河南南阳盆地东南耕区表层土壤养分地球化学综合评价及影响因素

为了全面加强河南南阳西南耕区土地资源的利用、开发和管理工作,充分了解当地土壤的养分状况,通过实地调研、样品采集、实验分析等手段对研究区内各乡镇耕地土壤的pH值及养分(TN、TP和K)的空间分布特征进行研究,讨论不同土地利用方式下pH值及养分数据之间的差异及其各自的影响因素。半方差分析结果表明,TP最佳拟合模型为指数模型,TN、pH值、K含量以及有机质为球状模型。研究区pH、养分均表现出较弱的空间相关性,反映其受到人类活动的影响较为强烈。研究区土壤pH平均值为5.44,偏酸性,总体上呈现南高北低的空间分布特征。养分等级评价显示:TN、TP、K含量较为丰富,而有机质较为缺乏,分别为分级标准中的Ⅲ级、Ⅲ级、Ⅱ级和Ⅳ级。土壤养分地球化学综合等级评价显示,全区养分等级总体上以中等为主,占总点位的69.1%,全区广泛分布。Pearson相关性分析发现研究区内土壤pH与有机质、TN弱负相关,与K显著正相关;有机质与TN表现为显著正相关,与K为负相关。不同土地利用方式下土壤各因子差异显著,旱地土壤pH值、TN、有机质以及K含量的平均值均小于灌木林地,而TP则相反。此外,区内作物调查显示玉米种植区平均pH值低于花生种植区。施肥方式、用量及种类、作物类型、土地管理、种植结构和土壤背景是造成全区养分及pH值分布差异的主要原因。

Comprehensive Evaluation and Influencing Factors of Surface Soil Nutrient Chemistry in Southeastern Cultivated Area of the Nanyang Basin,Henan Province

To comprehensively strengthen the utilization, development and management of local land resources and understand the local soil nutrient status, we conducted field investigation, sample collection and experimental analysis to characterize the spatial distribution, pH and nutrients in each township in the southeastern cultivated area of the Nanyang basin,Henan Province.We discussed the differences of pH and nutrients under different land use patterns and their influencing factors.The semi-variance analysis shows that the optimal fitting model for TP is exponential, and spherical model for TP, pH, K and organic matter.The local soil pH and nutrients show weak spatial correlation, indicating that the local soil is strongly affected by human activities.The average local soil pH is 5.44 (slightly acidic), and in terms of spatial distribution it is generally high in the south and low in the north.Nutrient grade evaluation shows that the contents of TN, TP and K are relatively rich, while organic matter is relatively lacking, which are Grade Ⅲ, Ⅲ, Ⅱ and Ⅳ, respectively.Comprehensive soil nutrient assessment shows that the nutrient level in the whole region is mainly medium, accounting for 69.1% of the total assessment points, and it is widely distributed in the whole region.Pearson correlation analysis shows that the local soil pH is weakly negatively correlated with organic matter and TN, and strongly positively correlated with K.Organic matter has a strong positive correlation with TN and a negative correlation with K.Soil factors are significantly different under different land utilization types.The data show that the average values of pH, TN, organic matter and K content in dry land soil are all lower than those in shrub land, while the values of TP are the opposite.In addition, local crop survey shows that the average pH in the maize growing area is lower than that in the peanut growing area.The main reasons for such variation are likely the different fertilization methods, dosage and types, crop types, land management, planting structure and soil background.Keywords:soil nutrient;land utilization type;spatial variation;influencing factor; Nanyang basin