- Author: Saoimanu Sope
California ranks number one in the nation for dairy production, with 1,100 to 1,200 dairy farms, each with an average of 1,436 cows, mostly concentrated in Tulare County in the San Joaquin Valley. A major dairy waste is cow manure, a byproduct that can require millions of dollars for each dairy to manage.
To help manage the manure, the California Department of Food and Agriculture provides funds to California dairy farms to install dairy digesters, a technology that can break down manure and produce methane (a form of renewable energy). The digesters provide additional benefits such as capturing greenhouse gases while improving the nutrient value of manure and water quality.
Pramod Pandey, UC Cooperative Extension specialist in the School of Veterinary Medicine Extension at UC Davis, has been studying dairy digesters for over 20 years to understand the conversion of manure into renewable energy. He also is trying to determine the effects of anaerobic processes (in low-oxygen conditions) on dairy manure quality, biogas production and the environment.
Between 2015 and 2022, CDFA supported approximately 133 dairy digester projects in California, with grants of more than $200 million to various dairy farms.
“The California state government plays a big role in the success of this technology because the majority of dairy farmers are not financially able to invest in implementing the manure management technology, which assist both dairy farms and community,” said Pandey.
According to Pandey, one cow can theoretically produce roughly 100 pounds of wet manure daily, and this manure contains nitrogen and phosphorous, which are important for soil. About 40 cubic feet of biogas is produced from the manure of one cow under anaerobic conditions, and this biogas has a potential to produce around 24,000 btu per cow. In California, a 1,000-square foot home uses 45,000 to 55.000 btu per day for heating and cooling. That means manure from two or three cows could meet the daily energy demand of a small home.
By using digesters, farmers can prevent greenhouse gas emissions and simultaneously generate energy and soil amendments, which provide nutrients to cropland, lessening the amount of commercial fertilizer needed. By connecting technologies, the liquid from digesters can be improved to produce water that can be used for irrigation and for meeting the water demands of a dairy farm.
“The main purpose of a dairy farm is to produce milk, and current low milk prices make it difficult for dairy farmers to focus on manure management without the support from government,” Pandey said, adding that managing waste is not only expensive but time-consuming. Although dairy digesters can cost $5 million to $10 million to build and install, the technology is helpful in manure management.
Dairy farmers traditionally use anaerobic or manure lagoons to store their liquid manure waste until they are ready to apply it to farmland as fertilizer. The issue is that the lagoons emit greenhouse gases such as methane into the atmosphere.
“It is important to not overexpect from a dairy digester because it doesn't reduce all forms of pollution from manure completely,” Pandey said. “But given the available resources, funding and technology, I would say that we're off to a good start.”
Dennis Da Silva, a dairy farmer in Escalon, has been working in the industry his entire life and used to be “totally against” digesters. In the late 1970s, Da Silva's father, who immigrated from Portugal, started Da Silva Dairy Farm, which Da Silva currently runs.
“I spend a lot of money getting solids out of my lagoons every year,” Da Silva said.
Although he does not have digesters set up on his farm just yet, Da Silva agreed with Pandey that the government has made it much easier for farmers like himself to tackle waste.
“I used to be against the dairy digester idea, but there's a lot more incentive to invest these days,” said Da Silva. “It's also likely that, in the future, there'll be regulations that will crack down on dairy farms if you don't already have digesters,” he added.
Currently, he is in the permitting phase, waiting for approval to begin building the digester on his farm, which is expected to take about two years.
Pandey said that the process is slow and there is still a lot of room for improvement, but the intention is a step in the right direction. “The only thing that the digester doesn't produce is milk,” Pandey said jokingly.
RELATED LINK
VetMed Extension Spotlight on Pramod Pandey https://youtu.be/qKcGMcT8-UI.
- Author: Dana Yount
- Contributor: Emily Lovell
- Contributor: Caddie Bergren
- Contributor: Nicki Anderson
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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.
The Issue
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.
The Impact
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.
UCCE-County Location |
Total CO2 equivalent in MT/year |
Sonoma, Mendocino, and Lake County |
314.2 |
Merced, Madera, Stanislaus |
5263.31 |
Glenn, Butte, Colusa, Tehama County |
4545.785 |
Yolo, Solano, Sacramento, San Joaquin, El Dorado, Sonoma, Colusa, Sutter |
11716.4 |
Santa Clara County |
58.85 |
Fresno County |
1353.924 |
Kern & Tulare Counties |
7060.283 |
Santa Barbara, Los Angeles, Orange, Ventura County |
630.5 |
San Diego and Riverside Counties |
300.18 |
Imperial County and Riverside County |
3689.1 |
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.
