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The Loam Ranger – Recycled plasterboard as gypsum

Dear Loam Ranger,

One of the sports fields under my control needs gypsum to correct a low calcium:magnesium ratio and a sulphur deficiency. My supplier has offered me recycled plasterboard. It's cheaper, but what are the implications of using this product? Is it going to cause more harm than good?

Plasterboard is made from gypsum sandwiched between two layers of paper. The gypsum (>95%) is mixed with clay, wax, fibre (typically paper), vermiculite and starch. So in theory, recycled plasterboard is almost identical to commercial gypsum. But there are some provisos.

The first proviso is that the use of all waste materials as fertilisers or soil amendments is governed in NSW by the Protection of the Environment Operations Act 1997 (the POEO Act). All wastes so used must comply with the associated Protection of the Environment Operations (Waste) Regulation 2005 – they must either be individually licensed or be specifically exempted. Fortunately, plasterboard waste is exempted. Click here to download a PDF of the exemption. It specifies the conditions that you are legally required to follow if you apply plasterboard waste to land as a fertiliser or soil amendment. These conditions relate to maximum contaminant concentrations, a written statement of compliance, application rates, soil testing and record keeping.

The quality of the material is also important. If the plasterboard supplier and processor have followed the rules, you will receive a statement of compliance (indicating that the material is suitable for use) and a copy of a Material Safety Data Sheet. You should also ask for a copy of the latest lab test report, which both the supplier and the processor are required to keep on file.

Besides compliance with the NSW waste regulations, the other consideration is the state or form of the product and the particle size. Obviously the finer the product, the faster it will modify your soil. Residual paper should not be a problem – it will decompose quickly in the environment.

Further information

Waste residue fact sheet: for farmers & landholders: http://www.environment.nsw.gov.au/waste/residue/rwFSfarmers.htm

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