ABSTRACT
Cotton (Gossypium spp.) was planted each year beginning in 1990 to determine the effect of nitrogen rate on yield when produced on a Red River alluvial soil (Norwood silt loam, pH near 8.0) in central Louisiana. Seven rates of N ranging from 0 to 150 lbs/A, in 25-lb increments, were applied prior to planting in randomized complete block designs. The optimum N rate ranged from 107 to 125 lbs/A whenever fertilizer was applied early in the season at planting time. These rates are nearly twice that previously recommended. In two instances where there was a delay between fertilizer application and planting, yield increased linearly with N up to 150 lbs N/A. These data indicated that timing and perhaps method of fertilizer application may be critical for efficient use of N.
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