Land application of swine manure offers the alternative use of its nutrients for crop production but growing concerns exist when not properly managed because of potential water quality problems;The field experiment consisted of 48 plots (15.24 x 3.04 m), located in a Clarion-Nicollet-Webster soil association. Corn (Zea mays L.) was rotated with soybean (Glycine max L.). Treatments applied were a factorial combination of Nitrogen (N) rates (0, 84, 168 and 252 kg-N/ha) of liquid swine manure and Urea-Ammonium-Nitrate (UAN) with methods of application (manure in spring, fall and side-dress; manure with nitrapyrin in fall and UAN side-dress), replicated three times. Ceramic cup lysimeters (5.08 x 12O cm) were used to collect subsoil water;Between 1996 and 1998, subsoil water Nitrate-N (NO3-N) means were lower at 84 kg-N/ha (5.76, 4.60 and 14.41 mg/L) and higher at 252 kg-N/ha (6.33, 8.14 and 19.27 mg/L) but N rate effects were non-significant. Methods of application significantly affected subsoil water N03-N in 1998 but were non-significant in 1996 and 1997. Sidedress applications had lower subsoil water N03-N concentrations even at the higher N rate while spring and fall manure applications had higher subsoil water NO3-N. Corn yields and total N uptake increased with N rate in 1998 and up to 168 kg-N/ha in 1996 and 1997. Nitrogen recovery decreased with increasing N rate. Higher NO3-N, corn yields and precipitation but lower N uptake and recovery were recorded in 1998;Residual soil N03-N increased with increasing N rate but decreased with depth, and at 0--30 cm, N rate effects were significant in 1998 but non-significant in 1996 and 1997;The effects of temperature (5, 20 and 35°C) and swine manure (168 kg-N/ha) on nitrification and N03-N leaching was investigated in 18 undisturbed soil columns. At 5, 20 and 35°C, the apparent nitrification rate constants and NO3-N means were 0.0026, 0.0253 and 0. 0046/week and 16.6, 89.5 and 45.1 mg/L, respectively. The inhibition of nitrification at 35°C may help explain the lower N03-N observed with side-dress applications;Careful swine manure N management is recommended because of potential increases in subsoil water NO3-N, surface soil NO3-N accumulation, reduced N recovery and limited yield responses at the high N rate.