Modeling the effects of winter wheat and spring maize rotation under different fertilization treatments on yield and soil water in rain-fed highland of Loess Plateau

The WinEPIC model was used to simulate the effects of winter wheat and spring maize rotation “spring maize→spring maize→winter wheat→winter wheat→winter wheat→winter wheat” under different level fertilization treatments on yield and soil water at Changwu rainfed highland of the Loess Plateau. The results showed that the simulated crop yield of the wheat-maize rotation under no fertilization, low fertilization, medium fertilization and high fertilization treatment decreased significantly with fluctuation, and the average yield was 1.573, 3.272, 3.877 and 4.138 t/ha, respectively. The suitable fertilization rates were N at 90#8722;120 kg/ha and P2O5 at 30#8722;60 kg/ha. Simulated monthly available soil water amount of all 4 fertilization treatments declined with annual and seasonal fluctuations, and the average annual decreasing rate was 8.5, 10.3, 12.3 and 12.0 mm, respectively. Differences of soil water amount among no fertilization, low fertilization and medium fertilization treatments were very significant. Soil moisture decreased and desiccated soil layers thickened gradually at the beginning of simulation (1957#8722;1962). Stable desiccated soil layers occurred during middle (1975#8722;1980) and end (1993#8722;1998) of simulation. Distribution depth of desiccated soil layers was 2#8722;3 m of no fertilization treatment, 2#8722;4 m of low fertilization treatment and 2#8722;5 m of both medium and high fertilization treatments, indicating that desiccated soil layers thickened with increasing fertilization and crop yield.