NOVELTY - Selenium-enriched mushroom cultivation material comprises 62-72 wt.% straw, 15-25 wt.% crushed clover powder, 6-14 wt.% wheat, 1-3 wt.% gypsum powder and 0.5-1.5 wt.% calcium superphosphate. The crushed clover powder is prepared by growing clover flower to 1 cm, spraying 80-190 mg/kg fertilizer water solution at 50 kg/667 m2 once/9 days for 3 times, re-spraying if it rains, harvesting clover flower during initial flowering period, drying and crushing into 0.8-1.2 mm powders.    USE - Straw mushroom enriched cultivation material.    ADVANTAGE - The material has reasonable proportion, balanced nutrition, high biological conversion rate, 0.15-3 mg/kg selenium content, iron, zinc and calcium mineral elements content, 10% higher selling price, and wide developing prospect. It meets required carbon/nitrogen balance.    DETAILED DESCRIPTION - Selenium-enriched mushroom cultivation material comprises 62-72 wt.% straw, 15-25 wt.% crushed clover powder, 6-14 wt.% wheat, 1-3 wt.% gypsum powder and 0.5-1.5 wt.% calcium superphosphate. The crushed clover powder is prepared by growing clover flower to 1 cm, spraying 80-190 mg/kg fertilizer water solution at 50 kg/667 m2 once/9 days for 3 times, re-spraying if it rains, harvesting clover flower during initial flowering period, drying and crushing into 0.8-1.2 mm powders. The fertilizer comprises 22-28 pts. wt. zinc sulfate heptahydrate, 17-23 pts. wt. copper sulfate, 15-20 pts. wt. ferrous sulfate heptahydrate, 9-16 pts. wt. manganese sulfate, 5-80 pts. wt. sodium selenite, 7-13 pts. wt. fulvic acid, and 5-10 pts. wt. sodium dodecyl benzene sulfonate. An INDEPENDENT CLAIM is included for the preparation of selenium-enriched mushroom cultivation material comprising taking raw materials, mixing, using 4 wt.% lime water, regulating water content to 65-70%, adjusting pH to 7-7.5, placing mixture in 17x 33 cm plastic bag, fastening ends with rough cotton thread, putting into boiler, heating, boiling at 100 degrees c, holding for 6-8 hours, stopping fire, cooling to 40 degrees c, taking out, and cooling to 35 degrees c.