| Vegetables are one of the foods on which people depend for their survival.With the prevalence of healthy diets activities,people’s demand for vegetables has increased significantly and they have also begun to pay attention to the problems of vegetable fertilizers.People from all walks of life work together to create an environment for vegetables safety.Because of its fast growth,large amount of fertilizer,high index of multiple cropping,and high yield,vegetables have high frequency of soil use,and the amount and frequency of application of chemical fertilizers are larger than those of general food crops.Therefore,the status of soil nutrients in vegetable areas affects the growth,development and fruit of vegetables directly,and is closely related to the yield and quality of vegetables.At present,there are problems such as blind fertilization and excessive fertilization in the field of soil nutrient management in vegetable areas.These unreasonable fertilization methods will cause ecological environmental pollution.Therefore,it is necessary to carry out a thorough investigation on the fertilization status of vegetable farmers in vegetable areas.Taking the soil nutrient environment in the concentrated vegetable growing area(vegetable area)of Xi’an City,Shaanxi Province as the research object,the traditional statistics and the geostatistics in GIS analysis techniques were used to study their spatial variability and spatial distribution characteristics of the pH value,electrical conductivity,organic matter,alkali-hydrolyzable nitrogen,available phosphorus and available K in vegetable areas.Comprehensive evaluation was performed based on fuzzy mathematics and cloud model methods from the single factor and comprehensive nutrient.Distribution map of soil nutrients environmental grade were drawn and explore the applicability of cloud models in the assessment of soil nutrient environment;Statistical methods were used to analyze the status of fertilization quantitatively for Chinese cabbage and tomato farmers,and evaluate their fertilizer amount and fertilization methods.Combined with the rule of vegetables requirement fertilization,find the existing problems,and put forward proposals for improving fertilizers.The research results provide theoretical and technical support for nutrient mapping in vegetable areas,partition management,precision fertilization and sustainable development of the vegetable industry.This research mainly achieved the following research results: pH value,organic matter,alkali-hydrolyzable nitrogen,available phosphorus and available K in vegetable areas of Xi’an have good spatial correlations.The properties of soil,climate,and topography are the dominant factors that cause spatial variation;The space correlation of electrical conductivity,alkali-hydrolyzable nitrogen is weak,and the cultivation system of vegetable farmers and soil fertility have a greater influence on their spatial pattern;the spatial variation of electrical conductivity is dominated by massive variation,and the other nutrients are mainly small variations;and soil nutrients according to vegetable areas in Xi’an From the content of spatial distribution map,and the perspective of zoning analysis,the soil content of available K and electrical conductivity is higher,the content of organic matter is lower,and the content of other nutrients is in the middle in Yanliang District;the soil available phosphorus,available K,and electrical conductivity are higher.The level of organic matter is low,and the content of alkali-hydrolyzed nitrogen is moderate in Gaoling District.In the Lintong District,the indicators of soil are average,and only the electrical conductivity value is low.The content of available phosphorus and available K is low,and the other indicators are generally in the same level in Zhouzhi District.In the Huyi District,the content of soil indicators is low,which needs to be further improved.The content of soil organic matter is good in Chang’an District,but the content of available phosphorus is low.The others indicators are at a general level,and according to the distribution characteristics of soil nutrients in the vegetable area,the decision of soil fertilization can be made and the appropriate amount of fertilizer can be formulated.The soil nutrient environment in vegetable areas in Xi’an was at a moderately good level overall.The percentage of total vegetable area occupied by each grade was calculate by Cloud model method: worst(0.63%),poor(9.11%),general(50.88%),good(35.65%),best(3.73%).The nutrient environment in Yanliang District,Gaoling District,Linyi District,and Yongqiao District was relatively good.The Chang’an District and Lanzi District were at a medium level.The soil nutrient environment in Zhouzhi County was relatively poor.Soil organic matter has become the primary factor limiting the soil nutrient environment in vegetable areas.At the same time,nitrogen fertilizer and potassic fertilizer are still necessary in worst and poor areas.The evaluation method of soil nutrient environment based on cloud model retains the ambiguity,randomness,statistical in the evaluation process.In this way,the evaluation of soil nutrient environment can be more objectively in Xi’an vegetable area,and the assessment results are more convincing.The fuzzy comprehensive evaluation system of cloud model is practical and feasible in the field of soil nutrient environment assessment.The proportion of N,P and K fertilization applied by vegetable farmers in Xi’an was imbalanced and the degree of rationality was low.In regard to the amount of fertilizer and the ratio of each nutrient,tomato nutrient fertilizer application is more scientific and more reasonable than Chinese cabbage.Vegetable growers generally have large differences in the application of potash fertilizers,especially for vegetable farmers who grow Chinese cabbage.Excessive fertilization of Chinese cabbage is nitrogen fertilizer and phosphate fertilizer,and the phenomenon is more serious,application amount of potassium fertilizer exists excessive and insufficient phenomenon;For fertilizer amount of tomato,the most appropriate amount is phosphorus fertilizer,application amount of nitrogen fertilizer and potassium fertilizer exists excessive and insufficient phenomenon,and the excess ratio is greater than the deficit ratio.The proportion of potash fertilizer in Chinese cabbage is far less than the recommended fertilization ratio.The recommended ratio of NPK to tomato is 1:0.44:1.33,while the actual fertilization ratio is 1:0.50:0.77;the planting yield of Chinese cabbage in Xi’an is at a low level,which is related to the low utilization rate of nitrogen fertilizer,and the Chinese cabbage yield level needs to be improved.The tomato production is at a medium level and there is growth space for increased production.If the amount of fertilization growers to a reasonable level,the average yield of reasonable fertilization can be achieved also,then the yield of Chinese cabbage in the vegetable area can increase by 7314 kg,and the tomato yield can increase by 15193 kg.Pay attention to vegetable topdressing,fertilization methods should smaller,and more frequent in order that increase topdressing frequency and reduce the amount of fertilizer.It is an important period for Chinese cabbage to require nitrogen fertilizer in rosette stage and cabbaging-phase,and it is necessary to supplement frequency of nitrogen fertilizer.In tomato fertilization,potassium fertilizer deficiency is the most serious,and vegetable growers need to increase potash fertilizer.The topdressing fertilizer rate needs to be increased.It can promote and popularize comprehensive integrated technologies such as straw return,organic fertilizer application and green manure cultivation,pay attention to the balanced application of organic fertilizer and chemical fertilizer,increase soil organic matter,vigorously study and improve the utilization rate of fertilizers,and standardize management measures for vegetable farmers to achieve the sustainable development of the vegetable industry. |
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