- Author: Emily C. Dooley, UC Davis
Low-cost wine industry additive also improved feed efficiency and milk quality
Researchers at University of California, Davis, added fresh grape pomace left over from winemaking operations to alfalfa-based feed for dairy cows and found that methane emissions were reduced by 10% to 11%.
The preliminary findings could offer a low-cost sustainable pathway for vineyards to reduce waste while helping dairy operations maintain quality while cutting back on emissions of methane, which is a powerful greenhouse gas.
“This is the first time anybody has shown that this can work in California,” said Ermias Kebreab, an animal science professor and associate dean of global engagement at UC Davis. “You're reducing emissions, you're improving the quality and it may also reduce the cost of production.”
The pilot research project, which will be detailed in a paper later this year, also found that mixing in grape pomace improved feed efficiency and increased healthful fats, said Selina Wang, an associate professor of Cooperative Extension in small scale fruit and vegetable processing.
“We found that the feed with the additive of grape pomace changed the fatty acid composition of the milk and, in particular, increased the polyunsaturated fats, which are the main fats in grape pomace,” Wang said. “This suggests that supplementing the feed with an optimal fatty acid profile may have positive impact on the fatty acid profile of the milk and increase their health benefits.”
Symbiotic commodities?
In 2022, California was the leading dairy producer in the country, generating $10.40 billion in sales, while 90% of wine production came from the Golden State, with a market value of $5.54 billion.
Processing grapes for wine generates thousands of tons of waste in the form of grape pomace, which consists of leftover seeds, skins and stems. Dairy and livestock are responsible for more than half of the state's methane emissions, owed largely to cow burps.
They are the top two agricultural commodities in California, according to state production statistics, and reducing waste and emissions for both industries are key to the state meeting its climate goals.
Tannins for emission reductions
Wine grapes are high in fats and tannin, which is known to reduce methane emissions, so Kebreab sought to test if adding grape pomace to feed could have a positive effect while not adversely affecting production.
“It's a byproduct that's not being used much,” he said. “This is something that can be included in our efforts to try to reduce emissions.”
A mix of feed options
To do the research, scientists worked with Holstein dairy cows and gave the animals feed consisting of alfalfa, wheat, almond hulls, cottonseed and grain. After two weeks, the cows were split into three groups: A control group with no change in diet, another where the feed combination included 10% grape pomace and a third that received 15% grape pomace.
Every four weeks, the cow groups would change feed combinations.
They were fed twice daily by postdoctoral students and interns, and emissions were monitored daily. Milk production was documented in the morning and evening and milk samples were collected weekly to analyze for fat, protein, lactose and other measurements, which showed no differences between the control and other groups.
Methane and hydrogen emissions were reduced compared with the control group, suggesting that grape pomace reduced enteric emissions without affecting production.
“I think the dairy industry will be very interested in this,” Kebreab said. “Sometimes when you're using additives, they have palatability issues. With grape pomace, they absolutely love it.”
Next on the list is a trial with olive pomace and working to understand the mechanism that reduces emissions. “If we have a better understanding of the mechanisms, we can select the feed additive or a mix of feed additives to reduce dairy cattle emissions and make dairy milk healthier while making use of the agriculture byproducts,” Wang said. “There's a lot of room to grow in this space and we're excited about this work.”
The research was supported by the California Dairy Research Foundation.
This article was first published on the UC Davis news site.
/h3>/h3>/h3>/h3>
Researchers say dairy farms on track to achieve full 40% reduction goal by 2030
The California Dairy Research Foundation and University of California, Davis CLEAR Center announced on Dec. 14 the release of a new analysis of methane reduction progress titled "Meeting the Call: How California is Pioneering a Pathway to Significant Dairy Sector Methane Reduction." The paper, authored by researchers at UC Davis affiliated with UC Agriculture and Natural Resources, concludes that efforts are on track to achieve the state's world-leading target for reducing dairy methane emissions by 40% by 2030.
The report, written by distinguished professors of livestock emissions and agricultural economics, takes a comprehensive look at progress and projections, expanding upon the analysis of progress previously conducted by the California Air Resources Board. By documenting achievements to date, additional reduction efforts already funded, historic and current economic trends, and the projected availability of new solutions, the analysis lays out a workable path toward meeting California's goal. The pathway shows that California dairy farms are on track to achieve the full 40% dairy methane reduction goal and will reach “climate neutrality” by 2030. Climate neutrality is the point in which no additional warming is added to the atmosphere.
