抄録
Two on-farm experiments (referred to as 1 and 2) were conducted to evaluate the suitability of ridge-making seeding for alleviating excessive soil moisture stress on silage corn (Zea mays L.) planted in upland paddy fields. In both experiments, corn was planted just after Italian ryegrass (Lolium multiflorum Lam.) was harvested in annual crop rotation system. In Experiment 1, the underground water table of the field was more than 200 mm below the ground surface frequently (66% of the total experimental period). The dry matter (DM) yield of corn was significantly low even with ridge-making treatment (9.9 tDM/ha), although its value was 54% higher than that achieved with conventional seeding treatment. In Experiment 2, the period during which the underground water table was more than 200 mm below the ground surface was 13% of the total experimental period. The dry matter yield achieved with ridge-making treatment was relatively high at 16.3 tDM/ha, which was 22% higher than that achieved with conventional seeding treatment. These data suggest that if soil moisture stress is at a moderate level, the application of ridge-making seeding can improve corn yields up to a level considered sufficient for farming practice. However, the effect of such seeding on corn yields is expected to be insufficient for fields with extremely poor drainage.
