NON-COMPOSTED GRAIN-BASED SUBSTRATES FOR MUSHROOM PRODUCTION (AGARICUS BISPORUS)

Abstract

Non-composted grain-based substrates were evaluated for the cultivation of mushrooms (Agaricus bisporus) withthe goal of eliminating the need for the lengthy and often malodorous composting process. Millet grain, millet grain mixedwith soybean, and commercial rye grain spawn were used as substrates. Treatments included different proportions (100%,75%, 50%, and 25%) of millet grain, or grain spawn with perlite as an inert bulking material. For the millet and soybeanmixtures, the biological matter (millet and soybean) was set at 75% by volume, while the ratios of millet to soybean werevaried. To induce fructification, all substrates were overlain with a sterilized mixture of peat and calcium carbonate (casing)containing 25% activated charcoal (v/v), which was shown to be as effective as a commercial non-sterile casing. Among thevarious treatments, the highest mushroom yield among all three grain treatments was recorded for the 100% millet/0% perlitetreatment (8.7 kg/m2), which was comparable to that of compost (7.7 kg/m2). In contrast, the millet/soybean mixtures failedto produce any mushrooms when soybean was added to the substrate. The highest recorded mushroom yield for commercialgrain spawn was 5.3 kg/m2 for the 100% spawn/0% perlite treatment. This yield was lower when compared to the millet grainand compost substrates. However, biological efficiency (fresh weight of mushroom divided by dry weight of substrates 100)was 117% for the 25% spawn/75% perlite treatment, while that of compost and the 75% millet/25% perlite treatment were98% and 55%, respectively. The results suggest that mushrooms can be grown in a non-composted substrate, but furthereconomic analysis will need to be performed to determine economic viability of alternative substrates.