Conservation Agriculture Systems Innovation
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Conservation Agriculture Systems Innovation

Conservation agriculture news

Cover crops: What goes around comes around

Cover crops, or vegetation that was grown after the cash crop was harvested, was a practice that was widely used in the 1940s and 1950s.  The vegetation was used to maintain or increase the fertility of the soil before commercial fertilizers became widely available. The cover crops also provided organic matter to the soil that was necessary to keep the soil easy to plow. When commercial fertilizers became more widely used, cover crops faded from the agricultural picture.

Cover crops are making a comeback of sorts due to the depletion of the organic matter over the intervening decades of intense farming as well as farmers taking advantage of a cover crop’s environmental benefits. A winter cover crop can add back to the soil the organic matter that was lost due to farming practices as well as take up the fertilizer left over from the previous crop that can potentially leach into the ground water or runoff in storm water. A well-managed cover crop can also provide needed protection from raindrop impact that can cause a crust to form on the surface of the soil that further reduces water penetration and adequate air movement through the soil. The vegetation can also keep soil moisture from evaporating when young crops need it most.

To help farmers learn more about the “lost art of cover cropping” and to see actual cover crop management techniques up close and personal, the University of California’s Conservation Tillage and Cropping Systems Workgroup conducted an interactive field day on March 18 at the West Side Research and Extension Center in Five Points, Calif. The session came on the heels of a three-day conference series the previous week that provided examples of successful high-residue cropping systems that also use cover crops from other irrigated regions of the U.S.

The backdrop for the field day was a field that has been comparing no-till cotton and tomato production techniques for the last eight years.  Comparisons between crops grown with and without winter cover crops have been measured against current standard “clean cultivation” management in which no cover crop is used.  Also compared was a standard tillage system in which winter cover crops are “green manured” or incorporated into the soil in the spring before the next crop is planted.

UC Davis researcher, Jeff Mitchell, reported that about two tons of cover crop dry matter - of which roughly 40 percent is carbon and 2 percent is nitrogen - has been produced in the cover crop plots each year with winter rainfall and no supplemental irrigation. These cover crops resulted in a 22 percent increase in soil carbon in the green manured, standard tillage system, and an even higher 29 percent increase in soil C in the no-till cover crop system following the eight years of study.

From year to year, the water available for agriculture can vary greatly so cover crops must be able to “work their magic” with little or no increased water requirements. Because wintertime temperatures are lower and the humidity is generally higher, evapotranspiration (ET) - or the water that both evaporates from the soil and water that is used by plants - during the winter growing period tends to be much lower than in summer.  However, a winter-growing cover crop is using water that would normally be available to a spring-planted crop. Therefore, farmers need to weigh the many advantages of a cover crop with the potential disadvantage of its winter water use.

Mitchell’s monitoring of the top foot of soil three days before the field day indicated about 3 inches of water in the fallow plots with only about 2.5 inches in the cover crop plots.  The cover crop that Mitchell used this year consisted of Tillage Radish™, forage pea, and Phacelia, and had produced about 7,000 pounds of dry matter per acre at the time of the field day.

The field day also featured Greg Wittenborn of Lockwood Seed and Grain of Chowchilla, Calif., and Chuck Cambra and Tom Johnson of Kamprath Seed in Manteca, Calif. The trio provided information on cover crop seed costs, the importance of selecting cover crop materials, and designing cover crop strategies to achieve specific cropping goals. Many cover crop species and mixes are now commercially available to address a farmer’s specific needs.

Additional information on cover crops will be posted at the Workgroup’s website and opportunities for viewing other field operations related to cover cropping will be publicized via the Workgroup’s email announcement service. To become involved with the Conservation Tillage and Cropping Systems Workgroup, contact workgroup chair Jeff Mitchell at

Two of the methods for terminating cover crops that were demonstrated at the cover crop field day in Five Points, Calif.  On the left is a conventional flail mower that flail chops standing cover crop materials leaving very small pieces of shredded above-ground material. On the right is a cover crop stalk chopper that is ground-driven and chops standing cover crops leaving 7- to 8-inch pieces of above-ground matter. (Photo by Ron Harben.)

Chuck Cambra of Kamprath Seed Company in Manteca, Calif., (in gray sweatshirt at center-left of photo) addressing participants of the cover crop field day held in Five Points, Calif., on March 18. (Photo by Ron Harben.)

