However, what goes inside the pen, to absorb animal urine and feces, is the most important thing.

Acosta says litter can range from dried grass to coconut frawns or leaves - basically any natural and absorbent material will do. "The benefits for the deep-litter hog pen would be that they're always in a clean environment. We're not using any water to wash down the pens, so it's conserving water for the farmers and economically too they're saving money," he explained.

Once the litter is soiled, it isn't thrown away. In fact, Soriano says it's a valuable resource when composted. The very rich compost is ready to be applied to plants and seedlings. "We're basically taking the compost and putting it into our plants as a soil amendment, as well as taking the animal waste and filtering it from getting into the aquifer by leaching," he told KUAM News.