白水河小流域退耕坡地土壤养分空间变异研究

以白水河小流域退耕坡地为研究对象,应用地统计学分析方法,分析研究区0~10 cm土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)和全钾(TK)的空间分布特征及其变异规律,探讨植被覆盖类型及其他环境因子对土壤养分空间分布的影响,为土壤养分的有效利用和管理提供理论依据。结果表明,(1)研究区SOC(Mean=18.847 g/kg)和TN(Mean=0.749 g/kg)的含量属于中等水平,TP(Mean=0.291 g/kg)和TK(Mean=3.333 g/kg)的含量则比较缺乏。各养分含量的变异系数(CV)在10%~100%之间,为中等变异性。(2)SOC拟合模型为高斯模型,TN和TK为球状模型,TP为指数模型。其中,TP和TK有强烈的空间自相关性,自相关变程范围分别为23.43 m和27.48 m,其空间变异主要由土壤母质、地形、气候等非人为的结构因素引起。SOC和TN表现为中等的空间自相关性,自相关变程范围分别为37.78 m和32.65 m,其变异是随机因素(施肥、耕作措施、种植制度等人为活动)和结构因素的共同作用。(3)各土壤养分总体呈空间连续分布的特点。不同的植被覆盖类型下土壤养分含量差异明显,植被自然恢复,人为干扰较小的灌木和樱桃+草本分布点的SOC和TN含量较高,经营管理强度较高的樱桃和樱桃+玉米分布点的SOC和TN含量较低。耕地施用磷钾肥明显提高了其TP和TK的含量。植被覆盖类型与TK的相关性不显著,说明植被对TK的分布影响较小。(4)相关性分析表明,SOC、TN、TP在土层浅薄、坡度大、岩石裸露率高的区域土壤养分含量较高,反之亦然。而TK含量的分布规律则与其他土壤养分相反,这可能与研究区施肥和土壤属性有关。不同土地利用方式施肥和种植结构的差异是引起这种空间分布特点的主要因素。

Research on the Spatial Variation of Soil Nutrients of De-farming Slope-land in Baishui River Small Watershed

Taking Baishui River small watershed de-farming slope-land as the research object, the spatial distribution charac-teristics and its variation law of soil organic carbon(SOC), total nitrogen(TN), total phosphorus(TP) and total potassium(TK) in 0~10 cm soil layer of study area were analyzed by geostatistical analysis method. Discussing the effects of vegetation cover types and other environmental factors on the spatial distribution of soil nutrient, which provided the theoretical basis for the effective utilization and management of soil nutrients. The results showed that: ①The contents of SOC (Mean=18.847 g/kg) and TN(Mean=0.749 g/kg) in the study area were moderate, and TP(Mean=0.291 g/kg) and TK(Mean=3.333 g/kg) were de-ficient. The nutrient content of coefficient variation (CV ) were between 10%~100%, belonging to moderate variability. ②The SOC fitting model was Gaussian model, TN and TK were spherical model, TP was exponential model. TP and TK had a strong spatial autocorrelation, the autocorrelation ranges were 23.43 m and 27.48 m, respectively. The spatial variability of TP and TK were mainly caused by non-artificial structural factors such as soil parent material, topography and climate. SOC and TN showed moderate spatial autocorrelation with the autocorrelation range of 37.78 m and 32.65 m, respectively. The variation was a combination of random factors(fertilization, tillage, cropping system and human activities) and structural factors. ③The spatial distribution of soil nutrient in the whole area was continuous. There were significant differences in soil nutrient con-tents under different vegetation cover types, the contents of SOC and TN were higher in the shrub and cherry+herbaceous plants with natural vegetation restoration and less human interference, and the contents of SOC and TN were lower in cherry and cherry+maize with higher management intensity. The contents of TP and TK significantly increased due to the application of phosphate and potash fertilizer in arable land. There was no significant correlation between vegetation coverage and TK, which indicated that vegetation had little effect on TK distribution. ④Correlation analysis showed that SOC, TN and TP had higher soil nutrient content in the area with shallow soil layer, high slope and high bareness rate, and vice versa. The dis-tribution of TK content was opposite to that of other soil nutrients, which may be related to fertilization and soil properties in the study area. Differences in fertilization and cropping patterns under different land using types were the main factors that contribute to this spatial distribution.