苏北滨海盐土区河流入海口土壤盐分及养分分布特征

Distribution characteristics of salinity and nutrient at the estuary in coastal saline soil of north Jiangsu

为系统了解淮河入海口两侧盐渍土养分及盐分分布状况,采用野外调查取样和室内分析相结合的方法,分析淮河入海口土壤养分(有机质、速效氮和速效磷)指标和盐分质量分数的空间分布特征。结果表明:1)研究区有机质和速效氮总体贫乏,随距入海口越来越远,呈缓慢上升趋势,速效磷总体适量。土壤养分有明显的表聚现象,与河漫滩相比较,对应堤防外侧土壤有机质、速效氮变异深度偏低,速效磷差异不明显。2)北堤河漫滩、南堤河漫滩、北堤外和南堤外临界脱盐位置分别在距入海口3 200 m、2 800 m、3 400 m和600 m处,土壤盐分剖面主要为表聚型、低聚型和平衡型,其分布较为集中,分别位于重度盐渍化区、中度盐渍化区、轻度盐渍化及脱盐区。3)有机质与速效氮呈极显著正相关,二者与土壤盐分呈显著性负相关,速效磷与其他3个指标相关性均不显著。该结果可为淮河入海口盐渍土的分区、改良和合理利用提供参考。

[ Background] Systematically understanding the distribution of saline soil nutrients and salts on both sides of the mouth of Huai River is important in establishing strategies for soil salinity management. [ Methods] In this paper, the spatial distribution characteristics of soil nutrient indexes, i. e. , soil organic matter （SOC） , available nitrogen （AN） and available phosphorus （AP） , and salinity mass fraction for various depth layers （0 - 10 era, 10 -20 cm, 20 -50 cm, 50 - 100 cm, 100 - 150 era, 150 - 200 era, 200 - 250 cm, 50 - 300 em and 300 - 350 era） at the estuary of Huai River were analyzed by the application of Outdoor survey and sampling as well as indoor analysis, including cluster analysis and correlation analysis. [ Results] 1） The research area was generally lacking in SOC and AN, the amounts of SOC and AN presented a slow increasing trend with the increasing distance from the estuary, while the amount of AP was appropriate in general. Soil nutrients showed an obvious surface aggregation phenomenon, compared with the floodplain, the variation depths of SOC and AN in the soil on the dike outer were low, while the difference of AP was not obvious. 2） The amounts of salinity in the research area presented a slow increasing trend with the increasing distance from the estuary. The critical desalinization positions of the north floodplain, south floodplain, north dike outer and south dike outer were respeetively located at 3200 m, 2800 m, 3400 m and 600 m from the estuary. The salinity profile types were obviously classified into the types of surfaee aceumulative, bottom aceumulative and balaneed, the distributions were eoneentrated and respectively located in the severe salinization zone, moderate salinization zone, mild salinization zone and desalinization zone. 3 ） SOC and AN presented highly signifieant positive correlation, and the two had significant negative correlation with the soil salinity, while AP was not signifieantly correlated with the other three indexes. [ Conclusions ] The research results ean serve as a theoretical and praetieal referenee to the partition, amelioration, management and rational utilization of saline soils in the estuary of Huaihe River.