In what sounds like a concept for a bad Banksy painting, the Department of Defense has recently put out a call for proposals for manufacturing biodegradable bullets that also contain seeds.
Released on November 30 through the Small Business Innovation Research (SBIR) agency—essentially a federal venture capital firm—the call for proposals is specifically looking for a bullet design that can be used on US military training facilities. According to the report, the US Army currently manufactures and consumes "hundreds of thousands" of rounds of ammunition at its proving grounds around the world, which range from small caliber bullets to "40 mm grenades, 60mm, 81mm, and 120mm mortars...20mm tank rounds; and 155mm artillery rounds."
Generally, these rounds are left on the ground after use given the lack of any efficient way of recovering them, despite the fact that they can take "hundreds of years or more" to degrade, posing a substantial environmental risk insofar as the casing could pollute water supplies or be discovered by animals. According to the Department of Defense call for proposals, these spent shells are also liable to be found by locals around the training facilities, who may be unable to differentiate the training rounds from tactical rounds.
Read more on Motherboard.