Abstract:

Dredger fill is an important soil resource for urban development in coastal areas, but due to its serious degradation of soil physical and chemical properties, it has made coastal areas become the key and difficult point of urban green construction. To carry out improvement test of dredger fill is very important, which can provide scientific guidance for the reuse of dredger fill in coastal areas. This study took Shanghai Lingang dredger fill as the research object, different proportions of peat, organic substrate and bio-organic fertilizer were added to improve the quality of dredger fill. A four-month pot experiment was set up to analyze the physical and chemical properties of each treatment soil, and the biomass of tagetes was also measured. Based on the research results, the optimal improvement ratio was evaluated. The results of the study showed that, compared with the unimproved soil treatment (CK), the addition of peat, organic substrate and bio-organic fertilizer could significantly reduce the bulk density and soil pH of dredger fill. The organic improvement materials could also increase the maximum soil water holding capacity, soil porosity and soil organic matter. Compared with those of CK, after adding peat, organic substrate and bio-organic fertilizer, the bulk density was reduced by 0.30, 0.23 and 0.24 g/cm³, respectively, the maximum soil water holding capacity was increased by 62%, 40% and 45%, respectively, and the soil organic matter was increased by 26.1, 39.8 and 39.1 g/kg, respectively. Compared with CK, after adding peat, organic substrate and bio-organic fertilizer, the biomass of the aboveground and underground parts of tagetes increased to varying degrees. The total fresh weight of tagetes was expressed as peat> organic substrate> bio-organic fertilizer. The comprehensive score of soil principal components’ analysis was significantly and linearly correlated with the dry weight of the aboveground part of tagetes, indicating that the comprehensive evaluation results of soil are of reference significance and the 50% peat addition is the optimal ratio.

Key words: dredger fill, organic improvement materials, comprehensive soil fertility, tagetes biomass