宁夏砂田小尺度土壤性质空间变异特征与肥力评价

发布时间：2018-02-02 23:42

  本文关键词： 土壤肥力 空间变异 隶属度函数 砂田 评价　出处：《中国农业科学》2016年23期 　论文类型：期刊论文

【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。
[Abstract]:[objective] the sandy field is a kind of natural condition in the arid and semi-arid areas of northwest China, such as harsh climate, soil and topography. In order to survive, a unique farming method is formed through long-term production practice and innovation. To maintain and improve the soil fertility is to improve the land productivity. [methods] 110 soil samples of 10 m 脳 10 m grid were collected, and soil organic carbon, total nitrogen, total phosphorus and total potassium were selected. Available phosphorus, available potassium and pH and electrical conductivity were used as evaluation factors of soil fertility characteristics. The weight of soil fertility indexes was determined by correlation coefficient method, according to the soil characteristics and crop varieties in Ningxia sandy field. Selecting the type of membership function curve and determining the turning point of membership function, then calculating the soil comprehensive fertility index value according to the weight and membership value of soil fertility factor. The optimum semi-variance function model of soil fertility factors was constructed by using geostatistical analysis method, and the spatial variation characteristics and spatial pattern of soil fertility factors in sandy fields were determined. Combined with soil comprehensive fertility index value and its spatial distribution, the soil fertility characteristics of sandy field were evaluated. [results] Classical statistics showed that the minimum coefficient of variation of pH was only 0.01, showing weak variation. The mean value was 9.15, the soil was alkaline, and the coefficient of variation of other fertility indexes was 0.10-0.72. Through the range, we can see that there are obvious differences of soil properties in farmland scale. The comprehensive fertility index value of soil in the study area is 0.18-0.59. The average value was 0.34. Geostatistics showed that the block gold coefficient of each fertility index of sandy soil was less than 25, showing a strong spatial autocorrelation, which can be seen by the ordinary Kriging spatial interpolation map. The distribution of soil organic carbon in the field scale was more uniform, with the concentration of 1.5-2.5 g 路kg ~ (-1), while in the southern side of the study area, there were island high organic carbon content points. The conductivity distribution is also uniform, concentrated in 100-300 渭 s 路cm ~ (-1) ~ (-1), and its content is higher in the north. The contents of total nitrogen, total phosphorus and total potassium in soil were generally low, showing obvious patch distribution characteristics in space. Soil available phosphorus and potassium were found in the northern part of the study area. The distribution of pH in the whole study area showed obvious patch shape. The spatial distribution of soil comprehensive fertility index showed that the study area was the most widely distributed, accounting for 56% of the total area of the study area. In the south of the sand field, the type 鈪，

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