This study examined the synergies and tradeoffs between nitrate leaching and net farm income of radish (Raphanus sativus L.) cultivation in a highland area of South Korea. Synergies describe economic and environmental benefits that are derived by agricultural management practices, which increase net farm income and decrease nitrate leaching simultaneously. The effects of different nitrogen best management practices (NMBP) in reducing nitrate leaching and their economic consequences, in terms of net farm income, were investigated via field experiments, modeling simulations of nitrate leaching and economic analyses of costs and benefits. Our results showed that the use of plastic mulch, fertilizer placement only in ridges, split fertilization and combination of these NBMP reduced nitrate that percolates into the groundwater system. The plastic mulching and fertilizer placement only in ridges were also shown to be economically profitable, demonstrating synergies between net farm income and nitrate leaching. However, there are tradeoffs in the cases of split fertilization and combination of NBMP as they lower both leached nitrate and net farm income. Thus, there are opportunities for policy makers to motivate farmers to adopt split fertilization and combine NBMP. This can be done by compensating farmers for the losses of their net farm income.