- Author: firstname.lastname@example.org
Cover crops can provide many soil and ecosystem benefits, like improving water infiltration and providing resources for pollinators. However, we don't yet know which cover crop species are best suited for specific cash crops.
To answer this, I planted potatoes into the residue of 5 cover crop mixes in Shafter (Kern County). Here are the mixes I planted:
1. Soil health mix: Merced rye, common vetch, berseem clover, and daikon radish
2. Soil builder mix: triticale, Dundale peas, common vetch, yellow mustard, and radish
3. Brassica pollinator mix: yellow mustard, daikon radish, Nemfix mustard, “Bracco” white mustard, and canola
4. Simple mix 1: Merced rye and Dundale peas
5. Simple mix 2: barley and common vetch
I wanted to see if the cover crops would reduce disease incidence or improve yield. Here's what I did in this trial:
|Potatoes were harvested on August 3, 2021.|
So, what did we see? We had a few challenges:
Southern blight and other soil borne pathogens
By June 9, all of the rows had some potato plants, but it was very patchy.
The plants were dying because they were infected with southern blight and other soil borne pathogens (right photo).
So, did we find anything interesting?
There was too much variability and not enough replication to see meaningful differences in the yields associated with the different cover crop mixes.
Further research is needed to identify the best cover crop species for each cash crop in Kern County.
Southern blight thrives under the conditions of the trial field in Shafter. It has historically only been a major problem in Kern County, but other areas of California are now reporting cases due to warming temperatures.
It grows best under these conditions:
- Warm temperatures
- Acidic soil – the soil pH in the top 6 inches of soil was between 5.8 and 6.3
- Decaying organic matter – in this case, the decomposing cover crops
- High soil moisture – we used sprinkler irrigation
Unfortunately, southern blight doesn't just attack potatoes. It has a wide range of hosts and can decimate other vegetable crops like tomatoes, cucumbers, and chard.
Should I not plant cover crops because of southern blight?
The potato trial in the neighboring field was also decimated by southern blight. That field was fallow before the potatoes were planted, with no cover crops.
If you plan to grow a crop that is susceptible to southern blight and you are in Kern County, you should focus on the cultural practices and chemical products that will reduce your risk of crop loss.
If you plant cover crops, make sure that the crop residue has completely decomposed before planting your cash crop. This might require terminating your cover crops early, so that there is enough time for complete decomposition.
In this trial, there was an incredible amount of biomass left over from the cover crops. They were irrigated and planted at 1.8X the recommended seeding rate. There was also plenty of nitrogen and warm weather to fuel their growth. If your cover crops do not produce as much biomass, especially ligneous biomass, then they should not take as long to break down as the ones in this study did.
More information about southern blight
For more information about the trial, contact Shulamit Shroder at email@example.com or 661-903-9442.
Many thanks to Jed Dubose, Jaspreet Sidhu, Jennifer Fernberg, Cristal Hernandez, Brian Marsh, Rick Ramirez, Caddie Bergren, and Samikshya Budhathoki for their help.
- Author: Dana Yount
Daniel Unruh, and his family, farm just under 200 acres of walnuts alongside the Sacramento River, just outside of Princeton, CA. The walnut orchard is irrigated with solid set sprinklers and is only irrigated when needed, or if there is not enough rain during the season. Daniel started cover cropping in 2013 with the main goal of nematode suppression, and soon after, he and his wife took over the orchard operations. The cover crops that show up now between rows is voluntary, as he has not spread seed in years, but still sees a successful cover. He also practices reduced till on his farm to encourage the cover crop growth and help increase biomass production.
Daniel has not received money from any grants, or other outside funding sources to establish cover crops, this was just something he saw benefit in after the first few years of nematode reduction. His passion for cover cropping has grown to encompass more than just nematode suppression however, and he is now seeing plenty of benefits elsewhere around his orchard.
Beneficials of all kinds consider his orchard a home, less water is running off of his property during storms and irrigation, and he has cut his input and commercial fertilizer bill down by close to 75%. The soil organic matter for his orchard has also increased from around 1.7-1.9% to 3.0% when tested in 2020. When Daniel and his wife first took over in 2014, the orchard was sprayed for husk fly, coddling moth and blight, but now only blight has been addressed in recent years. In fact, he has not used any fertilizer at all the past few years, but has seen a slight reduction in yield as a result. Daniel also has seen changes in his irrigation cycle in what used to be a rotation of every 7-10 days, has been extended to every 12-14 days due to moisture retention.
