WASHINGTON: The US Army is planning to use biodegradable bullets loaded with special seeds that sprout into plants which can eliminate ammunition debris and contaminants, reducing soil pollution in training grounds.Spent shells litter US Army training facilities around the world as there is no efficient way to clean them up.The shells, which contain metal and other chemicals, can rust and pollute soils and groundwater.The US Department of Defense (DoD) are soliciting proposals for biodegradable bullets loaded with seeds to grow environmentally beneficial plants that eliminate ammunition debris and contaminants.According to the request for proposal, the US Army Corps of Engineers' Cold Regions Research and Engineering Laboratory has already developed and tested seeds that can be embedded into a biodegradable composite.They have been bioengineered to only germinate after they have been in the ground for several months, 'Seeker' reported.Proposals are being solicited until February 8, after which the chosen contractors will produce the biodegradable bullets as part of a three-phase process.In phase one, the contractor will focus on making 40mm to 120mm training rounds.Phase II includes developing a prototype and the means to manufacture it and phase III has the biodegradable round transitioning to use at the Army training facilities.The plants that grow from the seeds could also help remove soil contaminants or feed local wildlife.According to the proposal, "animals should be able to consume the plants without any ill effects."