中文摘要：

Soil alkali-hydrolyzable nitrogen, which is sensitive to N fertilization rate, is one of the indicators of soil nitrogen supplying capacity. Two field experiments were conducted in Dongtai（120°19″ E, 32°52″ N）, Jiangsu, China in 2009 and Dafeng（120°28″ E, 33°12″ N）, Jiangsu province, China in 2010. Six nitrogen rates(0, 150, 300, 375, 450, and 600 kg ha-1) were used to study the effect of N fertilization rate on soil alkali-hydrolyzable nitrogen content（SAHNC）, subtending leaf nitrogen concentration（SLNC）, yield, and fiber quality. In both Dongtai and Dafeng experiment station, the highest yield(1709 kg ha-1), best quality(fiber length 30.6 mm, fiber strength 31.6 c N tex-1, micronaire 4.82), and highest N agronomic efficiency(2.03 kg kg-1) were achieved at the nitrogen fertilization rate of 375 kg ha-1. The dynamics of SAHNC and SLNC could be simulated with a cubic and an exponential function,respectively. The changes in SAHNC were consistent with the changes in SLNC. Optimal average rate(0.276 mg day-1) and duration（51.8 days） of SAHNC rapid decline were similar to the values obtained at the nitrogen rate of 375 kg ha-1at which cotton showed highest fiber yield, quality, and N agronomic efficiency. Thus, the levels and strategies of nitrogen fertilization can affect SAHNC dynamics. The N fertilization rate that optimizes soil alkali-hydrolyzable nitrogen content would optimize the subtending leaf nitrogen concentration and thereby increase the yield and quality of the cotton fiber.