Effects Of Nitrogen Fertilizer Optimization And Control Measures Of Continuous Cropping Obstacles On Facility Cucumber Yield And Nitrogen Use Efficiency

In recent years,our country facility agriculture develops rapidly and made great contribution to our country's vegetable supply and the development of agricultural economy.But it is also accompanied by a series of problems such as excessive fertilization and continuous cropping obstacle.Aiming at these problems in this study,by comparing the differences in nutrient absorption and utilization and the kinds of allelochemicals between healthy and diseased vegetable crops under continuous cropping.lt is analyzed that the deterioration of soil and allelopathy are the main causes of soil borne diseases.Take the cucumber as the research object,two field experiments were conducted on nitrogen fertilizer optimization and control measures of continuous cropping obstacles.The effects of different nitrogen supply and control measures on nutrient uptake and nitrogen use efficiency were studied.The experiment of nitrogen fertilizer optimization is mainly to reduce the nitrogen fertilizer based on the farmers' fertilizer practice.The optimal nitrogen fertilizer was selected by comparing cucumber yield and nitrogen use efficiency in different treatments.The test of control measures of continuous cropping obstacles is mainly focuses on improving soil characters and preventing cucumber fusarium wilt by adopting different prevention and control measures based on OPT1.From the aspect of nutrient utilization,the optimal prevention and control measures were selected by comparing the soil physicochemical properties,yield and nitrogen use efficiency under different prevention and control measures.This study aimed to provide theoretical and practical basis for the high efficiency fertilization and the prevention of soil borne diseases in the local facility agriculture.The major results are list as follows:1.The deterioration of soil and allelopathy are unfavorable to plant growth under continuous cropping.The surplus of the soil nutrient and EC value were higher under diseased plants and the soil pH value was lower compared with healthy plants.The nutrient content of healthy plants was higher than that of the diseased plants.There was a significant change in the kinds of allelochemicals in the rhizosphere and the accumulation of harmful substances increased after the plants become diseased.There are more kinds of allelochemicals in the rhizosphere in healthy plants,mainly alkanes,phenols,amines and alcohols.There are mainly alkanes and organic acids in diseased plants,which are one of the main components of inhibited allelopathy.2.OPT reduce can nitrogen fertilizer input while keeping yield and improve nitrogen use efficiency.The nitrogen use efficiency under OPT1 and OPT2 was significantly higher than that under FFP while no significant difference in yield was observed between FFP and OPT1 and OPT2.The nitrogen use efficiency increased by 4.4%and 2.2%respectively and OPT1 is better in improving the nitrogen use efficiency.3.Adopting different prevention and control measures based on OPT1 can improve soil properties,promote the absorption and utilization of nutrients and the nitrogen use efficiency was further improved.Compared with OPTl,the surplus of the soil nutrient decreased,while the yield and nitrogen use efficiency increased significantly.Among them,the comprehensive prevention and control measures have the best effect on improving soil quality and increasing yield and efficiency.The yield and nitrogen use efficiency increased by 19.4t hm-2 and 6.1%respectively.To sum up,the deterioration of soil and inhibited allelopathy are unfavorable to plant growth,nitrogen fertilizer optimization and control measures of continuous cropping obstacles can improve soil properties,promote the absorption and utilization of nutrients,and improve the yield and nitrogen use efficiency.