• ISSN 1008-505X
  • CN 11-3996/S

湖北长阳县土壤肥力要素时空演变规律及肥力评价

Spatio-temporal evolution of soil fertility indicators and assessment on the integrated fertility in Changyang County of Hubei

  • 摘要:
    目的 探究湖北长阳土家族自治县耕层土壤肥力要素时空演变规律,并进行土壤肥力等级评价,为该地区农业可持续生产提供科学依据。
    方法 选取长阳县2007—2015、2018和2022年的土壤酸碱度(pH)、有机质(SOM)、全氮(TN)、有效磷(AP)和速效钾(AK)作为土壤综合肥力评价指标,采用相关系数法确定各指标的权重,选择隶属度函数曲线,确定隶属度函数转折点,采用模糊数学(Fuzzy)综合评价法,根据各土壤肥力指标的权重值和隶属度值计算土壤综合肥力指数;利用地统计学和地理信息系统(GIS)技术分析土壤肥力指标及综合肥力指数的时空演变特征。
    结果 从2007到2022年的15年间,长阳县耕层土壤pH值、有机质、全氮、有效磷和速效钾含量均值分别增加了0.47个单位、1.24 g/kg、0.57 g/kg、38.67 mg/kg和119.44 mg/kg,均属于中等变异程度。2018—2022年长阳县pH中性土壤面积占比提升了29.41个百分点,有机质含量Ⅱ级的土壤面积占比提升了14.04个百分点,全氮含量Ⅱ级及以上土壤面积占比减少17.92个百分点,有效磷含量Ⅰ级和速效钾含量Ⅱ级的土壤面积分别提升了81.13个百分点和42.45个百分点。pH值和全氮的块金值/基台值(块基比)在25%~75%,呈现中等强度的空间自相关性,有机质、有效磷和速效钾的块基比小于25%,呈现强烈的空间自相关性。2018—2022年长阳县土壤肥力处于Ⅲ级以上的土壤面积占比达89%,处于Ⅱ级以上的土壤面积占比增加了7.87个百分点。土壤有机质和全氮是决定长阳县土壤肥力差异的主要因子。土壤有机质和全氮含量与土壤肥力指数的空间分布格局相似,肥力处于Ⅱ级以上的土壤均集中在长阳县的西部、北部及中部地区,东部、南部地区的土壤肥力等级为中等偏下。
    结论 15年间长阳县大部分地区土壤pH由酸性向中性变化,有机质、有效磷、速效钾和土壤肥力等级显著提高,全域土壤综合肥力呈现不断提高趋势,52%的耕地肥力在Ⅱ级以上,但分布不均匀。土壤有机质和全氮含量决定着土壤的综合肥力,因此,在土壤肥力等级低的东部、南部需重视增施有机肥,以提升土壤有机质含量,增强土壤对氮的固持力度。

     

    Abstract:
    Objectives This study aims to the spatio-temporal evolution characteristics of soil fertility indicators and the variation of soil fertility grades in Changyang Tujia Autonomous County, Hubei province, thereby providing a scientific basis for sustainable agricultural development in the region.
    Methods We collected soil pH, organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) data from Changyang County during 2007−2015, 2018, and 2022. The weights of each indicator were determined using the correlation coefficient method. Membership function curves were chosen and the turning points of the membership functions were identified. The fuzzy mathematics (Fuzzy) comprehensive evaluation method was employed to calculate the integrated fertility index (IFI) based on the weight values and membership values of each soil fertility indicator. The spatio-temporal evolution characteristics of each soil fertility indicator and IFI were analyzed using geostatistics and geographic information system (GIS) technologies.
    Results From 2007 to 2022, spanning a 15-year period, the average values of soil pH, organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) increased by 0.47 units, 1.24 g/kg, 0.57 g/kg, 38.67 mg/kg, and 119.44 mg/kg, respectively, all showing moderate variability. From 2018 to 2022, the proportion of neutral pH soil area in Changyang County increased by 29.41 percentage points, soil area with Grade Ⅱ SOM content increased by 14.04 percentage points, soil area with TN content of Grade Ⅱ or above decreased by 17.92 percentage points, and soil area with Grade I AP content and Grade Ⅱ AK content increased by 81.13 percentage points and 42.45 percentage points, respectively. The nugget coefficients for pH and TN fell within the 25% to 75% range, indicating moderate spatial correlation, whereas those for SOM, AP, and AK were below 25%, suggesting strong spatial correlation. In 89% of Changyang County’s farmland, IFI reached Grade Ⅲ or higher, with the area of farmland having IFI≥Grade Ⅱ increasing by 7.87 percentage points from 2018 to 2022. SOM and TN were identified as the primary factors contributing to variations in soil fertility. The spatial distribution patterns of IFI were comparable to those of SOM and TN, with farmland having IFI≥Grade Ⅱ predominantly concentrated in the northern, western, and central regions, while the eastern and southern regions displayed medium to lower soil fertility levels.
    Conclusions Over the 15-year period, the farmlands in Changyang County have transitioned from acidic to neutral, with SOM, AP, AK, and soil fertility levels consistently increasing. The soil fertility index in 52% of the farmlands has reached relatively high levels. However, the distribution of high-fertility farmlands across the county is uneven. SOM and TN are the key factors driving the improvement in the IFI. Therefore, considerable attention should be given to applying organic amendments to enhance SOM levels, thereby promoting high nitrogen sequestration and fertility potential.

     

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