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宁夏砂田小尺度土壤性质空间变异特征与肥力评价
引用本文:王幼奇,白一茹,赵云鹏.宁夏砂田小尺度土壤性质空间变异特征与肥力评价[J].中国农业科学,2016,49(23):4566-4575.
作者姓名:王幼奇  白一茹  赵云鹏
基金项目:国家自然科学基金(41461104)、宁夏自然科学基金项目(NZ14028,NZ16026)
摘    要:【目的】砂田是西北干旱、半干旱地区农民在恶劣的气候、土壤和地形等自然条件下,为了生存经过长期生产实践不断总结创新所形成的一种独特的耕作方式。保持和提高砂田土壤肥力质量是改善土地生产力、延缓砂田退化的基础。【方法】按照10 m×10 m网格方式采集110个砂田土壤表层(0—20 cm)样品,选取土壤有机碳、全氮、全磷、全钾、速效磷、速效钾、pH和电导率作为土壤肥力特征的评价因子,采用相关系数法确定各土壤肥力指标的权重,根据宁夏砂田土壤特征和作物品种,选择隶属度函数曲线类型,同时确定隶属度函数转折点取值,然后根据各土壤肥力因子的权重和隶属度值计算土壤综合肥力指数值;利用地统计学分析方法构建土壤各肥力因子的最适半方差函数模型,确定砂田土壤各肥力因子的空间变异特征和空间格局;结合土壤综合肥力指数值及其空间分布状况对砂田土壤肥力特征进行分级评价。【结果】经典统计表明,pH的变异系数最小仅为0.01,表现为弱变异,均值为9.15,土壤呈碱性。其他肥力指标变异系数处于0.10—0.72,属于中等变异。通过极差可以看出各项土壤性质含量在农田尺度存在明显的差异。研究区土壤综合肥力指数值在0.18—0.59,平均值为0.34。地统计学表明,砂田土壤各项肥力指标块金系数均小于25%,呈现出较强空间自相关性。通过普通克里格空间插值图可以看出,土壤有机碳在田块尺度上分布较为均匀,含量集中在1.5—2.5 g·kg-1,在研究区南侧有机碳有岛状高含量点存在;电导率分布也较为均匀,集中在100—300μs·cm~(-1),其在北部含量较高;土壤全氮、全磷和全钾含量普遍较低,在空间呈现出明显的斑块状分布特征;土壤速效磷和速效钾在研究区北部有岛状高含量点存在;pH在整个研究区呈现明显的斑块状分布特征。土壤综合肥力指数值空间分布状况表明,研究区Ⅲ类地分布最广,占整个研究区面积的56%,属中等肥力状况。砂田南部以Ⅱ类地为主,占整个研究区面积的25%,肥力状况良好。Ⅳ类地占整个区域面积18%,其肥力状况较差。【结论】土壤性质和土壤肥力指数在田块尺度上空间分布复杂、规律性不明显,呈斑块状分布特征。根据各项土壤属性指标和土壤综合肥力指数值的分布情况判断,砂田土壤肥力总体水平较低,其中有机碳和全氮是制约砂田土壤肥力的主要限制因子。应通过增施有机肥、轮作和休耕等方式改良和培肥土壤。

关 键 词:土壤肥力  空间变异  隶属度函数  砂田  评价  />
收稿时间:2016-05-23

Assessment of Soil Fertility and Its Spatial Variability Based on Small Scale in the Gravel Mulched Field of Ningxia
WANG You-qi,BAI Yi-ru,ZHAO Yun-peng.Assessment of Soil Fertility and Its Spatial Variability Based on Small Scale in the Gravel Mulched Field of Ningxia[J].Scientia Agricultura Sinica,2016,49(23):4566-4575.
Authors:WANG You-qi  BAI Yi-ru  ZHAO Yun-peng
Institution:College of Resources and Environment, Ningxia University, Yinchuan 750021
Abstract:【Objective】The gravel mulched field is a unique method of tillage in arid and semi-arid areas of northwest under the natural condition with severe weather, poor soil and terrain condition, through the long-term production practice, continuous summarization and innovation. Preservation and improvement of soil fertility quality is a foundation for maintaining land productivity, preventing land degradation in the gravel mulched field. 【Method】A total of 110 soil samples (0-20 cm) were collected in a grid of 10 m×10 m. Soil indices were selected as evaluating factors including soil organic carbon, total N, total P, total K, available P, available K, pH and electrical conductivity. Correlation coefficient method was used to determine the weight value of soil fertility index. The curve type and turning point value of membership function were defined by soil characteristics and crop varieties. Then membership degree and weight value were combined to calculate the soil integrated fertility index (IFI). The geostatistics method was used for building the best semi variance function models, and analyzing spatial variation and distribution pattern of soil fertility. The evaluation of classification of soil fertility could be studied by the soil IFI and its spatial distributions. 【Result】The classical statistics indicated that the mean value of pH was 9.15 showed alkalinity, and the coefficient of variation was 0.01 showed medium variation. The coefficient of variations for other fertility indexes ranged from 0.10 to 0.72 showed moderate variation. The range of soil characteristics showed an obvious difference at field scale. The soil IFI in the study area was 0.18-0.59 with the average value of 0.34. The coefficients of nugget for fertility indexes were less than 25%, which demonstrated strong spatial dependence. The ordinary Kriging interpolation map indicated that the soil organic carbon distributed evenly with the mean value of 1.5-2.5 g·kg-1, which had island high levels in the southern study area. The electrical conductivity also distributed evenly with the mean value of 100-300 μs·cm-1, which had high levels in the northern study area. Total N, total P and total K had low levels with plaque distribution. The available P and available K were higher in the northern study area. The pH value also distributed patchily. The land of Grade Ⅲ indicated medium fertility condition and distributed most widely in the study area, covered 56% of the total area. The land of Grade Ⅱ indicated fecund fertility condition and represented the main type in the south of the land, covered 25% of the total area. The land of Grade Ⅳ accounted for 18% of the total area, which indicated poor fertility condition. The soil property indexes and IFI value demonstrated that soil fertility level was relatively low in the gravel mulched field. 【Conclusion】The spatial distribution patterns of soil index and IFI were complicated and had no regularity with patch distribution at field scale. According to the soil index and IFI, the levels of soil fertility were low in the gravel mulched field. The soil organic carbon and total N were the main limiting factors restraining soil fertility. The methods of increasing organic fertilizers, crop rotation and fallow were practicable and necessary for fertilizing soil, increasing yields and improving crop quality.
Keywords:soil fertility  spatial variability  membership function  gravel mulched field  evaluate
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