Like many other farmers, his main concerns with cover cropping in an orchard system was termination, and the learning curve that comes along with it. Daniel was even able to design a roller crimper, with chevron crimps, specifically for his operation and the type of cover crops he uses for termination. His cover crop stand consists of brassicas, grasses and legumes and can easily grow to over 6 feet tall. When he originally planted, Daniel spread seed 17 feet across for almost 90% coverage. His roller crimper helps lay plant material down to protect the soil from the sun, improve water retention and creates an environment beneficial to microorganisms.
Daniel is so passionate about improving his soil microbiology and reducing his inputs, he even serves as a Mentor Farmer at the Chico State Center for Regenerative Agriculture. Daniel has presented at numerous events and has hosted workshops at his orchard to educate and encourage other growers to give soil management practices a try. Daniel says he is never done learning, and attends many workshops throughout the year as well.
Finally, Daniel encourages a holistic outlook, and motivates others to keep trying various approaches if it doesn't work the first time until you find a system that does work for your operation. He goes on to say you should try alternatives first before going straight to spraying fertilizer as eventually plants will rely on this synthetic ‘health' and it will not last.More on Daniel and how he has contributed to this research can be found at https://www.csuchico.edu/regenerativeagriculture/demos/daniel-unruh.shtml
Steven Cardoza farms 300 acres of organic raisin grapes with his father in Fresno County, California. He met with us recently to share his experiences with cover cropping and more broadly, his transition towards regenerative agriculture.
Steven remembers falling asleep as a kid on their tractor and following around his dad, who began farming before Steven was born, and has been certified organic for over 22 years. Steven joined the family business full-time six years ago and hasn't looked back.
Even though they were certified organic, they suffered from weed and pest pressure. Steven was introduced to the idea of ‘regenerative agriculture' and was intrigued, so he began learning as much as he could on his own. He estimates he has listened to thousands of hours of podcasts about agriculture while sitting on his tractor, and said it really came to life when he could see right in front of him what the podcasts were talking about.
Experience with cover crops
Cardoza made two significant changes from what his father had been doing. First, he began cover cropping every row instead of every other row, and second, he leaves the crop without mowing as long as possible, often as late as August. He has experimented with various cover crop seed mixes and blends, and continues to see what works best. “Nature does not like to be naked, and I want to keep living plants on the ground as much as possible”, says Cardoza.
Now that he cover crops all his vineyards, he has not seen a pest outbreak in the past two years. He also has not applied any nitrogen fertilizer at all, although sometimes he does use compost. He is most excited to experiment with cover crops' ability to suppress weeds, something that is a high priority for organic farmers with few herbicide options. Through trial and error, he is finding that barley has been reseeding along the berms of his rows and slowly outcompeting the Johnson grass. In some blocks, he has estimated a 98% reduction in Johnson grass in the past few years.
Through the CDFA Healthy Soils Demonstration Project program, he has received a grant in collaboration with the UC Coop extension in Fresno to experiment further with his cover crops. He is excited to try out a mower that ejects the mowed cover crops right onto the berms on each side of the row, further suppressing weeds near his vines.
A Central Valley question: But what about water use?
Most of Cardoza's vineyard blocks are drip-irrigated. This means that the cover crops, which are planted in between the rows of his vines, are not irrigated at all. He waits until the first rain in the fall/winter to plant. Some years are better than others, but he says he has always been happy with how they have grown. We were able to tour one block of vineyard that has the ability for flood irrigation. The cover crops were much taller, greener, and healthier looking than in the drip-irrigated sections. However, they have not been irrigated all winter; Cardoza does one post-harvest flood irrigation, plants his cover crops directly afterwards and lets them grow with only nature's inputs after that.
Advice for other growers?
“Get comfortable with being uncomfortable,” he says. He spends a lot of time thinking about and experimenting with his cover crops and other regenerative practices. He also says he's getting the local reputation of “the cover crop guy”, and other growers have called him with questions such as how to calibrate a drill seeder. He says the trend in some of the older generation of farmers was to closely guard your secrets to success from your neighbors and he'd like that to change. “I've spent a lot of time and effort to learn what I have, and I'm very happy to share it with other farmers who want to make similar changes”. When he sees another farmer successfully implementing regenerative practices, he knows it's not just benefiting their bottom line, but their land as well, and that makes him feel good.
Learn about Steven Cardoza in the video link below who is implementing innovative farming practices to improve the soil health of his vineyard!
