Mid-South farmers are starting to recognize that cover crops can play a big role in the suppression of weeds and lessen the need for deep tillage to control glyphosate-resistant Palmer pigweed.
As a result, the Natural Resources Conservation Service has seen increased interest in two programs involving cover crops, the Conservation Security Program and the Environmental Quality Incentives Program.
Mike and Michael Taylor, who farm 6,500 total acres, including 2,000 acres of wheat, 1,500 acres of corn, 700 acres of milo and 4,500 acres of full-season and double-cropped soybeans on Long Lake Plantation around Helena, Ark., are old hands at cover crops, having used a cocktail mix of primarily cereal rye and radishes for years.
See this Delta Farm Press article on the Taylors.
The Taylors farm less than half a mile from the Mississippi River. While ancient deposits have created an abundance of highly productive land on the farm, many of the Taylor’s soils tend to erode easily because of high sand content.
In the beginning, the Taylors used a cover crop strictly for conservation to minimize the need for deep tillage and reduce both wind and water erosion. In addition, tillage radishes and cereal rye can open channels in the soil for water penetration, the radishes as deep as five feet. After 20 years of cover crops, a three-foot rod can be pushed easily to the handle in cover cropped fields.
Cover crops have helped the Taylors develop a minimum tillage approach to farming their land. “We don’t have a disk, and our subsoilers are very low disturbance,” Mike said.
Over the past few years, the cover crops have had another impact, helping the Taylors do a better job of managing two glyphosate-resistant weeds, horseweed (marestail) and Palmer amaranth (pigweed).
Glyphosate resistance developed on the Taylor farm even though the Taylors have used a residual herbicide program with Roundup Ready technology. “We were anticipating resistance, but it didn’t matter,” Michael said. “We had the first resistant pigweed in the state.”
Cover crops, residual herbicides, light tillage and a zero tolerance program have helped the Taylors manage resistant weeds.
That’s not to say pigweed hasn’t changed the way the Taylors farm. Usually, corn residue will be lightly tilled at harvest to help with decomposition for planting either wheat or a cover crop, according to Mike. But pigweed has dictated the schedule in recent years.
“Tillage breaks the residual barrier of the corn herbicides, encouraging pigweed growth,” Mike said. “So we wait to just prior to planting around late September or early October. You want to get a cover crop established before the pigweed come up.”
When a healthy, uniform cover crop is established, it will keep resistant pigweed and horseweed (marestail) suppressed until it is time to burn it down in the spring. “If you have a good stand of cereal rye, you won’t see much else,” Michael said. “You’ll see very little Kentucky bluegrass and few horseweed.”
The cover mix is put out at 15 pounds to 20 pounds per acre, with a Humdinger 455. The rig consists of a 35-bushel Gandy air-seeder positioned between two rolling gangs, which disturb the soil about an inch deep in front of the Gandy and cover up the seed behind it.
“The cereal rye has to be shallow seeded. It comes up easily to a stand and is controllable by herbicides. It’s also widely accepted that it has allelopathic reaction that suppresses weeds, including horseweed and Palmer pigweed,” Mike said.
The cover is usually thick and tall by spring, but is burned down effectively. Killed cover crop residue can provide suppression of weeds for about three weeks, meaning the Taylors don’t like to delay planting too long after burndown.
The Taylors stress that glyphosate-resistant pigweed is still a major problem on the farm. Michael says he sees it when he closes his eyes at night and when he opens his eyes in the morning.
Where pigweeds do pop through, the Taylors follow the University of Arkansas’ zero tolerance program, which emphasizes not letting a single plant go to seed. They have two ATVs with booms that run constantly. The also employ chopping crews.
For the Taylors, a cover crop is mostly about taking care of the land, with weed control as a bonus. Allowing cover crops to decompose “builds organic matter, microlife and earthworm channels,” Mike said. “Our take is that cover crops are meant for a long return. It’s not a cheap, quick fix. It has its own set of problems. It’s almost like double-cropping.
“But there is a system there. I love the old Indian saying, ‘You don’t inherit the land from your forefathers, you borrow it from your children.’”
Tim Smith, a consultant who works with several Arkansas farms, including Felton Farms in Marianna, has been using a cover crop for several years primarily “to scavenge nutrients and create a green manure. Generally, a cover crop opens up and lets oxygen into the soil and creates a better growing environment for crops, and it competes with weeds. It also helps hold moisture after a rain.”
Smith noted that some cover crops, like triticale, “are allelopathic to a lot of the noxious weeds. If you get a crop planted early and you get a good canopy, it completes with weeds and they don’t seem to thrive.”
Smith said cover crops can help maintain stale seedbeds during the winter and are helpful during wet springs because farmers can plant into them earlier than in bare fields. “The cover crop can provide a shield that doesn’t allow dirt to build up on the tires.”
Farmers can apply for cost-share through EQIP or receive cash awards through the Conservation Security Program for their overall efforts at conservation, which includes planting of cover crops.
Noted Harmony Kalb, who handles conservation and paperwork for the Taylors, CSP pays producers who have already implemented practices such as cover cropping, minimum tillage, crop rotation and grass filter strips.
John Lee, NRCS state agronomist for Arkansas, has seen increased interest in cover crops in the state ever since pigweed became a major issue. “Farmers were really challenged by pigweed, and one solution was to go in and do deep tillage with a moldboard plow or a turning plow.”
Producers generally don’t prefer that option because of high diesel fuel costs, and because it works against the benefits gained by reducing tillage. Lee noted that the University of Arkansas helped drive interest in cover crops with research on its ability to suppress weeds.
Lee said that the EQIP is the primary tool farmers can use to obtain financial assistance for cover crops. “We encourage farmers to not only look at cover crops, but a conservation system. A farmer who is going to grow cover crops needs to address nutrient management, pest management and water management.”
Cover crops also mesh well with NRCS objectives. From a water quality standpoint, cover crops “are one of the most effective ways to get immediate results when attempting to reduce the amount of sediment leaving the field, and tying up nutrients that are leaving the field and getting into the water,” Lee said. “It’s something NRCS can assist farmers with doing in a reasonable amount of time.”
Like the Taylors have discovered, there are long term benefits of cover crop for the soil’s biological profile. “That’s one thing that we have not paid enough attention to when we start looking at farm production,” Lee said. “Microorganisms and small worms can really do a lot to enhance the performance of the soil for crop production. It helps increase yields and reduce the amount of water needed because it allows more water to infiltrate the soil.”
Water conservation is also an issue of concern for Lee, and cover crops could be part of the solution. “We really made a good crop last year, but we have to be realistic. We pumped a lot of water to make that crop, and we cannot continue to pump that much water out of the ground. We have to be able to sustain irrigated land in this state. We need to start conservations with farmers and consultants in this state to not only improve yields in this state, but to improve the Mississippi River Drainage Water Basin.”