ABSTRACT
A field study was conducted in 1998 on an alluvial-derived field in Bolivar county, MS to determine the effects of variable rate N fertilization on cotton growth and lint yield. Two variable rate sidedress treatments were compared to a constant fertilizer N check of 40 lb N/A. The first variable rate treatment was based solely on soil available N differences throughout the field, while the second treatment was based on these same available N differences but with additional adjustment factors for differences in field elevation, wetness, and % clay. Both of the variable rate treatments ranged from 15.2 - 62.0 lb N applied per acre. Plant height was not significantly affected by either variable rate treatment. Overall the variable rate prescription based on available N alone did not increase lint yield, while the prescription based on multiple factors did result in a significant lint yield increase, especially in those areas of the field where less fertilizer N was applied.
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