定安县耕地土壤主要养分的空间变异

运用地理信息系统（GIS）和地统计技术，对海南定安县145个土壤样本数据进行探索性空间数据分析，得知样点土壤的有机质、全氮、有效磷、速效钾存在空间自相关，然后采用Kring球体模型插值法，输出土壤养分空间分布图，据此分析土壤养分空间分布特征。结果表明，定安县土壤有机质、全氮含量较丰富，有效磷含量缺乏，速效钾含量严重缺乏。有机质与全氮的分布格局基本相似，南部含量较高，北部含量较低，四、五等级耕地的有机质、全氮含量高，二、三等级耕地的有机质、全氮含量较低。定安县西北部有效磷含量较高，东南部有效磷含量较低，四、五等级耕地有效磷含量较低，二、三等级耕地有效磷含量较高。整个定安县速效钾缺乏，尤其是北部，二、三、四等级耕地的速效钾含量均很低。

Spatial Variation of Soil Main Nutrients on Arable Land in Ding'an County

The GIS and geostatistical analysis technology was used to analyse the spatial data for 145 soil samples collected in Ding'an County, Hainan Province, and spatial autocorrelation was found among the organic matter, the total nitrogen, the available phosphorus, and the available potassium in the soil samples. A spatial distribution map of soil nutrients was exported by adopting Kriging's Spherical Model interpolation, and the characteristics of the soil nutrients for their spatial distribution were then analyzed. The results showed that the soil in Ding'an County contained rather high organic matter and total nitrogen, low phosphorus, and very low available potassium from the spatial distribution map of soil nutrients. The organic matter content and the total nitrogen content were distributed similarly in Ding'an County, rather high in the south but low in the north, high in Grade 4 or 5 arable land but low in Grade 2 or 3 arable land. The content of the available phosphorus was higher in the northwest than in the southeast, and higher in Grade 2 or 3 arable land than in Grade 4 or 5 arable land. The content of the available potassium was very low in the soil of the whole Ding'an County, especially in the north, and in Grade 2 or 3 arable land.