Guano is the oldest organic supplement in the book, dating all the way back to the early 1800’s when it was first mined from seabird islands. Guano is the hardened leftovers of layers and layers of bird poop, built up over time. Depending on the source diet of the birds and bats …producing the guano, varying levels of NPK exist in their blends. Guano is a useful supplement for both pre-amending soils, top dressing into soils, and brewing compost teas. Shop now to get your garden flying high with seabird and bat guano.