As the drought in California rolls through its fourth consecutive year, subsurface drip irrigation (SDI) of forage crops has garnered a lot of interest as a means to make more efficient use of water. The past two years, Sustainable Conservation and Netafim USA, an irrigation supplies manufacturer, have been investigating the feasibility of running dairy wastewater through a SDI system. Integrated into the drip irrigation system are controllers and sensors that help regulate not just the volume of water, but also the rate of wastewater nitrogen being applied to the crop.
The system mixes freshwater with filtered manure lagoon water. The wastewater and irrigation water are tested to determine both planned and applied nitrogen application rates to the corn silage crop. Before water is pumped through the buried drip lines in the field, the fresh and wastewater mixture moves through a double sand media filtration system to eliminate solids. The system, in its second year of testing, is designed to improve water-use efficiency, nitrogen application timing and reduce purchased fertilizer inputs. For further information on the system, go to the Sustainable Conservation website.