德阳旌阳区土壤氮素空间变异特征及影响因素分析

Spatial variability of soil nitrogen and its impacting factors in Jingyang District, Deyang City

根据德阳市旌阳区1803个土壤采样点数据,采用地统计学和回归分析方法,对其土壤全氮和碱解氮的空间变异特征进行分析,探讨不同因素对其空间变异的影响。结果表明,研究区土壤全氮和碱解氮含量范围分别为0.52-4.38 g/kg和15.00-326.74 mg/kg,均处于较丰富的水平。土壤全氮和碱解氮的块金值与基台值之化分别为0.264和0.505,具有中等空间相关性,受结构因素与随机因素共同影响。空间分布上均表现为西部平原区明显高于东部丘陵区。土壤母质可独立解释25.7%和12.2%的全氮和碱解氮空间变异。地形因素的解释能力分别为16.7%-29.7%和7.6%-16.2%,其中坡度因子的解释能力最大。土类、亚类和土属对全氮和碱解氮空间变异的独立解释能力分别为23.4%、28.0%、36.6%和12.5%、13.8%、18.6%。种植制度对全氮空间变异的解释能力为33.8%,小于土属的影响程度;对碱解氮的解释能力为22.4%,大于各种结构因素的独立解释能力。研究结果表明研究区土壤全氮空间变异主要受母质、地形等结构因素的综合影响,而人为活动因素是碱解氮空间变异的主控因素。

Spatial pattern of soil total nitrogen（TN） and available nitrogen（AN） in Jingyang district, Deyang City were analyzed using Geostatistics methods. The effects of the impacting factors were quantified by regression analysis, based on 1803 soil samples. Result show that the concentration of soil TN and AN range from 0.52-4.38 g/kg and 15.00-326.74 mg/kg respectively, with mean values of 2.19 g/kg and 140.68 mg/kg. This indicates that the study area is rich in soil nitrogen. The values of the nugget to sill ratio are 0.264 and 0.505, which suggests that TN and AN have moderate spatial dependence and their spatial variability are determined by structural （e.g., parental material and topography） and random factors. Within the study area, the concentration of TN and AN in plain area are much higher than that of hilly area. Soil parent materials could explain 25.7% and 12.2% of TN and AN spatial variability respectively. Topographical factors explain 16.7%-29.7% of TN variability and 7.6%-16.2% of AN variability respectively. Specifically, the explanation ability of slope is largest among all topographical factors. Soil group, subgroup and soil genus could explain 23.4%, 28.0%and 36.6% of TN variability and 12.5%, 13.8% and 18.6% of AN variability respectively. In addition, the cropping systems explain 33.8% of TN variability which is lower than that of soil genus. In contrast, 22.4% of AN spatial variability could be explained by cropping systems which is larger than those of all structural factors. This suggests that spatial variability of TN is mainly determined by parent materials, topography and other structural factors. In contrast, the dominant factor of AN spatial variability is anthropogenic factor.