Abstract:  Field experiments in Shangyu coastal saline soil were carried out to investigate coupling effects of salt stresses and fertilizer application （N and P） on rice yield and fertilizer using efficiency. It was shown that the salt contents in 0-40 cm soil layer increased sharply after drainage during the rice mature stage. Due to the low fertility of saline soil， the rice yields of the control plots with low and high salt content were only 1 260 and 520 kg·hm-2， respectively. The rice yields were significantly increased by N and P application， and the highest yields were obtained as 6 530 and 5 030 kg·hm-2 in either low or high saltstressed soil， respectively. Among yield components， the number of productive ear was the most influenced by N and P application. The economic optimum N and P application rate were 2818 and 107.5 kg·hm-2 in low saltstressed soil （1.0-2.0 g·kg-1）， and 344.9 and 161.3 kg·hm-2 in high saltstressed soil （2.0-4.0 g·kg-1）， respectively. The ratio of grain to straw was slightly decreased with N and P application. The N and P fertilizer using efficiency were 33.9%-58.2% and 51.2%-61.8%， respectively， in low saltstressed soil， and 25.1%-38.0% and 31.0%-43.2%， respectively， in high saltstressed soil.

Key words: rice, coastal saline soil, N and P application, yield, fertilizer using efficiency