Cotton N rate could be reduced further under the planting model of late sowing and high-density in the Yangtze River valley

Background:An optimal N rate is one of the basic determinants for high cotton yield.The purpose of this study was to determine the optimal N rate on a new cotton cropping pattern with late-sowing,high density and onetime fertilization at the first flower period in Yangtze River Valley,China.A 2-year experiment was conducted in 2015 and 2016 with a randomized complete block design.The cotton growth process,yield,and biomass accumulation were examined.Results:The results showed that N rates had no effect on cotton growing progress or periods.Cotton yield was increased with N rates increasing from 120 to 180 kg·hm^−2,while the yield was not increased when the N rate was beyond 180 kg·hm−2,or even decreased(9∼29%).Cotton had the highest biomass at the N rate of 180 kg·hm^−2 is due to its highest accumulation speed during the fast accumulation period.Conclusions:The result suggests that the N rate for cotton could be reduced further to be 180 kg·hm^−2 under the new cropping pattern in the Yangtze River Valley,China.