Application of nitrogen is usually split into pre-plant application (PPA), firstbloom application (FBA), and peak bloom application (PBA). Nitrogen fertilizerapplication rate was at 225kg/ha and FBA ratio was fixed at 20% for all treatments whiliePPA and PBA were allowed to vary among treatments, the effects of different balancesfor the remaining N between PPA and PBA on cotton (G.hirsutum L.var. HuazamianH318) yield and its components were studied in a field trials (2011) and pot trials (2010and 2011), at application ratio among treatments as: A; 0:2:8, B; 1:2:7, C; 2:2:6, D;3:2:5, E; 4:2:4, F; 5:2:3. The purpose of this study was to determine nitrogen content anddistribution in different parts of the cotton plants as affected by nitrogen split applicationand the response of different N ratio to cotton yield and its components.
　　 The results showed that, for example 2010 pot trial, the balance of 30% PPA and50% PBA had the highest yield, the bolls per plant is 43.33, boll weight is 5.50g, lintyield is 117.82g and seed cotton yield is 238.27g. Both field and pot trials showed thesame trend but significant differences existed among treatments in the pot trial. In thiefield trials the results showed that the same 30% PPA and 50% PBA produced a highyield of 1683.23 kg/ha with seed cotton yield of 3134.21 kg/ha and boll weight of 6.09g;.Because cotton production and dry matter accumulation are positively correlated, theseresults suggest that optimum nitrogen rates is good for dry matter accumulation, andallocating adequate nitrogen to PBA should increase cotton harvest index and yieldcomponents, which reach the aim of high-efficient production.