Abstract: A long-term field experiment with four factors (irrigation, nitrogen and phosphorus applications, and straw mulching) and five levels was conducted on a cinnamon soil in semi-arid area of western Liaoning to study the coupling effects of water and fertilizer on the nitrogen content in maize grain, with the regressive model built up by the quadratic rotation design statistic analysis method. The results showed that single factor had significant effects on the nitrogen content in maize grain, and the sequence was nitrogen application > straw mulching > phosphorus application > irrigation. When the irrigation amount was 700 m³·hm^-2, nitrogen application rate was 180 kg·hm^-2, phosphorus application rate was 120 kg·hm^-2, and straw mulching was 7500 kg·hm^-2, the maize grain had a high yield of 12000 kg·hm^-2, with the nitrogen content being 11.7 g·kg^-1 and the protein content being 73 g·kg^-1, suggesting that such a water-fertilizer combination was in optimum in both economy and ecology, and thus, could be applied in the practical maize production in western Liaoning.

Key words: Heihe River Basin, Transitional zone, Reaumuria soongorica, Nitraria sphaerocarpa, Spatial pattern, Spatial heterogeneity