Technical Abstract: Nitrogen fertilizer rates in excess of crop needs are common in the Arkansas River Valley of SE Colorado, which increases risk of groundwater contamination. The potential leaching of NO3-N into the groundwater is exacerbated by furrow irrigation (FrI), the predominant irrigation system in this region. Subsurface drip irrigation (SDI) could conserve water and reduce leaching of nitrate and salts but little information is available to confirm this hypothesis in the Arkansas Valley, including research on the effects of manure on soil productivity. A field experiment was conducted in 2005 through 2007 to test the effects of N fertilizer (0, 67, 134, and 201 kg N ha-1) and feedlot beef manure (0, 22.4, 44.8, and 67.2 Mg ha-1) on corn (Zea mays L.) yield, N and P soil tests and crop uptake, and salt concentration under SDI and FrI. There were no significant differences in corn yields between SDI and FrI in all three years even though on average, 42% less water was applied with SDI than with FrI. Nitrogen fertilizer or manure application generally increased grain yield, kernel weight, grain and stalk N uptake, and grain P uptake. Nitrogen rates above 67 kg ha-1 did not increase grain yield significantly in 2005 or 2006, nor did manure rates in excess of 22 Mg ha-1. High manure rates increased soil salinity early in the season, depressing corn yields in 2005 and 2006, particularly with SDI. Salts tended to accumulate in the lower half of the soil profile with SDI. The high manure rates resulted in oversupply of NO3-N and P. The long-term benefits of manure should be weighed against the potential risks to the environment such as groundwater contamination.