- Author: Trina Kleist, UC Davis
One more reason to adopt sustainable cultivation
California wheat farmers could both maintain their yields and improve soil health by growing annual wheat without tilling the soil year after year.
This could be one more encouragement to farmers to adopt a sustainable practice commonly called conservation tillage, no-till or minimum-till cultivation, impacting how we grow a grain that supplies about 20 percent of the calories and protein for people around the world.
A new study, by a team led by Mark Lundy, University of California Cooperative Extension specialist in UC Davis' Department of Plant Sciences, offers new insight for decades-long discussions around soil conservation, sustainable agriculture and climate-warming emissions related to growing our food. The study has been published in the journal Soil and Tillage Research. For the first time, researchers have shown that annual wheat that is not tilled each year is better for stashing carbon in the soil than perennial wheatgrass, while still yielding more crop in Central California.
Previous studies have looked at annual wheat that is tilled each year, annual wheat that is not tilled, and a cousin species, perennial intermediate wheatgrass (trademarked Kernza), which also is not tilled. But until now, no one has looked at all of the benefits and trade-offs together. Most importantly, “no one has ever controlled for tillage,” Lundy said. “And, no one has compared annual wheat to perennial intermediate wheatgrass over multiple years in a Mediterranean climate, which is what we have in California.”
This study also is unique because it delves into the deeper question of what is going on in the soil that drives the different results for carbon there. Soil carbon reflects various processes linked to plant activity and soil health. Measuring the different forms of soil carbon may also signal whether a farming system is accumulating carbon in the soil over time – a plus for reducing climate-warming gases in the atmosphere.
“Measuring soil carbon is complex and nuanced,” said Kalyn Taylor, the lead author on the paper. “We started this experiment because we wanted to know whether and how plant activity and tilling or not tilling would affect the carbon story belowground in California's climate.”
“When we started this study, we thought the crop being perennial or annual would drive the differences in carbon storage in the soil,” Lundy added. Specifically, they had expected perennial wheatgrass would lead to more carbon in the soil because of its deeper, better-established root system. “But that's not what we found,” he went on. “What we found was, it was the lack of tillage, plus the level of productivity of common annual wheat, that made the difference in soil carbon here in California.”
Soil carbon in annual vs. perennial grain
In 2017, Lundy, then-graduate-student Taylor, UC Davis Professor Emeritus Kate Scow and others on the team started measuring different forms of soil carbon in test plots at Russell Ranch, west of campus. Plots were planted with annual wheat that was tilled each spring, annual wheat that was not tilled and perennial intermediate wheatgrass (Kernza) that also was not tilled.
Each year, the researchers measured the carbon present in the soil, the amount of soil organisms (which have carbon in their bodies) and the amount of material the plants created.
At the end of three growing seasons, they found that land planted with no-till, common, annual wheat had the highest amount of soil organisms, measured as biomass, of the three treatments.
The researchers also found soil carbon is more likely to remain stable in the no-till, annual plots, compared to both tilled wheat and wheatgrass.
In addition, the no-till, annual wheat produced plant material more consistently than the perennial wheatgrass across the three years, which saw variation in rainfall.
“Overall, annual wheat grown without soil disturbance or tillage had both higher productivity and higher potential for storing carbon in the topsoil than perennial wheatgrass in our Mediterranean climate,” Lundy said.
Related research
“No-till annual wheat increases plant productivity, soil microbial biomass, and soil carbon stabilization relative to intermediate wheatgrass in a Mediterranean climate,” is online now and will be published in the January 2024 edition of Soil and Tillage Research.
The team also found that tilled annual wheat vs. Kernza stores total carbon at different depths in the soil profile and hosts distinct soil fungal communities, primarily in the root zone and topsoil: Taylor, K., Samaddar, S., Schmidt, R., Lundy, M. and Scow, K., 2023. Soil carbon storage and compositional responses of soil microbial communities under perennial grain IWG vs. annual wheat. Soil Biology and Biochemistry, p.109111.
Previous work comparing the perennial grain known as intermediate wheatgrass (trademarked Kernza) to annual wheat had not distinguished the extent to which soil health benefits are a function of the perennial nature of the crop. Read the story here.
This story was originally published on the UC Davis News site.
/h3>/h3>/h3>- Author: Jeffrey P. Mitchell
Documentary video on no-tillage in California being prepared
July 1, 2023
A video documentary featuring five of the CA and AZ farmers who have been part of the USDA NRCS Conservation Innovation Grant project, "No-till network for California," is in the final stages of production and will be released in the near future through the University of California's Conservation Agriculture Systems Innovation Center's You Tube channel.
https://www.youtube.com/channel/UCVd3wKF3P6fA4zQWVKIouWA
The documentary will feature Eddie Sajian of Hanford, CA, Rick Adams of Laton, Paul Strojan of Farmington, Dr. Henri Carter MD of Yuma, AZ, and Cary Crum, of Fresno, CA and will show them describing details of the innovative approaches that they are working on to improve the overall performance of their agricultural production systems. The release date for the documentary is scheduled for late July 2023.
- Author: Jeffrey P. Mitchell
June 17, 2023
CASI's Mitchell visits Low Desert no-tiller, Dr. Henri Carter MD, June 17, 2023!
Jeff Mitchell paid a very early morning visit in Yuma, AZ to the farm of retired surgeon and now no-till farmer, Dr. Henri Carter MD on Saturday, June 17, 2023, to learn about the very innovative efforts that he has been pursuing during the past several years. The visit was planned for quite some time and provided a very nice chance for Mitchell to meet Dr. Carter and to see up close and personal just what he has been up to with his no-till farming endeavors. The visit was recorded as a video case study that Mitchell will compile on innovative no-till farmers as part of a USDA NRCS project on establishing a no-till network in California.