- Author: Dana Yount
- Contributor: Kristian M Salgado
- Contributor: Emily Lovell
- Contributor: Caddie Bergren
UC ANR Climate Smart Agriculture Educator team assisted growers to win CDFA grants that reduced greenhouse gases equivalent to removing roughly 7,000 cars off the road, supporting UC ANR's public value of building climate-resilient communities and ecosystems.
Increasingly extreme and erratic weather patterns caused by climate change threaten crop yields and farm profits across the state. Growers must continue to adapt to climate stressors, such as increased temperatures and occurrences of drought, and can aid in reducing climate change through their farming practices.
How UC Delivers
A collaborative partnership between the Strategic Growth Council, California Department of Food and Agriculture (CDFA), and University of California Agriculture and Natural Resources (UC ANR) teamed up to support 10 Climate Smart Agriculture Community Education Specialists (CSA CES) throughout the state to provide technical assistance and outreach to promote Climate-Smart Agriculture Incentive Programs. These programs include:
- The Healthy Soils Program, which incentivizes the implementation of climate-smart agriculture practices such as cover cropping, composting, crop rotation, and mulching which reduce erosion and greenhouse gases
- The State Water Efficiency and Enhancement Program (SWEEP), which encourages farmers to install more efficient irrigation systems that decrease water consumption and greenhouse gas (GHG) emissions; and
- The Alternative Manure Management Program (AMMP), which awards funds to livestock producers who decrease their methane emissions by changing the way they manage manure.
Since establishing this partnership in 2019, the UC ANR Climate Smart Agriculture Educator team has provided hands-on assistance to over 200 farmers and ranchers through the complex application process. Collaborating with other CDFA technical providers to host workshops, field days, and events has expanded reach to a greater number of growers, over 120 of whom were able to receive funding after receiving technical assistance. UC CSA CES efforts don't stop at the outreach or application phase; educators work year-round to ensure successful implementation of climate-smart projects.
After the award process, educators assist awardees in completing grant invoicing and contract reporting requirements and connect them with vendors, industry experts, and service providers. UC CSA CES also engage in a variety of additional support activities. For example, to help establish successful cover crop adoption, one educator created a cover crop decision-making tool. A different educator started a small compost spreader rental program to assist small growers in spreading compost. Another facilitates full project management through translation services to a cooperative of Cantonese-speaking awardees.
Through assisting awardees in the adoption of practices such as cover cropping, installing solar panels, and installing dairy manure solid separator systems, the 10 UC CSA CES have collectively supported growers in reducing 33,000 MT/CO2 per year, as measured by California Air and Resources Board (CARB) Green House Gas Emission reduction calculator (SWEEP GHG Calculator on CDFA's website), and the HSP Comet planner tool. That's equivalent to removing 7,000 cars from the road per year.
Table A provides an overview of how much GHG has reduced in counties where the UC Climate Smart Agriculture Educator team has helped farmers implement climate-smart practices. Totals for all projects are much higher.
Total CO2 equivalent in MT/year
Sonoma, Mendocino, and Lake County
Merced, Madera, Stanislaus
Glenn, Butte, Colusa, Tehama County
Yolo, Solano, Sacramento, San Joaquin, El Dorado, Sonoma, Colusa, Sutter
Santa Clara County
Kern & Tulare Counties
Santa Barbara, Los Angeles, Orange, Ventura County
San Diego and Riverside Counties
Imperial County and Riverside County
Glenn County grower, Shannon Douglass says, “When producers have the support from the UCCE office that they already know and trust, they are more willing to implement new practices. The application process is intimidating, but with the help from UC, soil healthy practices are becoming much more widely adopted.”
Research shows that Healthy Soils Program practices such as compost application increases the amount of organic matter in soil, amongst numerous other benefits such as increasing the water and nutrient retention capacity of soils, providing a reservoir of nutrients for plants, improving aeration, improving water infiltration, reducing soil erosion, and supporting the abundance and diversity of soil organisms, which can improve plant health. Compost application is just one fundable practice farmers can implement to help reduce greenhouse gases on their operation.
Thanks to this unique partnership with CDFA, UC ANR is able to provide hands-on support to farmers statewide so that they can improve the health of their soils, reduce livestock methane emissions, and improve water use efficiency. In this way, the Climate-Smart Agriculture program contributes to UC ANR's public value of building climate-resilient communities and ecosystems.
