Effect of forced ventilation during composting on Agaricus bisporus substrate selectivity

Abstract

The production of mushroom substrate with limited aeration in phase I composting was studied. A standard mushroom compost made in windrow piles with forced aeration was compared with the experimental compost prepared under limited aeration during part of phase I. Limited ventilation resulted in a product with chemical parameters similar to those produced with full aeration. Despite this, loss of compost selectivity was observed. When aeration was limited during part of the composting process, 50% mushroom yield losses caused by strong infestation of Trichoderma aggressivum were observed. Limited ventilation in part of phase I resulted in a reduction of redox potential, increase of pH, and concentration of free ammonia, and thus disturbed the transformation of compost into selective medium for Agaricus. Mushroom yield correlated with redox potential in the compost, and prolonged high concentration of free ammonia was the main factor in delayed but faster organic matter degradation in non-ventilated compost. The changes of redox potential and electrical conductivity in the course of composting can be useful tools for process control and evaluation of the compost quality potential and susceptibility to green mould infestation.