Posted on Monday, April 4, 2011 at 8:21 AM

CT research shared at New Horizons conferences

By Jeff Mitchell

Whether it’s called “high residue farming” or “conservation agriculture,”  there’s very little of it currently done in California. For decades, the dominant production paradigm throughout California has been just the opposite - intense tillage, clean cultivation and residue-free fields.

There is, however, growing interest in these sorts of crop production alternatives as evidenced by the lively and engaging discussions that took place as part of the recent three-day conference series, "New horizons for conservation cropping in California," March 9, 10 and 11 in Davis, Tulare and Five Points, respectively. The events brought three leaders in the development of high residue conservation tillage systems under irrigated conditions to California’s Central Valley to share their experiences and to propose possible applications of these cropping approaches for California farmers.

Mike Petersen, precision tillage agronomist with Orthman Mfg. and former USDA Natural Resources Conservation Service Area soil conservationist for the 18 northeastern counties of Colorado, presented an extensive research base that he has helped develop demonstrating advantages of precise fertilizer placement at two depths below the seed, leading not only to increased early season root growth, but also grain yield for strip-till corn versus conventionally tilled corn.

By only tilling in the areas of the field where seed is sown, typically about 30 percent or less of the total soil area, less than about two gallons of diesel fuel are used, little or no soil erosion occurs, and yield increases averaging 11 to 30 bushels per acre have been seed over an eight-year field comparison.  Precision tillage and fertilizer placement that are readily afforded by strip-tillage planting systems would thus have considerable and multiple advantages that may have clear relevance for California producers.

Since 2004, Andy McGuire, educator with Washington State University based in Moses Lake, Wash., has been working with Central Washington farmers to develop successful high residue systems for a variety of the region’s diverse irrigated crops.  He has found that there tends to be typically no single factor motivating farmers to adopt high residue production techniques, but rather a suite of reasons that often combine to influence crop management decisions.

Compared to conventional systems, high residue farming systems involve less overall tillage, diesel fuel use and labor, opportunities for double-cropping, and more free time, as well as reduced soil water evaporation.  Essentially, all of the quite diverse crop production in this region of Washington relies on overhead center pivot irrigation, which McGuire pointed out is particularly well suited for high residue farming because furrows and beds do not need to be prepared to move water across a field as is done with surface irrigation.

High residue cropping opportunities that Washington farmers are now using that may have relevance for California include edible dry beans strip-till planted into alfalfa, strip-till seeded onions into burned down wheat cover crop residue for wind protection, and even potato production systems that reduce wind erosion by preserving surface residues of prior crops.

The progress and accomplishments of Dwayne Beck, the final presenter at the “New Horizons for Conservation Cropping in California” conferences, and the farmers in central South Dakota he has been working with since the 1980s are in many fundamental ways nothing short of phenomenal and transformative, and provided considerable “food for thought” for the California farmers, researchers, and consultants who participated in each of the three conference sessions.

Beck is the South Dakota State University manager of the Dakota Lakes Research Farm, a farmer-owned research facility just outside the state’s capital of Pierre that has been no-till farmed since 1990. The no-till, high residue systems developed by Beck and his farmer colleagues have resulted in reduced soil water evaporation, far greater cropping diversification and intensification, considerably lower pesticide inputs, and increased net farm income throughout the region by over a billion dollars since the early 1990s.

Tillage, Beck pointed out, reduces the ability to manage the overall crop production system and should be replaced by other cultural practices including surface residue conservation, rotation, sanitation and competition. The benefits of no-till high residue systems will eventually have relevance for California as well, Beck suggested, and farmers here should also be able to “take the E out of ET” as their counterparts in South Dakota have done, once they “take the T out of ‘can’t.’”

Posted on Tuesday, March 29, 2011 at 12:15 PM

Is there organized 'opposition' to conservation tillage?

A student at UC Irvine, Saumya Bhardwaj, who is working on a research project on "how to prevent soil damage from monoculture," sent a query to the Conservation Tillage workgroup about policies or interest groups standing in the way of CT implementation.

"Upon doing my research, I couldn't find any group arguing against it so I just need advice on it," Bhardwaj wrote.

"Your question is actually a bit complicated," workgroup chair Jeff Mitchell responded.

"While there is certainly no organized opposition to the broader use or adoption of conservation tillage systems and practices, there are and have been many of what we might call 'barriers.' This is a very interesting area of inquiry and I can well understand your wondering about it.

