Steel in the Field: A Farmer’s Guide to Weed Management Tools

	Dryland Crops: The Farmers Beds and Rod Weeder Boost Diverse Crops on Kansas Farm Jerome Berning Marienthal, Kansas 1,800 acres (600 of them fallow)  flat fields, silt loam soil seasonal deep-well irrigation half of acreage is organic weeds: kochia, pigweed, velvetleaf 16 inches precipitation; rapid evaporation row crops in 30-inch rows on 60-inch beds wheat (hard red winter), yellow corn, blue corn, soybeans, sunflowers, speciality seeds Weed management highlights Strategies: crop rotation... fallow cultivation... mechanical controls... herbicides Tools: rotary hoe... cultivator... rod weeder... sweep plow... stubble mulch plow... rotary tiller More steel means fewer headaches for Jerome Berning. Recent additions give him better control in maintaining 600 acres of fallow land and in managing early season weeds in tilled, bedded (furrowed) soil. Berning, who farms half his acres under herbicide-free organic management, keeps his systems as flexible as he can to stay in synch with moisture, soil condition and weed pressure. He uses four rotation sequences: wheat soybeans-corn-fallow (organic); wheat-fallow-wheat (organic and conventional); corn-fallow-corn (organic); and wheat-soybean-corn (conventional). Relatively dry, cool spring conditions allow Berning’s annual crops to germinate with or ahead of the first major flush of weeds. Some farmers find late planting gives them a chance to cultivate early weeds before planting crops into warmer soil for robust germination. But Berning’s experience is that early planting works best for him. Those planting dates let crops catch what passes for the “rainy season” in dry western Kansas—a time when he can expect a number of half-inch or quarter-inch rains. Careful preplant tillage creates smooth beds 60 inches wide and removes early weeds in the top inch or so of soil. His spring tillage for annual crops includes several steps. Bed preparation. After chopping then disking corn or sunflower stubble, Berning forms beds by making furrows about 1 foot deep and 1 foot wide every 60 inches with “lister” shovels. These shovels have flared, stocky, fairly vertical wings to throw soil up and out in both directions. These furrows nicely divide up the fields, guide the tractor and implement wheels, and later carry irrigation water through the field. Preplant weeding. Rains are possible during this pre-plant tillage season. But building up soil moisture is critical if annual crops are to start off strong. To assure topsoil moisture, Berning pre-irrigates the unplanted field. He greets the first flush of small, white-root weeds and larger weed survivors with one of two weed tools, depending upon the level of residue and whether its an organic or conventional field. He goes with his 30-foot Tilrovator rotary tiller if he needs to incorporate residue or pre-plant herbicides. The tool works in the top 4 inches of soil with its hard-surfaced, L-shaped blades designed for shallow mixing and cutting action. But Berning uses a 30-foot rod weeder if wiping out the weeds and achieving the finished bed condition are his goals. The tool’s PTO-powered, 1-inch square rod turns underground to flip up the weeds and “flow the soil across the beds” for even distribution, Berning reports. The pass at 4 mph knocks down the beds to about 8 inches tall. “The rod weeder means less row-crop tillage,” Berning explains. “Before, I used a disk just before planting to take care of the weeds. Then we had to furrow after we cultivated so we could irrigate. With the rod weeder we can make furrows early, maintain them and conserve moisture.” For the second irrigation and weeding sequence, he runs the weeder faster (7 mph) and shallower (1 to 2 inches deep). This keeps the moisture seal of the previous pass intact and does not stimulate new weed seeds. Rotary hoeing. After planting corn 1.5 inches deep and soybeans an inch deep a month later, Berning follows quickly with his 30-foot standard rotary hoe. Planting times are mid-April for yellow corn, early May for blue corn and mid-May for soybeans. If other crops fail, he can plant sunflowers as late as mid-June. He drives the John Deere 400 hoe 6 to 9 mph as soon as weed seedlings pop through or a rain-induced soil crust threatens to prevent crop emergence. The hoe’s two gauge wheels run in furrows bordering the two outside beds of the six-bed pass. The wheels stabilize the tool to prevent rough spots in the field from causing one side of the hoe to gouge down into the planted crop. Berning estimates that 90 percent of the benefit he derives from the rotary hoe is for weed control, with only 10 percent being for crust-breaking. Beyond the white-root weeds it’s known for controlling, Berning also depends on the hoe to pluck up larger weeds. These are usually plants with a developed root