Dr. Carter has an interesting background and evolution toward the work that he is now conducting. He started out as a student of agricultural science at Arizona State University and worked not only on his family's farm in the Yuma area when he was growing up, but also in many related jobs on farms and in packing sheds for cantaloupes, lettuce, hay, and other crops. Then, after he had the opportunity to go to medical school, he returned to Yuma where he dedicated his career to work as a trauma surgeon which was most gratifying for him. Now retired from surgery, he bought farming/range acreage just north of the confluence of the Gila and Colorado rivers where he showed Mitchell what he is trying to do in conjunction with a project he has with Arizona's Game and Fish Department to provide access to hunters on his property using the permanent cover and no-till approaches that he is pioneering. He showed Mitchell blocks of no-till, quite high surface residue sunflower and cowpeas that he successfully established this year after a number of bouts with trial and error learning.
While not the usual crop context in which we tend to imagine no-till applications, what Dr. Carter is doing is nonetheless quite intriguing and interesting.
More to come soon once the video on maverick farmers and the unusual things they're doing in CA and AZ is released!
- Author: Bruce A Linquist
- Editor: Consuelo Baez Vega
Last year roughly half of the rice acreage was left fallow. We have been conducting research (funded by the Rice Research Board) looking at the differences between rice grown after a fallow versus rice grown following rice. We have found that rice following a fallow has higher yield potential. In our two years of study we saw about a 2 to 3 sack yield advantage in rice after a fallow. Higher yields may be due to reduced disease incidence. In both years of the study we saw lower incidence of stem rot in rice following a fallow year. As mentioned, this can lead to higher yields but also to less lodging.
Regarding nitrogen management, we used a labeled nitrogen fertilizer to allow us to determine if the nitrogen in the plant came from fertilizer or from the soil. We found that fertilizer N was used similarly when rice followed a fallow or when it followed rice. Interestingly, we also found that when rice followed fallow, more nitrogen was available from the soil – particularly after PI. This has a couple of implications. First, it means if you had a fallow rice field last year, you may be able to back off on your overall N rate. In our data from one year, we found that you could back off by up 20 to 30 lb N/ac. Secondly, most of the additional N availability came after PI. This suggests that if you are routinely topdressing, it may not be necessary when rice is following a fallow year. Regardless, I would still suggest monitoring the crop at PI using a Leaf Color Chart or a GreenSeeker to make a more informed decision about N management.
Some of you may be asking “why do we get more nitrogen in a field that was fallowed?”. This is a great question. In fields that have been in rice where the rice straw is incorporated and flooded during the winter, phenols accumulate. Phenols are an organic compound that tend to build up when organic matter, such as straw, decomposes under anaerobic conditions. Given how most farmers manage their straw we would expect a build up of phenols. In fact, we have looked at soils around the valley and have found this to be the case. Phenols also bind nitrogen, making it unavailable for plants. Imposing long periods of time when the soil is aerobic such as during a fallow period, promotes the breakdown of these phenols and the release of nitrogen.
- Author: Jeffrey P Mitchell
- Author: Anil Shrestha, California State University, Fresno
- Author: Jeffery A. Dahlberg
- Author: Lynn Epstein
Since the advent of irrigation in California with the widespread drilling of wells in the 1930s and the proliferation of orchard crops during the past two decades, total annual water use in many watersheds exceeds supply. Partly as a consequence, California enacted the Sustainable Groundwater Management Act in 2014, which limits withdrawals to replenished levels.
Because irrigated agriculture accounts for nearly 80% of total water use, reductions in irrigation will be required, but preferably without decreasing either productivity or food supply. Furthermore, with some climate change projections suggesting a potential 20% water loss by the middle of the century, the need for more efficient water use could become acute. Fortunately, some water-saving methods such as drip irrigation have been supported by the government and there have been programs that have increased implementation and farmers understand these methods well.
Reduced disturbance tillage, or no-till, however, also offers an under-utilized strategy for increasing agricultural water use efficiency in California. There has been very little research and there is very little information available to farmers on no-till production systems for the diverse array of crops that have been produced in the state historically.
UC Cooperative Extension cropping systems specialist Jeff Mitchell led a diverse team of ANR, farmer, private sector and other public agency partners to evaluate the potential for producing sorghum and garbanzos, using high residue, no-till techniques in the San Joaquin Valley in a four-year study conducted at ANR's ag experiment station in Five Points, Calif.
Standard tillage practices have been used throughout the region for nearly 90 years. Using similar inputs and amounts and pest management, they showed that a garbanzo and sorghum rotation in no-till yielded at least as well as in standard tillage.
Sorghum yields were similar in no-till and standard tillage systems while garbanzo yields matched or exceeded no-till than in standard tillage, depending on the year.
In the trial, no-till garbanzos yielded an average of 3,417 pounds per acre versus standard tillage with an average of 2,738 pounds per acre; garbanzo production in California, which is almost all in standard till, averages 2,300 pounds per acre.
We envision that if water costs continue to rise and as curtailments on water supply increase, the value of agricultural land in California will eventually decline, providing more of an economic incentive for using no-till for growing a portfolio of crops, such as sorghum and garbanzo, amenable to these pending constraints on irrigation.
In addition, there already exists high acreage of relatively low-value field crops in the state. As annual row crop farmers are faced with the need to reduce water use, knowing which field crops perform well in no-tillage conditions is important for the region. For this reason, this work may serve as a decision-making tool for growers in the future, especially if there is the opportunity to both reduce management costs and maintain yields
An outgrowth of this work on no-till systems is the group of about 15 farmers who're now a part of a USDA NRCS Conservation Innovation Grant Program project that is looking at opportunities and approaches for reducing disturbance in organic vegetable production systems.