July 7, 2020
“Generating and preserving surface residues on the soil – despite being one of the core principles of just about all of the soil health movements and government programs these days – has had very little play in most agricultural fields in California now for nearly ninety years.” That stark assertion come from experienced Cropping Systems Extension Specialist and leader of the State's Conservation Agriculture Center, Jeff Mitchell, who's been in the trenches tinkering with systems that couple residue-preserving and reduced disturbance practices for nearly 30 years.
“The body of research knowledge and experiences on the values of high residue systems is enormous,” Mitchell says, “ and yet most folks in California have not come around to them.” Scientific theory supports the role of residues in reducing soil water evaporation and weed emergence, cooling the soil, and increasing soil carbon gain. “And this theoretical underpinning is now guiding our expanded work with high residue systems to better understand the value they may have in improving biodiversity as well as the efficiency of the carbon, nitrogen and water cycles in California's food production systems,” says Mitchell about the new work that is now underway at several farm study sites throughout the State.
Most annual crop fields that you'll drive by in California typically have close to zero residue on them. “Residues are pretty much managed to make them disappear,” Mitchell observes. Yet, several studies from both irrigated and rainfed regions around the US and including our own work in Five Points have shown that when no-tillage is coupled with high residues, annual irrigation savings can be as much as 4 to 5 inches. In several areas including the Central Great Plains of the US, no-till, high residue practices have positively affected agricultural management and local farm economies with both the intensification and diversification of cropping systems. “What we're doing at this point is trying to figure out just how these residue practices might actually work in various California production systems and minimizing risks associated with transitioning to them.”
More information on these types of systems will be shared on July 23rd as part of the Desert Southwest Soil Health Webinar (https://www.eventbrite.com/e/desert-southwest-soil-health-webinar-tickets-107732693386), slated for July 23rd from 8 AM through 6 PM.
Accompanying photo caption
High residue, no-tillage and cover cropped surface soil conditions achieved in 21-year conservation agriculture research study in Five Points, CA showing the extent of residue cover that can be achieved when these practices are coupled together.
Information on the dynamics of long-term use of winter cover crops in California's San Joaquin Valley will be shared with online participants as part of the Desert Southwest Soil Health Webinar (https://www.eventbrite.com/e/desert-southwest-soil-health-webinar-tickets-107732693386), slated for July 23rd from 8 AM through 6 PM.
“This will be one of the first outlets in which we'll share our 20-year findings on both the costs and benefits of using cover crops to improve agroecosystem biodiversity and the efficiencies of the C, N, and water cycles in SJV annual cropping systems,” says UC ANR's Jeff Mitchell, whose presentation on conservation agriculture falls in the 10:30 AM – 3:00 PM “Practices to improve soil health,” slot on the day-long program.
Mitchell will describe how over the course of the project that was characterized by recurring drought, a total of 37 tons of aboveground cover crop biomass representing 1580 lbs N and 14.8 tons C per acre was produced with a total precipitation of 127 inches and 16 inches of supplemental irrigation in that was applied in four of the years. These inputs averaged 3,695 lbs of organic matter or 0.79 tons of C annually. Year-to-year variability was quite large ranging from 8,818 lbs OM in 2000 when supplemental irrigation was applied, to 54 lbs/ac in 2007 when, as in most years, no irrigation was applied to the cover crops. The cover crops were typically seeded by November 15 and terminated around March 15 of the following year accounting for a growth period of 120 days capturing solar energy by the “green ground cover”, and living roots in the soil for about 90 additional days during the year relative to the standard practice system which was bare during this time. Based on cover crop growth during years when supplemental irrigation was applied, Mitchell estimates that an average of 6,082 lbs of dry cover crop biomass might have been produced with a modest input of 2 inches of water. Even greater amounts of cover crop biomass – approximately 12,000 lbs of dry matter per acre as is typically achieved with winter silage triticale crops in SJV dairies - could be produced were cover crops “treated more like cash crops” with additional supplemental strategically timed irrigation in a cropping system as in other regions of the US. He'll also be showing participants via recorded video clips just how this sort of sustained cover crop use improves key soil health indicator properties and function.
CCA and PCA credit for the online webinar have been requested.
UC ANR Cropping Systems Extension Specialist, Jeff Mitchell, shown sampling winter cover crop aboveground biomass in longstanding conservation agriculture study of the impacts of reduced disturbance, cover crops, and surface residues on soil function, productivity, and ecosystem services at the Conservation Agriculture Systems study site in Five Points, CA
Fifteen years of stunning conservation agriculture success at Rollin Valley Farms in Burrel, CA!
June 22, 2020
Andy Rollin, along with his brother, Donny, are dairy farmers near the small western San Joaquin Valley town of Burrel, CA. Their farm, Rollin Valley Farms, milks over 2,000 cows and has about 700 acres of silage crops including alfalfa, corn, oats, wheat, and sudangrass. About 15 years ago, they began some of the earliest efforts to develop reduced disturbance production techniques for their silage crops (see video below). They pioneered the successful development of strip-till corn way back in 2003 and 2004 and then a few years later, began working with Monte Bottens and Cary Crum of California Ag Solutions (CAS) in Madera, CA, to further improve their production systems. Monte and Cary helped them with state-of-the-art planter improvements, an Orthman 1-tRipR strip-till implement and also the use of CAS's Landoll no-till grain drill. (See Picture 1). In addition, the Rollins have in recent years added a late-summer multi-species silage “cover crop” which has now augmented their annual forage production over their prior double-cropping practices. Strip-till corn yields at their farm are up about 2 to 3 tons/acre over prior production rates and there have also been 10 to 15% improvements in their feed quality that have resulted from the coupled, innovative efforts that they have made.
