Self-sustaining nitrogen supply system in long-term unfertilized paddy-field

包括化学和有机形式的施肥对可持续作物生产至关重要。然而，日本的几个水田农民在不施肥的情况下成功地获得了30多年的高产。为了阐明这一机制，对东北地区6块稻田的氮素平衡进行了比较。营养生长期分蘖活动是水稻调控的重要组成部分。高产水田由于土壤分解活性高，提供矿化氮的能力比低产田高。

Fertilization including both chemical and organic forms is essential for sustainable crop production. However, several paddy field farmers in Japan successfully attain high yield without any fertilization for more than 30 years. To clarify this mechanism, six paddy rice fields in Tohoku region were compared in terms of nitrogen balance.Tillering activity during vegetative growth stage was a key component in regulating rice field. High-yield paddy fields had higher ability to supply mineralized nitrogen resulting from high soil decomposing activity than low-yield fields.