Groundwater contamination risks with manure-borne microorganisms under different land-application options

There is a huge potential for recycling animal manure in agricultural farms, but fecal microorganisms from land-applied animal manure can join shallow groundwater through leaching especially in alluvial formations. Thus, this study investigated the leaching rate of total viable count (TVC) below a 1.1-m soil depth in a field lysimeter planted with rice–maize–rice rotation, where the rotation received different treatments, i.e., chemical fertilizer, dry manure, fresh manure, alternate wetting and drying (AWD) irrigation, and traditional irrigation. Leachate samples of six major irrigation/rainfall events were collected and analyzed for TVC concentration. In the Aman rice season, manure application had a significantly higher TVC leaching (5.5 × 106 colony forming units (CFU) per milliliter) than the no-manure treatment (8.2 × 104 CFU/mL).…