Spatial and temporal variability of soil nutrients in township-scale agricultural fields
Based on the soil data of four periods in 1982(the second soil census),1998,2008,and 2018,geostatistic and Kriging interpolation methods were used to analyze the spatio-temporal variation characteristics of topsoil organic matter(SOM),total nitrogen(TN),available potassium(AK),and available phosphorus(AP)in Zong'ai Town of Shouyang County,Shanxi Province.Combined with the center of gravity model,the center of gravity migration direction of nutrients was explored,and the spatio-temporal variation patterns of the soil nutrients and their influencing factors were revealed during the period of 1982-2018 in Zong'ai Township.The results showed that the average contents of soil SOM,TN and AP,AK increased by by 3.30,0.19 g·kg-1 and 7.75,53.13 mg·kg-1,with the increase rate of 26.92%,26.39%,131.80%and 70.31%,respectively,from 1982 to 2018.SOM and AP contents showed an increase-decrease-increase trend from 1982 to 2018,while AK and TN contents kept increasing.Compared with 1982,the block-base ratios of SOM,TN,AP,and AK increased in 2018,indicating that the nutrients of the four periods of time were jointly influenced by structural and non-structural factors(random factors)and the degree of influence by non-structural factors gradually increased,and the influence of anthropogenic activity interference became more significant.In 2018,the spatial distribution characteristics of SOM contents in the study area showed a pattern of high content in the southeast and low content in the northwest.While AK contents high in the south and low in the north.The spatial distribution characteristics of AP and TN content were relatively uniform.The contents of SOM and TN increased in the south and the contents of AP and AK increased in the southeast of the study area;the spatial distribution of SOM content tended to be concentrated and the spatial distribution of AP,AK,and TN content appeared to be dispersed.Fertilization and straw returning were the major factors affecting the spatio-temporal difference of nutrient content in Zong'ai Town.The water-suitable straw returning to the field must be carried out according to the field conditions and attention must be paid to"controlling nitrogen,stabilizing phosphorus,and reducing potassium to supplement micro-fertilizer"to ensure the stable improvement of cultivated land quality.
agricultural soilsoil nutrientKriging interpolationcenter of gravity modelspace-time evolution
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