Delaying Nitrogen Application for Optimal Algae Control in Waterseeded Rice Fields

摘要

Controlling algae in waterseeded rice (oryza sativa L.cv L202) fields is critical for stand establishment. Management practices which optimize fertilizer efficiency can stimulate algae growth. This research was initiated in 1996 to develop a nitrogen (N) management system which effectively controls algae witthout inhibiting plant growth. Treatment responses of waterseeded rice to seven N quantities and six application timings were examined under field conditions near portageville, MO, on a gideon clay loam. Total quantities of 0, 12.5,25,50,75,100,125 Ibs N/acre as urea were evaluated with each quantity applied 15,20,25,30,35,40 days after seeding. The effects of midseason N applications were also studied by comparing plots receiving two additional 25 Ibs N/acre midseason applications to plots receiving no additional N fertilizer. Preliminary data indicates that N applications can be delayed up to 30 days after seeding without impeding tillering. Greatest yields were obtained when early season N was delayed at least 30 days after seeding. plots receiving the additional midseason applications produced an average 37 bu/acre more grain.