The biodegradable shells will contain time-delayed seeds that will begin growing after several months.
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.
As such, the DoD wants to manufacture munitions out of naturally occurring biodegradable materials to eliminate the environmental hazard posed by used munitions. In the report, the DoD cites a number of biodegradable materials, such as bamboo fiber, that are already used in manufacturing commercial plastics and may end up being good candidates for replacing the materials used in non-biodegradable rounds.
The DoD also wants these biodegradable shells to have special seeds embedded in the material that have been bioengineered by the Army Corps of Engineers' Cold Regions Research and Engineering Laboratory. These seeds should be engineered such that they will not germinate until after being in the ground for several months. The plants that grow from these seeds will then consume the biodegradable bullets and should be safe for animals to consume.
The call for manufacturing methods of these bullets ends on February 8 and whether this dream of a sustainable bullet will come to fruition remains to be seen.