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

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14.51-376.18mg.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。

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.