Spatial And Temporal Variation Of Soil Nutrients In Cultivated Land Of Fujin City Based On GIS

Soil nutrient is an important part of soil and is the source of plant nutrients,which can supply and coordinate the nutrition and environmental conditions of plant growth,and it is of great significance in soil fertility,environmental protection,agricultural sustainable development and so on.Soil is in a dynamic process of change at a time,and different land use patterns and years of cultivation will result in changes and flows of soil nutrient content.Therefore,it is of great significance to master the spatial distribution of soil nutrients and to understand the changes of soil nutrients in different cultivated years to realize sustainable utilization of soil and sustainable agricultural development.In this paper,the semi-variation function of SOM,TN,AP and AK was studied by using GIS technology in Fujin city,Heilongjiang province,using the principles of mathematical statistics and geostatistics,and the theoretical model was established.;analyzed the law of spatial variability of soil nutrients.This paper discusses the relationship between the length of cultivation and soil nutrient content,and analyzes the characteristics of soil nutrients under different tillage years.:(1)Analysis of nutrient characteristics of cultivated land in fujin city.The results showed that the average content of SOM,TN,AP and AK were 38.62g/kg,1.89g/kg,24.82mg/kg and178.40mg/kg respectively.The four kinds of soil nutrients are abundant,which can basically meet the growing demand of crops.The variation coefficient of the four soil nutrient contents in Fujin city was in the range of 28.04%~55.16%,which was moderate variation.The order of variability was:available phosphorus>available potassium>organic matter>total nitrogen.(2)The soil nutrient in the study area has a strong spatial autocorrelation,and its spatial variation is influenced by structure and random factors.From the large to small Moran’s I index,the order is: AK>AP>SOM>TN,Z(I)is greater than 2.58,with obvious spatial clustering characteristics.Spherical model is the optimal semivariable function model of soil SOM and AP,and soil TN and AK are exponential models.The block gold coefficients of SOM,TN,AP and AK in the study area were 53.8%,58.7%,50.1% and 51.7%,respectively,with moderate spatial correlation,and the four soil nutrients were all affected by human and natural factors.Soil total nitrogen has strong variability in the southeast and northwest directions,and the variation degree of the soil quick-effect potassium is significantly correlated with the distance in the northeast and southwest,and the degree of organic matter variation varies significantly with the increase of distance over 40 km.(3)The four kinds of soil nutrient contents in Fujin city have obvious spatial variation characteristics,and the spatial interpolation analysis of soil nutrients by kriging method is carried out.According to the second soil census and the grading standard of cultivated land force in heilongjiang province and combined with the actual classification,the soil nutrients are classified and graded according to the actual soil nutrients in Fujin city From the interpolation level diagram,SOM and TN have similar spatial variation trend.The content of SOM and TN in the central and southern soils is higher than that in the northwest region,and the effective phosphorus content in the east is higher than the effective phosphorus content in the west,which is decreasing from west to east.(4)There are significant differences between different years of reclamation and soil organic matter.The organic matter content of soil with different years of reclamation has the following relationship:reclamation of 10a>reclamation of 15a>reclamation of 25a>reclamation of 50 a.There are significant difference between different cultivated years and total nitrogen in soil,the variation of total nitrogen content in soil was small,but fluctuated greatly.There are significant difference between different cultivated years and soil available phosphorus.The content of available phosphorus in the study area increased with the cultivation slowly,followed by the decrease trend with the increase of the cultivated age.There is a significant difference between different cultivated years and soil available potassium,and the available potassium content can exhibit unregularity with the increase of the reclaiming period,and decrease the trend after the first increase.The findings provide data support new ideas for the improvements of soil salinization in Fujin city of Heilongjiang province.