Management of wet-direct seeded rice: 1. crop establishment, seeding rates and nitrogen management
1998
Javier, E.F. | Casayuran, P.R. | Cruz, R.T. | Obien, S.R. (Philippine Rice Research Inst., Maligaya, 3119 Munoz, Nueva Ecija (Philippines))
With the availability of water supply, relatively inexpensive herbicides and reduced labor costs, more farmers shift from transplanted rice to wet direct-seeded rice. Nevertheless, some farmers still use more than 200 kg seeds/ha when higher yields could be obtained at 40 kg seeds/ha than at 80 and 160 kg/seeds/ha given proper land preparation, water and pest management. Yields of PSB Rc 14 in the 1996 and 1997 dry season (DS) generally increased as N fertilizer increased from 0 to 180 kg/ha. The optimum yield, however, can be attained at 90 kg N/ha, 2/3 of which is either applied as basal or at 10 days after sowing (DAS) and the remaining 1/3 at early panicle initiation (EPI). During 1997 DS, however, the rice plants exhibited N deficiency symptoms at the start of tillering stage, hence the leaf color chart (LCC) and chlorophyll meter (SPAD) were used to determine their physiological need of N. Generally a better yield was observed using these tools rather than using the fixed rate and schedule of N application. Using LCC with critical reading set at 3, direct seeded PSB Rc 14 used up to 65 to 84 kg N/ha only and yet obtained higher yield than using the higher N rates. As to crop establishment, direct-seeding can be done either by drumseeding or broadcasting pre-germinated seeds right after the final harrowing and leveling
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