分类： 农、林、牧、渔 >> 土壤学 提交时间： 2017-12-08 合作期刊: 《干旱区科学》
摘要： Ecological restoration by Tamarix plants on semi-arid saline lands affects the accumulation, distribution patterns and related mechanisms of soil water content and salinity. In this study, spatio-temporal variations of soil water content and salinity around natural individual Tamarix ramosissima Ledeb. were investigated in a semi-arid saline region of the upper Yellow River, Northwest China. Specifically, soil water content, electrical conductivity (ECe), sodium adsorption ratio (SARe), and salt ions (including Na+, K+, Ca2+, Mg2+ and SO42–) were measured at different soil depths and at different distances from the trunk of T. ramosissima in May, July, and September 2016. The soil water content at the 20–80 cm depth was significantly lower in July and September than in May, indicating that T. ramosissima plants absorb a large amount of water through the roots during the growing period, leading to the decreasing of soil water content in the deep soil layer. At the 0–20 cm depth, there was a salt island effect around individual T. ramosissima, and the ECe differed significantly inside and outside the canopy of T. ramosissima in May and July. Salt bioaccumulation and stemflow were two major contributing factors to this difference. The SARe at the 0–20 cm depth was significantly different inside and outside the canopy of T. ramosissima in the three sampling months. The values of SARe at the 60–80 cm depth in May and July were significantly higher than those at the 0–60 cm depth and higher than that at the corresponding depth in September. The distribution of Na+ in the soil was similar to that of the SARe, while the concentrations of K+, Ca2+, and Mg2+ showed significant differences among the sampling months and soil depths. Both season and soil depth had highly significant effects on soil water content, ECe and SARe, whereas distance from the trunk of T. ramosissima only significantly affected ECe. Based on these results, we recommend co-planting of shallow-rooted salt-tolerant species near the Tamarix plants and avoiding planting herbaceous plants inside the canopy of T. ramosissima for afforestation in this semi-arid saline region. The results of this study may provide a reference for appropriate restoration in the semi-arid saline regions of the upper Yellow River.
分类： 农、林、牧、渔 >> 农业基础学科 提交时间： 2023-04-13 合作期刊: 《干旱区科学》
摘要：In Tunisia, water scarcity is only adding pressure on water demand in agriculture. In the context of sustainable development goals, Tunisia has been reusing treated wastewater (TWW) as a renewable and inexpensive source for soil fertigation and groundwater (GW) recharge. However, major risks can be expected when the irrigation water is of poor quality. This study aims for evaluating the potential risk of TWW and GW irrigation on soil parameters. Accordingly, we evaluated the suitability of water quality through the analysis of major and minor cations and anions, metallic trace elements (MTEs), and the sodium hazard by using the sodium adsorption ratio (SAR) and the soluble sodium percentage (SSP). The risk of soil sodicity was further assessed by SAR and the exchangeable sodium percentage (ESP). The degree of soil pollution caused by MTEs accumulation was evaluated using geoaccumulation index (Igeo) and pollution load index (PLI). Soil maps were generated using inverse spline interpolation in ArcGIS software. The results show that both water samples (i.e., TWW and GW) are suitable for soil irrigation in terms of salinity (electrical conductivity<7000 µS/cm) and sodicity (SAR<10.00; SSP<60.00%). However, the contents of PO43–, Cu2+, and Cd2+ exceed the maximum threshold values set by the national and other standards. Concerning the soil samples, the average levels of SAR and ESP are within the standards (SAR<13.00; ESP<15.00%). On the other hand, PLI results reveal moderate pollution in the plot irrigated with TWW and no to moderate pollution in the plot irrigated with GW. Igeo results indicate that Cu2+ is the metallic trace element (MTE) with the highest risk of soil pollution in both plots (Igeo>5.00), followed by Ni2+ and Pb2+. Nevertheless, Cd2+ presents the lowest risk of soil pollution (Igeo<0.00). Statistical data indicates that Ca2+, Na+, Ni2+, and Pb2+ are highly distributed in both plots (coefficient of variation>50.0%). This study shows that the use of imagery tools, such as ArcGIS, can provide important information for evaluating the current status of soil fertility or pollution and for better managing soil irrigation with TWW.
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