NOVELTY - Preparation of composite microbial function Enteromorpha fertilizer involves putting Enteromorpha dry powder into reaction kettle; adding 10-15 times of water and 0.5-1% potassium hydroxide; heating at 50-70 degrees C while stirring at 50 revolutions per minute; ultrasonic extracting at 150 W for 1-4 hours; adjusting pH of extract to neutral; filtering via plate-and-frame filter; vacuum concentrating filtrate at 40-50 degrees C for 2-3 times to obtain Enteromorpha antibacterial liquid with high active ingredient content and insecticidal activity.    USE - Preparation of composite microbial function Enteromorpha fertilizer.    ADVANTAGE - The method produces composite microbial function Enteromorpha fertilizer with antibacterial and insecticidal active substances of Enteromorpha, phosphate, potassium, and nitrogen fixation that improve soil microbial activity and crop growth. The fertilizer reduces pesticide usage, improves crop yields, and environment friendly.    DETAILED DESCRIPTION - Preparation of composite microbial function Enteromorpha fertilizer comprises putting Enteromorpha dry powder into reaction kettle; adding 10-15 times of water and 0.5-1% potassium hydroxide; heating at 50-70 degrees C while stirring at 50 revolutions per minute; ultrasonic extracting at 150 W for 1-4 hours; adjusting pH of extract to neutral; filtering via plate-and-frame filter; vacuum concentrating filtrate at 40-50 degrees C for 2-3 times to obtain Enteromorpha antibacterial liquid with high active ingredient content and insecticidal activity; performing functional complex microbial screening and amplification of Enteromorpha antibacterial liquid; mixing with bacteria; inoculating; further screening to obtain Enteromorpha symbiotic liquid containing phosphorus, potassium, and nitrogen; adding Enteromorpha symbiotic liquid with functional microorganism including 300 billion/ml Bacillus subtilis, 200 billion/ml Bacillus licheniformis, and 100 billion/ml solid nitrogen bacteria at ratio of 1:2:3:4; standing at room temperature for 30 days to obtain product at viable count of 20-50 hundred million/ml and product activity increased by 20%; taking 24-28% Enteromorpha solution, 6-7% Bacillus subtilis bacteria liquid, 12-14% Bacillus licheniformis bacterial liquid, 18-21% brown spherical solid nitrogen bacteria bacterial liquid, 20-25% calcium nitrate tetrahydrate, 10-12% magnesium nitrate hexahydrate, and 2-3% of copper, iron, manganese, zinc, boron, and molybdenum to obtain composite microbial function Enteromorpha fertilizer.