Abstract: A field experiment was carried out over three years to clarify the effects of mechanized direct dry seeding in drill with controlled-release formula fertilizer and seeding rate on growth and yield of rice, with indica and japonica rice varieties being used. There were three treatments with a one-time application of controlled-release compound fertilizer (OTA), one-time application of controlled-release compound fertilizer with increased seeding rate (OTA+S), and three-time fertilization, representing typical farmer fertilization practices (FFP). The results showed that the yields of indica and japonica were 8.9% and 8.8% higher on average, respectively, under the two controlled-release compound fertilizer treatments (OTA, OTA+S) than that under FFP over the three years, but with no significant difference between OTA and OTA+S treatments. In addition, the effective tiller percentage, shoot and root biomass, root-shoot ratio, and harvest index of the population and the biomass per individual of Indica and Japonica were improved under the two controlled-release compound fertilizer treatments. There were no significant differences in the above parameters between the two controlled-release compound fertilizer treatments for the same variety. Both indica and japonica under FFP treatment had higher total N accumulation but lower fertilizer partial productivity than that under the two controlled-release compound fertilizer treatments. The net benefits of both varieties under the two controlled-release compound fertilizer treatments were higher than those under FFP. The net benefit of indica under OTA was 41.1% higher than that under FFP, while that of japonica under OTA was 57.0% higher than that under FFP. Therefore, mechanicaldirect seeding through drilling combined with one-time application of controlled-release compound fertilizer could increase rice yields, reduce fertilizer and labor costs, and increase the economic benefits of rice production, with wide application prospects.

Key words: mechanically dry direct-seeded rice, controlled-release compound fertilizer, yield, matter accumulation, partial fertilizer productivity.