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Title: NITROGEN MANAGEMENT FOR CONSERVATION-TILLED COTTON FOLLOWING A RYE COVER CROP

Author
item REITER, M - AUBURN UNIVERSITY
item Reeves, Donald
item BURMESTER, C - AUBURN UNIVERSITY

Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/25/2002
Publication Date: 7/13/2003
Citation: Reiter, M.S., Reeves, D.W., Burmester, C.H. 2003. Nitrogen management for conservation-tilled cotton following a rye cover crop. International Soil Tillage Research Organization Proceedings.

Interpretive Summary:

Technical Abstract: Over 70% of the more than 100,000 ha of cotton (Gossypium hirsutum L.) in the Tennessee Valley of northern Alabama, USA, is currently produced using conservation tillage systems with cereal cover crops. Decreased N efficiency, as a result of N immobilization and/or NH3 volatilization in these high-residue systems, require development of new N fertilizer recommendations. We conducted a replicated 3-year field study (2000-2002) on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudults) to test a factorial arrangement of N source (ammonium nitrate (AN) and urea-ammonium nitrate 32% (UAN)), N rates (0, 45, 90, 135, and 179 kg N ha-1), N application timing (all at-planting and 50-50 split between at-planting and first match head square), and N application method (banded or broadcast) for cotton grown in a high-residue rye (Secale cereale L.) conservation system. Optimal yields were obtained with 135 kg N ha-1 in 2000 and 2001 (875 kg lint ha-1 and 1150 kg lint ha-1) and 179 kg N ha-1 in 2002 (895 kg lint ha-1). Generally, highest yields were obtained when N was applied at-planting (900 kg lint ha-1, 1073 kg lint ha-1, and 969 kg lint ha-1 for 2000, 2001, and 2002, averaged over N rates, sources, and application methods). Urea-ammonium nitrate applications resulted in greater yields when banded, regardless of application timing. Preliminary data suggest the most efficient and economical practice for cotton grown in high-residue conservation systems would be to apply 135 kg N ha-1 as UAN in a banded at-planting application.