High-yield SRI in West Java by decomposing straw in waterlogged paddy field

Abstract

System of Rice Intensification (SRI) often achieved higher yield than conventional practice. We identified the high-yielding farmers from the yield records of 1909 paddy fields belonging to an organic farmers’ association. Farmers whose yields were from 8.4 to 10.4 t ha⁻¹ were interviewed and their fields surveyed. Their yields had increased by an estimated average of 40% following the adoption of SRI practices. They applied 2–12 t ha⁻¹ of compost. Compared to the conventional practice, they shortened seedling age at transplanting from 27.4 to 17.6 days and reduced the number of seedlings per hill from 4–6 to 2–3, while hill spacing remained unchanged. Instead of intermittent irrigation which is recommended in standard SRI, they kept shallow flooding of 1–2 cm. Although they applied a lot of compost, no correlation was found between the amount of compost application and the yields. Instead, high-yielding farmers returned rice straw into waterlogged paddy after harvest, which presumably is an ideal condition for biological nitrogen fixation. This may occur around rice straw during decomposition under waterlogged condition and might supplement the negative nitrogen balance, thereby enabling the high yield as compared with conventional practices where the fresh rice straw is removed and/or burned.