“This analysis shows that California's dairy sector is well on its way to achieving the target that was established by SB 1383 in 2016,” said CDRF's Executive Director Denise Mullinax. “With much important work still ahead, a clear understanding of this pathway helps dairy farmers, policy makers, researchers, and other partners make decisions to strategically press forward.”
The report outlines the need for continued implementation of California's four-part strategy for dairy methane reduction: farm efficiency and herd attrition, methane avoidance (alternative manure management), methane capture and utilization (digesters), and enteric methane reduction. Continued alignment of state and federal climate-smart agricultural approaches and incentives will also be critical to maintaining progress.
"Milk demand is growing, and California is among the world's low-cost suppliers of dairy products. It follows that effective California policy to reduce dairy greenhouse gas emissions must recognize that measures that cause milk production to exit the state do not mitigate global climate change," said study co-author Daniel Sumner, Distinguished Professor in the Department of Agriculture and Resource Economics at UC Davis. "Therefore, measures to help off-set mitigation costs, provide positive incentives for adoption of low-cost emission-reducing practices, and help stimulate innovation in methane reduction, are the economically efficient approaches."
The paper recognizes that enteric methane from the dairy and other livestock sectors is a significant source of greenhouse gas emissions in the U.S. and California. Several feed additives are expected to become commercially available in the next several years, which could be used to reduce enteric methane emissions from California's dairy herd.
“Adoption of enteric feed additives will become a valuable tool for dairy value chains to meet their greenhouse gas reduction goals,” said co-author and professor Ermias Kebreab, associate dean of global engagement and director of the World Food Center at UC Davis. “While this report provides only a broad overview of some of the most promising solutions, there is an incredible amount of research being conducted at UC Davis, nationally and internationally. The dairy industry, global food companies, state and federal agencies, and others continue to invest heavily in supporting enteric mitigation research efforts.”
The report finds that methane reductions from California's programs and projects in place today, coupled with the implementation of a moderate feed additive strategy to reduce enteric emissions, is on track to reduce between 7.61 to 10.59 million metric tons of methane (CO2e) by 2030, all from the dairy sector alone.
The collective investment in California's dairy methane reduction effort — from public and private funding — now exceeds $2 billion and counting. The California dairy sector, in coordination with the California Department of Food and Agriculture, was recently awarded up to $85 million by the United States Department of Agriculture under the Partnerships for Climate-Smart Commodities. The funding will leverage additional matching state funds and private capital investments, for a total of more than $300 million in new investment.
“It is important to highlight California's investments and success to date as an example of what is possible within the global livestock sector,” said co-author Frank Mitloehner, UC Davis animal science professor and air quality specialist in Cooperative Extension, and director of the UC Davis CLEAR Center. “California dairy farmers have demonstrated tremendous progress toward the state's methane reduction goal over the past several years. Given the short-lived nature of methane, this rapid reduction is an important contribution to the global effort to quickly limit climate warming.”
The author's analysis was prepared by Gladstein Neandross & Associates (GNA). Funding was provided by CDRF as part of its work to support an innovative and sustainable California dairy industry.
/h3>- Author: Sara Tiffany
- Author: Dr. Martin Burger
The Solution Center for Nutrient Management brought together growers, advisors and university researchers for a breakfast meeting to discuss nitrogen management in processing tomatoes. A number of growers attended to share their experiences and learn about research including a new protocol for accurate soil nitrate sampling, and the latest updates on agricultural greenhouse gas emissions research. Cooperative Extension Specialist Daniel Geisseler also presented the CDFA-FREP website that provides Fertilization Guidelines for California's Major Crops, including tomato: https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Guidelines.html
Research Highlights:
Soil nitrate sampling protocol
For maximum accuracy that can reliably predict nitrate availability in the soil, growers should sample according to the following protocol:
- For fields with 60-inch beds: soil cores should be taken at 3 lateral distances from drip tape, in at least 4 locations within a field.
- For fields with 80-inch beds: soil cores should be taken 2 lateral distances from drip tape, in at least 3 locations within a field.
click here to read full summary (or scroll down)
Research on agricultural greenhouse gas emissions in tomatoes
- The adoption of subsurface drip irrigation substantially reduces greenhouse gas emissions in tomato production (compared to furrow irrigation).
