Abstract: A biodegradable resin composition utilized in the manufacture of biodegradable bottles and other biodegradable containers, and a method of manufacturing such containers via injection molding and ultrasonic welding. A biodegradable resin composition includes, in percent by weight: 1 to 80% starch; 1 to 8% cellulose; 1 to 5% sodium stearate; and 1 to 2% oleic acid. Another biodegradable resin composition includes, in percent by weight: 1 to 70% starch; 1 to 8% cellulose; 1 to 12% hydroxyl-polypropylene; and 1 to 5% calcium carbonate. Another biodegradable resin composition includes, in percent by weight: 1 to 30% starch; 1 to 40% poly(butylene adipate-co-terephthalate); 1 to 20% poly(lactic acid); and 1 to 5% hydrated magnesium silicate.