Growth and Yield of Wet Direct-Seeded Paddy Rice Cultivation Using Only Delayed-Release Coated Urea Fertilizer without Use of Phosphorus and Potassium in Rice-Barley Double-Cropped Paddy Field

[摘要] Although rice direct seeding cultivation is increasing in warm regions, the practice area is still small, few fertilizers are suitable for direct seeding, and fertilizers for transplantation must be applied. However, direct seeding tends to cause lodging by overgrowth due to vigorous tillers, and the reduction in the seeding amount practiced to avoid the lodging sometimes results in insufficient number of seedlings. Accordingly, it is necessary to practice cultivation without reducing the seeding amount as well as reducing the amount of basal fertilizer to suppress overgrowth. It is not realistic to distribute the fertilizer for direct seeding and it is troublesome for farmers to prepare the fertilizer by mixing. Therefore, in the rice-barley double-cropped paddy fields, we conducted rice direct seeding cultivation using only delayed-release coated urea fertilizer, the amount of nitrogen of which was 80% of that used in the conventional transplantation, and did not apply phosphorus, potassium or basal nitrogen. The study was conducted in 3 districts including the paddy fields of the farmers in comparison with the plots where the conventional fertilizer for transplantation was applied. As a result, there were no significant differences in growth or yield between the two cultivation methods. Therefore, the fertilization method using only delayed-release coated urea fertilizer could be applicable for wet direct seeding in rice-barley double-cropped fields. This fertilizer application can save fertilizer cost and labor because the amount applied is small.

[关键词] Delayed;release coated urea fertilizer;Direct-seeded paddy rice;No basal nitrogen;No phosphorus;No potassium;Rice-barley double-cropped paddy field.