Analysis Of Crop Stubble Relationship In Chestnut Soil Field In Cold And Arid Region Of Northwest Hebei Province

In the coordinated development strategy of Beijing,Tianjin and Hebei,the cold and arid areas in northwest Hebei are clearly defined as national important water conservation areas and ecological conservation areas.The regional climate is cold,low temperature and short season,drought and less rain,is a typical cool crops once a year mature area.Because of the wide fluctuation of precipitation between years and seasons and the limitation of soil water and fertilizer storage capacity and input,the regional crop yield is low and unstable,so the forage animal husbandry,which is the raw material,is very difficult.Facing the problem of random planting mode and no evidence of crop stubble connection,this study was based on setting up field positioning experiment to monitor the output effect of all intercropping relationships among crops,as well as the corresponding characteristics of stubble moisture,nutrients,and so on.Based on the ecological qualitative evaluation and quantitative analysis of the intercropping relationship between crops,the characteristics and adaptability of the main crops planted in the cold and arid areas of northwest Hebei Province and the mechanism of the formation of the stubble characteristics were clarified.It provides a theoretical basis for crop selection and timing allocation of farmland production in this area.The main results were as follows:1.There was significant difference in yield effect among different crop stubble patterns.Potato,naked oats and beet continuous cropping significantly reduced the yield;The average yield of potato in naked oats stubble,corn stubble,beet stubble and broad bean stubble was 1.94（P<0.05）,1.78（P<0.05）,1.59 and 1.58 times higher than that in continuous cropping potato 2852.34 kg.hm^-2,respectively.The average economic yield of continuous cropping oats was 1541.59 kg.hm-2,potato stubble,broad bean stubble,corn stubble and beet stubble,which were 1.70（P<0.05）,1.46,1.43 and 1.16 times higher than those of continuous cropping oats,respectively.The yield of beet in potato stubble,corn stubble,forage bean stubble and naked oats stubble was 1.53（P<0.01）,1.41,1.40（P<0.05）and 1.28 times higher than that in continuous cropping beet 7187.91 kg.hm^-2.The yield of faba bean and forage maize also decreased,but the difference was not significant.2.The stubble effect of crops in cold and arid region of Northwest Hebei Province was clarified.Among the 20 rotation patterns,85%of the rotation patterns made the subsequent crops gain"favorable effects",of which 30%were significantly different,and 15%were"harmful effects".Naked oats stubble,forage maize stubble,faba bean stubble,beet stubble potato,forage maize stubble,potato stubble,naked oats stubble,potato stubble,faba bean stubble,forage maize stubble,beet stubble naked oats stubble,potato stubble,corn stubble,broad bean stubble,beet stubble naked oats were observed in the favorable effect（LERc>1）.3.It is clear that the stubble combination with high land use efficiency i in cold and arid region of Northwest Hebei Province.Among the 10 rotation ways,the LERr value of potato with oat was the highest（1.87）,and reached a significant level with other rotation methods.Followed by potato with beet,potato with corn LERr,respectively,is 1.58,1.45,very significantly higher than the following stubble mode,potato with faba bean,faba bean with naked oats,faba bean with forage maize,naked oats with beet,naked oats with forage maize,The LERr values were1.36,1.27,1.23,1.22,1.21,1.12 and 1.12,respectively.4.It was clear that stubble obviously affected the water use effect of stubble crops.Naked oats,as the preceding crop of potato,could significantly increase the economic yield by 93.98%and the WUE by 95.75%compared with the continuous cropping of potato.Potato and forage maize could increase the WUE of oats by 59.11%and 49.40%.Rotation could increase WUE of beet by 26.79%³9.99%compared with continuous cropping,but the difference was not significant.Each stubble had no significant effect on the WUE of faba bean and forage maize.5.It was clear that stubble obviously affected the nutrient utilization effect of stubble crops.The nutrient N output-input ratio of continuous cropping potato was 0.44,that of naked oats stubble and forage maize stubble was 97%and 88%higher than that of continuous cropping（P<0.05）.The nutrient P output-input ratio of continuous cropping potato was 0.22,that of naked oats stubble and forage maize stubble was 72%and 68%highter than that of continuous cropping respectively（P<0.05）.The nutrient N output-input ratio of continuous cropping beet was 0.58,that of potato stubble and forage maize stubble was 102%and 79%higher than that of continuous cropping（P<0.05）.The nutrient P output-input ratio of continuous cropping beet was 0.15,and that of potato stubble,faba bean stubble and forage maize stubble was 94%（P<0.01）,64%（P<0.05）and 50%（P<0.05）,respectively.The nutrient output-input ratio of faba bean,forage maize and naked oats in each stubble was not significantly different.6.It was coinfirmed that the increase of disease index is an important reason for reducing crop yield of continuous cropping on chestnut soil in meadow.The disease index of continuous cropping sugar beet and potato was higher than that of stubble treatment in 2018.The disease index of brown spot in continuous cropping of beet was 32%,which was 1.28 times of that of potato stubble and faba bean stubble,1.33and 2.0 times of that of naked oats stubble and corn stubble.The disease index of potato late blight was the highest at 47%,1.18,1.68,1.74 and 2.76 times that of faba bean stubble,oats stubble,forage maize stubble and beet stubble.In conclusion,the main crops in meadow chestnut soil field in northwest Hebei showed partial benefit compensation effect and mutually beneficial gain effect,and the optimal order of stubble mode was oats with potato,potato with beet,potato with forage corn,Potato with faba bean,faba bean with naked oats,faba bean with corn,naked oats with beet,naked oats with corn,faba bean with beet,corn with beet;Compared with the soil nutrients of stubble,successive crops are more sensitive to soil moisture of stubble,potato and beet continuous cropping aggravate the disease and become an important reason for yield reduction.