"For a number of reasons -- tradition, unfamiliarity, fear of risks, uncertainty, lack of information, unwillingness or not seeing any need to change what has been done successfully in the past, lack of 'know how' about options, and many other things -- far wider adoption of these sorts of systems is only now beginning to be taken on.  Increasingly, however, more folks are becoming interested in the potential.  And, as evidenced by the responses we've received from our events last week, there WILL be more up take in the future."

Posted on Monday, March 14, 2011 at 8:15 AM

California farmer Michael Crowell details his no-till experience

National No-till Farmer magazine has published an article by a member of the UC Conservation Tillage and Cropping Systems Workgroup, Michael Crowell.

The Crowell family has been in the dairy business in Turlock for more than 100 years. Currently, Crowell's son Adam manages Bar-Vee Dairy and milks about 700 cows. The family raises their own heifers, so in all the herd is about 1,400 head.

One way the Crowells have dealt with dairy industry volatility is growing as much of their own forage as possible. In his article, Crowell said no-till farming has allowed the family to produce three high-quality forage crops per year.

Crowell began no-till farming six years ago.

"Once I started no-tilling I’ve never missed a single National No-Tillage Conference, I read magazines and get hands-on advice from my University of California-Davis extension contact, Jeff Mitchell," Crowell wrote.

Read Crowell's full account in National No-Till Farmer magazine.
Read Crowell's full account in National No-Till Farmer magazine.

Posted on Friday, February 25, 2011 at 2:26 PM

New Horizons for Conservation Cropping in California Conferences March 9, 10 and 11

California’s Conservation Tillage and Cropping Systems Workgroup will present educational tours and programs at three locations in California March 9-11 to convey information on innovative conservation tillage crop production systems that are being developed in irrigated regions of South Dakota, Nebraska, Colorado and Washington.

In addition to sharing information about the conservation cropping systems in these states, the speakers will discuss how the principles and practices can be implemented on California farms.

The first conference will be held March 9 at the UC Davis Western Center for Agricultural Equipment. The second meeting convenes on March 10 at the SCE Ag-TAC facility in Tulare and continues in the afternoon with tours of three Central Valley farms. The final session is March 11 at the UC West Side Research and Extension Center in Five Points. The presentations at the three locations will be the same. There is no registration fee and no pre-registration necessary.

The three featured speakers, all national leaders in the practice of conservation tillage, are:

  • Dwayne Beck, manager of the Dakota Lakes Research Farm in Pierre, South Dakota. Beck has been inducted into South Dakota’s Hall of Fame for introducing cost-saving conservation tillage practices to the region’s agricultural industry when, in the early 1990s, farms were closing due to a lack of economic viability.
  • Mike Peterson, retired USDA NRCS Conservationist and currently the California precision tillage specialist for Orthman Mfg.  Throughout his career, Peterson has researched and developed information on strip-till approaches.
  • Andy McGuire, cropping systems advisor with Washington State University in Moses Lake, Washington.  McGuire has been working to evaluate and develop high-residue cropping systems for the irrigated crops of the Central Washington region.

“The main reason we invited these out-of-state experts is to learn how the conservation tillage systems they have developed relate to California,” said Jeff Mitchell, UC Davis Cooperative Extension cropping systems specialist and coordinator of the conference. “All of them come from areas where farmers practice irrigated agriculture. We are planning to very thoroughly and thoughtfully consider with them, through a series of dialogues and discussion, the relevance and application of their work on farms in California.”

Conservation agriculture systems reduce overall tillage or soil disturbance, maintain surface residues, seek make production systems more efficient, and reduce costs.  Speakers will address the integrated management of the conservation production systems.

Conference details:

March 9, 12 noon to 4 p.m.: UC Davis Western Center for Agricultural Equipment, off Hutchison on Hills Drive, just west of 113.

March 10, 8 a.m. to 1 p.m.: Southern California Edison AgTAC, 4175 S. Laspina St., Tulare, Calif.

March 11, 9 a.m. to 12 noon: UC Westside Research and Extension Center, 17252 W. Oakland Ave., Five Points, Calif.

For additional information on these conferences see the Conservation Tillage and Cropping Systems Workgroup website or contact Mitchell at, (559) 646-6565.

Posted on Monday, January 31, 2011 at 8:21 AM

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