Nutrient leaching differs between annual and perennial crops, but nutrient losses from rotations containing both annual and perennial crops are not well documented.  This study compared NO₃-N and total phosphorus (TP) concentrations in soil water under three crop rotations in Iowa, including two-year (corn-soybean; 2YR), three year (corn-soybean-small grain/red clover; 3YR), and four-year (corn-soybean-small grain/alfalfa-alfalfa;  4YR) systems.  Using spring soil-test results, nutrient applications comprised synthetic fertilizers to 2YR corn, and composted manure to supplement legume-residue sources for 3YR and 4YR.  Soil water was collected from suction samplers at 1.2 m depth during eight years (2004-2011).  The 4YR rotation, during the alfalfa and following corn years, showed smaller NO₃-N concentrations and less frequent detection of TP.  Mean concentrations of NO₃-N were 1.1 mg NO₃-N L^-1 under alfalfa and 6.5 mg NO₃-N L^-1 during the following corn crop, compared to average concentrations between 8.7 and 18.1 mg NO₃-N L^-1 among all other crop-years.  Seasonal NO₃-N dynamics were distinct among rotations due to differences in mineralization-immobilization of N from decomposing crop residues.  Total P results showed the importance of landscape hydrology, as the greatest total P concentrations occurred in one 2YR plot where preferential flow was evident.  Among the remaining plots, detection of total P (i.e., >0.02 mg L^-1) occurred less frequently (p<0.01) under the 4YR alfalfa and corn crops (0.12) than all crop-years (0.34).  Results suggest nutrient management may not always involve a tradeoff between N and P losses, and that crop rotations including alfalfa may reduce losses of both nutrients.