Effect of nitrogen, phosphorus and water coupling on spring wheat yield in semi-arid areas of western Liaoning Province

To seek for effect of water and fertilizer coupling on spring wheat, with 312-D optimized saturation design, field experiments were conducted in the western Liaoning Province during 2000～2003 to study effect of water and fertilizer coupling on spring wheat yield. Results showed that irrigation quantity was the chiefly factor to affect spring wheat yield, phosphorus quantity was the secondly factor, nitrogen quantity was the thirdly factor. Yield effect was the highest in the condition of middle level water and fertilizer, but which was the lowest in low level water and low fertilizer, and which was between the two in high level water and high fertilizer. The effect order of interaction is: nitrogen and water coupling>nitrogen and phosphorus coupling>nitrogen and water coupling. When spring wheat yield accessed 4000 kg/hm², amounts of water and fertilizer were nitrogen 240.1～361.2 kg/hm², phosphorus 103.1～152.6 kg/hm², water 337.5～450.0 mm. Amounts for highest yield 4610 kg/hm² were nitrogen 315.1 kg/hm², phosphorus 111.1 kg/hm² and water 354.6 mm.