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Cotton (Gosspium hirsutum L.) growth and yield following a white lupin (Lupinus albus L.) grain crop may be influenced by tillage system and rate of N fertilizer application. Field studies were conducted on Dothan sandy loam from 1995 through 1997 to evaluate the influence of conventional (CT) and strip-tillage (ST) systems in combination with four rates (0, 67, 134, and 202 kg N ha-1) of sidedress N on growth, development, and yield of ‘Deltapine 5409’ cotton following a white lupin grain crop. The 202 kg N ha-1 rate was split into two applications so that 134 kg ha-1 was applied 4 wks after planting and 68 kg ha-1 was applied 7 wks after planting. There were significant year by tillage by N rate interactions for lint yield, plant height, bolls plant-1, and bolls meter-2, and significant tillage by N rate interactions for boll weight and lint weight boll-1. Because of higher bolls m-2, lint yields were greater from cotton grown under ST than CT. For every 1 kg N ha-1 applied to cotton, lint yield increased by 2.49 kg ha-1 under ST in 1995, 1.07 and 1.69 kg ha-1 under CT and ST, respectively, in 1996, and 1.81 kg ha-1 for CT in 1997. Based on regression analysis, maximum lint yields were achieved with the application of 76 kg N ha-1 under CT in 1995, and 78 kg N ha-1 under ST in 1997. Plant height, bolls plant-1, and bolls m-2, and boll weight increased with increasing N rates. Lint yields were primarily correlated with bolls m-2. Following a white lupin grain crop, cotton can be successfully grown in ST. Nitrogen application to cotton increased lint yields due to increased bolls m-2. The optimal N rate for cotton following white lupin was 78 kg N ha-1.
