TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The controlled-release fertilizer contains (wt.%) urea nitrogen ( greater than or equal to 50), calcium superphosphate ( greater than or equal to 16, based on phosphorus pentoxide), potassium chloride ( greater than or equal to 60, based on potassium oxide), seaweed powder organic material ( greater than or equal to 65), and beneficial bacteria including nitrogen-rich bacteria and Bacillus mucilaginosus. The marine polysaccharide is obtained from shrimp shell and/or crab shell (30-70%) and kelp, Eucheuma and/or dragon's beard (30-70%). The marine polysaccharide is prepared by (i) removing impurities from raw materials, drying until moisture content of less than 38%, and keeping under salt leaching condition for a long time; (ii) soaking raw materials in 7-12% sodium hydroxide solution at 55-65 degrees C for 3-4 hours; (iii) washing with water until pH of less than 7.5; (iv) mixing hydrochloric acid and sulfuric acid at volume ratio of 1.8-2.2:1 and diluting to pH 1.5-2, and soaking washed raw materials in mixed acid for 15-30 minutes; (v) washing with water until pH of greater than or equal to 6.5; (vi) soaking in enzyme solution comprising water (2.5-3.5%) and protease (1.5-2.5%) for 8-12 hours, heating to 110-130 degrees C, and preserving heat for 2-3 hours; (vii) filtering at 85 degrees C; (viii) mixing potassium chloride (5-8%) and calcium chloride (8-10%) at volume ratio 6-8:1 to obtain mixed liquid, uniformly mixing filtrate with mixed liquid to at volume ratio of 8-12:1, and solidifying and aging for 1-1.5 hours; (ix) pressing aged solid product through plate filter press under 8 MPa until moisture content of 20-30%; (x) crushing dehydrated bulk solid material into particles with size of 2-5 mm; (xi) drying until moisture content of 22-26%, in which inlet temperature is less than 90 degrees C and outlet temperature is greater than 40 degrees C; and (xii) microwave sterilizing at 70-85 for 1.5-2 minutes and steam sterilizing at 121 degrees C for 10-20 minutes. ACTIVITY - Fertilizer.