高阳县农田土壤速效养分空间变异特征研究

Spatial variability of available nutrients contents in cropland soils in Gaoyang County of Hebei Province, China

  • 摘要: 土壤养分空间变异的研究对指导测土配方施肥具有重要意义。为了便于土壤养分的管理, 以河北省保定市高阳县为例, 应用地统计学和GIS相结合的方法, 研究了农田土壤速效氮、磷、钾含量的空间变异特征。结果表明: 土壤速效氮、磷、钾的含量范围分别为10.50~210.00 mg·kg-1、1.02~197.75 mg·kg-1和14.51~376.18 mg·kg-1, 平均值分别为76.32 mg·kg-1、22.28 mg·kg-1和128.34 mg·kg-1, 变异系数范围为36.11%~79.71%, 属于中等强度变异。速效氮、磷、钾的C0/(C0+C)值均介于25%~75%, 表现出中等强度的空间自相关, 空间变异是结构因素和随机因素共同作用的结果, 空间相关距离分别为43.96 km、1.05 km和51.94 km。通过插值误差的比较得出最优拟合模型, 速效氮、磷、钾最好的理论模型分别为球状模型、指数模型和球状模型, 趋势效应参数宜选取0阶。然后用普通克里格方法绘制了土壤速效氮、磷、钾的空间分布图, 速效氮含量绝大部分属低等水平, 无明显分布特征, 速效磷空间分布呈条带状, 速效钾空间分布呈条带状和岛状分布相结合的特点。

     

    Abstract: This study used GIS and geostatistics to analyze the spatial variability and content distribution of available N, P and K as part of a comprehensive management of soil nutrients in Gaoyang County of Hebei Province. Results showed that available N and P distribution was lognormal while that of available K was normal. The averages of soil available N, P and K were respectively 76.32 mg·kg-1, 22.28 mg·kg-1 and 128.34 mg·kg-1. The coefficients of variation ranged from 36.11% to 79.71%, which suggested that the variations were at medium levels. The result showed that C0/(C+C0) of available N, P and K were respectively 38.79%, 74.27% and 32.33%, which suggested moderate spatial self-correlations. The spatial variability was caused by structural and random factors. Available K had the longest correlation range (51.94 km), available P the shortest (1.05 km) and that of available N was 43.96 km. Integrated comparisons in interpolation errors were conducted, and the best theoretical model of semivariogram of soil available N, P and K were established, which turned out to be spherical, exponential, spherical models, respectivley, with preferable 0-order trend effect. Spatial distribution maps of available N, P and K contents in cropland soils constructed by using universal Kriging interpolation objectively reflected nutrient abundance/deficiency in the study area. The maps suggested that the characteristics of the spatial distribution of available N was insignificant, available P was mainly with a banding distribution and available K was with both banding and island distribution. The content of available N was low, the area of land with 60~90 mg·kg-1 available N accounted for 93.13% of the investigated region. This suggested that there was the need to increase soil nitrogen in the study area. The contents of available P and K were in the medium-to-high range in most of the study area. Also the spatial distribution of available P showed that areas of low, medium, high and very high grades were respectively 0.34%, 31.97%, 46.98% and 20.71% of the study area. Available K map showed that the areas of low, medium, high and very high grades were respectively 0.04%, 40.36%, 54.12% and 5.48% of the study area. The figures of the GIS-based nutrient variability reflected the spatial distribution of soil nutrients and provided the theoretical basis for decision-making and soil nutrient management in the study area.

     

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