Abstract
Every year, a significant quantity of dredged soil is generated as a result of channel dredging operations. However, there is relatively little evidence available regarding the sustainable reuse of dredged soils. In this study, an improved substrate material mainly composed of dredged soil was developed to examine the effects of three substrate amendments on the soil’s nutritional content, physical properties, and water retention capacity, as well as the germination rate of tall fescue. The orthogonal combination of the three substrates was controlled in a pot experiment using polyacrylamide (PAM), rice straw, and superabsorbent polymer (SAP) at application rates of 0.5, 1, 1.5, 2, and 2.5 g/kg; 15, 20, 25, 30, and 35 g/kg; and 0, 3, 6, 9, and 12 g/kg, respectively. The results showed that adequate application of PAM may improve the water retention capacity and available N retention capacity of dredged soil. PAM inhibited tall fescue germination significantly when the concentration exceeded 0.5 g/kg (p < 0.05). The addition of rice straw significantly improved the nutritional content of dredging soil and the germination rate of tall fescue (p < 0.05). Increased SAP significantly decreased the bulk density of dredged soil (p < 0.05). The lowest test group was 48.20% less than CK. This study offers novel ideas for the sustainable reuse of dredged soil and serves as a guide for future research aimed at increasing the effectiveness of external‐soil spray seeding technologies.
Highlights
Dredged soil is a sediment mixture of loose particles consisting of clay, silt, and sand generated by the erosion and weathering of soils, rocks, and organic materials, as well as human activity [1]
Dredged soil was obtained from the dumping area of Xiaoxing Village (32°4′49′′N, 119°34′34E), Zhenjiang, China, near the Beijing-Hangzhou Grand Canal. e substrate materials were as follows: (1) anionic PAM, provided by Xingbang Environmental Protection Technology Co., Ltd., Yiwu, China, with a high molecular weight of 8 million and a hydrolysis degree of 23.5%; (2) rice straw smashed into 1-2 cm pieces; and (3) superabsorbent polymer (SAP), provided by Chengqi Chemical Engineering and Technology Co., Ltd., Shanghai, China, which consisted of a suspension-polymerized and covalently cross-linked acrylamide/acrylic acid copolymer
Effects of Different Substrates on Nutrient Contents. e results of this study show that rice straw had a significant effect on nutrient contents (organic C and extractable N, P, Saturated water content (%)
Summary
Dredged soil is a sediment mixture of loose particles consisting of clay, silt, and sand generated by the erosion and weathering of soils, rocks, and organic materials, as well as human activity [1]. Ese dredged soils, which are considered waste materials, are deposited in the sea or on land. Dredged soils are often classified as waste materials and dumped in the ocean or a storage yard [3, 4], these materials should ideally be reused. Several studies have focused on the reuse of dredged soils as pavement materials, such as subgrade, selected material subbase, and base courses [5, 6]. The majority of dredged soils are fine-grained materials, such as silts and clays, with a high void ratio, high compressibility, poor strength, low bearing capacity, and the presence of organic matter [1]. A novel product with improved water conservation, thermal insulation, low cost, and ease of maintenance, has been studied as a promising slope material [7,8,9]
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