Nutrient Management
Cows in California generate 65 billion pounds of manure each year. This is a serious issue in the San Joaquin Drainage Basin where there are over 600,000 cows on 900 dairies. Dairies have been criticized for impairing drinking water quality by contaminating hundreds of square miles of ground and surface water with nitrates and salts from liquid and solid waste.
The Nutrient Management component of Sustainable Conservation's Dairies program is designed to reduce the impact of dairy waste by promoting the composting of dairy manure. Sustainable Conservation encourages developing "satellite composting sites" that professionally manage sites near clusters of dairy farms or other sources of animal waste. It is a manure management strategy that both economically benefits farmers and improves the environment. Compost stabilizes nutrients, inhibiting them from leaching into the groundwater or running off into surface water, and kills pathogens. Compost can also be sold, applied as an amendment to improve soil quality, and used as a supplement or replacement for chemical fertilizer.
The Dairies program's first composting initiative created a city/farm waste–composting site. Green waste from Sacramento was brought to the Nilsen Turkey Farm to be co–composted with manure. This project received national attention from the Environmental Protection Agency, and laid the groundwork for a partnership with the County of Merced to use their municipal green waste compost site to compost excess dairy manure.
Sustainable Conservation promotes lagoon liquid methods developed by the University of California Cooperative Extension (UCCE) and UC Davis. Most dairy waste is put into storage lagoons and typically ends up being applied to cropland in amounts that can contaminate ground and surface waters. The majority of this contaminated water drains to the San Francisco Bay Delta, a water supply source for 22 million people. Nitrates and salts also migrate into the basin aquifers that are the exclusive source of domestic and municipal drinking water for much of California's Central Valley. UCCE and UC Davis developed an approach that uses an in–the–field "nitrogen quick test" and properly sized and installed flow meters. Evidence has shown that adjusting the timing and rates of lagoon liquids land application to suit the crop and soil type can reverse groundwater contamination.
