed falls through the slot and never sees the light of day," he
Benefits outside of yield
Yield comparisons between conventional and reduced tillage aren't conclusive, Idowu says, but reduced tillage's long-term improvements in soil quality eventually should push yields from those fields to overtake conventionally tilled fields.
Branton says his soybean and sweet corn per-acre yield averages reached new highs in the past two years.
Even without yield gains, other benefits make the switch attractive. Reducing the tilled area and the number of times plows and planters run through fields saves fuel and labor.
Branton says his fuel use during planting is now less than 2 1/2 gallons per acre.
The practice also evens out impacts of moisture extremes, he says. Healthier soil with more organic content absorbs and holds moisture better, giving him a two-week window during drought periods before plants show stress. Spring rains infiltrate his fields more quickly, allowing him to work fields sooner.
Getting a jump on planting can mean early harvests that draw premium prices, Idowu says.
With better retention and reduced evaporation, irrigated crops require less water, says Sjoerd Duiker, associate professor of soil management at Penn State University in University Park.
Reduced tillage dramatically decreases erosion and runoff, in part from greater use of cover crops but also because fields are disturbed less, Magdoff says.
Branton says flooding complaints from neighbors have dropped, while fewer dust clouds rise when working fields during dry periods.
Test the water before diving in
Before switching from conventional tillage, growers should test fields and make any necessary pH and fertility adjustments, Magdoff says. Zone or no-till practices call for slower-working surface treatments of fertilizers and lime.
Correcting pH levels with highly soluble, finely ground lime helps speed the process, Duiker says.
Fertigation works well with zone or no-till practices, he says. For surface applications, he suggests dribbling urea-based fertilizers on soil rather than broadcast methods to cut volatilization losses.
In the long run, healthier soil should require less nitrogen and other inputs, the researchers say. Branton has cut nitrogen applications for each bushel of sweet corn by a half-pound per acre below standard recommendations.
Reduced tillage shifts the weed spectrum in a field from annual weeds to perennials, Idowu says. He recommends fall applications of 2,4-D for best control.
Over time weed control should become easier as cover crops suppress unwanted plants, Magdoff says. And reducing the plowed area means fewer weed seeds have opportunities to germinate in the first place.
Cover crops can make it harder to gauge correct planting depths, Duiker says. Residue also provides perfect habitat for slugs, a potential problem for lettuce and cabbage crops, but it can also shelter insect predators.