• ISSN 1008-505X
  • CN 11-3996/S

近40年江苏农田土壤pH时空变化特征及驱动因素

Spatial and temporal variation of cropland pH and the driving factors in Jiangsu over the past 40 years

  • 摘要:
    目的 从县域尺度探究江苏农田土壤pH的时空变化特征及其驱动因素,为农田土壤酸化的预测、阻控以及土壤质量的提升提供科学依据。
    方法 基于第二次全国土壤普查(1980年)、全国测土配方施肥(2006—2012年)以及江苏省土壤农化性状普查(2018年)数据,分析不同时期江苏农田土壤pH的时空变化特征,并利用回归分析探究影响农田土壤pH变化的主要驱动因素。
    结果 2018年江苏全省农田土壤pH范围为5.61~8.31,平均7.02,其中,东部沿海和北部各市农田土壤pH较高,以中性和碱性为主;南部各市农田土壤pH较低,以酸性为主。近40年,江苏农田土壤pH平均下降0.57个单位,其中1980—2006、2006—2012和2012—2018年,年均降幅分别为0.016、0.008、0.007个pH单位。1980—2006年,江苏农田土壤pH快速下降,Ⅰ级(pH>7.5)样本点占比由60.6%降至38.0%,Ⅲ级(pH 5.5~6.5)样本点占比由8.5%增加至28.2%。2006—2018年,农田土壤pH下降趋势得到有效抑制,各级样本点占比趋于稳定。农田土壤pH变化主要与土壤初始有机碳密度、作物秸秆碳还田量和化肥施用量密切相关,其中,土壤初始有机碳密度贡献近40年江苏农田土壤pH变化的48.7%,分别高于作物秸秆碳还田量和化肥施用量的26.9%和24.4%。
    结论 江苏农田土壤pH总体呈现“南酸北碱”和“东部沿海高于内陆”的空间分布特征,主要与土壤性质、土壤类型和土地利用方式有关。40年间农田土壤pH的下降并非匀速,1980—2006年的快速下降是由于大量化肥的施用,而2006—2018年的缓慢下降则是由于秸秆还田量的增加。

     

    Abstract:
    Objectives The spatial and temporal variation characteristics of cropland soil pH were surveyed at county scale, and the driven factors were investigated for prevention of future cropland acidification.
    Methods The data were collected from the Second National Soil Survey (1980), the National Soil Formula Fertilization Survey (2006−2012), and the Survey of Soil Agrochemical Traits in Jiangsu Province (2018). The four decades were divided into three periods, according to the data acquisition time. The whole province was composed of 13 regions, according to the administrative divisions. The main driving factors were assessed using stepwise regression analysis.
    Results The mean pH cropland in Jiangsu Province in 2018 was 7.02 (5.61−8.31). Soil pH was high in Nantong (7.80) and Yancheng (7.52), and low in Wuxi (6.05) and Changzhou (6.20). In the past 40 years, the cropland pH in Jiangsu Province decreased by 0.57 pH units on average, with quick decrease period and gentle stable period. The rapid annual decrease rate was 0.016 pH unit during 1980−2006, and the gentle decrease rate was 0.008 and 0.007 pH units, respectively, during 2006−2012 and 2012−2018. During 1980−2006, the proportion of sample sites in level I (pH>7.5) decreased from 60.6% to 38.0%, and the proportion of sample sites in level III (pH in 5.5−6.5) increased from 8.5% to 28.2% in whole Jiangsu Province. During 2006−2018, the decreasing trend of cropland soil pH was effectively suppressed. The variation of cropland pH was closely related with the initial soil organic carbon density, crop straw incorporation, and chemical fertilizer application rate, and the contribution of the three factors to soil pH change were 48.7%, 26.9%, and 24.4% for the forty years.
    Conclusions The overall spatial distribution of soil pH in Jiangsu was characterized by “acidity in the south and alkalinity in the north”, which was mainly driven by soil properties, soil types and land use practices. Over the forty years, soil pH did not decrease evenly. The pH decrease was quick from 1980 to 2006 due to the rapid increase of chemical fertilizer application rate, and gentle from 2006 to 2018 as straw returning to field increased.

     

/

返回文章
返回