Strip-tillage in California’s Central Valley
With recently implemented waste discharge regulations that limit field applications of dairy waste nutrients to 140 to 165 percent of expected crop removal (see CVRWQCB 2007), triple-cropping of forages may become an important cropping system for dairies with limited forage production acreage. This system permits the production of more forage on the same acreage in a given time. Shortened intervals between crops also facilitates the capture of nitrogen before it becomes subject to leaching.
click image to zoomJeff MitchellFigure 5. Downwind sampling of PM10 at Burrell, California, dairy, 2003. Strip-tillage can dramatically reduce the amount of dust that is generated by tillage and soil preparation operations in dairy forage systems. From 2001 through 2004, PM10 (particulate matter < 10 microns in aerodynamic diameter) downwind emissions from tillage operations between crops were quantified in no-till and strip-till fields at two San Joaquin Valley (SJV) dairies relative to traditional tillage (Madden et al. 2008). PM10 emissions were reduced by 65 to 90 percent using strip-tillage for corn and no-till winter forage establishment (fig. 5).
Finally, strip-tillage systems also can preserve earthworms that burrow, decompose surface residues, cycle nutrients, and create macropores in the soil. Studies of strip-till corn production in Oregon have reported higher populations of the nightcrawler worm (Lumbricus terrestris), compared with traditional tillage systems (Luna and Staben 2003). A number of California producers have begun to report increases in anecic, or horizontal-burrowing, worms in strip-till corn and tomato systems.
The greatest problems that have been encountered with strip-tillage in California dairy forage systems are the difficulties in achieving uniform crop stands and managing weeds. Work by Mike Petersen in Greeley, Colo., has shown that corn root growth can be reduced by roughly a third at 55 days after planting with a misalignment between the strip-tiller and the planter of as little as 4 inches (Reichenberger 2007). Assuring that the corn planter tracks or follows precisely in strip-tilled zones is essential and can be accomplished either by using the same global positioning system (GPS) for both strip-tillage and planting operations, or simply by having the planter hooked up to the strip-tiller and performing both operations together in one pass (fig. 6).
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