江津市紫色土中N、P养分元素区域空间变异性研究

利用地统计学,结合GIS研究紫色土土壤表层(0～20cm)的全氮、碱解氮、全磷和速效磷4种养分含量的空间分布特征结果表明,全氮和速效氮为正态分布,全磷和速效磷为对数正态分布;通过半方差函数分析,发现全氮存在纯块金效应,块金值为0.2,其它养分在一定间距内(50m)存在空间相关性,且为中等强度的空间自相关性(块金值与基台值之比在25%～75%之间);用普通克立格法和对数正态克立格法进行最优内插,做各种养分含量的分布图.结合GIS可充分了解土壤中N、P养分的空间变异性规律,并可进一步应用于精确施肥和农业非点源污染预测和控制.

Investigation of the Spatial Variability of Nitrogen and Phosphorus in Purple Soils in Jiangjing City, Sichuan, China

In this paper, the spatial distribution pattern of the total nitrogen, available nitrogen, available phosphorus and total phosphorus in surface purple soil (0-20 cm) with a city region were analyzed by applying geostatistics combined with GIS. The spatial distribution pattern of the four soil nutrient parameters were quantitatively described with semivariogram and the soil nutrient content distribution pattern was constructed by using Ordinary Kriging and lognormal Kriging optimal interpolation. The results indicated that total nitrogen, available nitrogen showed a normal distribution, the others with a lognormal distribution; the analyst of semivariogram indicated that the total nitrogen showed the pure nugget effect with the nugget of 0.2, others were correlated in a given spatial range (50 m) with mild spatial relativity, the nugget-to-sill ratio was from 25% to 75%. Preliminary analysis was made for the spatial variability of the soil nutrients by using the group map of the soil nutrients with Ordinary Kriging. These results could be useful for further application in precision fertilization and for evaluation of non point polluting of agricultural lands.