- Author: Britta Leigh Baskerville
Located in Laytonville, CA, 150 miles North of San Francisco and 12 miles from the Pacific Ocean, sits Alder Springs Vineyard. This remarkable piece of land is home to approximately 140 acres of wine grape vines ranging in cultivars and management practices. To a UC Climate-Smart Ag Specialist, speaking to owner/manager Stuart Bewley and visiting this land is always an informative and inspirational experience. In my work with the CDFA Healthy Soils Program, and later with the North Coast Soil Health Hub, I've had a chance to meet with Stuart on several occasions, and recently got to sit down and record a few of his thoughts on the matter of ecological land stewardship.
A scientist at heart, Stuart took viticulture courses at UC Davis and traveled the world, meeting with other vineyard managers, industry contacts, consultants and experts, to better understand how to produce quality grapes.
“We're in the vineyard business, and in order to attract and keep clients, we have to make great wine. Most of our clients are relatively small, so they have a competitive disadvantage… a smaller company lacks the competitiveness of an army of salespeople being able to twist the arms of distributors, they have to compete on quality. And that quality has to be superior. The wines have to just be extraordinary. And in order for those wines to be extraordinary, their grapes have to be extraordinary. And I believe, in order to keep my clients competitive, I have to grow extraordinary grapes.”-SB
Because of this, Stuart is constantly experimenting with management strategies, tailoring each varietal to their unique management needs. But beyond business, he has a strong pull to make his production more ecologically sustainable for a number of reasons. Increasing Carbon in his soils and reducing herbicide use were the reasons I first received a phone call from Stuart, just a few weeks after joining the UCCE office in Ukiah.
This was early February 2019, and Stuart was interested in applying for a Healthy Soils Program award. His project idea was to apply heavy bands of compost and mulch under his vines to suppress weeds while reducing Nitrogen lockup and erosion, inoculating the soil with microorganisms, and increasing soil Carbon.
“With more and more evidence that Round-Up is carcinogenic, our winery clients are starting to demand we use another method of weed control under-vine. Not wanting to continue to put ourselves, our labor, our customers, or our ecosystems in harm's way, we feel that it is time to change our methods. The only other method used by most Organic or Biodynamic growers is tilling. This method releases carbon into the atmosphere and reduces the organic matter in the soil. We are on hillsides with year-round class 1 streams near our vineyards. (These streams are spawning grounds for Steel Head, King Salmon, and Coho Salmon.) We need a method of under-vine weed control that protects the soil from erosion. Through a small experiment on another parcel, we were able to determine that a one-time application of a 3" mulch layer is enough to suppress weeds and reduce soil erosion for up to 3 years. A thick band of compost under the mulch was shown to add enough available Nitrogen to maintain vine vigor. Together they proved to be an effective practice for suppressing weeds with the added benefit of soil protection from erosion and ultraviolet light. We would also like to measure the effects of these practices on the structure and quality of soil organic matter, the reduction of GHG emissions, and the capacity of soil Carbon sequestration.” -Excerpt from the Alder Springs HSP application (unsubmitted)
Unfortunately, due to the strict implementation requirements of the HSP Incentives Program, we weren't able to submit an application for the last HSP round in March of 2019. Based on their calculations and guidelines of their scientific committee, HSP requires farmers implementing compost and mulch as their project to apply both once a year for three years, instead of the desired one-time application. This requirement was beyond the realms of possibility, because the cost of the project skyrocketed well beyond the max award amount of $75k when tripled, even at the smaller scale of approx. 30 acres. We considered a HSP Demonstration Project, which allows for experimental trials at different application rates, but with the lack of time and resources, the scope of the project unfortunately became bigger than we could chew. Sadly, we had to pull out of the application process at the last moment, with the hopes that we could fine tune a project by the next round in early 2020. The silver lining to this is, upon deciding to go through with the project without CDFA funding, Stuart discovered a large challenge that would have made it nearly impossible to pull off, even with a one-time application of mulch:
“I got too ambitious last time. I should have been simpler and just done a compost application grant. You know what's interesting is I ended up doing a certain amount of this on my own, and I've learned a few things: Putting the mulch on, even though I still like the idea of the program, the amount of time and expense of doing that is astronomical, on any kind of a volume basis. Just because there's so much material you're putting out. Even though the woodchips don't break down very quickly, and they last quite a few years, there's a lot of woodchips out there and the only equipment we can get out there is relatively small equipment. And the number of loads was just massive, and the amount of time it took was incredible. I calculated 1 full time guy, I couldn't even do it in a year if he worked 50 hours a week. I was going, ‘wow I can't put that kind of commitment into this.'”- SB
Pulling off the grandiose scope of work commitment with these grant agreements is one potential pitfall, I've discovered from working on these grants this year. Several of the HSP award winners I've worked with are operating with a sort of shell-shock as they are starting their projects and fully realizing what they signed up for. Scope of work revisions are possible, but with the winter season approaching and the year 1 deadline looming, getting out there sooner rather than later is key. This is advice I will be preaching in the following rounds: go for what you realistically want to do on your land with just a few months' notice. It's better if you consider this opportunity as spending your own time and money instead of getting piles of free money from the government. A small project may be funded more readily than an ambitious project that will need to be revised when it's understood you can't actually pull it off.
