Research On The Effect Of Long-Term Fertilization And Climate Factors On Soil Nutrient Changes And Production Sustainability Based On APSIM Model

With the emergence of global ecosystems and environmental problems,the long-term evolution of soil properties from different time and space scales is of great significance for the sustainable development of agricultural production.The current study is carried out based on the historical data from eight-station of the national soil fertility and fertilizer efficiency long-term monitoring network and using the Agricultural Production System Simulator(APSIM)to study China’s black soil(Gongzhuling,Jilin),red soil(Qiyang,Hunan),paddy soil(Hangzhou,Zhejiang),and loessial soil(Yangling,Shaanxi),purple soil(Beibei,Chongqing),cinnamon soil(Changping,Beijing),fluvo-aquic soil(Zhengzhou,Henan),gray desert soil(Urumqi,Xinjiang),the evolution of soil nutrients after longterm use of organic fertilizer and chemical fertilizer,as well as the sustainability of crop production,and yield stability.The main results are as follows:1.The Agricultural Production System Simulator(APSIM)model was used to simulate soil nitrogen in black soil in Yangling Jilin Province for 20 years.The observed values are consistent with the simulated values.The predicted values of total soil NO3--N and NH4+-N nitrogen are 10 kg ha-1 and 5 kg ha-1 higher than the observed values.The total soil NO3--N loss has the same trend as the rainfall,and it increases with the number of rainfall days over the years.The average 20 years losses of NO3--N and NH4+-N observed were 1375.91 kg ha-1,and 9.24 kg ha-1,while in the simulation increase was 1387.01 kg ha-1 and 9.28 kg ha-1,respectively.The difference between the observed and simulated values of NO3--N and NH4+-N of mean loss was 11.15 kg ha-l and 0.04 kg ha-1 respectively.2.Agricultural Production System Simulator(APSIM)well simulated the climatic change model in maize-spring wheat-winter wheat cropping system in Urumqi,Xinjiang-China.Two models with CO2 levels of 350 ppm and 650 ppm were used to simulate the effects of APSIM on soil moisture over 20 years.The simulated and observed values R2 of soil water content,runoff water,and leaching water were 0.986**,0.998**and 0.8216*,respectively.The maximum and minimum temperature varies by+2℃;average reduction in precipitation-10 mm.The prediction value of total rainfall for 20 years was 4400 mm,while the observation value was 4888.9 mm,the difference between them is 488.9 mm.The soil moisture content reduces from 191.2 mm to 181.1 mm from surface to 180 cm,soil surface runoff observed was 0.43 mm,and in simulated was 0.40 mm.The simulated and observed R2 values are 0.995***and 0.920**,respectively.The total NO3--N of soil decreased from 1444.0 to 1422.5 kg-ha-1,and the NO3--N of leached soil from 0.75 to 0.73,while total NH4+-N rose from 35.1 kg ha-1 to 41.72 kg ha-1.Soil N balance was positively correlated with P balance and K balance,r was 0.95***and 0.91**,respectively.There was also a significant positive correlation between N uptake and P and K uptake,r2 values of 0.75***and 0.78**,respectively.The sustainable yield index of spring wheat and maize was 0.82 and 0.85,respectively,higher than winter wheat.The grain yields of NPKM2,NPKS,NPKM,and treated crops all showed an upward trend with the planting year,while the yields of all crops treated with NPK were only slightly different.3.For six other long-term trials,crop yields were used to estimate PAWC(Plant Effective Water Holding Capacity)based on crop yield,and use APSIM to analyze soil water characteristics.The soil available water in maize season was 36 mm and 57 mm respectively from the surface layer to 180 cm in Yangling,Shaanxi Province.The available soil water in winter wheat season was 36 mm and 69 mm respectively.Hunan in the long-term experiment in Qiyang,the soil bulk density is 1.26 g cm-3,and the soil profile is 180 cm from the surface to the bottom.The available soil water in the wheat season is 30 mm and 42 mm,and the available soil water in the maize season is 36 mm and 69 mm,respectively.Hangzhou,the soil profile from the surface to the bottom 180 cm,the available soil water in the barley season was 37 mm and 27 mm,respectively;the available soil water in the corn season was 30 mm and 42 mm,respectively.In the long-term experiment in Zhengzhou,the soil profile from the surface to the bottom 180 cm,the available soil water in the winter wheat season was 36 mm and 69 mm,respectively;the available soil water in the maize season was 30 mm and 42 mm,respectively.The long-term experiment in Changping,Beijing,the soil bulk density was 1.5 g cm-3,from the surface of the soil profile to the bottom 180 cm,the available soil water in the corn season is 30 mm and 40 mm respectively.The principal component analysis results of the experiment in Qiyang,Hunan showed that the total variation was as high as 92.2%.Therefore,the first principal component(PC1)explained 54.2%of the maximum variance;followed by principal component analysis 1 and 2 of Shaanxi Yangling showed 83.4%and 69.3%of the total variance;the characteristic value of Chongqing Beibei was greater than 0.5,and the principal component analysis The contribution of the highly weighted variables(PC1 and PC2)is 85.71%.The study concluded that,compared with inorganic fertilization,the long-term combined application of manure and inorganic fertilizer improves the sustainability of crop yields and organic carbon sequestration.