Investigation And Analysis Of Soil Obstacles In Facilities And Its Correction Effect

With the rapid development of economy and the gradual adjustment of agricultural industrial structure,the area of facility agriculture,especially facility vegetable cultivation,had been expanding in China.The area of protected vegetable accounted for more than 95%of the total protected cultivation area.In recent years,high input of chemical fertilizers has been adopted in order to achieve high yield,the capacity of sustainable production of protected vegetable soil has been continuously reduced in the protected vegetable production.A number of problems emerged,such as obstacles cause by continuous cropping,nematode damage,salinization of greenhouse soil,seasonal destructive diseases and insects,etc.Among them,the problems of excessive accumulation of nitrogen and phosphorus in soil,secondary soil salinization,nitrogen and phosphorus pollution in water environment and safety of agricultural products are becoming prominent.Researches have been carried out on the secondary salinization of various types of greenhouse soils,but they mainly focus on the occurrence mechanism,salt accumulation characteristics,soil ion composition,water pollution load and so on,but the application technology to solve the problem of soil secondary salinization is insufficient.The problem of soil secondary salinization has become an important factor restricting the development of protected agriculture in China.Presently,the facility vegetable industry has become an important item of modern agricultural development in Suqian,Jiangsu provinces.It is critical to increase the income of the people and ensure the effective supply of vegetables.However,the soil obstacles have seriously hindered the development of facility vegetable industry and the increase of farmers' income.In order to reduce production losses caused by continuous cropping obstacles,some vegetable farmers have increased the use of chemical fertilizers and pesticides.Statistically,the annual production cost has increased by 2,000-6,000 yuan per hectare,while the production income has decreased by 20-50%and the crop failed in the worst scenario.Moreover,it caused the high content of pesticide residues in vegetable products and polluted the regional ecological environment.This papers aimed to find a solution to eliminate the soil continuous cropping obstacle via fertilization technology.The objectives were:(1)to study the effect of balanced fertilization on the yield and quality of Muskmelon,water-soluble nitrogen and salt in soil,and to provide effective reference for the treatment of soil obstacles in greenhouse.(2)to study the effect of nitrogen reduction measures based on balanced fertilization on yield and quality of purple cabbage,reduction of soil nitrogen pollution and elimination of secondary salinization.The methods used in this paper included literature review,interview on special topics,questionnaire survey,sampling analyses,field experiment and statistical analyses.In view of the problems of soil secondary salinization caused by fertilization of local vegetable farmers in Suqian City,a survey was carried out,followed by the experiments of balanced fertilization and nitrogen reduction fertilization.1.Investigation and analyses of soil barrier of protected vegetableThrough multi-site investigation and analysis of protected soils in Suqian,the results are as follows:(1)there was a problem of low organic matter content and available phosphorus level in the typical greenhouse soils in the whole region,and secondary salinization in some soils.The contents of available nitrogen and available potassium were higher than required,with big variation among different sites.There are still problems of insufficient supply of nitrogen and potassium in some sites.(2)The content of water-soluble salt in soils varied greatly,high concentration of salt leads to salinization of soil,while low concentration of salt could not meet the basic demand of crop growth;K+/Mg2+ was high in some soils,K+/Mg2+ was low in some soils,and Mg2+/Ca2+was low in most soils.(3)the level of micronutrients in some soils was low.2.The balanced fertilizer experimentThrough the diagnosis of the influencing factors of soil nutrient imbalance,the type and degree of nutrient deficiency were defined,the formula of balanced fertilizer was designed and the experiment of balanced fertilizer dosage was carried out.The response of crops to balance fertilizer was observed and compared to determine the optimal formula of balance fertilizer.The results showed that the recommended dosage of balanced fertilizer was 450 kg/hm2,which could not only maintain high yield and good quality of crops,but also reduce the pollution load of soil water-soluble nitrogen and other ions to the environment.Tt was beneficial to improve the soil fertility and eliminate many obstacle factors.3.The experiment of nitrogen reduction under balanced fertilizationThe representative soils were selected with disturbance factors such as nutrient imbalance,nitrogen surplus,secondary salinization and so on for the nitrogen reduction experiment.The results demonstrate that soil testing and balanced fertilization according to crop yield,quality and soil properties is necessary.The amount of nitrogen fertilizer could be reduced to 50%of that of conventional fertilization.