As for Stuart, he's got another project in mind for this next round of funding: undervine cover crops. He's already started experimenting on a small scale on another parcel.
“I apply compost and then I put down clover seed and just sort of rake it in. Then it pops out and it only grows about 4-5in tall, which is no problem. And then I bought a Fischer Twister, which is an Italian machine that mows under the vine. I had done about 3-4 acres and it worked fantastically. It eliminates tilling, it eliminates herbicide, it uses compost, and it also sequesters Carbon through the growing plant material, and it totally prevents and eliminates erosion, and it also builds bacteria and fungi (particularly fungi for vineyards) in the soil. Any volunteer weeds that grow taller than clover get mowed out.” -SB
He admitted this experiment does work better on older vines, with no noticeable reduction to vine vigor and without a need to increase irrigation. In contrast, younger vines still require twice as much watering as their roots compete for available soil moisture. But the benefit of reducing erosion on the hillsides makes it a valuable management practice regardless.
“Where I've got grass or cover crop only in the [tractor rows], after 20 years it's higher than the [vine]row itself. The [vine]row is sinking. That's probably the result of erosion or it's just naturally losing Carbon and we're not reapplying Carbon. Whereas on mowing, I probably have to mow 4-5 times a season. So not only do I have plants that are growing and have root mass, but I'm also adding all their cuttings to the same area 5x a year. Over 20 years the tractor rows are building up and the vine rows are sinking. So now the vine rows are becoming a stream bed, and we're seeing even more erosion.” -SB
Stuart intends on applying for the next round of HSP Incentives Program awards for his undervine cover crop experiment, but he's also got something else on his mind that hasn't made it onto the HSP list of eligible management practices: biochar.
“We have massive numbers of acres of forest that are tremendously over-populated with underbrush. So my forest, and everyone else's forests, are tinderboxes waiting to explode on an October afternoon with low humidity and high winds. So instead of sequestering Carbon, we're releasing it into the air in massive forest fires. If you were to take a substantial percent of that Carbon, and chip them up and turn them into biochar, not only would you be able to prevent forest fires, you would be able to sequester it in agricultural soils for a thousand years. Biochar changes the whole structure of the soil. It absorbs a tremendous amount of moisture, and a small piece of biochar can be the home for millions of bacteria and fungi. Because they absorb and hold so much moisture, you can create an environment where soil biology functions properly, and it sequesters moisture for the plants that are growing there. It doesn't hold moisture like clay does, it allows it to pass through slowly. It both holds it and allows it to drain.” –SB
For now, the matter is up for debate. It will not be included in the Healthy Soils Program until enough people ask for it during a public comment period and then they would need to collect enough data on it through Demonstrations before it could become eligible through the Incentives Program. But that won't stop Stuart from doing a few small experiments here and there as he can swing them.
“I don't want to say ‘Oh, I'm not going to play in your sandbox, cause you're not playing the right game.' I'm going to play in the sand box, and at some point I will introduce the right approach, and maybe somebody will say ‘wow that really works.' … I want to participate AND I want to do the right thing.” –SB
To learn more about Stuart and Alder Springs Vineyard, you can find their website online at https://www.alderspringsvineyard.com/ and follow them on Instagram @alderspringsvineyard.
To learn more about the work of the North Coast Soil Health Hub, particularly their soil health assessments for Northcoast vineyards, their website is http://soilhub.org/.
Climate smart agriculture encompasses management practices that increase soil carbon sequestration, reduce greenhouse gas emissions, improve yields and efficiencies, and promotes climate resilience. The California Department of Food and Agriculture (CDFA) supports three funding opportunities in climate smart agriculture: the Healthy Soils Program, the State Water Efficiency & Enhancement Program, and the Alternative Manure Management Program.
In a collaborative partnership, CDFA and UC Agriculture and Natural Resources have teamed up to support 10 Community Education Specialists throughout the state to provide technical assistance and outreach for the climate smart agriculture programs. To learn more and locate a specialist near you, visit http://ciwr.ucanr.edu/Programs/ClimateSmartAg/.