| China's land area accounts for one fifth of the world's total,with a large population base and relatively rapid development of agricultural industry.But at the same time,the uneven distribution of cultivated land resources and the far lower per capita cultivated land area are also the basic national conditions.As a basic agricultural element,cultivated land is the material basis to guarantee the basic livelihood and production of our people and the source of strength to support the rapid development of our country.With the rapid development of urbanization in China,the long-term high intensity and overload of cultivated land resources and the extensive operation mode of farmer's cultivated land resources in rural areas have made the contradiction between supply and demand of cultivated land,the degradation of soil fertility and the related ecological environment increasingly prominent,affecting the balance between the quality and quantity of cultivated land in China,and restricting the industrialization and production of agriculture in China.Sustainable development of ecological environment.Dryland double cropping area is the four typical grain and oil crop producing areas in China.It has abundant land types and excellent natural resources such as light and temperature.It is the core area for producing,supplying and selling cash crops and other agricultural products.It raises more than 600 million people nationwide and plays an important role in food security and "agriculture,countryside and farmers".However,the great development and prosperity of urbanization have intensified the pressure of regional cultivated land resources,and put forward higher requirements for the protection of cultivated land and the sustainable development of ecological environment.Therefore,to clarify the temporal and spatial changes of soil nutrient content and comprehensive fertility and the analysis of related influencing factors in Dryland double cropping area will play a key role in guiding the ecological environment protection and the development of agricultural industrialization in the study area.In this paper,the dry land double cropping area is taken as the research object,and a large number of investigations and studies on cultivated land soil resources in the dry land double cropping area are carried out by combining macro-statistical data with micro-soil data and household survey data.On the basis of relevant literature research,using classical statistics,geostatistics and regression analysis,the spatial and temporal variation characteristics of soil nutrient fertility between the data of the second national soil survey period(1980s)and the national soil testing formula period(2014 s)were studied,and the effects of natural environment and human activities(farmers' perspective)on the spatial and temporal variation of soil nutrient fertility were comprehensively analyzed.Sound effect and development trend.Finally,combined with the field investigation of farmer's cultivated land use behavior in typical areas,using binary logistic regression analysis model,the main influencing factors of cultivated land use behavior in the area were analyzed and the corresponding countermeasures and suggestions for cultivated land protection and sustainable development of ecological environment were put forward.Through the above research process,the following conclusions are drawn:1.The comprehensive fertility of cultivated land soil nutrients in Dryland double cropping area has been continuously improved,but the fertility of cultivated land in the five regions has a trend of increasing or decreasing in varying degrees.After more than 30 years of change,the Dryland double cropping area changed from V to I-V grade uniform distribution.With the development of agricultural policies and economy,the positive response of human activities such as increasing fertilizer application and agricultural mechanization development,the trend of soil fertility agglomeration in dry land double cropping areas is becoming more and more obvious,especially in Chengdu,Xi'an,Nanjing,Hefei,Jinan,Taiyuan,Shijiazhuang,Beijing and Tianjin.The overall fertility of the dry land double cropping area has been increasing,but the regional statistics show that the fertility of cultivated land in the other four areas has a downward trend in varying degrees,except in the southwest area.Among them,the central and southern areas of North China and the northwest areas are the most serious,and the area of V and other areas account for a large proportion,and the fertility of cultivated land and soil is not optimistic.2.The change of soil nutrient fertility of cultivated land in Dryland double cropping area is influenced by natural environment and human activities,but the natural environment is weakening and the influence of human activities is increasing.With the development of economy and the gradual improvement of agricultural policy,the degree of agricultural mechanization has been strengthened,the proportion of cultivated land irrigation has been expanded,and the input of agricultural materials such as nitrogen,phosphorus,potassium fertilizer and compound fertilizer has been continuously increased.Until the national formulation period(2014s),the correlation between soil nutrients and soil comprehensive fertility of cultivated land and natural environmental factors is not significant.In this period,except annual average precipitation and soil comprehensive fertilizer of cultivated land is not significant.There was a significant correlation between the force(P<0.05),but the influence of other natural environmental factors gradually weakened.However,with the increasing interference of human activities,the influence of structural factors such as natural environment is gradually blurred,and non-structural factors such as human activities gradually become the main factors affecting the spatial and temporal changes of nutrients and fertility of cultivated land.3.The proportion of primary industry employment positively drives the content of soil organic matter and total nitrogen in cultivated land.The income gap between urban and rural residents positively drives the content of soil total nitrogen and available phosphorus.The other factors negatively drive the content of soil organic matter and total nitrogen.Excessive fertilization easily leads to the degradation of farmland fertility.With the development of economy,the agricultural income of farmers growing agricultural products is increasing year by year,but the income gap between urban and rural residents is widening year by year.In order to improve the income of farmers,the proportion of"part-time" farmers or "non-agricultural" farmers is increasing.Increasing the amount of chemical fertilizer application has become a "efficient" way to increase crop production in the short term.Farmland soil fertility is a comprehensive reflection of many indicators.The change of single indicator will not cause great changes,but the proportion of farming is low,the amount of chemical fertilizer application is much higher than the safe line of international fertilizer application.It will continue to increase the load of farmland soil,and the trend of soil fertility reduction will be particularly obvious.4.According to the questionnaire survey,the farmer's behavior of farmland utilization,such as reducing fertilizer application,is mainly affected by the gender of farmers and the identity of village cadres.Family characteristics,such as crop sowing area,agricultural income and the proportion of grain output,are significantly related to the cognition of fertilizer pollution,fertilizer brand and policy recognition.Among them,the agricultural income,policy recognition and brand recognition of chemical fertilizer are higher,while the proportion of gender,sowing area and grain yield of farmers is lower.Farmers' policy support to the government depends on government financial subsidies and related agricultural technology training,which are conducive to the promotion of agricultural income.Therefore,the next step can be based on the existing research basis to formulate reasonable government funding subsidies or technical support for arable land protection projects to carry out exploratory research. |
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