Sonoma County Dairy Improves Manure Management

Author: Dana Brady Yount

Social Media Summary: Renati Dairy, located in Sonoma County, received a California Department of Food and Agriculture (CDFA) Alternative Manure Management Program grant in the 2019 funding cycle. Funding was acquired to install a cross gutter mechanical separator, a concrete trough to connect manure to existing separator, a reception pit agitator and a pump to further improve manure management and decrease greenhouse gas emissions.

Renati Dairy, located in Petaluma CA, was established in 1958 by Dan Renati’s father and grandfather. The dairy is now ran by Dan and his brother, Denny, who are third generation dairymen, and Rocky Renati, who is fourth generation. The dairy has 750 lactating cows, and transitioned to an organic dairy in 2012. Prior to the grant award, Renati Dairy already owned a manure separator and a flush barn. The other barns were scraped into a pond, which was cleaned out annually.

The Issue:

Liquid manure stored in holding ponds around dairies, or other livestock operations, emits methane, a potent greenhouse gas. With respect to California agriculture, methane is primarily emitted from manure storage ponds and enteric emissions from dairy cattle (CDFA, 2018).

Greenhouse gas emissions from manure systems that use solid separation, composting, compost storage, and separated liquid storage are reduced substantially compared to traditional liquid storage (Fillingham et al. 2017). Changing manure management practices so that manure is handled in a dry form can help reduce methane emissions and limit the effects of climate change.

To address livestock and dairy methane emissions, CDFA developed the Alternative Manure Management Program (AMMP), which supports farmers in reducing emissions. The AMMP grant incentivizes the development of manure management practices that facilitate the reduction of manure solids in liquid storage and protect water and air quality.

Farmers can select from four practices: pasture-based management, alternative manure treatment and storage, solid separation, and conversion from flush to scrape. The University of California's Agriculture and Natural Resources Climate Smart Agriculture Team, along with the University of California's advisors and other organizations, help local producers apply for the CDFA's AMMP grant, and assist with implementation and verification of the new practices.

Above: Example of a dairy manure pond

How UC Delivers:

In the most recent round of AMMP, livestock and dairy operations could apply for up to $750,000 to implement methane reduction practices.

Renati Dairy applied for an award in the 2019 cycle to install a cross gutter mechanical scraper, a concrete trough, a reception pit agitator, and a pump. Their main goal for this project was to reduce solids in the manure lagoon, allowing for improved and increased compost production for manure application on pasture and bedding in the free stall beds. Renati Dairy was assisted by Randi Black, a Dairy Advisor, for the University of California Cooperative Extension in Sonoma County, and a representative from the Arolo Company on their grant application and implementation process.

Example of mechanical scraper in dairy barn

Though their project was slightly delayed by the COVID pandemic, it was completed before the winter rains.

After receiving the AMMP grant, manure is now dry scraped into a catch gutter and processed through an existing mechanical separator. The solids ponds are newly equipped with multiple aerators, and solids from each of the barns are spread onto a roofed concrete slab for further composting.

Since implementation, Renati Dairy has seen an 80 percent improvement in the efficiency of their manure management system. Trucking costs have decreased by about 70 percent, manure excavation costs were cut by over $40,000, and diesel fuel costs decreased significantly. Electricity costs have gone up slightly and regular maintenance expenses will be incurred. In total, the range of savings for this size and scope of project is $90,000 - $104,000 total (see economic analysis for detailed report of this project). This project is estimated to reduce methane emissions by 2,548 MTCO2 over a five year period (equivalent to taking 111 cars off the road each year).

For more information, please visit http://ciwr.ucanr.edu/Programs/ClimateSmartAg/     

Sources: 

California Department of Food and Agriculture. (2021). Alternative manure management program (AMMP). Retrieved May 05, 2021, from https://www.cdfa.ca.gov/oefi/AMMP/ 

The California Department of Food and Agriculture Dairy Digester Research and Development Program and Alternative Manure Management Reduction Program. (2018). A Report to the Joint Legislative Budget Committee. https://www.cdfa.ca.gov/oefi/ddrdp/docs/MethaneReduction_July2018.pdf. 

 Fillingham, M. A., VanderZaag, A. C., Burtt, S., Baldé, H., Ngwabie, N. M., Smith, W., Hakami, A., Wagner-Riddle, C., Bittman, S., & MacDonald, D. (2017, September 19). Greenhouse gas and ammonia emissions from production of compost bedding on a dairy farm. Waste Management. https://www.sciencedirect.com/science/article/abs/pii/S0956053X17306815.