Abstract: The objective of this research was to determine the effect of tillage method and long-term fertilization on yield of winter wheat in semi humid and semi-arid areas of the Loess Plateau. The study was based on a long-term experiment of tillage and fertilizer conducted for 12 years. A split-plot design was adopted for the experiment, traditional tillage and no tillage were set as the main treatments, and 6 fertilizer treatments [control check (CK), nitrogen (N), phosphate (P), manure (M), nitrogen and phosphate (NP), & nitrogen and phosphate and manure (NMP)] as the sub-treatments. The cultivation system comprised a rotation of 1 year in maize and 3 years winter wheat. Highest wheat yields were produced by application of inorganic and organic fertilizers (NMP). Wheat yields after manure application (M) were significantly higher than NP chemical fertilizer application while the yield from N application was significantly higher than that of P. Under same fertilizer treatments, traditional tillage treatments had higher grain yields than no tillage treatments; yield were highest in high rainfall years, intermediate in normal rainfall years and lowest in dry years. In dry years the increased yields of cultivation and fertilization treatment was significantly higher than wet and normal years, while no significance was found between wet year and normal year. The combination of traditional tillage and NMP fertilizer optimized the canopy temperature and increased the photosynthetic rate, stomatal conductance and transpiration rate, increasing key yield components including number of productive spikes, grain number per spike and 1000 grain weight and resulting in increased yields. In the arid rain-fed planting areas of Eastern Gansu Province (mean rainfall of 550 mm·annumal^-1), the long-term use of organic and inorganic fertilizer or a combined application of N & P had a positive effect on crop yields under traditional tillage, no tillage systems and different years. The combined application of organic and inorganic fertilizers was the best strategy for enhancing winter wheat yields in semi humid and semi-arid areas of the Loess Plateau, eastern Gansu.

Key words: long-term located application, tillage method, organic manure, chemical fertilizer, yield, physiological index