客土造林后滨海盐碱地土壤盐分分布及影响因素分析

土壤盐碱化问题严重制约着盐碱地生态绿化环境和农业可持续发展。为研究客土造林后滨海盐碱地土壤盐碱化状况的空间分布格局及影响因素,该研究开展实地调查采样,结合地统计学、经典统计学和Kriging插值等方法分析徐圩新区滨海盐碱地0～10、>10～20、>20～40、>40～60、>60～100 cm土层土壤盐分分布格局及其影响因素。结果表明：1）研究区5个土层土壤电导率均为中等强度变异,pH值是弱变异。大多数土层土壤电导率和pH表现为弱空间相关性,由随机因素引起的空间变异性较弱,自相关引起的空间变异性较强。水平方向上看,研究区从西向东盐碱程度逐步加深,垂直方向上,土壤电导率随着土层深度增加而不断变大;2）研究区客土0～100 cm土层土壤电导率均值为2.91dS/m,属于轻度盐渍化土;原土0～100 cm土层土壤电导率均值为31.00dS/m,属于极重度盐渍化土,原土上只有极少数耐盐作物能自然正常生长。客土土壤电导率明显低于原土,但pH值与原土差异不大,客土土壤盐分表聚和底聚现象明显,存在返盐返碱的问题,长期来看,客土造林并不是该地区绿化最好的方式。3）影响研究区土壤...

Spatial distribution pattern and influencing factors of soil salt in coastal saline-alkali land after afforestation with foreign soil

Abstract: Soil salinization has seriously restricted the ecological greening environment of saline-alkali land in the sustainable development of modern agriculture. This study aims to study the spatial distribution pattern and influencing factors of soil salinization in the coastal saline-alkali land after afforestation with foreign soil. The study area was taken as the coastal saline-alkali land in Xuwei New Area, Lianyungang City, Jiangsu Province, China. The field survey and soil sampling were then carried out. The soil electrical conductivity and pH value were also selected as the main indicators to evaluate the soil salinization. An analysis was made to determine the distribution pattern of soil salt in the 0-10 cm, >10-20 cm, >20-40 cm, >40-60 cm, and >60-100 cm layers of coastal saline-alkali land, combining with geostatistics, classical statistics, and Kriging interpolation. The spatial variation was explained using the semi-variance function optimization model, which fully and effectively reflected the soil saline-alkali information from the horizontal and vertical aspects. A comparison was finally made on the soil saline-alkali differences between the foreign and the original soil. The results showed that: 1) The soil electro conductivity of 0-10cm, >10-20cm, >20-40cm, >40-60 cm, and >60-100 cm soil layers varied with the medium intensity, particularly with the weakly variable pH value. The variation coefficient increased with the increase of the soil depth. A weak spatial correlation was found in the soil electro conductivity and pH values of most soil layers. The weak spatial variability was caused by random factors, where the autocorrelation caused the strong spatial variability. In addition, the salinity of the study area gradually deepened from the west to the east in the horizontal direction. By contrast, the soil conductivity value continuously increased with the increase of soil depth in the vertical direction. There was the highest correlation between the soil electro conductivity and the two adjacent soil layers. The correlation gradually decreased with the increase in depth. 2) The saline-alkali soil belonged to the extremely severe salinized soil, where only a few salt-tolerant crops can grow naturally and normally. There was an outstanding surface and bottom accumulation of salt in the foreign soil, indicating the salt return and alkalization. The measures of salt drainage and salt isolation can be checked regularly to slowly infiltrate into the soil by small water irrigation in the later maintenance. Plants with more salt-tolerant should be selected to plant on the land beside saline rivers and lakes. The foreign soil can also be improved for greening in the long run. 3) The influencing factors of the soil electro conductivity included the electro conductivity and pH value of rivers and lakes, soil pH value, altitude, vegetation, and climate. Therefore, more attention should be paid to formulate more suitable for the subsequent afforestation projects. There was also time variability in the soil salinity. Future research can be expected to focus on the temporal and spatial distribution of soil salinity, the physical and chemical characteristics of foreign soil in different years, and the influencing mechanism of the nature of rivers and lakes on the surrounding soil salinity. The finding can provide a strong reference for the development and utilization rate of heavy saline-alkali soil, in order to improve the construction of landscape and green space, particularly for the formulation of comprehensive improvement measures and management systems in the precise saline-alkali soil.