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The richness of the organic residues in certain fertilizing elements justifies their valorization in horticulture. However, their contents in pathogenic and toxic elements can restrict their use. In this context, this study was conducted in order to evaluate the effect of three organic residues on the environmental medium and the risks of water contamination by the release of heavy metals. Physocarpus opulifolius `Nanus' was transplanted into four substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). The three other substrates (25% of peatmoss was substituted by organic residue) contained 10% of fresh bio-filters (FBF), 10% of composted sewage sludges (CSS), or 10% of de-inking sludges (CDS). The pots (5l) were placed in plastic vats and the drainage water was recovered in vessels (17l). The experimental design was in complete blocks with six replications. Samples of the drainage water were collected every 2 weeks for analysis. The pots were fertilized every week (400 mg/Ll of N) and growth parameters were statistically analyzed by ANOVA. The chemical analysis of the residues proves that they contain weak concentrations in organic contaminants. There is an accumulation of
Large spaces are required to eliminate waste by burying and this method is very costly. The horticulture use of waste seems to be one of the best optional methods of disposal. This study was performed to evaluate the effects of fresh bio-filters (FBF), composted sewage sludges (CSS), and composted de-inked sludges (CDS) on growth of three woody ornamental species (Spiraea japonica `Little Princess', Spiraea nipponica `Snowmound', and Physocarpus opulifolius `Nanus') produced in containers. Three fertilization regimes (N at 200, 400, and 600 mg·L–1 in the form of soluble fertilizer 20–20–20) were applied weekly onto containers during 3.5 months. Plants were potted in 10 substrates. The control substrate contained 4 peatmoss: 5 composted conifer bark: 1 fine crushed gravel (by volume). In the other nine substrates, peatmoss was partially substituted by one of the three organic residues (10%, 20%, or 30% of FBF, CSS, or CDS). The experimental design was a split-split-plot with four replicates and two samples by treatment. Chemical analysis of the organic residues proved that the fertilization value of CSS was greater than the other residues and heavy metals are below the undesirable limits for the three residues. The amount of available major mineral elements in these residues is too low to satisfy the mineral nutrient needs of plants. In addition, there is a linear effect of the fertilization on plant growth. The CDS required a high dose of the fertilizer (600 mg·L–1) which may be due to the immobilization of N. The 10% proportion of FBF and CDS, combined with the other materials, was the most adequate proportion and did not reduce the growth of plants (height, aerial, and root dry matter). However, CSS can be used with a high proportion (20%) especially for Spiraea japonica `Little Princess'.
Three ornamental species (Spiraea japonica `Little Princess', Physocarpus opulifolius `Nanus', and Prunus × cistena) were potted in seven different substrates. The control substrate contained peatmoss, composted conifer bark, and fine crushed gravel (5:4:1, by volume). In the other six substrates, peatmoss was partially or completely substituted by different proportions of three organic residues (10% or 50% of the mixture made up of fresh bio-filters, 5% or 10% in composted sewage sludges, and 10% or 40% in composted deinking sludges). Four fertilization regimes (0, 200, 400, and 600 mg N/liter in the form of soluble fertilizer 20–20–20) were applied weekly onto containers. The experimental design was a split-plot with six replications. Physical and chemical analysis of the organic residues proved that the composted sewage sludges were richer in minerals than the other residues. Moreover, fresh bio-filters and composted deinking sludges were less granular than composted sewage sludges. The 10% proportion of each organic residue, combined with the other materials, was the most-adequate proportion and did not reduce the growth of plants (height, aerial and root dry matter). In addition, a dose of 400 mg·liter–1 generally gave good results, especially for fresh bio-filters and for composted sewage sludges. However, it is preferable to use a higher dose (600 mg·liter–1 if composted deinking sludges are used.
The agricultural valorization of waste, rich in organic matter and minerals, is one of the best economical and ecological methods of disposal. This study was carried out to evaluate the release of mineral elements restrained in fresh bio-filters, composted sewage sludges, and composted de-inking sludges, and their effects on growth of Physocarpus opulifolius `Nanus' produced in containers. The physical and chemical analysis of the organic residues proved that the fertilization value of composted sewage sludges was greater than the other residues. Moreover, the granular characteristics of fresh biofilters and composted de-inking sludges were finer than composted sewage sludges. Each organic residue was combined, in proportion of 10%, with peatmoss, composted conifer bark, and fine crushed gravel. The regular leaching of container medium showed that the composted sewage sludges release a higher quantity of major mineral elements. Physocarpus opulifolius `Nanus' plants were larger than those plants grown in the control substrate (without residue). The results obtained in media containing fresh bio-filters or composted de-inking sludges were similar to those obtained in the control substrate.