To address the impacts of extreme climate events on agricultural production and to accelerate the transition toward net-zero agriculture, the Taiwan Seed Improvement and Propagation Station has established a “Farmland Carbon Sequestration Demonstration Site” since 2023 in the rice-growing area of Dajia, Taichung City. In alignment with the Ministry of Agriculture’s policies on “carbon-sequestering farming” and soil management, the Station has integrated green manure (cover crops) incorporation into the soil with rice-based rotation systems, and has established a three-year continuous field monitoring program and database. Results to date indicate that introducing green manure under existing rice cultivation conditions did not lead to a decline in paddy rice yield. The average yield in the first crop season of 2025 showd a marked increase compared with the first crop season of 2024, and the sunn hemp and rapeseed treatments generally outperformed the no–green manure control, demonstrating that green manure inputs provide practical benefits for maintaining and improving rice productivity. In terms of soil organic carbon stocks, carbon storage in the 0–30 cm soil layer under all green manure treatments showed an accumulating trend within the rotation system, with rapeseed and sunn hemp plots exhibiting greater increases than plots under rice-only cultivation. 

  The Station explained that the demonstration site centers on green manure incorporation as the key management practice. Field treatments are designed according to site conditions, and data are systematically collected on green manure biomass, rice yield, incorporation operations, and soil monitoring indicators. Changes in soil organic carbon serve as the main basis for carbon sequestration assessment, enabling the Station to accumulate year-by-year evidence on performance differences among treatments. Through continuous tracking, the Station has established a foundational data structure suitable for analysis. This ensures that green manure is no longer a practice evaluated merely through intuition-based-judgment, instead consistent records and standardized methods can demonstrate in how management measures influence soil carbon sequestration, thereby forming a technical base for expanding demonstrations and extension efforts.

  At the same time, while green manure practices enhance soil carbon sequestration, they may also interact with nitrogen cycling and potential risks of greenhouse gas emissions in the field. Examples include the nitrogen-fixation effects of leguminous cover crops, or changes in nitrous oxide (N₂O) emissions resulting from adjustments in nitrogen fertilizer management under rotation systems. To make carbon sequestration outcomes more complete and verifiable, the Station will further refine monitoring items and record-keeping methods according to the characteristics of different management practices, strengthening the usability of results for linkage with relevant systems. This includes parameters for sequestration performance evaluation, extension guidance, and promotion programs, thereby supporting policy implementation and broader adoption.

  The Station emphasized that green manure is not a single crop or a one-time measure, but rather a soil management strategy compatible with rice production systems. By building long-term datasets and standardizing methodologies, the Station will continue to make the benefits of incorporating green manure into fields more data-driven and communicable, enabling carbon-sequestering farming to move from concept to on-the-ground implementation. In doing so, it will help Taiwan’s agriculture steadily strengthen soil carbon sequestration capacity while balancing productivity and sustainability, advancing toward net-zero transition goals.

▲Fig.1. Soil sampling is conducted in green manure cultivation areas to enable long-term monitoring of soil carbon stocks.

▲Fig.2. Under the green manure–rice rotation system, methane (CH₄) and nitrous oxide (N₂O) emissions are monitored over the long term at each key stage.