A recent report highlights the efficacy of California dairy conservation practices in achieving water savings and protecting water quality. Sustainable Conservation was awarded support funding for a project from the Natural Resources Conservation Service as part of a National Conservation Innovation Grant. The project looks at using a modified subsurface drip irrigation (SDI) system for applying liquid manure as a natural fertilizer source for feed crops on dairy operations.
“Over two years, the manure SDI fields studied applied over 900 acre-feet less water and 190 fewer metric tons of nitrogen to produce similar yields, as compared to the flood irrigated fields,” the report states. “As adoption of manure SDI increases, the water and nitrogen savings afforded by the technology can provide significant local and regional benefits.”
The Subsurface Drip Irrigation System Utilizing Dairy Manure Effluent report shows that fields with manure SDI generally created less need for applied nitrogen and resulted in greater nutrient-use efficiency. While utilizing less water than flood-irrigation, most of the manure SDI fields in the report produced similar yields. based on the median per-acre results from the project, the estimated annual impact at scale was measured at 61 billion fewer gallons of water applied and 55 million fewer pounds of nitrogen applied.
Because of the amount of solid particles in liquid manure, the performance of a manure SDI relies heavily on the effectiveness of pre-system solid separation. The report acknowledges there is significant cost involved with establishing a manure SDI system. Cost-share funding made possible through the Environmental Quality Incentives Program (EQIP) plays a significant role in investment return. Through assistance provided by EQIP, annual per acre increase in net income was measured at a little more than $110.
Sustainable Conservation notes that the next step in the project is to explore further opportunities to partner with research institutions for the development of real-time nitrogen values for manure effluent. Other project partners are also working to highlight the value of a manure SDI system to encourage further adoption within the industry. California accounts for 21 percent of all domestic milk production. The adoption of manure SDI presents another effective means for furthering California dairy conservation practices.