Comparative Evaluation of Compost Supplements for White Button Mushroom (Agaricus bisporus) Cultivation

Compost supplementation is widely used to improve yield and crop consistency in the cultivation of white button mushroom (Agaricus bisporus), yet practical alternatives to conventional protein-rich supplements and rapid candidate-screening approaches are still needed. In this study, plant- and byproduct-based supplements were first compared by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) to obtain qualitative fingerprints of extractable protein fractions, and were then evaluated in Phase III cultivation under both bag-based screening conditions and in a large-scale pull-mat system. Supplements differed notably in protein banding patterns and cultivation performance. In the bag trials, lupin grist and corn pellet produced the largest yield increases relative to the non-supplemented control, whereas in the commercial pull-mat trials lupin grist was the best-performing supplement, reaching 240.77 kg t−1 compost. Under the present conditions, SDS-PAGE was useful as a qualitative screening aid for prioritizing candidates for cultivation trials, but not as a stand-alone predictor of yield. These results identify lupin grist as a practically relevant supplement candidate for commercial A. bisporus production.