The rapid growth and concentration of the livestock production industry has increased concerns about potential water quality problems from land application of manure. A study was conducted using 14 lysimeters to observe the transport of bacteria and nutrients with subsurface drainage water as a Junction of liquid swine manure application rate. Lagoon liquid was surface-applied to no-till soil in lysimeters at rates of 0 (control), 280,000 and 830,000 L/ha. At the lower rate, two additional management strategies or treatments were used: tilling the surface soil before application, and air-pressurizing the drainage tube in the lysimeters during and after application. The subsurface drainage water was analyzed for flow volume, bacteria, and nutrients. The higher rate of application initiated flow and increased levels of nutrient and bacterial contamination within 1 h after application as well as throughout the 15-day study period. No-till lysimeters had flow and higher levels of contamination earlier in the study than did tilled or air-pressurized lysimeters. Although there were no consistent statistically significant differences between the control and the lower-rate treatments nor between individual lower-rate treatments, there were statistically significant differences between the high- and low-rate treatments, which suggest that over-application of liquid swine manure poses a direct threat to water quality.
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