Successive incorporation of Azolla ( A. filiculoides Lam.) as green manure increases rice yield in lowland paddy soil

作者：Samuel Munyaka Kimani, Nanami Sekishita, Yuka Hosogoe, Valensi Kautsar, Keitaro Tawaraya, Takeshi Tokida, Weiguo Cheng · 发表于：Soil Science & Plant Nutrition · 年份：2025 · DOI：10.1080/00380768.2025.2477127 · 被引用次数：3 · 研究领域：Biological Control of Invasive Species、Agricultural Science and Fertilization、Cassava research and cyanide

A 3-year field trial was conducted to evaluate the impact of Azolla as green manure (AGM) applied in a lowland paddy field at the rate of 7.0 g N m−2 in combination with floating Azolla cover (herein Cover) on rice yield in comparison with inorganic fertilizer (NPK) alone or NPK + Cover (herein NPK-amended) treatments. In the initial year, AGM + Cover significantly lowered the rice grain yield by an average of 36.5% compared with NPK-amended treatments. This decline was associated with fewer panicles, total spikelets, and a lower ratio of filled grains, and was attributed to the gap in time between nutrient release from Azolla and nutrient demand from rice during the growth period as reflected in a smaller nitrogen content in the rice grains. Conversely, successive application of AGM + Cover in the 2nd and 3rd years of rice growth significantly increased grain yields to levels equal to those of NPK-amended treatments. This recovery was ascribed to an increase in total spikelet number, an improved filled grain ratio, and an increase in 1000-seed weight. The significant (p < 0.05) upward trend in rice grain yield following AGM + Cover amendment across the 3 years (392.9–745.9 g m−2) was likely due to enhanced soil nutrient availability associated with residual effects of AGM amended in the previous crops. These results indicate that sustainable rice yield can be achieved by replacing chemical fertilizers with Azolla as manure in the long term. However, a combined application of...