The Rollins were also involved with a research study back in 2004 and 2005 with CASI's Nick Madden, Randy Southard, and Jeff Mitchell to determine the impacts of their reduced disturbance practices on air quality. (See Picture 2.)This work showed that over 85% of dust emissions were reduced by strip-till compared to their previous standard till system (see the attached article by Madden et al. 2008). (See Picture 3).
The Rollins are now firmly behind their transition to strip-till and no-till cover crops and small grain seeding schemes and attribute an early spring savings of about 10 days to their reduced disturbance corn planting systems. They now have switched to watering up their strip-till corn following the very minimal soil work they do following winter small grain chopping and harvesting. In recognition of their innovative and steadfast progress, they were Finalists in the 2018 Leopold Conservation Award Program. The following short video shows one of their strip-till corn fields this spring. (See Picture 4.)
Here is a link to a You Tube video of this project: https://youtu.be/mq8itVs3Iak
About 80 Master Gardeners of the UCCE group in El Dorado County came together to learn about the principles and practices of conservation agriculture in a lively discussion with CASI Workgroup Chair, Jeff Mitchell, on June 23rd at the group's monthly meeting in Placerville. The meeting was organized by Master Gardener event coordinator, Catherine Mone, and drew a very animated and engaged group of participants.
Mitchell talked about the core principles of conservation agriculture and the extent to which they're now being used around the world and recently in California. He showcased examples of pioneering innovation that have been achieved in a number of cropping contexts and also provided information and ideas as to why it will be increasingly likely that these sorts of production system options may have greater receptivity and resonance in California in the future. He ended his discussion with some examples of motivation that he has benefited from over the years from his professional mentor, Dwayne Beck of South Dakota State University. "Take the E out of ET and the T out of can't," was Beck's encouragement to Mitchell. This can be accomplished by protecting the soil surface with crop residues that cool soil temperatures and reduce soil water evaporation, and by not giving in to merely accepting the status quo, but by identifying bold, ambitious, and long-term cropping system goals and then coming up with the ways to achieve them. This is, according to Beck, "Nothing short of the agronomic and ecological equivalent of the space race back in the 1960's" and we are going to need to really dedicate tremendous creativity and effort toward achieving it.
CASI was very honored to be invited by the Master Gardeners of El Dorado County and we look forward to returning to Placerville in late September!
- Author: Jeannette E. Warnert
Mitchell, the chair of the UC Conservation Agriculture Systems Innovation Center, made the comment at the 6th World Congress on Conservation Agriculture in Winnipeg, Manitoba, last month.
After attending the congress, Mitchell said he is more strongly convinced that greater efficiencies and brighter economics in California agriculture could be achieved by employing conservation principles.
“Focusing on soil care will improve soil water intake and storage,” he said. “Reducing soil water evaporation can be achieved by preserving surface residues. Together these steps reduce energy use and greenhouse gas emissions – very important goals.”
The Manitoba congress drew more than 350 participants representing 47 countries. It was co-sponsored by the Conservation Agriculture Systems Alliance, the Conservation Technology Information Center, and the Canadian Soil and Water Conservation Society. California's CASI was represented by Mitchell and Monte Bottens, president of California Ag Solutions of Madera, a consulting and custom fertilizer support company.
Speakers at the conference suggested conservation agriculture principles are “transformative and not merely incremental means for achieving the kinds of change must be made to meet the global challenges of food production and natural resource conservation in the 21st Century,” Mitchell said. Modestly tweaking today's conventional agricultural systems, he said, “is not an option.”
Today conservation agriculture is used on about 11 percent of the world's total arable land. Implementation is increasing at an annual rate of about 7 to 8 million hectares, according to the U.N.'s Food and Agricultural Organization. Nearly half of the world's conservation agriculture acreage is found in the developing world. The South American countries of Brazil, Argentina and Paraguay, where the movement had its beginnings as a farmer-led process dating back to the mid-1970s, has about 80 percent implementation.
During his keynote address at the conference, David Montgomery, University of Washington professor of geology and author of Dirt: The Erosion of Civilizations, issued a “call to action.”
“Global soil degradation,” he said, “is an under-appreciated environmental crisis that occurs because of how we farm. We need to be more creative in terms of how we're intensifying agriculture to feed the post-oil world without cheap, fertilizer-intensive agriculture.”
Congress speaker Dwayne Beck, agronomy professor at South Dakota State University, also sounded an alarm.
“Never in history has mankind knowingly faced this type of impending catastrophe,” Beck said. “It is time to stop doing incremental things and start doing transformative things. You do not cross a chasm in two steps. We need to focus on where we want to be and emphasize systems, not details; actions, not reactions; and commitment, not merely involvement.”
CASI members are working with foundations and granting agencies to better position the organization to support implementation of conservation agriculture in California. For more information, contact Mitchell at (559) 303-9689.