This study was conducted to select promising green manure crops, providing sufficient amount of nutrients for satisfying fruit tree growth, with the overwintering cover crops grown in organic orchards in 2009. The cover covers were investigated in 13 organic orchards in Chonnam province in April and June. The dry matter in cover crops observed in April and June was the highest for Lolium multiflorum Lam. and Bromus japonicus Thunb., respectively. Total N and K production in April was the highest for Lolium multiflorum Lam, Vicia hirsuta (L.) S. F. Gray and Vicia angustifolia var. segetilis (Thuill.) K. Koch., respectively, with Bromus japonicus Thunb. in June. This study showed that the leguminous crops, Vicia hirsuta (L.) and Vicia angustifolia, would be the prospective cover covers as the both crops provided sufficient amount of N and K2O into the soil. Amount of P2O5 producing from all cover crops provided less than nutrient levels than those of recommended nutrient requirement for satisfying 10- to 15-year-old fruit tree growth.