鄂西北耕层土壤全氮含量空间分异特征及其影响因素分析

Total Nitrogen in Plough Layer Soil in Northwest Hubei:Spatial Variability and Influencing Factors

旨在分析鄂西北耕地表层土壤全氮含量的空间变异特征及其影响因素。采用地统计学、逐步回归方法和GIS技术。研究结果表明:(1)十堰市耕层土壤的全氮平均含量为1.12 g/kg,耕层土壤全氮含量较高,701个土壤样点全氮含量变异系数为0.49,属于中等变异程度。(2)土壤全氮的空间变异最佳模型为高斯模型,块金效应值为48.09%,全氮具有较强的空间变异性特征,且受随机性因素和结构性因素的共用影响。(3)十堰市耕层土壤全氮含量在空间分布上具有明显的差异,全氮含量高的方向为南、西、西南和东南,全氮含量低的方向为东、东北和西北,全氮含量在南北方向的变异性最明显,差别较大。(4)全氮与有机质、海拔、有效土层厚度有正相关关系,与土壤pH有负相关关系。在黏土、棕壤、水田、河湖冲积物、第四纪老冲积物、一年一熟、种植水稻的土壤中全氮含量较多,在砂壤、紫色土、紫色岩类风化物和种植水果、小麦、喷灌方式下的耕地的全氮含量较少。(5)10种因素对全氮的影响程度排序为土壤环境>成土母质>熟制>生物多样性>农作物种类>耕层质地>土类>地形>耕地利用方式>灌溉方式,其中前5个因素是影响全氮空间分异的主导因素。在今后的农业生产活动中,需要在河谷和山谷带、一年二熟区、红砂岩类风化物和紫色岩类风化物带、有机质含量较少区可适当地增加氮肥的施用量,需保护生物多样性并重视人为因素对耕地质量的影响,采用农作物轮作等方式提高耕地质量和耕地生产能力。

The objective is to understand the spatial variation of total nitrogen and its main influencing factors in plough layer soil of northwest Hubei Province.The geostatistics,stepwise regression method and GIS technology were used in the study.The results show that:(1)the average nitrogen content of Shiyan City is1.12 g/kg,and the total nitrogen content of plough layer soil is relatively high,with a variation coefficient of 0.49 among the 701 sampling sites,the degree of variation is moderate;(2)the best model for spatial variability of soil total nitrogen is Gaussian model,and the nugget effect value is 48.09%;total nitrogen has strong spatial variability and is affected by the sharing of random factors and structural factors;(3)the total nitrogen content of the plough layer soil in Shiyan City has obvious difference in spatial distribution,areas in the south,west,southwest and southeast have high total nitrogen content,but areas in the east,northeast and northwest have low total nitrogen content,the north-south direction variation is the most obvious and the difference is large;(4)total nitrogen has a positive correlation with organic matter,elevation,and effective soil thickness,and has a negative correlation with soil pH;there is more total nitrogen in plough layer soil such as clay,brown soil,paddy fields,alluvial deposits of rivers and lakes,quaternary alluvial deposits,double cropping and rice planting soils,there is less total nitrogen in sandy soil,purple soil,purple rock weathering materials,fruit planting soil,wheat soil,and soil under sprinkler irrigation;(5)the influence degree of ten factors on total nitrogen is ranked as soil environment>soil parent material>maturity>biodiversity>crop species>soil texture>soil type>terrain>land use mode>irrigation method,and the first five factors are the dominant factors affecting the spatial differentiation of total nitrogen.In future agricultural production,it is necessary to appropriately increase the application amount of nitrogen fertilizer in the river valley and mountain valley,the double cropping area,the red sandstone weathering and the purple rock weathering zone,and the areas with less organic matter content area.Biodiversity needs to be protected and the impact of human activities on soil quality should be highlighted,and crop rotation could be adopted to improve the quality and production capacity of cultivated land.