Abstract:

The aim is to study the best combination of irrigation and nitrogen application affecting the yield of wheat. Spring wheat ‘Dingxi 42’ was used as material. Water-nitrogen interaction method was adopted with four kinds of irrigation quantities (water depth per unit area 50 mm, 100 mm, 150 mm and 200 mm) and three fertilizer application methods (40 kg/hm ² pure nitrogen fertilizer at jointing stage, 40 kg/hm ² pure nitrogen fertilizer at flowering stage, 40 kg/hm ² and 50 kg/hm ² pure nitrogen fertilizer at jointing stage and flowering stage). (1) The yields of wheat were all the highest when the irrigation amount was 150 mm and the nitrogen fertilizer was 40 kg/hm ² at flowering stage. (2) The water content of the three soil layers were the highest when the irrigation amount was 150 mm, the order of water content in three soil layers was tillering stage < flowering stage < jointing stage under different nitrogen application treatments. (3) The water consumption of wheat plant increased with the increase of irrigation, water use efficiency decreased with the increase of irrigation amount. (4) When irrigation amount was 150 mm at tillering stage, nitrate nitrogen content in three soil layers was the highest; at jointing stage, the content of ammonium nitrogen and nitrate nitrogen in 0-10 cm soil layer was the highest; at flowering stage, nitrate and ammonium nitrogen contents in three soil layers were the highest when the irrigation amount was 150 mm and pure nitrogen fertilizer was 40 kg/hm ². The combination of 150 mm irrigation depth per unit area and 40 kg/hm ² pure nitrogen fertilizer application at flowering stage is the most beneficial to the yield of spring wheat, soil available nitrogen content and water conservation in Loess Plateau of Central Gansu.

Key words: Loess Plateau in Central Gansu, wheat, yield, soil nitrate nitrogen, soil ammonium nitrogen, soil water content