- Use of nitrification inhibitors lowers nitrous oxide emissions in tomato fields with subsurface drip irrigation.
click here to read full summary (or scroll down)
Full Summaries:
Soil nitrate sampling protocol
UC Davis researcher Dr. Martin Burger presented the results of a survey conducted by post-doctoral scholar Cristina Lazcano on pre-plant nitrate, phosphorus (Olson-P), and exchangeable potassium levels in 16 processing tomato fields in Yolo, San Joaquin and Fresno counties. The purpose of the study was to develop an economical sampling protocol that reliably predicts nitrate availability and allows growers to adjust fertilizer rates taking the residual soil nitrate into account.
While the conversion to subsurface drip irrigation has enabled growers to precisely deliver water and nutrients close to plant roots, there is still pressure for growers to increase nitrogen use efficiency, for example to reduce the risk of nitrate leaching. Previously, the spatial distribution of macronutrients in fields under drip irrigation was not well known. One concern has been that nitrate may accumulate at the periphery of the wetted soil volume, whereas the less mobile nutrients phosphorus and potassium may be depleted near the drip tape where roots can be expected to proliferate.
According to the survey encompassing more than 1000 soil analyses, pre-plant nitrate levels in the 16 fields varied widely, ranging from 45 – 438 lbs NO3- - N per acre in the top 20 inches of soil, with higher levels of nitrate found in fields under consecutive tomato cultivation. No depletion of Olsen-P or potassium in the root feeding areas close to the drip tape was detected. The majority of the fields showed phosphorus concentrations lower than 15 ppm, which based on earlier research is the threshold below which a yield response can be expected from a P addition. In contrast, potassium levels were higher than previously reported values, ranging from 293 ppm on average in Yolo County to 468 ppm in Fresno County.
The nitrate sampling protocol was based on a Minimax analysis by selecting the minimum number of samples within the field and locations within the beds (i.e. lateral distance from the drip tape). The combination of samples with the lowest relative error across all fields (< 5% from the field average) and the lowest number of samples taken was selected as the best sampling procedure to estimate average soil NO3-N. The analysis showed that soil cores should be taken at three (60-inch beds) or two (80-inch beds) lateral distances in at least four (60-inch beds) or three (80-inch beds) locations within a field.
Table 1. Pre-plant nitrate sampling protocol for 60-inch beds in Yolo (Y), San Joaquin (SJ), and Fresno (F) County SDI tomato fields.
Table 2. Pre-plant nitrate sampling protocol for 80-inch beds in Yolo (Y), San Joaquin (SJ), and Fresno (F) County SDI tomato fields.
***The full article about this study will appear in the Oct-Nov-Dec 2015 issue of California Agriculture.
Research on agricultural greenhouse gas emissions in tomatoes
An update on agricultural greenhouse gas emissions research included results of field studies testing a nitrification inhibitor for mitigation of nitrous oxide in subsurface drip irrigated tomato.
Nitrous oxide (N2O) is arguably the most important greenhouse gas produced in the agriculture sector, with its global warming potential 300 times that of Carbon Dioxide. N2O is produced by soil microbes during N transformations. N2O is a by-product of nitrification and denitrification.
Recent studies have shown that N2O produced during nitrification can be as important as that resulting from denitrification (Zhu et al., 2013). The highest rates of N2O emissions typically occur shortly after N fertilizer applications when soils are re-wet. The main regulatory factor is the availability of oxygen since microbes use nitrate (denitrification) and nitrite (nitrification) as electron acceptors of respiration when oxygen is in short supply. Soil processes that consume oxygen, such as the presence of a carbon source, and conditions that limit replenishment of oxygen levels in the soil, such as high soil water content, promote N2O production in soil. Compacted soils lead to rapid depletion of oxygen because of the reduced air spaces and greater tortuosity of pathways of oxygen diffusion.
Although the use of the nitrification inhibitor significantly lowered nitrous oxide emissions in SDI tomato in one of the two years of the study, the reduction in absolute values is rather small (64 lbs carbon dioxide per acre) to make a significant contribution to California's greenhouse gas inventory. With the adoption of subsurface drip irrigation, tomato growers have already lowered the impact of greenhouse gas emissions from tomato production substantially as furrow irrigation generated leads to greater nitrous oxide emissions than SDI.
References
Zhu, X., Burger, M., Doane, T.A., Horwath, W.R., 2013. Ammonia oxidation pathways and nitrifier denitrification are significant sources of N2O and NO under low oxygen availability. Proceedings of the National Academy of Sciences of the United States of America 110, 6328-6333.