ball that were dislocated by the rod weeder then began regrowing in the soil. He has no shields on his cultivator to protect plants from moving soil, so Berning runs his rotary hoe in more mature crops than some farmers. He estimates maximum heights at 10 inches for yellow corn and 6 inches for sunflowers. Because blue corn tillers, the stalks will range from 3 to 10 inches at the last hoe pass. He experiences some plugging of his hoe with corn and sunflower root crowns. He’s trying simple flat iron extender arms that double the space between front and rear wheels. The expansion to 15 inches allows residue to pass between the hoe wheels more easily. Cultivation. His 30-foot row-crop cultivator features 18- to 24-inch sweeps on the bed tops between the 30-inch rows, with lister shovels in the furrows. He selects the two types of tooling for opposite results: the one-piece flat sweeps move virtually no soil into the row, while the upturned wings of the listers deflect soil up and to either side, reforming the furrow. Berning targets pigweed and kochia with his single cultivation. Thanks to dry conditions after the corn reaches 10 to 15 inches tall, weeds aren’t much of a problem for the rest of the season. He usually hand-rogues escapes in soybeans, averaging $8 per acre per year for labor. Post-harvest tillage is left until spring so the stalks can collect snow on the fields over winter. Berning runs his double-rotor, rotary stalk chopper over all the cornfields, then hits the 140- to 180-bushel-per-acre yellow corn fields twice with a disk. The blue corn, which typically yields only 45 to 80 bushels per acre, needs just a single disking. In his wheat-fallow-wheat system, tillage usually starts in August after the late-June wheat harvest. The first pass is with his 30-foot Flex King wide-blade sweep plow. This dryland specialty tool has blade assemblies 6 feet wide on 5-foot centers. Each replaceable V-blade attaches to an angle iron base at the bottom of rigid standards. Hard-surfacing keeps the blades running through Berning’s soils for four seasons before they need to be replaced. The mass of the sweep plow gives it the ability to keep the leading edge of the large blades submerged 3 to 6 inches below the soil surface. The 3.5-inch height of the angle iron base prevents it from working more shallowly without bulldozing soft soil or popping out of harder soil. Berning avoids using the blade plow when soil is moist so as not to cause compaction. The sweep plow’s widely spaced standards cut few surface paths through the residue. As long as it runs at least 4 inches below the surface, it can leave 85 to 95 percent of non-fragile residue on the surface. If volunteer wheat or other weeds become enough of a threat, Berning makes a second sweep plow pass through the wheat stubble in late fall. During the following year before re-planting wheat in mid-September, Berning will make four to six tillage passes to control weeds. Each time his goal is to leave as much residue—and cause as little moisture loss—as possible. He wants to go shallower in the last several cultivations to bring subsoil moisture closer to the surface. His sweep plow ridges soil during these passes, which causes moisture loss and clod formation in the peaks. It also leaves some well-rooted 6-inch kochia weeds unkilled. The repeated plowing seems to train their dense, fine roots to grow sideways. “I’ve got flex-tine harrow sections on the sweep plow to help with weeding,” says Berning. Mulch treaders would be more aggressive at knocking soil from the kochia weed rootcrowns. He has that extra-tough weed fighter on his new 42-foot Quinstar Fallow Master II™, a stubble mulch plow with 26-inch sweeps on 20-inch centers. Each 7-foot section has a 7-foot angled rolling bar of treader wheels (curved, bevel-tipped arms) on 7-inch centers. Now he has to balance between too much and too little. “The treaders can chew up brittle residue and powder the soil if things are dry. I watch the results carefully toward planting time,” he says. The sweep’s flat profile sweeps allows them to travel within 2 inches of the surface without causing ridging, yet retain 80 to 90 percent of non-fragile residue. Tillage has been crucial to manage the late-summer moisture that comes up from lower soil levels. “With chem-fallow (using herbicides to control weeds), our soil cracks open and the moisture escapes,” he says. Berning credits better tillage equipment with decreasing weed pressure over the 25 years he’s been farming. First, higher horsepower tractors on the farm in the ’80s let him drop the sweep blade low enough to cut off large weeds. Now the lighter-draft fallow tool lets him finesse the final fallow passes. He’s got a better chance now to approach wheat planting with weeds down and moisture up on the west-Kansas prairie. Next farmer All Farmer Profiles