NOVELTY - Cultivation substrate comprises corncob, apple stem, wheat bran, weathered coal, soybean meal, sawdust, peat, superabsorbent polymers, ultrafine powder of fleece flower root, urea, glucose, radix polygonati officinalis, flower of Chinese scholar tree, cortex lycii radicis, dandelion, Saussurea, vermiculite powder, powdered activated carbon, clay, and nutritional additive.    USE - As cultivation substrate of Agaricus subrufescens (claimed).    ADVANTAGE - The substrate supplements calcium and magnesium to A.subrufescens, has improved water holding capacity, and produces healthy A.subrufescens.    DETAILED DESCRIPTION - Cultivation substrate comprises 60-65 pts. wt. corncob, 50-55 pts. wt. apple stem, 30-32 pts. wt. wheat bran, 18-20 pts. wt. weathered coal, 16-18 pts. wt. soybean meal, 12-14 pts. wt. sawdust, 14-15 pts. wt. peat, 6-8 pts. wt. superabsorbent polymers, 4-5 pts. wt. ultrafine powder of fleece flower root, 1-2 pts. wt. urea, 2-3 pts. wt. glucose, 4-5 pts. wt. radix polygonati officinalis, 3-4 pts. wt. flower of Chinese scholar tree, 5-6 pts. wt. cortex lycii radicis, 3-4 pts. wt. dandelion, 2-3 pts. wt. Saussurea, 25-28 pts. wt. vermiculite powder, 4-5 pts. wt. powdered activated carbon, 28-29 pts. wt. clay, and 10-12 pts. wt. nutritional additive. The nutritional additive comprises 0.1-0.2 pts. wt. Coix seed oil, 15-18 pts. wt. diatomite, and 30-32 pts. wt. vinegar. The nutritional additive is prepared by mixing the vinegar and the Coix seed oil, soaking diatomite in mixture for 15-20 minutes, drying soaked product, and crushing dried product. An INDEPENDENT CLAIM is included for method for preparing the cultivation substrate, which involves (a) dissolving urea and glucose in 10-12 times water, (b) mixing vermiculite, powdered activated carbon and clay, adding water to mixture until water content becomes 28-30%, pressing mixture into rod, roasting the rod at 500 degrees C for 2 hours, (c) drying and crushing remaining materials with the rod, and adding water to crushed product until water content becomes 65-68%, (d) mixing products of steps (a) and (c), sealing mixture in polyethylene plastic bag, and sterilizing the bag using steam at 100 degrees C under normal pressure to obtain finished product.