- Posted By: Jaime Adler
- Written by: Bill Stewart, UCCE Forest Specialist
Making estimates of the life cycle benefits of harvested sawlogs are now required as part of every timber harvest plan in California. While forest managers are intimately familiar with what happens in the forest and at the landing, we are dependent on others to synthesize current and historical data to come up with accurate estimates of the ‘carbon footprint’ of sawlogs after they have left our control. Unfortunately, a number of the common calculators used in California to estimate the life cycle benefits from sawlogs depend on historic and poorly documented estimates that significantly undercount the climate benefits of harvested products. This post highlights some noticeable differences between accounting systems and concludes that data-based estimates will clarify the often underestimated benefits of wood products with respect to global carbon storage impacts.
As anyone who has seen new wood buildings going up, there are many technological innovations, such as the I-Joists (shown below), that suggests that ever more building performance is being squeezed out of logs. A key question for any accounting system that is predicting future trends is how technological innovation is addressed in the estimates.
Both the Climate Action Reserve (CAR) Forest Protocol 3.2 (http://www.climateactionreserve.org/how/protocols/adopted/forest/current/) and the Calfire GHG Estimator (http://www.fire.ca.gov/resource_mgt/resource_mgt_forestpractice_pubsmemos_memos.php) refer to a USDA Forest Service document, GTR-NE-343 (Smith 2006) or the DOE 1605b publications with the same data tables as the key source for their estimates. For simplicity, I will compare estimates based on current efficiencies with the California relevant data tables in Smith (2006). The following bar chart compares the estimated climate benefits from an initial delivery of 100 tons of sawlogs to a sawmill in California through all the end uses over a century.
The bioenergy benefits estimates for the 2006 and 2009 USDA Forest Service publications are fairly similar but are ignored by both Climate Action Reserve (CAR) and Calfire. For whatever reason, CAR and Calfire treat bioenergy from wood residues as if they create no useful energy. However, the use of wood residues for energy is considered to be a climate benefit by both the California Energy Commission and in the national accounting that the US EPA provides to the International Program on Climate Change (IPCC) since they replace fossil fuel based sources of energy.
The other differences are how much wood gets wasted in the sawmill (an estimated 15.6% in Smith 2006 versus a measured 1.5% in the 2010 RPA document), the useful life span of the wood products, the efficiency of the collection of wood waste after consumers toss it out, and whether the landfill storage gets counted as carbon storage or not. We do not need to go into great detail here, but more recent data such as Skog (2008), Smith (2009), and US EPA (2011) all provide estimates that wood carbon is stored much longer in both products and landfills than estimated by Smith (2006). The difference between more recent and better documented life cycle analyses and the CAR and Calfire protocols are even greater since CAR and Calfire ignore bioenergy.
After all the numbers are in, it appears that the best practices for utilizing sawlogs in California can retain over 90% of the initial carbon storage benefits. Unfortunately, project level accounting systems that choose to use poorly documented historic estimates and ignore bioenergy (even though bioenergy meets the Renewable Portfolio Standard –RPS - in California) come up with much lower numbers that are out of sync with more recent work in North America and Europe. For example, accounting systems that only include the carbon in wood products assumes a carbon storage efficiency of only 25%. As I mentioned earlier, any consideration of technological innovation will further improve the amount of initial wood carbon that stays in storage or is used as bioenergy.
As California moves towards our stated goals to become more energy-efficient, reduce fossil fuel related emissions, and shift away from energy-intensive building materials, we will need to ‘double check’ our math when it comes to thinking about sawlogs once they leave the landing.
References
Skog, Kenneth E. 2008 Sequestration of carbon in harvested wood products for the United States. Forest Products Journal 58 (6):56-72.
Smith, James E., Linda S. Heath, Kenneth E. Skog, and Richard A. Birdsey. 2006. Methods for calculating forest ecosystem and harvested carbon with standard estimates for forest types of the United States GTR-NE-343. USDA Forest Service, Northeastern Research Station: Newtown Square, PA.
Smith, W. Brad, tech. coord; Miles, Patrick D., data coord.; Perry Charles H., map coord,; Pugh, Scott A. Data CD coord. GTR-WO-78. 2009. Forest Resources of the United States, 2007. Washington, DC: USDA Forest Service, Washington Office.
U.S. Environmental Protection Agency. 2011. Inventory of U. S. Greenhouse Gas Emissions and Sinks: 1990 – 2008. http://epa.gov/climatechange/emissions/usinventoryreport.html
- Author: Rebecca Snell
http://twitter.com/WoodyBiomass