/h3>/h3>/h3>- Author: Lynn M. Sosnoskie
Are you considering introducing cover crops into your production system?
Are you wanting to plant hedgerows or wind breaks?
Are you interested in prescribed grazing?
Are you implementing reduced or no-tillage practices?
If your are 1) interested in adopting these or other conservation management strategies (i.e. reduce tillage, riparian plantings, compost additions, etc...) or if your are interested in 2) showcasing your successful implementation of conservation techniques, then there may be funding available to you through CDFA's Healthy Soils Program (HSP).
The HSP has two components:
1) the HSP Incentives Program (https://www.cdfa.ca.gov/oefi/HealthySoils/IncentivesProgram.html)
2) the HSP Demonstration Program (https://www.cdfa.ca.gov/oefi/HealthySoils/DemonstrationProjects.html)
How do they differ? From the CDFA website:
The HSP Incentives Program provides financial incentives to California growers and ranchers to implement conservation management practices that sequester carbon, reduce atmospheric greenhouse gases (GHGs), and improve soil health. GHGs benefits are estimated using quantification methodology and tools developed by California Air Resources Board (CARB), USDA-NRCS and CDFA and soil health improvement will be assessed by measuring soil organic matter content.
The The HSP Demonstration Projects aim to improve soil health, sequester carbon and reduce atmospheric greenhouse gases (GHGs) funding on-farm demonstration projects that collect data and/or showcase conservation management practices that mitigate GHG emissions and increase soil health, and creating a platform promoting widespread adoption of conservation management practices throughout the state. There are two types of demonstration projects that will be funded: Type A and Type B.
Type A projects will demonstrate implementation of conservation management practices, measure field GHGs emissions, and conduct analysis on cost/benefits for adoption of the proposed practice(s) and anticipated barriers;
Type B projects will demonstrate implementation of HSP conservation management practices and/or conduct analysis on cost/benefits for adoption of the proposed practice(s) and anticipated barriers.
A total of $15 million is available. (Incentives for $75,000 per farm/ranch; Demonstrations for up to $250,000)
Grant applications are due by 5:00 p.m. on March 8, 2019. The review process is expected to occur between March and June 2019, with the awards being announced this summer.
Please see the following links for more information about funding details, the application process, frequently asked questions, and award payments. https://www.cdfa.ca.gov/oefi/HealthySoils/
- Author: Jordon Wade
- Contributor: Hannah Waterhouse
- Contributor: Martin Burger
In order to be accurate and effective, fertilizer recommendations must factor in a wide range of considerations, ranging from the site-specific to the climatic. To help guide these decisions, “the 4 R's” have been developed: Right rate, Right place, Right time, and Right form. These 4 R's can be utilized in tandem to maximize a given goal, whether that is maximum yield, maximum profitability, minimize adverse environmental effects, or perhaps a combination of factors. However, the specific recommendations will vary according to farm- or field-specific factors, such as climate, soil mineralogy, crop choice, or labor constraints. As such, it is difficult to make “best management” prescriptions across regions.
Several UC Davis researchers—Hannah Waterhouse, Martin Burger, and Will Horwath—recently investigated the 3 of the 4 R's of corn production over two years (2013-2014) on a farm near Stockton in the San Joaquin Valley. They were particularly interested in how nitrogen fertilizer rate, placement, and timing affected nitrous oxide (N2O) emissions. Additionally, they were comparing emissions and yields between drip and furrow-irrigated corn.
Right Rate: For both years of this study, fertilization rates were adjusted using the preplant (or residual) nitrogen levels, which were 65 lbs/ac in 2013 and 77 lbs/ac in 2014. These rates of residual nitrogen were then subtracted from the target fertilization rates to have an equal level of available N across years. To learn more about calculating residual nitrogen rates, visit our page on residual nitrogen budgeting. Overall, emissions increased with increasing rate, although there was a high degree of variability. Yield-scaled emissions, which allow for emissions to be examined in terms of agronomic efficiency, also increased as N rates increased. Using the corn stalk nitrate test in 2014, they found that there was no N deficiency, except a marginal deficiency in the 65 lbs/ac rate. At the highest rates (227 lbs/ac and 307 lbs/ac), the corn stalk nitrate test found hugely excessive levels of plant-available N.
Right Place: They also looked at the effect of applying fertilizer in a single band or a double band. They applied fertilizer at the same rate—202 lbs/ac in 2013 and 227 lbs/ac in 2014—on either the inside (1-band) or both sides (2-band) of the corn plant line. Comparing emissions from the single band vs. the double band, they saw twice as many emissions from the single band in 2013 and 3-4 times as much emissions in the single band in 2014, without seeing any differences in yield. There was also much higher residual nitrogen in the 1-band application, resulting in a higher fertilizer use efficiency in the 2-band treatment.
