Effects of tillage, winter cover crops, and inorganic N fertilization on watermelon production were examined in a split-plot factorial experiment. Main plots received tillage or no tillage, whereas cover crops consisted of hairy vetch, winter rye, or a mix. Nitrogen treatments consisted of plus or minus addition of ammonium nitrate. Following melons not receiving inorganic N, vetch produced cover crop total N yields of ≈130 kg·ha–1, which were four times greater than those obtained with rye. Melon yields and foliar N concentrations obtained without inorganic N fertilization following vetch were similar to those obtained with N fertilization following rye. Available soil N in vetch treatments remained significantly (P < 0.05) higher than in rye treatments for ≈70 days after melon planting and was greater in tilled treatments. Tillage significantly (P < 0.05) reduced melon yields by 20% and also reduced soil temperatures compared with no-till treatments. We conclude that N fixed by vetch could sustain watermelon production and no tillage may be useful when soil erosion is a problem.