Coir dust is the remaining waste product when long fibers are
extracted from coconut husk. It constitutes the short fibers and mesocarp pith of coconuts. Because coir dust has many characteristics, such as high water-holding capacity and slow decomposition, it has been extensively used as an environmentally friendly substitute for natural peat in potting media. In addition, coir dust has been used as a soil amendment.
Because unripe nuts are usually soaked in brine to make the fiber easier to extract, the problem of excess salinity with some coir dust products has been recognized. The physical and chemical properties of coir dusts varied significantly with source, degree of grinding, screen size, and age. With increasing needs in production of coir-based media and as a soil amendment, the use of coir dust is currently shifting from the aged coir dusts, e.g., 100 year old Sri Lankan coir, to young, even fresh, coir dusts.
The use of fresh coir dusts can involve serious problems of high salinity , and phytotoxicity. In a comparative study of peat and other media for containerized forest tree seedlings, it was found that no plant of E.urophylla survived and growth of E. deglupta wasseverely retarded in coir dust media. Unfortunately, the salinity and phytotoxicity of the coir dust were not determined. One possibility for the phytotoxicity could be the phenolic compounds in the coir dust, like uncomposted sawdust and bark if the Cl content in the coir dust was normal.
The phytotoxicity of the potting substrates based on barks and
sawdusts has been extensively studied and varies with species and age of source trees. Most of the barks and sawdusts used in potting media contain phytotoxins which were found to be phenolic compounds. It was found that catechin, procyanidins B-1 and B-3, and 3,5,30,40-tetrahydroxystilbene and its glucoside from Pinus radiata bark and ellagitannins from sawdust of E. regnans and E. camaldulensis were responsible for the phytotoxicity. Addition of a phenol-fixing compound to aqueous substrate extracts markedly reduced the phytotoxicity.
extracted from coconut husk. It constitutes the short fibers and mesocarp pith of coconuts. Because coir dust has many characteristics, such as high water-holding capacity and slow decomposition, it has been extensively used as an environmentally friendly substitute for natural peat in potting media. In addition, coir dust has been used as a soil amendment.
Because unripe nuts are usually soaked in brine to make the fiber easier to extract, the problem of excess salinity with some coir dust products has been recognized. The physical and chemical properties of coir dusts varied significantly with source, degree of grinding, screen size, and age. With increasing needs in production of coir-based media and as a soil amendment, the use of coir dust is currently shifting from the aged coir dusts, e.g., 100 year old Sri Lankan coir, to young, even fresh, coir dusts.
The use of fresh coir dusts can involve serious problems of high salinity , and phytotoxicity. In a comparative study of peat and other media for containerized forest tree seedlings, it was found that no plant of E.urophylla survived and growth of E. deglupta wasseverely retarded in coir dust media. Unfortunately, the salinity and phytotoxicity of the coir dust were not determined. One possibility for the phytotoxicity could be the phenolic compounds in the coir dust, like uncomposted sawdust and bark if the Cl content in the coir dust was normal.
The phytotoxicity of the potting substrates based on barks and
sawdusts has been extensively studied and varies with species and age of source trees. Most of the barks and sawdusts used in potting media contain phytotoxins which were found to be phenolic compounds. It was found that catechin, procyanidins B-1 and B-3, and 3,5,30,40-tetrahydroxystilbene and its glucoside from Pinus radiata bark and ellagitannins from sawdust of E. regnans and E. camaldulensis were responsible for the phytotoxicity. Addition of a phenol-fixing compound to aqueous substrate extracts markedly reduced the phytotoxicity.
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