Right Time: For both years of the study, the majority of the fertilizer was applied as a sidedress during V2 stage of crop growth in 2013 (202 lbs/ac) and during V4/V6 in 2014 (227 lbs/ac). The use of the nitrification inhibitor AgrotainPlus helped to maintain the fertilizer in the less mobile ammonium form for longer, to better sync nitrogen supply with crop nitrogen demand. In the first year (2013), the application of fertilizer and nitrification inhibitor at V2 was a bit too early and did not reduce emissions. In 2014, the fertilizer and nitrification inhibitor were timed better to coincide with crop N demand and reduce emissions by 60%, although no yield difference was observed. This better syncing also resulted in an “excess” reading from the stalk nitrate test, suggesting that fertilization rates could likely be decreased in subsequent years.
These results were supported in another field trial of corn by the same group of researchers in Yolo County, where the AgrotainPlus also decreased emissions by approximately 50% in the sandier, coarser soils. In this study, AgrotainPlus also decreased easily-leached residual nitrate by 10 lbs/ac.
Irrigation Method: In 2013 and 2014, irrigation types were varied in the 202 lbs/ac and 227 lbs/ac treatments, respectively. Using subsurface drip to supply fertilizer and irrigation to the corn resulted in a 50-80% reduction in nitrous oxide emissions, relative to the furrow-irrigated field. The drip also had double the grain yield of furrow-irrigated corn in 2013, but no difference in total yield when growing for silage in 2014.
While the results of this study are subject to much of the same inherent variability associated with agricultural studies, it does support much of the current body of knowledge and show that California is not an exception. The central take-home messages from this research (that are well-supported by other studies) are:
- Testing for residual nitrate prior to planting helps to adjust fertilizer recommendations to minimize environmental effects, such as nitrous oxide emissions.
- Concentrating N fertilizer (especially ammonia/ammonium) into a single applied band will greatly increase emissions and decrease your fertilizer N use efficiency.
- Nitrification inhibitors can substantially decrease nitrous oxide emissions and increase your fertilizer N efficiency. Although they might not increase yields, they have the potential to increase N cycling within the system.
- Using subsurface drip irrigation can increase your yields (especially grain yields) while cutting your N2O emissions in half.
For more on nitrogen budgeting and nitrous oxide emissions, visit our Focus Topic pages.
- Author: Yoni Cooperman
- Contributor: Jordon Wade
A variety of cover crops exist, way too many to be fully covered in this blog post. Generally speaking, cover crops tend to be grasses or legumes, and many growers utilize mixes to achieve targeted results. Legumes can be a source of N fertilization, though they can also contribute to N pollution if N levels exceed crop needs. Grasses have the potential to hold on to excess soil N and limit losses through nitrate leaching. Mixes of multiple cover crop types with different uses are used to maximize inputs of organic matter in hopes of building soil carbon.
While cover crops can have many potential benefits, like any other management decision tradeoffs are involved. While competition for soil water and nutrients can be used to control vigor, under certain conditions this can be harmful for vine development. Another possible downside to using cover crops, their potential to increase the production of greenhouse gas emissions, was the focus of our study conducted in a three year old Merlot vineyard in Lodi, CA. The vineyard soil is classified as a Devries sandy loam.
In our two year study, we compared rates of greenhouse gas (GHG) emissions from vineyard alleyway soil grown under three different cover crop mixes: a legume mix, a “soil builder” mix, and a ryegrass treatment all planted at 100 lbs/ac.
These three treatments were chosen to represent three reasons growers might utilize cover crops in a vineyard. The legume mix was chosen to be a “green manure” and increase soil nitrogen. The “soil builder” mix was meant to maximize plant biomass and increase soil organic matter. The ryegrass was chosen as a “catch crop” that can take up large amounts of soil N, limiting N losses through nitrate leaching.
After our two year monitoring period, we found that cover crops had little effect on soil N2O emissions, while they increased soil CO2 emissions. While CO2 emissions were higher when cover crops were used, there were no differences between the different cover crop types. These findings suggest that during drought years, growers are free to choose the cover crop mixes they think will best serve their needs, without being overly concerned about excess N2O emissions stimulated by cover cropping. However, the legume mix did result in higher levels of soil N and the ryegrass treatment did decrease leachable soil nitrate. It is unclear if the "soil builder" mix resulted in increased soil organic matter, although that is to be expected, considering it takes several years to substantially increase soil organic matter content.
For more information about utilizing cover crops visit the Solutions Center for Nutrient Management page on cover crops.