all rights reservedIn the united Kingdom and Ireland, mushroom casing is usually a blend of sphagnum peat and a lime-based neutralising agent that offers optimum properties for economic mushroom production. nevertheless, the significant physical and chemical variation that can exist within these raw materials 1 impacts on the quality of casing supplied to the grower and is often a major source of variability within the mushroom production process. 2 the function of casing is to induce fruiting, support mushroom growth and provide a source of water to the mushroom as compensation for water lost through evaporation and transpiration. 3 properties such as air-and water-holding capacities are important physical parameters, 4 whereas salinity, osmotic potential and pH are chemical parameters that impact on mycelial growth. 5 the type and formulation of casing influences the weight and size of the individual mushrooms, as well as how they spread over the growing surface, 6 and also the populations of aerobic bacteria that are necessary for fructification. 7 Visscher 8 concluded that a dense casing is the most productive, b applied plant Science and Biometrics division, agri-food and Biosciences Institute, newforge lane, Belfast Bt9 5pX, uK c Horticulture and plant Breeding Station, loughgall, co. armagh, Bt60 8JB, uKCasing soil is a crucial component in the production of mushrooms (Agaricus bisporus) and in the United Kingdom and Ireland it is prepared by neutralising raw peat with lime. The initial peat quality determines many of the physical and chemical properties of the subsequent casing product and this, in turn, significantly impacts on the yield and quality of mushrooms produced. Information on the physical and chemical properties of the casing supplied, in particular those associated with water retention and absorption, is critical to an optimal management strategy. The casing suppliers need a rapid method to evaluate key properties, but the available analytical techniques are slow and laborious, often taking 7-15 days to complete. Raw peat and casing samples were scanned for visible and near infrared (vis-NIR) spectra and the results assessed using principal component analysis. The samples (177) were also analysed for pH, electrical conductivity, moisture content, ash, water absorption, water retention and bulk density. Using partial least squares regression analysis of the spectra and the measured values of the target parameters, calibration equations were generated and cross-validated within the sample set. The equations were then validated using an independent sample set (44) collected from casing suppliers and growers. Early indications show good potential for the prediction of commercially important properties, such as dry matter, ash content, water absorption, water retention and pH. With a turnaround time of minutes, from initial scanning to the presentation of results, vis-NIR spectroscopy affords both the casing suppliers and, ultimately, the growers the opportunity to progress and improve upon curren...