Study On Adaptability Of Two Cropping Systems Based On APSIM Simulation Models

APSIM model was used to simulate the climate,irrigation,economic effect and water use efficiency of winter wheat(Triticum L.)-summer maize(Zea mays L.)double cropping and single maize with different sowing dates from 1961 to 2015.Nitrogen use efficiency and partial productivity were analyzed.The main results are as follows:(1)The climate change in 1961-2015 is mainly reflected in the temperature,the average temperature,the highest temperature and the lowest temperature show a significant upward trend,with a temperature increase of about 0.3 ℃ every five years.The solar radiation decreased at first and then increased,and the total rainfall fluctuated greatly from year to year,but on the whole,there was no obvious decreasing trend.(2)In the past 55 years,the daily average temperature of winter wheat increased by0.32 ℃ and the accumulated temperature increased by 25.80 ℃ before overwintering.The temperature change in other growth stages was not obvious.The temperature of spring sowing maize was slightly higher during the period of male silking,and there was more rainfall during the period,and the probability of rainfall in cloudy days was higher.From April 10 to July 20,the probability of high temperature and low temperature risk of 11 sowing dates was 82%,87.1%,76.9%,57.3%,68.3%,57.1%,41.4%,45.7%,51.5%,130.7% and 167%,respectively.The probability of days of exposure to cloudy rainfall risk was 42.7%,49.6%,53.1%,53.8%,48.6%,52.4%,50.3%,32.5%,36.6%,25.1% and 21.9%.The probability of temperature and cloudy rainfall on June 20 was lower than that of the other 10 sowing dates.It can be seen that the temperature of maize sown from June 10 to June 20 is the most suitable,and the yield from May 10 to May 20 is the highest,between13666.4~14678.1kg/ha.(3)When the annual yield of winter wheat and summer maize was between16177.5~20306.8kg/ha,the field water consumption of wheat-maize double cropping was between 578.4~848.4mm and 26.73~35.86kg/ha/mm,and the water use efficiency of wheat and summer maize was between 26.73~35.86kg/ha/mm.When the yield of spring maize was in the range of 12152.4~13542.6kg/ha,the field water consumption and water use efficiency were 466.7 ±736.0 mm and 21.98 ±33.38 kg / ha,respectively.The field water consumption and water use efficiency were significantly higher than those of spring maize.The coefficient of variation of simulated yield of spring maize in 55 years was12.6% ~15.2%,while that of wheat and maize was 7.4% ~13.7% respectively.Under the same irrigation scheme and the same yield level,the irrigation amount of wheat-maize double cropping was 42.4%(12749.1kg/ha),39.9%(13075kg/ha),48.4%(13361.2kg/ha)and 49.9%(13542.6kg/ha),lower than that of spring maize,respectively.(4)The yield of winter wheat and summer maize increased significantly with the increase of fertilizer application rate,and the highest yield was 20455.5 kg / ha.when the fertilizer rate was 180kg/ha,the yield was about 17114.5kg/ha and the highest nitrogen use efficiency was 26.00 kg /kg.When the amount of fertilizer 120kg/ha was applied,the yield was about 14540.8kg/ha,and the highest partial productivity of nitrogen fertilizer was43.22 kg/kg.When the fertilizer amount of spring maize reached 120kg/ha,the yield of13221.3kg/ha was no longer increased,the highest nitrogen use efficiency was 30.91kg/kg,and the highest partial productivity of nitrogen fertilizer was 35.37 kg/kg,when the fertilizer application rate was 180kg/ha,the highest nitrogen use efficiency was 30.91kg/kg,and the highest nitrogen partial productivity was 35.37 kg/kg.At the same yield level,the nitrogen requirement of spring maize was 10.7%(13134.0kg/ha),29.6%(13207.2kg/ha),43.4%(13215.1kg/ha)and 54.7%(13221.3kg/ha)higher than that of wheat and maize double cropping,respectively.(5)The net output value of winter wheat and summer maize at different yield levels was between 14628.6 ~6510.9 yuan / ha,and that of spring maize was between 11585 ~17819.8 yuan / ha.Compared with wheat-maize double cropping,spring maize can save69.1% and 72.6% of material cost.The two cropping systems invested the most money in chemical fertilizer,wheat-maize double cropping fertilizer accounted for 37.2% of the total material cost,spring maize maturing accounted for 33.5%.