Simulation of yield and soil desiccation effects of continuous spring maize in different precipitation areas of the Loess Plateau

Based on model validation,the Win EPIC model was used to simulate yield and soil desiccation effects of continuous spring maize under different fertilization treatments on different precipitation areas of the Loess Plateau during 1960-2000.The simulated results showed as following:(1)The difference of spring maize yield in Luochuan,Yan'an,Shouyang,and Yulin was significant,and its average was 4.40 t/hm2,3.75 t/hm2,2.50 t/hm2 and 1.75 t/hm2,respectively.The difference of water used efficiency(WUE)and increased rate of yield by fertilizer(RYF)in Luochuan,Yan'an,Shouyang and Yulin were both notable and reduced by the order.The WUE enhanced with the increase of fertilizer,and the maximum value of RYF was in different fertilizer range in difference areas.(2)Monthly available soil water in 0-7m soil profile was significantly different and the value of Luochuan,Yan'an,Shouyang,and Yulin was reduced in sequence.In the same area,the higher fertilizer applied,the more water consumption,the less monthly available soil water remained.The difference of annual reduced soil water among different areas was significant,and increased with sequences of Luochuan,Yan'an,Shouyang and Yulin.Difference of annual reduced available soil water in 0-7m soil profile among different fertilizer treatments was notable at the earlier simulation stage,but was not significant at the later stage.(3)A relative stable desiccated soil layers shaped in 0-7m soil profile after soil water depleted and desiccated soil layers thickened period.Soil desiccated rate in Luochuan,Yan'an,Shouyang,and Yulin increased in the sequence.The higher fertilizer applied,the faster soil desiccate rate reached.(4)The suitable yield of continuous spring maize in Luochuan,Yan'an,Shouyang,and Yulin was 5.25-5.54 t/hm2、4.26-4.58 t/hm2、2.34-2.74 t/hm2、1.37-1.62 t/hm2,respectively,and reasonable fertilizer amount in corresponding area was N240(N 240 kg/hm2,P 120 kg/hm2)-N300(N 300 kg/hm2,P 150kg/hm2)、N180(N 180 kg/hm2,P 90kg/hm2)-N240(N 240 kg/hm2,P 120 kg/hm2)、N120(N 120 kg/hm2,P 60kg/hm2)-N180(N 180 kg/hm2,P 90kg/hm2)、N60(N 60 kg/hm2,P 30kg/hm2)-N120(N 120 kg/hm2,P 60kg/hm2),separately.