Objective Soil nutrient is necessary for agricultural production. Understanding the spatial variation of soil nutrients is of great significance to guide fertilization.
Methods The contents of soil organic matter, available phosphorus, readily available potassium and total nitrogen in Keshan County, Heilongjiang were acquired from a soil survey collected in Keshan County. Based on geostatistics method and ArcGIS software, the kriging and pan-kriging interpolation were obtained from the soil nutrients data, and the spatial distribution maps of soil nutrients in Keshan County were drawn. The topographic factors, including slope, slope direction and curvature which were obtained from DEM data of Keshan County, and the relationship between these factors with the kriging and pan-kriging interpolation were also analyzed with the SPSS software.
Results The average contents of soil organic matter (OM), available P (AP), readily available K (AK) and total N (TN) in Keshan County were 43.89 g/kg, 28.35 mg/kg, 184.75 mg/kg and 1.81 g/kg, respectively. Both the variation coefficients of OM and TN were 0.09, belonging to weak variation, and those of AP and AK were 0.18 and 0.11 respectively, belonging to medium variation. The OM, TN and AK contents showed extremely significant correlation with the altitude (P < 0.01), and OM and TN contents were significantly affected by the slope degrees as well. The OM, TN and AK contents in dryland and vegetable land were significantly higher than those in paddy fields, and the AP contents were opposite.
Conclusions The soil organic matter and total nitrogen are evenly distributed as the strong human impaction, and the available phosphorus and potassium are the uneven distributed in the Keshan area as the less fertilization practices. Altitude is found to be the main factor influencing the spatial distribution of nutrients. The land use type, soil type and soil parent material type also play roles in the distribution of nutrient.
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