Strategies to Optimize Spray Irrigation by

Monitoring Soil Assimilation Capacity

Principal Investigator:  Steven I. Safferman

Problem Statement

• Many plant based commodity food processing industries use spray fields to treat wastewater. 

•  A properly operating field assimilates the wastewater by aerobically biodegrading the biochemical oxygen demand (BOD).  Oxygen serves as the electron acceptor. 

• Ponding and continuous saturation results in oxygen deficiencies, potentially preventing the complete assimilated before percolating into the saturated zone.

• Large quantities of wastewater with high BOD may produce anaerobic zones, potentially causing iron and other minerals to become mobile

• "Capacity of Soils to Assimilate Wastewaters from Food Processing Facilities" by Dr. Mokma, MSU Crops and Soil Sciences, reported organic and hydraulic loadings ranged from 40 to 1800 lb BOD/acre/day and 2,700 to 16,000 gal/acre/day, respectively. 

• No justifications for the loadings and no coherent irrigation strategies that minimize environmental harm and maximize loadings. 

• Long Term - develop site-specific irrigation strategies that are protective of the environment. 

• Short Term - investigate soil monitoring tools to measure  assimilation.  Included are moisture, DO, ORP, and temperature sensors and soil microbiological  analysis.